stop filling in this questionnaire after two consecutive days with an absence of pain. By doing so, the subjective values

#### **6. Objective assessment of pain — Crevicular fluid analysis** this study, specifying the amount of pain (0= No pain; 1= discomfort; 2 =slight pain; 3= intense pain) they experienced each day (from day 1 to day 14) and the time of day (morning, afternoon and night) they felt it. They were instructed to

Secondly, an objective evaluation of pain was performed by analyzing the biochemical pain mediators in the crevicular fluid, in the laboratory. were obtained on an arbitrary scale. The appraisal of the questionnaire allowed us to assess both the subjective level of pain at each moment after the archwire was fitted and the total pain level experienced during the entire process of adapting to the archwire, obtained as the sum of the reported pain.

The crevicular fluid samples were taken at the following stages of orthodontic treatment: **OBJECTIVE ASSESSMENT OF PAIN. CREVICULAR FLUID ANALYSIS***.*

Before bracket bonding. Secondly, an objective evaluation of pain was performed by analyzing the biochemical pain mediators in the crevicular

**2. METHOD.**

archwires. Of the 49 patients with SS archwires, 31 were females and 18 males and of the 63

Table 1 shows the distribution of the sample depending on age, gender, archwire type and

**Table 1.** Sample distribution according to gender, the arch on which the archwire was fitted, age and archwire type

After completing the appropriate orthodontic diagnosis, bracket bonding, which was carried out by 8 previously trained students of the Master of Orthodontics, Faculty of Medicine and

Once the bonding of the brackets was performed, a 0.12"(diameter) Ni-Ti or SS arches were placed ramdomly in the patients enrolled in the study in order to compare the difference between groups in relationship with pain. In order to standardize the protocol, o elastomeric ligatures were used in all patients to hold the arches into the bracket system. The placement

First of all, a questionnaire was designed in order to assess the subjective level of pain. Having fitted the orthodontic appliance and the different archwires (SS and Ni-Ti), the patients filled in a pain questionnaire especially designed for this study, specifying the amount of pain (0=No pain; 1=discomfort; 2=slight pain; 3=intense pain) they experienced each day (from day 1 to day 14) and the time of day (morning, afternoon and night) they felt it. They were instructed to stop filling in this questionnaire after two consecutive days with an absence of pain. By doing so, the subjective values were obtained on an arbitrary scale. The appraisal of the questionnaire allowed us to assess both the subjective level of pain at each moment after the archwire was fitted and the total pain level experienced during the entire process of adapting

of the selected type of archwires did not alter the treatment of each patient.

**5. Subjective assessment of pain — Patient questionnaire**

to the archwire, obtained as the sum of the reported pain.

**Arch upper**

44 19 38 25 4 22.6

31 18 31 18 2 17.2

**Arch lower**

**Both arches**

**Age (mean)**

according to where their archwires were fitted (upper, lower or both arches).

patients with Ni-Ti archwires, 44 were females and 19 males.

**Archwire type Female Male**

420 Emerging Trends in Oral Health Sciences and Dentistry

Dentistry, University of Valencia, was scheduled.

Ni-Ti Archwire (N =63)

**4.2. Method**

(N=49)

used.

Stainless-Steel Archwire

After 24 hours of placement of the archwire (Stainless Steel or Nickel Titanium). fluid, in the laboratory.

A week after the archwire and bracket placement. The crevicular fluid samples were taken at the following stages of orthodontic treatment:

One month after the positioning of the initial archwire. - Before bracket bonding.

Crevicular fluid, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York), was collected. Each sample was collected according to the technique described by Offenbacher et al. [34] and later modified by Uematsu et al. [11], without removing the plaque of the tooth in order to not alter the outcome of the study. However, efforts were made to collect the sample in the absence of plaque. The collection of all the crevicular fluid samples was taken by the same observer. - After 24 hours of placement of the archwire (Stainless Steel or Nickel Titanium). - A week after the archwire and bracket placement. - One month after the positioning of the initial archwire. Crevicular fluid, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York), was collected. Each sample was collected according to the technique described by Offenbacher et al. [34] and later modified by Uematsu et

The technique used for sample collection was made by: firstly, drying of the mouth with suction; after that, isolating the area with cotton rolls;thirdly, looking for drying places where the paper strip is placed; and then, taking the sample of crevicular fluid by placing the Periopaper ® in the binding groove between the tooth and gum. The paper strip is kept in this position within 30 seconds; and finally, the samples are placed between the sensors of the Periotron® 8000 (Proflow Incorporated. New York. USA) in order to obtain the crevicular fluid collection in Periotron units (Figures 1 and 2). al. [11], without removing the plaque of the tooth in order to not alter the outcome of the study. However, efforts were made to collect the sample in the absence of plaque. The collection of all the crevicular fluid samples was taken by the same observer. The technique used for sample collection was made by: firstly, drying of the mouth with suction; after that, isolating the area with cotton rolls;thirdly, looking for drying places where the paper strip is placed; and then, taking the sample of crevicular fluid by placing the Periopaper ® in the binding groove between the tooth and gum. The paper strip is kept in this position within 30 seconds; and finally, the samples are placed between the sensors of the Periotron® 8000 (Proflow Incorporated. New York. USA) in order to obtain the crevicular fluid collection in Periotron units (Figures 1 and 2).

*Figure 1. Sample collection of crevicular fluid with Periopaper®.* **Figure 1.** Sample collection of crevicular fluid with Periopaper®.

The extracted samples obtained were measured by ELISA immunofluorescence technique. To quantify the levels of substance P and PGE2, all samples were measured in duplicate. In our case, kits of high purity of the R & D Systems (Inc Minneapolis brand, USA) were used.

4 The spectrophotometer UV.vis shown in Figure 3 was used for the sample analysis. The spectrometer is an instrument used in biochemical analysis that measures, as a function of

**Figure 2.** Crevicular fluid sample placement between Periotron® sensors.

wavelength, the relationship between the values of the same photometric magnitude related to two beams of radiation and the concentration and chemical reactions that are measured in a sample.

The Periotron® (Figure 4), must be properly calibrated before its use. It consists in a device for measuring the volume of the gingival crevicular fluid, collected by the paper strips (Periopa‐ per®). Usually, a number, defined as Periotron unit, appears on the screen; constructing calibration graphs is required to obtain microliters, by using known amounts of fluid.

Once the device is switched on, it should be heated for 10 minutes. Then, it should be set to zero. After that, a dry paper strip must to be placed inside and the dial has to be adjusted until the zero value appears on the digital screen. A Hamilton microsyringe is then used (maximum volume 2µl, with 0'02µl gradations) to dispense known volumes of calibration liquid (human serum, being similar to the gingival crevicular fluid viscosity and composition) in the paper strips.

In our study, the paper strips were transferred to the Periotron® sensors (2-3 seconds) quickly to avoid evaporation errors. These paper strips were positioned in a standardized way, with the orange tips off the sensors.

Pain Evaluation Between Stainless Steel and Nickel Titanium Arches in Orthodontic Treatment — A Comparative Study http://dx.doi.org/10.5772/59125 423

**Figure 4.** Periotron® machine.

wavelength, the relationship between the values of the same photometric magnitude related to two beams of radiation and the concentration and chemical reactions that are measured in

**Figure 2.** Crevicular fluid sample placement between Periotron® sensors.

422 Emerging Trends in Oral Health Sciences and Dentistry

The Periotron® (Figure 4), must be properly calibrated before its use. It consists in a device for measuring the volume of the gingival crevicular fluid, collected by the paper strips (Periopa‐ per®). Usually, a number, defined as Periotron unit, appears on the screen; constructing calibration graphs is required to obtain microliters, by using known amounts of fluid.

Once the device is switched on, it should be heated for 10 minutes. Then, it should be set to zero. After that, a dry paper strip must to be placed inside and the dial has to be adjusted until the zero value appears on the digital screen. A Hamilton microsyringe is then used (maximum volume 2µl, with 0'02µl gradations) to dispense known volumes of calibration liquid (human serum, being similar to the gingival crevicular fluid viscosity and composition) in the paper

In our study, the paper strips were transferred to the Periotron® sensors (2-3 seconds) quickly to avoid evaporation errors. These paper strips were positioned in a standardized way, with

a sample.

**Figure 3.** Spectrophotometer UV. vis

the orange tips off the sensors.

strips.

After about 16 seconds, the Periotron Unit of each of the samples analysed was obtained. This occurred when the screen went from position I to position II in the frontal side of the device. Using moistened gauze with alcohol, the Periotron® sensors were cleaned between each sample.

Each volume was measured at least three times and the machine was set after each sample to zero.

In this way two variables were obtained:

**1.** The volume (in µl) of serum dispensed with Hamilton microsyringe (Figure 5).

**Figure 5.** Hamilton Microjsyringe.

**2.** The Periotron Unit values of each of the parameters of the sample (average of the measurements made three times).

With these measurements, a linear regression curve was performed, obtaining a formula of the type y=ax+b, where "a" is the slope of the curve, "b" the intersection of the axis, and "x" in the crevicular fluid in Periotron Units.

#### **6.1. Statistical method**

The normality of the total pain (TP) distribution experienced by the patients throughout the treatment was checked using the Kolmogorov-Smirnovtest, which allows us to compare the means of independent samples using Student's *t*-test.

A two-factor (time and archwire type) ANOVA was applied with the Scheffé test for multiple comparisons.

The χ2 test was used to analyse factor dependence.

Non-linear regression was used for the variables, PL: pain level and T: time elapsed from fitting the dental archwire, with an estimation of best-fit parameters and quality assessment of the same through R2 , which indicates the percentage of variation of one variable that can be explained by the variation of the other.

## **7. Results**

The total pain (TP) experienced throughout treatment, the pain level (PL) associated with each time section (morning, afternoon, night) and, therefore, the time elapsed from the beginning of treatment and the peak of maximum pain experienced have all been analysed.

#### **7.1. Subjective study of pain**

#### *7.1.1. Total pain associated with treatment*

From the data provided by the patients in the questionnaire, the total subjective pain (TP) reported by each patient throughout the study was determined as the sum of pain level at each time of the day.

With both types of archwires, there was no case of pain after the tenth day onwards so, in the study that follows, we are only going to consider the data up until that moment, which amounts to 232 hours following the fitting of the initial archwires. With these considerations, the maximum TP possible would be 90 points, even though the maximum value suffered was 48 points for the SS archwires and 36 points for Ni-Ti archwires.

TP data distribution for each type of archwire (Ni-Ti and SS) corresponded to a normal distribution with p>0.850 and p>0.150, respectively. Data on level, mean, standard deviation and percentiles of 25% and 75% for each type of archwire and for the total of the sample are presented in Table 2.

It could then be confirmed that the mean pain value for SS archwires was greater than for Ni-Ti archwires with p<0.007.

Using the percentile values of the total group, the pain suffered throughout the treatment can be classified as: "slight" for under 10 points; "moderate" for between 10 to 20 points; and

**6.1. Statistical method**

424 Emerging Trends in Oral Health Sciences and Dentistry

comparisons.

same through R2

**7. Results**

time of the day.

presented in Table 2.

Ti archwires with p<0.007.

explained by the variation of the other.

**7.1. Subjective study of pain**

*7.1.1. Total pain associated with treatment*

points for the SS archwires and 36 points for Ni-Ti archwires.

The χ2

means of independent samples using Student's *t*-test.

test was used to analyse factor dependence.

The normality of the total pain (TP) distribution experienced by the patients throughout the treatment was checked using the Kolmogorov-Smirnovtest, which allows us to compare the

A two-factor (time and archwire type) ANOVA was applied with the Scheffé test for multiple

Non-linear regression was used for the variables, PL: pain level and T: time elapsed from fitting the dental archwire, with an estimation of best-fit parameters and quality assessment of the

The total pain (TP) experienced throughout treatment, the pain level (PL) associated with each time section (morning, afternoon, night) and, therefore, the time elapsed from the beginning

From the data provided by the patients in the questionnaire, the total subjective pain (TP) reported by each patient throughout the study was determined as the sum of pain level at each

With both types of archwires, there was no case of pain after the tenth day onwards so, in the study that follows, we are only going to consider the data up until that moment, which amounts to 232 hours following the fitting of the initial archwires. With these considerations, the maximum TP possible would be 90 points, even though the maximum value suffered was 48

TP data distribution for each type of archwire (Ni-Ti and SS) corresponded to a normal distribution with p>0.850 and p>0.150, respectively. Data on level, mean, standard deviation and percentiles of 25% and 75% for each type of archwire and for the total of the sample are

It could then be confirmed that the mean pain value for SS archwires was greater than for Ni-

Using the percentile values of the total group, the pain suffered throughout the treatment can be classified as: "slight" for under 10 points; "moderate" for between 10 to 20 points; and

of treatment and the peak of maximum pain experienced have all been analysed.

, which indicates the percentage of variation of one variable that can be

**Table 2.** Total pain (TP) over the 10 days following the beginning of treatment with Ni-Ti or SS archwires regardless of the archwire used. Mean and standard deviation (SD), minimum and maximum values and the percentiles of 25 and 75% were also presented.

"intense" for over 21 points. Applying this criterion, figure 6 shows the percentage of TP suffered using the two types of archwire in the study.

**Figure 6.** Percentage of total pain, slight (less than 10 points), moderate (between 10 and 20 points) and intense (over 20 points) for the two types of archwire studied (SS and Ni-Ti).

Dependence between the pain level and type of archwire was found to be p<0.006. It can be observed that the percentage of cases with intense pain in the SS group, 34.7%, is greater than in that of the Ni-Ti group, 19.7%, whereas in the case of slight pain, the percentage is the other way around being greater in that of the Ni-Ti group with 21.2% than the 12.2% of the SS group, although, in this case, without statistically significant difference.

Furthermore, the mean of the days that the patients experienced pain was 4.84 days in general, with 4.5 of mean for patients with Ni-Ti archwires as opposed to 5.4 days of mean for the group with SS archwires, with a statistically significant difference of p<0.04.

#### *7.1.2. Pain level depending on the time elapsed from beginning of treatment*

The subjective pain level (PL) for each time period was analysed according to the pain experienced during those same periods. As has been indicated in Material and Methods section, the possible evaluation in this case ranges from 0-3 points. The experimental results for each type of archwire are shown in figure 7.

**Figure 7.** Experimental results and fit to the proposed curve PL=a\* T-3+c \* exp (-b\*T) for the two types of archwires studied. PL values have been categorized as slight: less than 0.5; moderate from 0.5 to 1.5; and high: greater than 1.5.

It can be observed that, in general, the shape of the curve is similar for both types of archwires, pain appearing after a few hours and decreasing gradually. This similarity in pain behaviour encouraged us to look for a mathematical function that would fit the points of the curve in order to evaluate pain depending on time and that, therefore, would provide a predictive study of the pain associated with the archwire or with the physiological characteristics of the process them self.

Given that the representation of pain level (PL) with the time period, regardless of the archwire used, also had a similar shape to that shown in figure 7, we then analysed this situation, as here the number of cases was higher and the fitting of the mathematical function would have more statistical validity and offer information on the evolution of pain in general. The points were fitted using non-linear regression curves of different types, the maximum fit being found to be a curve of the form: PL=a\* T-3+c \* exp (-b\*T), where PL, is pain level, T is the time elapsed in hours and the values "a", "b" and "c" correspond to the best-fit parameters that could differ or not depending on the type of archwire. The curve chosen for fitting consists of two terms: a decreasing exponential in which the parameters "b" and "c" are related, respectively, to the fall in the exponential and to PL in each time period, and a potential term that becomes insignificant for long times, but which modulates the growth of the exponential for low times, being responsible for the height that the peak of the curve reaches and is characterized by the "a" parameter. In this way, the first term of the equation and, therefore, the "a" coefficient is important in the first hours following the fitting of the archwire and represents the higher or lower PL corresponding to the "peak". The "b" parameter indicates the greater or lesser speed in the reduction of pain and value "c" represents the higher or lower PL throughout the treatment.

*7.1.2. Pain level depending on the time elapsed from beginning of treatment*

for each type of archwire are shown in figure 7.

426 Emerging Trends in Oral Health Sciences and Dentistry

them self.

The subjective pain level (PL) for each time period was analysed according to the pain experienced during those same periods. As has been indicated in Material and Methods section, the possible evaluation in this case ranges from 0-3 points. The experimental results

**Figure 7.** Experimental results and fit to the proposed curve PL=a\* T-3+c \* exp (-b\*T) for the two types of archwires studied. PL values have been categorized as slight: less than 0.5; moderate from 0.5 to 1.5; and high: greater than 1.5.

It can be observed that, in general, the shape of the curve is similar for both types of archwires, pain appearing after a few hours and decreasing gradually. This similarity in pain behaviour encouraged us to look for a mathematical function that would fit the points of the curve in order to evaluate pain depending on time and that, therefore, would provide a predictive study of the pain associated with the archwire or with the physiological characteristics of the process

Given that the representation of pain level (PL) with the time period, regardless of the archwire used, also had a similar shape to that shown in figure 7, we then analysed this situation, as here the number of cases was higher and the fitting of the mathematical function would have more statistical validity and offer information on the evolution of pain in general. The points were fitted using non-linear regression curves of different types, the maximum fit being found to be a curve of the form: PL=a\* T-3+c \* exp (-b\*T), where PL, is pain level, T is the time elapsed in hours and the values "a", "b" and "c" correspond to the best-fit parameters that could differ or not depending on the type of archwire. The curve chosen for fitting consists of two terms: a decreasing exponential in which the parameters "b" and "c" are related, respectively, to the

The parameters of fit for the 3 cases considered (pain in general regardless of the type of archwire, pain due to Ni-Ti archwire and pain due to SS archwire) are shown in Table 3. The goodness of fit for the three cases analysed is provided by the correlation coefficient R2 , which is very high, 0.983, 0.964 and 0.987, for the total group, the SS archwires group and the Ni-Ti group respectively.

**Table 3.** Values of parameters (a,b,c) and IC95% of the same corresponding to the non-linear fit of pain level (ND) depending on time in hours (T) elapsed since the beginning of treatment for the two types of archwires used and for the set of all cases. The non-linear fit corresponds to the expression PL=a\* T-3+c \* exp (-b\*T)

The values of the best-fit parameters indicate that: patients with SS archwires have a higher pain level at first than Ni-Ti patients (statistically significant difference in parameter a); a parallel reduction in pain level takes place (statistical equality in parameter b); but during the entire treatment patients with SS archwires experience more pain (statistically significant difference in parameter c).

Figure 7 also shows that after the tenth day no patient reported any pain, which is why our study ended at that point, 232 hours from the fitting of the archwire. The moment of the pain disappearing was practically the same for the two types of archwires, but it is interesting to calculate the average time that pain may be considered as high, moderate or slight. To do so, the PL experienced during the treatment was categorized on these three levels. The criterion was established that under 0.5 points (approximately 30% of the maximum PL experienced) pain could be considered as slight, between 0.5 and 1.5 as moderate, and above 1.5 (approxi‐ mately 70% of the maximum PL experienced) as high. These stratification values are shown in figure 7. Using this categorization we can consider that the Ni-Ti archwires cease to hurt from 85h (3.5 days) from beginning of treatment as opposed to 109 hours (4.5 days) for SS archwires.

#### *7.1.3. Peak of maximum pain*

It is interesting to analyse the moment at which the peak of maximum pain intensity is reached. In our experimental data, the maximum pain is reached in the morning of the day after fitting the archwires, both for Ni-Ti and SS archwires. More specifically, if we observe the fits made (figure 7), maximum pain arrives at between 10 to 12 hours after fitting either of the types of archwire. However, if we consider the peak of the pain when the PL≥ 1.5, as we commented earlier, we can see that that the peak takes place between 8-36 hours in SS and 8-20 hours in Ni-Ti, being, therefore, longer in patients with SS archwires.

#### *7.1.4. Comparison of pain between time periods*

Figure 8 represents the average PL for each time period and it can be observed that there are no "pain peaks" associated with night time, although in the first 5 days, during the night time period a slight increase in pain or a lower decrease than that which would correspond to the 8 hours elapsed from the previous afternoon is noted. This has no statistical significance as the increase or decrease in pain is associated more with the number of hours elapsed since fitting the appliance. Indeed, the AVOVA carried out on the PL values for morning, afternoon and night, the results of which can be seen in Table 4, shows that there is no difference between the mean values with p>0.999, although a very slightly higher mean value of PL can be appreciated for the night period.

**Figure 8.** Pain level (PL) for each time period, regardless of the archwire used. The points in red correspond to the PL of night time periods.

**Table 4.** Mean values and standard deviation (SD) of pain level (PL), confidence interval for the mean of PL at 95% (IC95%) and minimum and maximum values of each time period (morning, afternoon and night), regardless of the type of archwire used.

#### **7.2. Subjective study of pain**

was established that under 0.5 points (approximately 30% of the maximum PL experienced) pain could be considered as slight, between 0.5 and 1.5 as moderate, and above 1.5 (approxi‐ mately 70% of the maximum PL experienced) as high. These stratification values are shown in figure 7. Using this categorization we can consider that the Ni-Ti archwires cease to hurt from 85h (3.5 days) from beginning of treatment as opposed to 109 hours (4.5 days) for SS

It is interesting to analyse the moment at which the peak of maximum pain intensity is reached. In our experimental data, the maximum pain is reached in the morning of the day after fitting the archwires, both for Ni-Ti and SS archwires. More specifically, if we observe the fits made (figure 7), maximum pain arrives at between 10 to 12 hours after fitting either of the types of archwire. However, if we consider the peak of the pain when the PL≥ 1.5, as we commented earlier, we can see that that the peak takes place between 8-36 hours in SS and 8-20 hours in

Figure 8 represents the average PL for each time period and it can be observed that there are no "pain peaks" associated with night time, although in the first 5 days, during the night time period a slight increase in pain or a lower decrease than that which would correspond to the 8 hours elapsed from the previous afternoon is noted. This has no statistical significance as the increase or decrease in pain is associated more with the number of hours elapsed since fitting the appliance. Indeed, the AVOVA carried out on the PL values for morning, afternoon and night, the results of which can be seen in Table 4, shows that there is no difference between the mean values with p>0.999, although a very slightly higher mean value of PL can be

Ni-Ti, being, therefore, longer in patients with SS archwires.

*7.1.4. Comparison of pain between time periods*

appreciated for the night period.

.000

D1A

of night time periods.

D1N

D2M

D2A

D2N

D3M

D3A

D3N

D4M

D4A

D4N

D5M

D5A

D5N

**Figure 8.** Pain level (PL) for each time period, regardless of the archwire used. The points in red correspond to the PL

D6M

D6A

D6N

D7M

D7A

D7N

D8M

D8A

D8N

D9M

D9A

D9N

D10M

D10A

D10N

.500

1.000

1.500

2.000

archwires.

*7.1.3. Peak of maximum pain*

428 Emerging Trends in Oral Health Sciences and Dentistry

#### *7.2.1. Biochemical mediators analysis*

To complete the study of pain, an objective assessment was performed. Two biochemical mediators of pain (Prostaglandin E2 (PGE2) and Substance P (SP)) were determined for each patient during treatment in four time intervals: prior to bracket bonding, 24 hours after bonding, a week and a month after bonding. In all cases, direct measurements were not considered but the proportion to the amount of crevicular fluid collected.

It was analyzed the possible correlations between the subjective pain reported by the patient with the levels of these mediators in the crevicular fluid for all the times studied.

#### *7.2.2. Prostaglandin E2 (PGE2).*

Correlations have been found between the concentration of PGE2 (PC) in the 4 times in which the determinations of this mediator were taken (PCT1: start, PCT2: 24 hours, PCT3: 7 days and PCT4: 30 days) and the subjective pain level of each individual in each interval analyzed, taking into account the 10 days in which there was existence of subjective pain. The results are shown in Table 5.

**Table 5.** Study of the correlation between the level of concentration of PGE2 (PC) in the 4 time times analyzed (PCT1 correspond to the time prior to bracket bonding, PCT2 to 24 hours after, PCT3 a week after and PCT4 a month after) and the level of pain reported by each patient. Values with \* correspond to the times when correlation was found between the two measures of pain.

It can be seen that, in general, individuals with initially high values of PC mediator have a correlation with higher levels of pain one week after the archwire placement. This situation is also shown with PCT3 values and with those of PCT4, with no significant correlation with PCT1.

If the correlation of this mediator is analysed, not with the level of pain but with the total pain experienced by the subjects during the first 10 days, we find that high values of PC are correlated with subjects having more total level of pain throughout the treatment (Table 6). This finding does not happen with this marker in the other periods of time.

**Table 6.** Study of the correlation between the level of PGE2 concentration (PC) and total pain level.

Furthermore, we analyzed whether there was correlation between the values of PGE2 in the four times studied. The results are shown in Table 7 and confirm that initially high values of this mediator are correlated to high values along the entire treatment.

**Table 7.** Study of the correlation between the values of prostaglandin PGE2 in the four times tested. CP (Pearson Correlation) and SG (Sig. Bilateral) \*\* significant correlation at the 0.01 level and \* at the 0.05 level (bilateral).

#### *7.2.3. Substance P (SP)*

In orther to analyse this biochemical mediator, 86 cases were taken into account. The mean values of SP in the four times analysed of the study are shown in Table 8 and Figure 9.

Pain Evaluation Between Stainless Steel and Nickel Titanium Arches in Orthodontic Treatment — A Comparative Study http://dx.doi.org/10.5772/59125 431

**Table 8.** Mean values of SP for each of the times studied.

It can be seen that, in general, individuals with initially high values of PC mediator have a correlation with higher levels of pain one week after the archwire placement. This situation is also shown with PCT3 values and with those of PCT4, with no significant correlation with

If the correlation of this mediator is analysed, not with the level of pain but with the total pain experienced by the subjects during the first 10 days, we find that high values of PC are correlated with subjects having more total level of pain throughout the treatment (Table 6).

Furthermore, we analyzed whether there was correlation between the values of PGE2 in the four times studied. The results are shown in Table 7 and confirm that initially high values of

**P\_Ct1 P\_Ct2 P\_Ct3 P\_Ct4**

r- Pearson 0,229\* 0,059 0,025 0,166 Sig. (bilateral) 0,048 0,616 0,831 0,156

**Total Sum P\_Ct1 P\_Ct2 P\_Ct3 P\_Ct4**

CP -0,042 1 0,484\*\* 0,352\* 0,365\* SG 0,797 0,002 0,026 0,021 N 40 40 40 40 40

CP -0,037 0,484\*\* 1 0,120 0,297 SG 0,821 0,002 0,462 0,063 N 40 40 40 40 40

CP -0,268 0,352\* 0,120 1 0,318\* SG 0,094 0,026 0,462 0,046 N 40 40 40 40 40

CP -0,004 0,365\* 0,297 0,318\* 1

N 40 40 40 40

SG 0,978 0,021 0,063 0,046

**Table 7.** Study of the correlation between the values of prostaglandin PGE2 in the four times tested. CP (Pearson Correlation) and SG (Sig. Bilateral) \*\* significant correlation at the 0.01 level and \* at the 0.05 level (bilateral).

In orther to analyse this biochemical mediator, 86 cases were taken into account. The mean values of SP in the four times analysed of the study are shown in Table 8 and Figure 9.

This finding does not happen with this marker in the other periods of time.

**Table 6.** Study of the correlation between the level of PGE2 concentration (PC) and total pain level.

this mediator are correlated to high values along the entire treatment.

PCT1.

430 Emerging Trends in Oral Health Sciences and Dentistry

Total Pain

P\_Ct1

P\_Ct2

P\_Ct3

P\_Ct4

*7.2.3. Substance P (SP)*

**Figure 9.** SP concentration at each time for each of the times studied.

According to these data, no statistical difference was found between the objective pain (SP crevicular fluid analysis) with the SS or Ni-Ti archwires, and the total subjective pain experi‐ enced according to the questionnaire.

## **8. Further research**

In the literature, we have found few studies that compare pain depending on the type of archwire used [5, 32, 35] and none that introduces a mathematical equation for predicting pain level or peak of pain.

#### **8.1. Subjective study of pain**

#### *8.1.1. Pain level*

Our results coincide with those of Lee *et al.* [32] in stating that there is less pain in the group of patients treated with Ni-Ti archwires than in the group treated with SS archwires. However, neither our results nor the previously mentioned ones coincide with those of Jones and Chan [5], who did not find differences in the pain experienced by patients between Ni-Ti archwires or SS archwires. Moreover, despite being a quite different study, Fernandes et al. [35] also did not find any difference on comparing conventional Ni-Ti archwires with super elastic Ni-Ti archwires.

In our results, pain receded at 4.5 days in cases treated with SS archwires, whereas it receded one day earlier (at 3.5 days) in those cases treated with Ni-Ti archwires. Moreover, the pain level was lower in the group with Ni-Ti archwires than in those with SS archwires.

If we analyse the results of the subjective study of pain recorded by the patients, we observe how 38.2% of patients felt discomfort and 43.1% felt slight pain, whereas only 18.6% experi‐ enced intense pain. These results do not coincide with those of Kaneko et al. [36], where only 10.3% felt discomfort and the great majority (72.4%) felt only slight pain. However, their results are in line with ours in stating that 17.2% experienced intense pain.

### *8.1.2. Peak of maximum pain*

If we analyse when the peak of maximum pain takes place, the results of our study show that the peak occurs 15 hours after fitting the archwires into the mouth of the patient, both in the Ni-Ti group and the SS archwire group, results that are similar but not identical to those of other authors [1, 3, 6,18, 25, 37] who observed a maximum peak of pain 24 hours after fitting the archwire in the patient's mouth.

In contrast, our results and those mentioned above do not coincide with the results of the work of Jones and Chan [5] who found the maximum peak of pain to be on the same morning when fitting the archwire in the mouth, or the results of Jones and Richmond [38] who found the maximum peak of pain in the afternoon or night of the same day that the archwire was fitted.

#### *8.1.3. Duration of pain*

On studying how long pain lasts, the results of our study show that pain ceased at 3.5 days in the Ni-Ti group, whereas, in the SS group, it ceased at 4.5 days, the decrease in pain taking place earlier in the Ni-Ti group than in the SS group. These results do not coincide with those of Jones and Richmond [38], Jones and Chan [5], Ngan et al. [4] or Scheurer et al. [6] in whose studies, the pain caused by the fitting of the archwires was observed to last for approximately 5 days.

Our results show how both groups of patients, both the patients fitted with SS archwires and those fitted with Ni-Ti archwires, began to experience pain at 4 hours, results similar to those of Jones and Richmond [38] with the same intensity of pain.

However, SS and Ni-Ti metals do not have the same stress deformation curve and it can be observed that in order to achieve the same deformation, the stress that has to be applied in the case of steel is greater than in the case of Ni-Ti, which would account for the greater initial pain of the patient in cases treated with SS archwires. Nevertheless, as the teeth adapt to the forces applied and, therefore, the stress applied on the archwire material diminishes, these two materials behave differently, SS maintains a residual deformation, whereas Ni-Ti returns to practically its original dimensions, meaning that its effect on the tooth is more continuous and produces a sensation of pain over a longer time, so evening out the total time of pain duration for both types of archwire.

#### *8.1.4. Comparison of pain between time periods*

In our study, we did not find pain peaks associated with night time, unlike those shown in the results of Kaneko et al. [36] but that the increase or decrease of pain was similar in the morning or afternoon and was only associated with the number of hours following the fitting of the appliance. These results coincide with those of Scheurer et al. [6] who found that pain increased as the day elapsed.

### **8.2. Objective study of pain**

[5], who did not find differences in the pain experienced by patients between Ni-Ti archwires or SS archwires. Moreover, despite being a quite different study, Fernandes et al. [35] also did not find any difference on comparing conventional Ni-Ti archwires with super elastic Ni-Ti

In our results, pain receded at 4.5 days in cases treated with SS archwires, whereas it receded one day earlier (at 3.5 days) in those cases treated with Ni-Ti archwires. Moreover, the pain

If we analyse the results of the subjective study of pain recorded by the patients, we observe how 38.2% of patients felt discomfort and 43.1% felt slight pain, whereas only 18.6% experi‐ enced intense pain. These results do not coincide with those of Kaneko et al. [36], where only 10.3% felt discomfort and the great majority (72.4%) felt only slight pain. However, their results

If we analyse when the peak of maximum pain takes place, the results of our study show that the peak occurs 15 hours after fitting the archwires into the mouth of the patient, both in the Ni-Ti group and the SS archwire group, results that are similar but not identical to those of other authors [1, 3, 6,18, 25, 37] who observed a maximum peak of pain 24 hours after fitting

In contrast, our results and those mentioned above do not coincide with the results of the work of Jones and Chan [5] who found the maximum peak of pain to be on the same morning when fitting the archwire in the mouth, or the results of Jones and Richmond [38] who found the maximum peak of pain in the afternoon or night of the same day that the archwire was fitted.

On studying how long pain lasts, the results of our study show that pain ceased at 3.5 days in the Ni-Ti group, whereas, in the SS group, it ceased at 4.5 days, the decrease in pain taking place earlier in the Ni-Ti group than in the SS group. These results do not coincide with those of Jones and Richmond [38], Jones and Chan [5], Ngan et al. [4] or Scheurer et al. [6] in whose studies, the pain caused by the fitting of the archwires was observed to last for approximately

Our results show how both groups of patients, both the patients fitted with SS archwires and those fitted with Ni-Ti archwires, began to experience pain at 4 hours, results similar to those

However, SS and Ni-Ti metals do not have the same stress deformation curve and it can be observed that in order to achieve the same deformation, the stress that has to be applied in the case of steel is greater than in the case of Ni-Ti, which would account for the greater initial pain of the patient in cases treated with SS archwires. Nevertheless, as the teeth adapt to the forces applied and, therefore, the stress applied on the archwire material diminishes, these two materials behave differently, SS maintains a residual deformation, whereas Ni-Ti returns to

of Jones and Richmond [38] with the same intensity of pain.

level was lower in the group with Ni-Ti archwires than in those with SS archwires.

are in line with ours in stating that 17.2% experienced intense pain.

archwires.

*8.1.2. Peak of maximum pain*

*8.1.3. Duration of pain*

5 days.

the archwire in the patient's mouth.

432 Emerging Trends in Oral Health Sciences and Dentistry

Authors like Erdinic and Dincer [8] or Awawdeh et al. [39] have observed that the perception of pain during orthodontic movement is related to substance P. Substance P is involved in the nervous system signals required to perceive pain [40] also influencing the concentration of other pain mediators associated with dental pain like the metalloproteinase 8 [41], and in the secretion of IL-1β from the monocytes. These three substances (IL-1β, PG-E2 and SP) were independently associated with pain [15-17] and are expressed during initial tooth movement in sufficient amounts to be detected in the crevicular fluid [18].

Then we will discuss some variables affecting the collection of this sample.

#### *8.2.1. Sources of error in the collection of the crevicular fluid*

Before taking the samples, one have to keep in mind that the most frequent sources of contamination of the crevicular fluid samples are blood, saliva and plaque. Respect to the presence of plaque, its presence in the paper strips used for collecting the sample has a considerable effect on the volume of the sample, thus being a source of bias [42-44].These considerations have been supported also by other authors, who demonstrate that the nonremoval of the plaque has a bad effect on the determination of the volume [43,45].

In order to avoid these problems of contamination prior to bracket bonding, scaling was performed to all patients of the study, thus reducing the possibility of bleeding and contami‐ nation by plaque.

Also, in our study, in order to reduce saliva contamination, a good insulation protocol was carried out by placing the aspiration system and cotton rolls in each patient. Saliva contami‐ nation is a problem when the sample is collected with paper strips, as it can alter the volume of the sample collected [46].

#### *8.2.2. Sample recording time*

The first authors who described the use of Periotron® [43] recommended a sample recording time of five seconds. However, to increase the volume of the sample in order to subsequently analyze it sometimes it is necessary to increase the sample time.

Therefore, in our work, a sample time of 30 seconds was established following the recommen‐ dations from other authors [32, 47-50]. For the analysis of the crevicular fluid, the collection should be made in such way that minimum groove environment deterioration occurs in the shortest time possible. By doing so, correct protein concentrations are maintained and also sufficient time is achieved to collect the required sample volume.

#### *8.2.3. Methods of collection of crevicular fluid*

There are many ways to collect the crevicular fluid; gingival washing, micropipettes and paper strips. Gingival washing method is suitable for obtaining cells of the gingival groove. It is a complex method and has limited applications since it can only be used in the maxillary arch due to the complexity of the technique. On the other hand, samples cannot be analyzed later in the laboratory and all the fluid cannot be recovered during aspiration and re-aspiration.

With micropipettes is difficult to collect a necessary amount of fluid in a short period of time unless there is gingival inflammation, resulting in more volume of crevicular fluid. It can cost up to 30 minutes to collect the amount of fluid necessary and this makes this technique traumatic [51].

The crevicular fluid analysis it is a useful and advantageous method, especially for in vivo studies, it is not invasive, and the sample can be split as many times as necessary. This allows the perfect monitor development in a given area for a certain period of time. Therefore and because of the complications mentioned above with the two methods described, in our work we decided to take the sample by this method, using paper strips, like other authors [32, 47-50] because it is a simple, rapid and non-traumatic method and can be applied to isolated areas.

Crevicular fluid samples of each patient who also had filled the subjective pain questionnaire were collected, in order to later compare the subjective data of pain with the objective values obtained from the analysis of the biochemical mediators.

#### **8.3. Biochemical mediators analysis**

#### *8.3.1. Prostaglandin E2 (PGE2)*

In our study, PGE2 production reached its maximum peak at 24 hours, coinciding with the results found by Bergius et al. [37], Giannopoulou et al. [18] and Grieve et al. [52]. In another study by Lee et al. [32], initial measurements of IL-1 β and PGE2 showed little variation, however, once force is applied, the individual variation became large enough to estimate the overall response.

Lee et al. [32] observed an increase in the levels of interleukins in patients during the third week, even without the revive forces, causing an increase in the average concentration but without statistical significance. Iwasaki et al. [30] found that IL-1β levels fluctuate with a period of 28 days when a force is applied continuously.

Interestingly, when a discontinuous force (equivalent to steel arches) is reactivated after a week, a significant increase in the levels of IL-1β, 24 hours after reactivation was found, compared with the results found 24 hours after the initial activation. This finding implies that timely reactivating discontinuous forces might be more effectively in the regulation of IL-1β than the continuous application of forces. Instead, they did not found any increased after a second reactivation. This could be due to a refractory period or excessive applied pressure. Since excessive pressure causes a large area of hyalinization in the pressure side and a wide acellular area, which produces impairment in cytokine secretion and its spread to the perio‐ dontal space. These results suggest that the application of a suitable pressure force intermittent and timely recovery may be effective to promote secretion of IL-1 β. However, authors like Yamaguchi et al. [26], Tian et al. [27] or Uematsu et al. [11], argue that the intense and discon‐ tinuous forces tend to significantly reduce levels of IL1β suggesting the need for reactivation to maintain sufficient production of IL1β. Such forces not only increase the risk of root resorption but also increase the hyalinization of periodontal tissue [28,29] which also induce very pronounced rise and fall peaks in the levels of cytokines, leading to undesirable tissue level and the need for the reactivation of the forces.

Therefore, in our work, a sample time of 30 seconds was established following the recommen‐ dations from other authors [32, 47-50]. For the analysis of the crevicular fluid, the collection should be made in such way that minimum groove environment deterioration occurs in the shortest time possible. By doing so, correct protein concentrations are maintained and also

There are many ways to collect the crevicular fluid; gingival washing, micropipettes and paper strips. Gingival washing method is suitable for obtaining cells of the gingival groove. It is a complex method and has limited applications since it can only be used in the maxillary arch due to the complexity of the technique. On the other hand, samples cannot be analyzed later in the laboratory and all the fluid cannot be recovered during aspiration and re-aspiration.

With micropipettes is difficult to collect a necessary amount of fluid in a short period of time unless there is gingival inflammation, resulting in more volume of crevicular fluid. It can cost up to 30 minutes to collect the amount of fluid necessary and this makes this technique

The crevicular fluid analysis it is a useful and advantageous method, especially for in vivo studies, it is not invasive, and the sample can be split as many times as necessary. This allows the perfect monitor development in a given area for a certain period of time. Therefore and because of the complications mentioned above with the two methods described, in our work we decided to take the sample by this method, using paper strips, like other authors [32, 47-50] because it is a simple, rapid and non-traumatic method and can be applied to isolated areas.

Crevicular fluid samples of each patient who also had filled the subjective pain questionnaire were collected, in order to later compare the subjective data of pain with the objective values

In our study, PGE2 production reached its maximum peak at 24 hours, coinciding with the results found by Bergius et al. [37], Giannopoulou et al. [18] and Grieve et al. [52]. In another study by Lee et al. [32], initial measurements of IL-1 β and PGE2 showed little variation, however, once force is applied, the individual variation became large enough to estimate the

Lee et al. [32] observed an increase in the levels of interleukins in patients during the third week, even without the revive forces, causing an increase in the average concentration but without statistical significance. Iwasaki et al. [30] found that IL-1β levels fluctuate with a period

Interestingly, when a discontinuous force (equivalent to steel arches) is reactivated after a week, a significant increase in the levels of IL-1β, 24 hours after reactivation was found,

sufficient time is achieved to collect the required sample volume.

obtained from the analysis of the biochemical mediators.

of 28 days when a force is applied continuously.

**8.3. Biochemical mediators analysis**

*8.3.1. Prostaglandin E2 (PGE2)*

overall response.

*8.2.3. Methods of collection of crevicular fluid*

434 Emerging Trends in Oral Health Sciences and Dentistry

traumatic [51].

On the contrary, continuous light forces [30-32] tend to maintain high levels of IL1β so the need for reactivation is reduced. These forces maintain, high longer, cytokine levels, which are necessary for continuous periodontal remodeling.

The efficiency on the recovery is shown in a series of experiments in rats done by King et al. [53] where the reactivation during the end of the cycle stimulates bone resorbing osteoclasts and reduce root resorption.

In the study by Lee et al. [32], changes in the levels of PGE2 to mechanical stress and the interactions between the IL-1β and PGE2 in vivo were investigated. The mechanical loads applied to the periodontal ligament cells are known to induce the expression of cyclooxyge‐ nase-2 (COX-2), which facilitates the formation PGE2 [54]. In the study of Saito et al. [55], a significant increase in PGE2 was observed when IL-1β was applied to periodontal ligament cells alone or in combination with mechanical stress. The synergistic action of IL-1β and mechanical stress on the production of PGE prove the hypothesis that mechanical stress provides more substrate for cyclooxygenase by activation of phospholipase A2, while IL-1β formation increases cyclooxygenase.

PGE2 levels in this initial study showed significant peaks at 24 hours (T2) of the application of force, compared to the control site. This appears to be a direct effect of mechanical stress. By applying continuous force, high levels of PGE2 was observed only temporarily, compared to the control site, even though the average concentration is maintained at a high level during the experiment. With discontinuous forces, significantly higher levels of PGE2 for 1 week were observed. This regulation is an example of the synergistic effect of the mechanical stresses sustained and secreted IL-1β.

In this study we found that, if the total pain recorded by the subjects is determined and their correlation is sought with the values of this mediator, patients with high values of PC1 have more total level of pain during the treatment. Furthermore, PC3 high values are related with high values one week after the archwire placement. We did not find association between patients who had elevated levels of PC4 with high levels of pain between the 6th and 8th day. These results cannot be compared with other authors as there are no studies reported in the literature.

#### *8.3.2. Substance P (SP)*

The results of the substance P values were inconsistent with what would be expected of a biochemical mediator of pain as, in the initial time of the study, when no level of pain exists (and therefore this substance should have a baseline), we found higher values, both overall levels and concentrations, than in the rest of study for 56 of the 86 patients analyzed.

The apparently anomalous behavior of this marker with a decrease at 24 hours and a later increased tendency to grow up is not statistically significant because, due to the high variability of the data. However, other authors as Giannopoulou et al. [18], found more predictable values in the levels of these biochemical mediators after insertion of ligatures.

The experience of pain has its peak 1 day after starting treatment and is reduced to normal levels at 7 days. The IL-1β, SP, PGE2 mediators are expressed during initial tooth movement. The initial perception of pain (1h) is related to the levels of PGE2, the IL-1β is related to pain at 24 hours and the SP has its peak at 24 hours. This is possible because of the relationship that has with PGE2 as an indicator of periodontal inflammation [56].

On the other hand, Yao et al. [57], did not find relationship between pain intensity and PGE2 at 12, 24 and 72 hours of the beginning of tooth movement. Another authors, though [26], found no relationship between IL-1β and substance P. Indirectly, this finding also has an association between IL-1β and pain.

## **9. Conclusions**

This paper has analyzed the pain associated with the placement of the first archwire in the beginning of the orthodontic treatment, analyzing the influence that several variables have (such as the type of wire used) on pain.

A questionnaire for the subjective assessment of pain has been designed, registering the pain indicated by the patient at each time interval (morning, afternoon and evening), from the time of placing the archwire for the first time until it disappears. Furthermore, the objective assessment of pain has been determined in the crevicular fluid through the different biochem‐ ical mediators of pain, such as prostaglandin 2 (PGE2) and substance P (SP).

PL=a\* T-3+c \* exp (-b\*T) where parameters a, b and c represent: "a" coefficient represents the higher or lower PL corresponding to the "peak". The "b" parameter indicates the greater or lesser speed in the reduction of pain and value "c" represents the higher or lower PL through‐ out the treatment.

## **Author details**

These results cannot be compared with other authors as there are no studies reported in the

The results of the substance P values were inconsistent with what would be expected of a biochemical mediator of pain as, in the initial time of the study, when no level of pain exists (and therefore this substance should have a baseline), we found higher values, both overall

The apparently anomalous behavior of this marker with a decrease at 24 hours and a later increased tendency to grow up is not statistically significant because, due to the high variability of the data. However, other authors as Giannopoulou et al. [18], found more predictable values

The experience of pain has its peak 1 day after starting treatment and is reduced to normal levels at 7 days. The IL-1β, SP, PGE2 mediators are expressed during initial tooth movement. The initial perception of pain (1h) is related to the levels of PGE2, the IL-1β is related to pain at 24 hours and the SP has its peak at 24 hours. This is possible because of the relationship that

On the other hand, Yao et al. [57], did not find relationship between pain intensity and PGE2 at 12, 24 and 72 hours of the beginning of tooth movement. Another authors, though [26], found no relationship between IL-1β and substance P. Indirectly, this finding also has an association

This paper has analyzed the pain associated with the placement of the first archwire in the beginning of the orthodontic treatment, analyzing the influence that several variables have

A questionnaire for the subjective assessment of pain has been designed, registering the pain indicated by the patient at each time interval (morning, afternoon and evening), from the time of placing the archwire for the first time until it disappears. Furthermore, the objective assessment of pain has been determined in the crevicular fluid through the different biochem‐

**•** Total pain (TP) and the maximum level of pain (PL) are lower in the group of patients fitted with Ni-Ti archwires than in the group fitted with SS archwires, although pain for both

PL=a\* T-3+c \* exp (-b\*T) where parameters a, b and c represent: "a" coefficient represents the higher or lower PL corresponding to the "peak". The "b" parameter indicates the greater or lesser speed in the reduction of pain and value "c" represents the higher or lower PL through‐

ical mediators of pain, such as prostaglandin 2 (PGE2) and substance P (SP).

**•** Pain level (PL) is determined by the mathematical equation:

levels and concentrations, than in the rest of study for 56 of the 86 patients analyzed.

in the levels of these biochemical mediators after insertion of ligatures.

has with PGE2 as an indicator of periodontal inflammation [56].

literature.

*8.3.2. Substance P (SP)*

436 Emerging Trends in Oral Health Sciences and Dentistry

between IL-1β and pain.

(such as the type of wire used) on pain.

groups recedes at the same time.

**9. Conclusions**

out the treatment.

M. Larrea1 , N. Zamora1\*, R. Cibrian2 , J.L. Gandia1 and V. Paredes1

\*Address all correspondence to<EMAIL_ADDRESS>
1 Department of Orthodontics. Faculty of Medicine and Dentistry, University of Valencia, Spain

2 Department of Physiology. Faculty of Medicine and Dentistry, University of Valencia, Spain

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## **Non-Surgical Treatment of Class III with Multiloop Edgewise Arch-Wire (MEAW) Therapy**

Paulo Beltrão

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59257

## **1. Introduction**

The incidence of class III malocclusion among the western population is low, but in Japan and South Korea is high and since many patients don`t accept orthognatic surgery, a conservative/ camouflage treatment is often necessary. The MEAW (multiloop edgewise arch wire) was developed in 1967 by Dr. Young H. Kim to correct open bite malocclusions and was found to be extremely effective. Further development of Meaw technique extends its application to treat any type of malocclusion, especially Class III malocclusion.

The MEAWs are constructed with 0.016 x 0.022stainless steel (bracket 0.018 inch slot) or 0.017x0.025 stainless steel (bracket 0.022– inch slot). The arches have ideal arch form with five loops on each side of the arch.

Prof. Sadao Sato developed the use of MEAW and introduced different concepts about the etiology of malocclusions. According to Sato genetics may not be the only reason to class III malocclusion, the posterior discrepancy may be the major contributing factor to class III malocclusion.

The degree of basicranial flexion differs in the various types of malocclusion. According to Hooper (1986) the spheno-basilar articulation is the most important among the cranial bones and it is where the movement of flexion-extension occurs. The cranial base angles (Na-S-Ar) comes to approximately 124,2 ° in class I patterns.

From this average value a more obtuse (extension) angle indicates skeletal Class II and a more acute (flexion) angle means skeletal Class III.The rotating movement of the cranial base (flexion/extension) occurs at the spheno-occipital articulation and it is transmitted to the maxilla through the Vomer. This dynamic mechanism has a great influence on the growth pattern of an individual during the growth period.

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

When the sphenoid makes flexion the rotating force of the vomer is postero-inferior and the maxilla is strongly pushed down. This causes vertical elongation of the maxillary complex, short anteroposterior dimension and posterior crowding. This is related to the development of a class III skeletal frame (Sato 2001).

The posterior discrepancy increases the probability of wisdom teeth impaction and once their impaction occurs a "squeezing-out "effect may occur, causing an over-eruption of the adjacent teeth, flatten the posterior occlusal plane and an increase in the posterior occlusal vertical dimension. The over-erupted molars produce occlusal interferences that act as a fulcrum causing a mandibular forward adaptation with subluxation of the mandibular condyles and active remodeling of the condylar cartilage. The result is a mandibular prognathism.

The skeletal Class III relationships may be due to a lack of sagital development of maxillary or mandibular overdevelopment, or a combination of both.

Skeletal class III malocclusion is usually characterized by a steep mandibular plane angle, obtuse gonial angle, a small cranial base angle which may displace the glenoid fossa anteriorely to cause a forward positioning of the mandible, flat occlusal plane, short antero posterior diameter of the maxilla, increased vertical growth of the maxilla, labial tipping of the maxillary teeth, lingual tipping of the mandibular teeth.

In adults patients,without growing ability, orthognatic surgery is indicated for severe skeletal class III malocclusion, but moderate class III cases (borderline cases) can be treated orthodon‐ tically if the patients refuse surgery. The MEAW is often used in skeletal class III treatment without orthognatic surgery or extraction of intermediate teeth.

The objectives of the treatment are: a) to eliminate posterior discrepancy, b) to intrude the posterior teeth and to upright them, c) reconstruction the occlusal plane (steepning the occlusal plane) which induces mandibular backward adaption. The entire lower dentition is moved distally and uprighted using a MEAW with short class III elastics after extraction of the third molars. The skeletal features of the class III malocclusions are closely related to the deviation in the vertical aspect of the occlusion. According to this correcting the occlusal plane by controlling the vertical dimension is extremely important in the treatment of class III maloc‐ clusion.

To eliminate the posterior discrepancy, the upper and lower third molars should be extracted prior to the onset of treatment. The upper second molars can be extracted, if the patient is young and if the the upper third molars have quality in terms of size, shape and direction of eruption. This approach will allow steepen the occlusal plane with the elimination of the "squeezing-out effect "at the upper molars. The treatment mechanics use tip back bend activations of the MEAW and vertical or short class III elastics (3/16 inch – 6 oz) on the anterior teeth.

The steps of treatment of the class III malocclusion are: a) Levelling, b) elimination of occlusal interference,,c) establishing mandibular position d) reconstruction of the occlusal plane, e) achieving a physiological occlusion.

Sassouni and Nanda (1964) proved the vertical disproportion were, in many cases, at the origin of anteroposterior dysplasias. Therefore, treatment strategies should focus on vertical control in order to correct anteroposterior disharmony.

Angle(1899) – The class III malocclusion occurred when lower teeth occluded mesial to their normal relationship by the width of one premolar or even more in extreme cases.The class III can be defined as a skeletal facial deformity characterized by a forward mandibular position with respect to the cranial base and/or maxilla.

## **2. The etiology of class III malocclusion**

When the sphenoid makes flexion the rotating force of the vomer is postero-inferior and the maxilla is strongly pushed down. This causes vertical elongation of the maxillary complex, short anteroposterior dimension and posterior crowding. This is related to the development

The posterior discrepancy increases the probability of wisdom teeth impaction and once their impaction occurs a "squeezing-out "effect may occur, causing an over-eruption of the adjacent teeth, flatten the posterior occlusal plane and an increase in the posterior occlusal vertical dimension. The over-erupted molars produce occlusal interferences that act as a fulcrum causing a mandibular forward adaptation with subluxation of the mandibular condyles and

The skeletal Class III relationships may be due to a lack of sagital development of maxillary

Skeletal class III malocclusion is usually characterized by a steep mandibular plane angle, obtuse gonial angle, a small cranial base angle which may displace the glenoid fossa anteriorely to cause a forward positioning of the mandible, flat occlusal plane, short antero posterior diameter of the maxilla, increased vertical growth of the maxilla, labial tipping of the maxillary

In adults patients,without growing ability, orthognatic surgery is indicated for severe skeletal class III malocclusion, but moderate class III cases (borderline cases) can be treated orthodon‐ tically if the patients refuse surgery. The MEAW is often used in skeletal class III treatment

The objectives of the treatment are: a) to eliminate posterior discrepancy, b) to intrude the posterior teeth and to upright them, c) reconstruction the occlusal plane (steepning the occlusal plane) which induces mandibular backward adaption. The entire lower dentition is moved distally and uprighted using a MEAW with short class III elastics after extraction of the third molars. The skeletal features of the class III malocclusions are closely related to the deviation in the vertical aspect of the occlusion. According to this correcting the occlusal plane by controlling the vertical dimension is extremely important in the treatment of class III maloc‐

To eliminate the posterior discrepancy, the upper and lower third molars should be extracted prior to the onset of treatment. The upper second molars can be extracted, if the patient is young and if the the upper third molars have quality in terms of size, shape and direction of eruption. This approach will allow steepen the occlusal plane with the elimination of the "squeezing-out effect "at the upper molars. The treatment mechanics use tip back bend activations of the MEAW and vertical or short class III elastics (3/16 inch – 6 oz) on the anterior

The steps of treatment of the class III malocclusion are: a) Levelling, b) elimination of occlusal interference,,c) establishing mandibular position d) reconstruction of the occlusal plane, e)

active remodeling of the condylar cartilage. The result is a mandibular prognathism.

or mandibular overdevelopment, or a combination of both.

without orthognatic surgery or extraction of intermediate teeth.

teeth, lingual tipping of the mandibular teeth.

clusion.

teeth.

achieving a physiological occlusion.

of a class III skeletal frame (Sato 2001).

444 Emerging Trends in Oral Health Sciences and Dentistry

## **3. Classification of class III malocclusion**

Moyers classified the class III malocclusion according the cause: osseous; muscular; dental.Ac‐ cording to him, it was necessary to determine whether the mandible on closure was in centric relation or "convenient" anterior position.

In 1966 Charles Tweed divided class III malocclusion in pseudoclass III and skeletal class III. Tweed also divided the class III onto two distinct categories : The category A-the FMA ranges between 10° and 22°,with a large mandible ; underdeveloped maxilla and a ANB between 7° to 10° and the category B – FMA ranges between 30° to 50° with an obtuse gonial angle and a lower lip overactive.

The characteristics of Pseudoclass III are the following: normal mandible and underdeveloped maxilla, concave straight profile, skeletal pattern is class I, normal gonial angle and the retrusion of the mandible is possible.

The skeletal class III discrepancy may be the result of a large mandible, a small maxilla, a distally positioned maxilla or a combination of the three. Vertically the class III can be divided in high angle, average and low angle.

The class III subdivision is characterized by a class I molar relation on one side and a class III on the other side.

## **4. The differential diagnosis of skeletal class III malocclusion**

The diagnostic criteria for pseudo class III according to Rabie and Yan Gu (AJODO 2000) is the following : a) 72 % showed no family history; b) molar class I in CR and class III at habitual occlusion ; c)decreased midface length ; d) forward mandibular position with normal length ; e) retroclined upper incisors with normal lower incisors; f) presence of mandibular anterior sliding into a edge-to-edge or crossbite relationship due to premature tooth contact (with CO– CR discrepancy), absence of skeletal signs of class III malocclusion. The differential diagnosis of skeletal class III malocclusion with skeletal class I include the following differences:

The dentoalveolar class III malocclusion present a normal ANB angle and a lingual tipping of upper incisors and labial tipping of lower incisors. The skeletal class III malocclusion show a maxillary retrusion or mandibular protrusion, or both with negative ANB, increased mandib‐ ular length, increased gonial angle, labial tipping of upper incisors and lingual tipping of lower incisors.

There are three important diagnostic principles of class III such as:

## **5. Treatment of pseudo class III malocclusion**

The characteristics of Pseudoclass III are the following: normal mandible and underdeveloped maxilla, concave straight profile, skeletal pattern is class I, normal gonial angle and the

The skeletal class III discrepancy may be the result of a large mandible, a small maxilla, a distally positioned maxilla or a combination of the three. Vertically the class III can be divided

The class III subdivision is characterized by a class I molar relation on one side and a class III

The diagnostic criteria for pseudo class III according to Rabie and Yan Gu (AJODO 2000) is the following : a) 72 % showed no family history; b) molar class I in CR and class III at habitual occlusion ; c)decreased midface length ; d) forward mandibular position with normal length ; e) retroclined upper incisors with normal lower incisors; f) presence of mandibular anterior sliding into a edge-to-edge or crossbite relationship due to premature tooth contact (with CO– CR discrepancy), absence of skeletal signs of class III malocclusion. The differential diagnosis of skeletal class III malocclusion with skeletal class I include the following differences:

The dentoalveolar class III malocclusion present a normal ANB angle and a lingual tipping of upper incisors and labial tipping of lower incisors. The skeletal class III malocclusion show a maxillary retrusion or mandibular protrusion, or both with negative ANB, increased mandib‐ ular length, increased gonial angle, labial tipping of upper incisors and lingual tipping of lower

**•** To determine whether the mandible on closure is in centric relation or in a "convenient

**•** To evaluate the potential growth and development of a patient with a class III malocclusion

**4. The differential diagnosis of skeletal class III malocclusion**

retrusion of the mandible is possible.

446 Emerging Trends in Oral Health Sciences and Dentistry

in high angle, average and low angle.

**•** In class III the SNA is lower

**•** The SNB is greater in class III

incisors.

" anterior position

**•** The mean ANB angle in class III is negative

**•** The lower anterior facial height is increased

**•** Identify the nature of skeletal discrepancy

**•** Cranial base angle is smaller in class III patients

There are three important diagnostic principles of class III such as:

**•** The gonial angle is more open in class III

on the other side.

The ideal age to treat pseudo class III is between 6 to 9 years, because treating the pseudo class III during the mixed dentition has some advantages such as : the stability of correction is better, prevent unfavourable growth of skeletal frame,prevent deleterious habits.There are many options to treat the pseudo class III malocclusion such as : equilibration of occlusion, bionator appliance, fixed appliance, acrylic crowns, acrylic inclined planes, functional appliance therapy, and orthopaedic appliances.

## **6. Treatment of skeletal class III malocclusiom in growing patients**

During the primary, mixed and permanent dentition the growth is present and the treatment is different from when the growth is finished. The first step is to distinguish if the class III is due to maxillary undergrowth, mandibular overgrowth or both or a skeletal class I with anterior cross bite. When the class III is due to mandibular overgrowth the options of treatment are : chin cap therapy, reverse class III activator (to produce retrusive force on the mandible), low or high pull head gear (HPHG) to control posterior eruption.

When class III is due to maxillary undergrowth and/or retrognatic maxillary with a orthognatic mandible, it is necessary to promote the growth and protact the maxillary using a face mask (Delaire or Petit) or a functional appliance therapy (activator or Frankel III regulator).

## **7. Treatment of skeletal class III malocclusion in non growing patients**

The treatment of class III in adults and non growing patients can be a surgical treatment or a camouflage treatment. When a non growing patient is diagnosed as a class III malocclusion and has a strong skeletal component, the treatment of choice is usually orthodontic/orthognatic surgery. After determined that the surgery will be necessary the surgeon usually waits until the growth is finished. Maxillary growth may be completed at age 14-15 years, but mandibular growth may continue until 20 years. Then the orthodontist will decompensate the incisors and after that the surgery will be done.

## **8. Camouflage treatment of class III malocclusion**

Beyond the adolescent growth spurt, to correct a mild skeletal class III, teeth must be displaced relative to their supporting bone to mask the underlying class III discrepancy by dental compensation. This is termed camouflage treatment. A patient with class III malocclusion, with the growth completed, a slight skeletal class III, acceptable alignment of teeth and acceptable facial proportions is a good candidate for a camouflage treatment. Since 1967 the MEAW technique has proved to be an effective treatment camouflage and a non-surgical treatment of class III malocclusion. The extraction theraphy of premolars may have limited applicability in class III treatment, for example extractions in the lower arch will increase the lingual inclination of the incisors which were already inclined. Another contraindication to extract is the cases that combine orthodontics and surgery.

## **9. Non-surgical treatment of class III with multiloop edgewise archwire(MEAW) therapy**

Many times during the diagnosis process the etiology of the malocclusion and the mechanism of its development are depreciated. The cephalometric analysis doesn`t clearly shows the cause of malocclusion, it only localizes the site of skeletal malocclusion and shows the degree of deviation. This means that current orthodontics many times identifies and treats symptoms rather than aiming the cause. Hence there is a need for the insertion of a new treatment philosophy based on the function rather than esthetic needs of the patient. It is necessary to understand the dynamic mechanism of development of malocclusion and to know the treatment technique for orthodontic occlusal reconstruction.

#### **9.1. The dynamic mechanism of the development of class III malocclusion**

During the human evolution the cranial base was modified with the bipedalism and erect posture, producing a flexion of the cranial base and a displacement of the foramen occipitale magnum from one end to the middle of the skull. The result of this displacement, is a vertical growth pattern rather than horizontal. The degree of basicranial flexion is different according to the type of malocclusion. Thus a cranial base angle (Na-S-Ar) about 124,2 degrees is characteristic of class I pattern. When the angle is closed to 130 degrees (extension of cranial base) indicates a class II malocclusion and a more acute angle closer to 120 degrees (flexion) indicates a skeletal class III. If more severe is the class III pattern, more pronounced is the flexion of the cranial base and greater is the tendency of vertical growth. Thus the vertical component of class III malocclusion is very important, contrary to be considered just a sagital problem. According to this the use of chin cap, long class III elastics, premolar extraction, surgery are treatment approaches of skeletal class III malocclusion in the sagital direction, neglecting the vertical component. When the angle of cranial base presents a flexion, the rotating movement occurs at the spheno-occipital synchondrosis and it is transmitted to the maxillary through the vomer. This dynamic mechanism affects the growth pattern of the growing patients. With the flexion of the sphenoid, the rotating force of the vomer is poster‐ oinferior and the maxillary is pushed dowm. This produce vertical elongation, undersized sagital dimension and posterior crowding of the maxillary. The lack of maxillary translation creates a deficit of space in the tuberosity, and a posterior crowding, that causes the "squeezing out effect ". The squeezing out effect is an over-eruption of the molars and modifies the inclination of the occlusal plane, making it flatter. Once the over-eruption of the molars occurs, then occlusal interferences appear and in order to avoid them, the mandible adapts for‐ ward.This mandibular forward movement, produces a distraction of the mandibular condyles and active reformulation of the condylar cartilage, resulting in mandibular prognathism.

Figure 1 –The dynamic mechanism of the development of class III malocclusion **Figure 1.** The dynamic mechanism of the development of class III malocclusion

#### **9.2. General characterization of class III malocclusion**

The class III malocclusion has the following characteristics:

technique has proved to be an effective treatment camouflage and a non-surgical treatment of class III malocclusion. The extraction theraphy of premolars may have limited applicability in class III treatment, for example extractions in the lower arch will increase the lingual inclination of the incisors which were already inclined. Another contraindication to extract is the cases

Many times during the diagnosis process the etiology of the malocclusion and the mechanism of its development are depreciated. The cephalometric analysis doesn`t clearly shows the cause of malocclusion, it only localizes the site of skeletal malocclusion and shows the degree of deviation. This means that current orthodontics many times identifies and treats symptoms rather than aiming the cause. Hence there is a need for the insertion of a new treatment philosophy based on the function rather than esthetic needs of the patient. It is necessary to understand the dynamic mechanism of development of malocclusion and to know the

During the human evolution the cranial base was modified with the bipedalism and erect posture, producing a flexion of the cranial base and a displacement of the foramen occipitale magnum from one end to the middle of the skull. The result of this displacement, is a vertical growth pattern rather than horizontal. The degree of basicranial flexion is different according to the type of malocclusion. Thus a cranial base angle (Na-S-Ar) about 124,2 degrees is characteristic of class I pattern. When the angle is closed to 130 degrees (extension of cranial base) indicates a class II malocclusion and a more acute angle closer to 120 degrees (flexion) indicates a skeletal class III. If more severe is the class III pattern, more pronounced is the flexion of the cranial base and greater is the tendency of vertical growth. Thus the vertical component of class III malocclusion is very important, contrary to be considered just a sagital problem. According to this the use of chin cap, long class III elastics, premolar extraction, surgery are treatment approaches of skeletal class III malocclusion in the sagital direction, neglecting the vertical component. When the angle of cranial base presents a flexion, the rotating movement occurs at the spheno-occipital synchondrosis and it is transmitted to the maxillary through the vomer. This dynamic mechanism affects the growth pattern of the growing patients. With the flexion of the sphenoid, the rotating force of the vomer is poster‐ oinferior and the maxillary is pushed dowm. This produce vertical elongation, undersized sagital dimension and posterior crowding of the maxillary. The lack of maxillary translation creates a deficit of space in the tuberosity, and a posterior crowding, that causes the "squeezing out effect ". The squeezing out effect is an over-eruption of the molars and modifies the inclination of the occlusal plane, making it flatter. Once the over-eruption of the molars occurs, then occlusal interferences appear and in order to avoid them, the mandible adapts for‐

**9. Non-surgical treatment of class III with multiloop edgewise**

**9.1. The dynamic mechanism of the development of class III malocclusion**

treatment technique for orthodontic occlusal reconstruction.

that combine orthodontics and surgery.

448 Emerging Trends in Oral Health Sciences and Dentistry

**archwire(MEAW) therapy**

**•** Increased FH-MP angle

#### **9.3. Non-surgical treatment of class III malocclusion**

It is very important to understand the dynamic mechanism of the development of class III malocclusion to establish a correct treatment plan. In the development of class III malocclusion the key point is the molar over-eruption (due to the posterior crowding) which is responsible for the flatness of the upper posterior occlusal plane.The upper posterior flat occlusal plane produces a forward mandibular adaptation. According to this there are two significant goals to attain with the treatement of class III:

The posterior crowding is usually solved, by extraction of third molars prior to the onset of the treatment. The upper second molars can be extracted if the patient is young and the third molars are too high in the tuberosity. Before the decision to extract the upper second molars, the third molars should be radiographically evaluated to check if they have correct size and shape as well as appropriate position and inclination to erupt properly, replacing the extracted second molars. Another significant goal to attain with the treatment of class III is the recon‐ struction of the occlusal plane, because the class III malocclusion requires a steeper occlusal plane for backward adaptation of the mandible. The tip back bends of the MEAW correct the premolars and molars to an upright position and intrude the molars. The correct treatment mechanics used are progressive tip back bends activations of 3° to 5° from the premolars teeth to molar area along with short class III elastics 3/16 inch, 6 oz) on the anterior teeth. requires a steeper occlusal plane for backward adaptation of the mandible. The tip back bends of the MEAW correct the premolars and molars to an upright position and intrude the molars. The correct treatment mechanics used are progressive tip back bends activations of 3º to 5º from the premolars teeth to molar area along with short class III elastics 3/16 inch , 6 oz) on the anterior teeth.

Figure 3 -The MEAW's are constructed with .016x.022 stainless steel (bracket 0.018 – inch

The arches have ideal arch form with five loops on each side of the arch.

**9.3.1. treatment steps of class III malocclusion**

\* Elimination of occlusal interferences

slot) or .017x.025 ss (bracket 0.022 – inch slot).

\* Establishig mandibular position

\* Occlusal plane reconstruction

\* Obtain a physiologic occlusion

 Figure 2 - The tip back bends of MEAW **Figure 2.** The tip back bends of MEAW

**\*** Levelling

#### *9.3.1. treatment steps of class III malocclusion*

**•** Levelling

**•** Labial tipping of maxillary teeth

450 Emerging Trends in Oral Health Sciences and Dentistry

**•** Skeletal frame is class III (APDI is more than 85)

to attain with the treatement of class III: **•** Elimination of the posterior crowding

6 oz) on the anterior teeth.

Figure 2 - The tip back bends of MEAW

\* Elimination of occlusal interferences

slot) or .017x.025 ss (bracket 0.022 – inch slot).

\* Establishig mandibular position

\* Occlusal plane reconstruction

\* Obtain a physiologic occlusion

**9.3.1. treatment steps of class III malocclusion**

**\*** Levelling

**Figure 2.** The tip back bends of MEAW

**9.3. Non-surgical treatment of class III malocclusion**

**•** ANB angle is negative

**•** flexion of the cranial base

**•** lower anterior teeth are inclined lingually (dento-alveolar compensation)

**•** To Rebuilt the occlusal plane (to steepen the upper posterior occlusal plane)

to molar area along with short class III elastics 3/16 inch, 6 oz) on the anterior teeth.

It is very important to understand the dynamic mechanism of the development of class III malocclusion to establish a correct treatment plan. In the development of class III malocclusion the key point is the molar over-eruption (due to the posterior crowding) which is responsible for the flatness of the upper posterior occlusal plane.The upper posterior flat occlusal plane produces a forward mandibular adaptation. According to this there are two significant goals

The posterior crowding is usually solved, by extraction of third molars prior to the onset of the treatment. The upper second molars can be extracted if the patient is young and the third molars are too high in the tuberosity. Before the decision to extract the upper second molars, the third molars should be radiographically evaluated to check if they have correct size and shape as well as appropriate position and inclination to erupt properly, replacing the extracted second molars. Another significant goal to attain with the treatment of class III is the recon‐ struction of the occlusal plane, because the class III malocclusion requires a steeper occlusal plane for backward adaptation of the mandible. The tip back bends of the MEAW correct the premolars and molars to an upright position and intrude the molars. The correct treatment mechanics used are progressive tip back bends activations of 3° to 5° from the premolars teeth

requires a steeper occlusal plane for backward adaptation of the mandible. The tip back

bends of the MEAW correct the premolars and molars to an upright position and intrude the

molars. The correct treatment mechanics used are progressive tip back bends activations of

Figure 3 -The MEAW's are constructed with .016x.022 stainless steel (bracket 0.018 – inch

The arches have ideal arch form with five loops on each side of the arch.

3º to 5º from the premolars teeth to molar area along with short class III elastics 3/16 inch , **Figure 3.** The MEAW's are constructed with.016x.022 stainless steel (bracket 0.018 – inch slot) or.017x.025 ss (bracket 0.022 – inch slot).

The arches have ideal arch form with five loops on each side of the arch.

## **10. Case report 1**

Patient female 13 years old and 3 months of age, with skeletal class III and dental class III on a normodivergent face pattern, mandibular prognathism, overbite (0 mm), overjet (0 mm), flat occlusal plane in the upper molar area producing interference in the posterior area. The patient began the treatment with 13 years old and 3 months and the duration of the treatment was 18 months. The type of appliance was an edgewise multi-bracket 0,022x0,028 slot, 0° torque, 0° angulation and MEAWs arch wires. The appliance was removed in January 2013 (14Y+11M).

The purpose of the treatment for this patient with class III malocclusion was to provide a steep occlusal plane in order to achive a posterior adaptative repositioning of the mandible, to correct the crowding and improve the occlusion by uprighting and alignment the dentition. First the impacted upper and lower third molars should be removed, but she refused. It was explained to the patient and the parents, that without the extractions the probability of relapse was high. It was then accepted to extract the teeth later, after the end of treatment.During the last control visit (one year after the end of treatment) the patient was informed that she should extract the third molars and she agreed.

The steps of the treatment:

a-Leveling; b-Elimination of occlusal interferences ; c-Establishing mandibular position ; d-Reconstruction of the occlusal plane; e-Achieving a physiological occlusion.

Step one-Levelling – The levelling was performed using 0.016 SS wire arches.

mandibular superposition shows a slight mandibular posterior shift.

Step two-Elimination of occlusal interferences-0,017x0,025 multiloop edgewise archs wire (MEAW) were incorporated in both dental arches. The alignment and intrusion began through progressive tipback of 3° to 5°,from premolars to the molar area along with the use of short class III (3/16 inch, 6oz) elastics on both sides. Step four/five - Reconstruction of the occlusal plane and achieving a physiological

Step three-Establishing mandibular position: At the end of this phase the molar occlusion was in class one. occlusion: In this step the tipback in molar area was removed and the occlusal plane in the molar area was steepen. A stable occlusion was obtained after 18 months of treatment the

Step four/five-Reconstruction of the occlusal plane and achieving a physiological occlusion: In this step the tipback in molar area was removed and the occlusal plane in the molar area was steepen. A stable occlusion was obtained after 18 months of treatment the retention phase was done with maxillary Hawley plate for night time use (6months) and bonded lingual wire from 33 to 43. retention phase was done with maxillary Hawley plate for night time use (6months) and bonded lingual wire from 33 to 43. Post-treatment results show an improved profile, occlusion and a pleasant smile. The intraoral photos show a class I molar relationship and a correct overbite and overjet. The

FMIA 67º+- 3 71 77 75 FMA 25º+- 3 27 28 28 IMPA 88º+- 3 82 75 77 SNA 82º+- 2 85 86 86 SNB 80º+- 2 85 84 84 ANB 2º-+ 2 0 2 2 Ao-Bo 2mm -2mm 3mm 3mm OP 10º-14º 6 5 5 Z 75º+-5 91 88 88 PFH 45mm 45 46 46 AFH 65mm 62 64 66 INDEX 0,69 0,73 0,72 0,70

Range Beginning End of treatment End of retention

 Figure 5- Pre-treatment extraoral (A - C) and intraoral (D - F) photographs **Figure 4.** Pre-treatment extraoral (A-C) and intraoral (D-F) photographs

Post-treatment results show an improved profile, occlusion and a pleasant smile. The intraoral photos show a class I molar relationship and a correct overbite and overjet. The mandibular superposition shows a slight mandibular posterior shift.

**Table 1.** Cephalometric analysis (Tweed-Merrifield)

impacted upper and lower third molars should be removed, but she refused. It was explained to the patient and the parents, that without the extractions the probability of relapse was high. It was then accepted to extract the teeth later, after the end of treatment.During the last control visit (one year after the end of treatment) the patient was informed that she should extract the

a-Leveling; b-Elimination of occlusal interferences ; c-Establishing mandibular position ; d-

Step two-Elimination of occlusal interferences-0,017x0,025 multiloop edgewise archs wire (MEAW) were incorporated in both dental arches. The alignment and intrusion began through progressive tipback of 3° to 5°,from premolars to the molar area along with the use of short

Step three-Establishing mandibular position: At the end of this phase the molar occlusion was

occlusion: In this step the tipback in molar area was removed and the occlusal plane in the molar area was steepen. A stable occlusion was obtained after 18 months of treatment the retention phase was done with maxillary Hawley plate for night time use (6months) and

Step four/five - Reconstruction of the occlusal plane and achieving a physiological

Step four/five-Reconstruction of the occlusal plane and achieving a physiological occlusion: In this step the tipback in molar area was removed and the occlusal plane in the molar area was steepen. A stable occlusion was obtained after 18 months of treatment the retention phase was done with maxillary Hawley plate for night time use (6months) and bonded lingual wire

Post-treatment results show an improved profile, occlusion and a pleasant smile. The intra-

oral photos show a class I molar relationship and a correct overbite and overjet. The

A B C

D E F

FMIA 67º+- 3 71 77 75 FMA 25º+- 3 27 28 28 IMPA 88º+- 3 82 75 77 SNA 82º+- 2 85 86 86 SNB 80º+- 2 85 84 84 ANB 2º-+ 2 0 2 2 Ao-Bo 2mm -2mm 3mm 3mm OP 10º-14º 6 5 5 Z 75º+-5 91 88 88 PFH 45mm 45 46 46 AFH 65mm 62 64 66 INDEX 0,69 0,73 0,72 0,70

Range Beginning End of treatment End of retention

Figure 5- Pre-treatment extraoral (A - C) and intraoral (D - F) photographs

**Figure 4.** Pre-treatment extraoral (A-C) and intraoral (D-F) photographs

mandibular superposition shows a slight mandibular posterior shift.

Reconstruction of the occlusal plane; e-Achieving a physiological occlusion.

Step one-Levelling – The levelling was performed using 0.016 SS wire arches.

third molars and she agreed.

452 Emerging Trends in Oral Health Sciences and Dentistry

class III (3/16 inch, 6oz) elastics on both sides.

bonded lingual wire from 33 to 43.

The steps of the treatment:

in class one.

from 33 to 43.

**Table 2.** Cephalometric analysis (Kim)

Beginning End of treatment End of retention

ODI MP/AB 60 60 60 60 60 60 FH/PP 0 0 0 APDI HF/FP 95 93 94 87 92 87 FP/AB -02 -05 -05 HF/PP 0 -2 0 CF ODI+APDI 153 147 147

Table 1- Cephalometric analysis (Tweed- Merrifield)

 Figure 6 – pre-treatment records (A-C) **Figure 5.** pre-treatment records (A-C)

Figure 7-Photos during the treatment (A –M) **Figure 6.** Photos during the treatment (A –M)

Non-Surgical Treatment of Class III with Multiloop Edgewise Arch-Wire (MEAW) Therapy http://dx.doi.org/10.5772/59257 455

 A B C D E F A B C

 Figure 8 –post-treatment extraoral (A-C) and intraoral (D-F) photos **Figure 7.** post-treatment extraoral (A-C) and intraoral (D-F) photos D E F

Table 1- Cephalometric analysis (Tweed- Merrifield)

Table 2- Cephalometric analysis ( Kim )

Figure 6 – pre-treatment records (A-C)

454 Emerging Trends in Oral Health Sciences and Dentistry

**Figure 5.** pre-treatment records (A-C)

Figure 7-Photos during the treatment (A –M)

**Figure 6.** Photos during the treatment (A –M)

Beginning End of treatment End of retention

A B C

A B C

D E F

G H I

J L M

ODI MP/AB 60 60 60 60 60 60 FH/PP 0 0 0 APDI HF/FP 95 93 94 87 92 87 FP/AB -02 -05 -05 HF/PP 0 -2 0 CF ODI+APDI 153 147 147

Figure 8 –post-treatment extraoral (A-C) and intraoral (D-F) photos

**Figure 8.** Post-treatment records (A-D),superimpositions (E-F)

Figure 9-Post-treatment records (A-D),superimpositions (E-F)

Figure 10- post-retention extra oral photos (A - C) and intraoral photos (D-F) **Figure 9.** post-retention extra oral photos (A-C) and intraoral photos (D-F) Figure 10- post-retention extra oral photos (A - C) and intraoral photos (D-F)

Figure 12- superimpositions (A- C)

**Case Report 2**

D E F

Figure 11- post-retention records (A – C) **Figure 10.** post-retention records (A – C)

Patient female (15 years old/10 months), with skeletal class III (ANB -2º , APDI 91 )and dental class III on a hypodivergent face pattern ( FMA 22º), mandibular prognathism, open bite tendency (ODI 55); overjet (0 mm), flat occlusal plane in the molar area producing

The z angle of 85º confirms an unbalanced face which is based on a prognathic chin.

According to Kym's analysis, the ODI (55º) indicates a openbite skeletal pattern. The APDI (91º).indicates a class III skeletal pattern and the CF (combination factor of 146) indicates a skeletal pattern requiring extraction of permanent teeth (third molars). The posterior

crowding was solved by extraction of third lower molars and upper second molars prior to the onset of the treatment. The upper second molars were extracted because the third molars were too high in the tuberosity. Before the decision to extract the upper second molars , the third molars were radiographically evaluated to check if they had correct size and shape as well as appropriate position and inclination to erupt properly, replacing the second

Treatment began with age (15/10), 0.016 ss arch wires were inserted for levelling and

After 2 months, the use of MEAW and short class III elastics (3/16 inch, 6 oz) started. The elastics were used 24 hours per day and were removed only for brushing the teeth and to eat. The correct treatment mechanic used was progressive tip back bends activations of 3º to

**Figure 11.** superimpositions (A-C)

interference in the posterior area.

alignment of both dental arches.

molars.

## **11. Case Report 2**

Figure 9-Post-treatment records (A-D),superimpositions (E-F)

456 Emerging Trends in Oral Health Sciences and Dentistry

Figure 9-Post-treatment records (A-D),superimpositions (E-F)

A B C

A B C

D E F

D E F

A B C

A B C

A B C

Patient female (15 years old/10 months), with skeletal class III (ANB -2º , APDI 91 )and dental class III on a hypodivergent face pattern ( FMA 22º), mandibular prognathism, open bite tendency (ODI 55); overjet (0 mm), flat occlusal plane in the molar area producing

The z angle of 85º confirms an unbalanced face which is based on a prognathic chin.

According to Kym's analysis, the ODI (55º) indicates a openbite skeletal pattern. The APDI (91º).indicates a class III skeletal pattern and the CF (combination factor of 146) indicates a skeletal pattern requiring extraction of permanent teeth (third molars). The posterior

crowding was solved by extraction of third lower molars and upper second molars prior to the onset of the treatment. The upper second molars were extracted because the third molars were too high in the tuberosity. Before the decision to extract the upper second molars , the third molars were radiographically evaluated to check if they had correct size and shape as well as appropriate position and inclination to erupt properly, replacing the second

Treatment began with age (15/10), 0.016 ss arch wires were inserted for levelling and

After 2 months, the use of MEAW and short class III elastics (3/16 inch, 6 oz) started. The elastics were used 24 hours per day and were removed only for brushing the teeth and to eat. The correct treatment mechanic used was progressive tip back bends activations of 3º to

Figure 10- post-retention extra oral photos (A - C) and intraoral photos (D-F)

Figure 10- post-retention extra oral photos (A - C) and intraoral photos (D-F)

Figure 11- post-retention records (A – C)

Figure 12- superimpositions (A- C)

**Case Report 2**

interference in the posterior area.

**Figure 11.** superimpositions (A-C)

alignment of both dental arches.

molars.

Figure 11- post-retention records (A – C) **Figure 10.** post-retention records (A – C)

**Figure 9.** post-retention extra oral photos (A-C) and intraoral photos (D-F)

Patient female (15 years old/10 months), with skeletal class III (ANB-2°, APDI 91)and dental class III on a hypodivergent face pattern (FMA 22°), mandibular prognathism, open bite tendency (ODI 55); overjet (0 mm), flat occlusal plane in the molar area producing interference in the posterior area. 5º from the premolars teeth to molar area along with short class III elastics ( 3/16 inch , 6 oz) on the anterior teeth. This treatment lasted 18 months. At the end of the treatment, the maxillofacial disharmony

The z angle of 85° confirms an unbalanced face which is based on a prognathic chin. and the profile were improved. The patient displayed a pleasant smile, a normal canine and

According to Kym's analysis, the ODI (55°) indicates a openbite skeletal pattern. The APDI (91°).indicates a class III skeletal pattern and the CF (combination factor of 146) indicates a skeletal pattern requiring extraction of permanent teeth (third molars). The posterior crowding was solved by extraction of third lower molars and upper second molars prior to the onset of the treatment. The upper second molars were extracted because the third molars were too high in the tuberosity. Before the decision to extract the upper second molars, the third molars were radiographically evaluated to check if they had correct size and shape as well as appropriate position and inclination to erupt properly, replacing the second molars. molar class I relationship, the overbite and overjet were corrected. The lower incisors were lingually tipped (IMPA 85º) and the lower molars were moved distally. The general superimposition shows that the entire lower dental arch was moved distally and uprighted. The final ODI of 63º show that the vertical aspect of the occlusion (open bite tendency) was improved. This case shows a successful orthodontic treatment of a skeletal class III

Treatment began with age (15/10), 0.016 ss arch wires were inserted for levelling and alignment of both dental arches. malocclusion, eliminating the posterior crowding and reconstructing the occlusal plane using the MEAW technique.

Figure 15 –Pre-treatment extraoral( A-B-C) and intraoral (D-E-F) photos **Figure 12.** Pre-treatment extraoral(A-B-C) and intraoral (D-E-F) photos

After 2 months, the use of MEAW and short class III elastics (3/16 inch, 6 oz) started. The elastics were used 24 hours per day and were removed only for brushing the teeth and to eat. The correct treatment mechanic used was progressive tip back bends activations of 3° to 5° from the premolars teeth to molar area along with short class III elastics (3/16 inch, 6 oz) on the anterior teeth.

This treatment lasted 18 months. At the end of the treatment, the maxillofacial disharmony and the profile were improved. The patient displayed a pleasant smile, a normal canine and molar class I relationship, the overbite and overjet were corrected.

The lower incisors were lingually tipped (IMPA 85°) and the lower molars were moved distally.

Figure 16 – Pre-treatment records (A-C) **Figure 13.** Pre-treatment records (A-C)

G H I

J L M

**Table 3.** Cephalometric analysis (Tweed-Merrifield)

The general superimposition shows that the entire lower dental arch was moved distally and uprighted.

the premolars teeth to molar area along with short class III elastics (3/16 inch, 6 oz) on the

This treatment lasted 18 months. At the end of the treatment, the maxillofacial disharmony and the profile were improved. The patient displayed a pleasant smile, a normal canine and

The lower incisors were lingually tipped (IMPA 85°) and the lower molars were moved

A B C

**Range Beginning End of treatment End of retention**

FMIA 67º+- 3 68 74 74 FMA 25º+- 3 22 21 22 IMPA 88º+- 3 90 85 84 SNA 82º+- 2 73 75 75 SNB 80º+- 2 75 74 74 ANB 2º-+ 2 -2 1 1 Ao-Bo 2mm -7mm -2mm -2mm OP 10º-14º 3 3 3 Z 75º+-5 85 80 81

A B C

D E F

G H I

J L M

molar class I relationship, the overbite and overjet were corrected.

Figure 16 – Pre-treatment records (A-C)

**Figure 13.** Pre-treatment records (A-C)

PFH 45mm AFH 65mm INDEX 0,69

**Table 3.** Cephalometric analysis (Tweed-Merrifield)

anterior teeth.

458 Emerging Trends in Oral Health Sciences and Dentistry

distally.

The final ODI of 63° show that the vertical aspect of the occlusion (open bite tendency) was improved. This case shows a successful orthodontic treatment of a skeletal class III malocclu‐ sion, eliminating the posterior crowding and reconstructing the occlusal plane using the MEAW technique.

Figure 17 - Photos during the treatment.(A-P) with MEAW upper and lower and short class **Figure 14.** Photos during the treatment.(A-P) with MEAW upper and lower and short class III elastics (6 oz, 3/16 inch).

FMIA 67º+- 3 68 74 74 FMA 25º+- 3 22 21 22

Range Beginning End of treatment End of retention

III elastics (6 oz, 3/16 inch).

AFH 65mm

IMPA 88º+- 3 90 85 84 SNA 82º+- 2 73 75 75 SNB 80º+- 2 75 74 74 ANB 2º-+ 2 -2 1 1 Ao-Bo 2mm -7mm -2mm -2mm OP 10º-14º 3 3 3

**Table 4.** cephalometric analysis (Kim) Table 4– cephalometric analysis (Kim)

Figure 18 – Post-treatment extraoral photos (A-C) and intraoral photos (D-F) **Figure 15.** Post-treatment extraoral photos (A-C) and intraoral photos (D-F)

A B

A B C

Figure 19 – Post-treatment records **Figure 16.** Post-treatment records

Figure 20 – superimpositions ( D – E)

Non-Surgical Treatment of Class III with Multiloop Edgewise Arch-Wire (MEAW) Therapy http://dx.doi.org/10.5772/59257 461

A B C

Figure 19 – Post-treatment records

Figure 20 – superimpositions ( D – E)

**Figure 17.** superimpositions (D – E)

**Beginning End of treatment End of retention**

FP/AB 4 2 2 90

63

90

D E F

A B C

67

92

63

67

92

Beginning End of treatment End of retention

FH/PP -5 -4 -4

ODI MP/AB 60 55 67 63 67 63 FH/PP -5 -4 -4 APDI HF/FP 92 91 92 90 92 90 FP/AB 4 2 2 HF/PP -5 -4 -4 CF ODI+APDI 146 153 153

A B C

Figure 18 – Post-treatment extraoral photos (A-C) and intraoral photos (D-F) **Figure 15.** Post-treatment extraoral photos (A-C) and intraoral photos (D-F)

A B

A B C

Figure 19 – Post-treatment records

**Figure 16.** Post-treatment records

Figure 20 – superimpositions ( D – E)

IMPA 88º+- 3 90 85 84 SNA 82º+- 2 73 75 75 SNB 80º+- 2 75 74 74 ANB 2º-+ 2 -2 1 1 Ao-Bo 2mm -7mm -2mm -2mm OP 10º-14º 3 3 3 Z 75º+-5 85 80 81

HF/PP -5 -4 -4 CF ODI+APDI 146 153 153

ODI

APDI

MP/AB 60

PFH 45mm AFH 65mm INDEX 0,69

460 Emerging Trends in Oral Health Sciences and Dentistry

HF/FP 92

**Table 4.** cephalometric analysis (Kim)

55

Table 3- Cephalometric analysis (Tweed- Merrifield)

91

Table 4– cephalometric analysis (Kim)

A B C

**Figure 18.** Post-retention extraoral photos (A-C) and intraoral photos (D-F)

Figure 21 – Post-retention extraoral photos (A-C) and intraoral photos (D-F)

D E

Figure 22- post-retention records (A –E)

A B C

Figure 21 – Post-retention extraoral photos (A-C) and intraoral photos (D-F)

D E F

**Figure 19.** post-retention records (A –E)

Figure 22- post-retention records (A –E)

#### **12. Conclusion**

The MEAW technique proved to be effective in the treatment of class III malocclusion. The MEAW is a valid alternative in the treatment of class III malocclusion, when patients refuse surgery and when the disharmony of the skeletal structure is not harsh. The MEAW used correctly can properly reconstruct the occlusal plane, allowing toachieve a correct and stable occlusion, improving the profil and facial balance.

## **Author details**

Paulo Beltrão\*

Address all correspondence to<EMAIL_ADDRESS>
French Board Of Orthodontics, Portugal

## **References**

A B C

Figure 21 – Post-retention extraoral photos (A-C) and intraoral photos (D-F)

D E

The MEAW technique proved to be effective in the treatment of class III malocclusion. The MEAW is a valid alternative in the treatment of class III malocclusion, when patients refuse surgery and when the disharmony of the skeletal structure is not harsh. The MEAW used correctly can properly reconstruct the occlusal plane, allowing toachieve a correct and stable

Figure 22- post-retention records (A –E)

occlusion, improving the profil and facial balance.

Address all correspondence to<EMAIL_ADDRESS>
French Board Of Orthodontics, Portugal

**Figure 19.** post-retention records (A –E)

462 Emerging Trends in Oral Health Sciences and Dentistry

**12. Conclusion**

**Author details**

Paulo Beltrão\*

D E F

A B C

## **Clinical Consideration and Management of Impacted Maxillary Canine Teeth**

Belma Işık Aslan and Neslihan Üçüncü

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59324

## **1. Introduction**

[14] Sato,Sadao; Akimoto (2007)-Development and orthodontic treatment of skeletal class III malocclusion without surgical intervention, The bulletin of kanagawa dental col‐

[15] Sato, Sadao(2001) –A treatment approach to malocclusions under the consideration

[16] Sato,Sadao (2008),orthodontic marathon course at Kanagawa dental college-Japan

lege,vol,35,n°1, March 2007

464 Emerging Trends in Oral Health Sciences and Dentistry

of craniofacial dynamics,Grace printing press, inc

Impaction is a retardation or halt in the normal process of tooth. There are various terminology in literature to define impaction including delayed eruption, primary retention, submerged teeth, impacted teeth ets. A canine is considered as being impacted if it is interrupted after complete root development or the contralateral tooth is erupted for at least 6 months with complete root formation [1].

Impaction of maxillary canines is a frequently encountered clinical problem. The cause of canine impaction can be the result of localized, systemic or genetic factor(s). There are a number of possible sequelae to canine impactions. The diagnosis and localization of the impacted canines is the most important step in the management of impacted canines based on clinical and radiographic examinations. Treatment of impacted maxillary canines usually requires an interdisciplinary approach. Treatment options include no treatment, interseptive approach, extraction, autotransplantation and surgical exposure and orthodontic alignment of the impacted canine. The most desirable treatment approach is early diagnosis and interception of potential impaction. However, in the absence of prevention, surgical exposure and ortho‐ dontic alignment should be considered. Surgical treatment techniques and orthodontic considerations depend on the location of the impacted canine in the dental arch.

## **2. Incidance of impacted canines**

Maxillary canines are the second-most frequently impacted teeth after the third molars [2] with prevalence from 0.8-5.2 % depending on the population examined [3,4]. The incidence of maxillary canine impaction is about 20 times more than mandibular canine impaction [5].

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Approximately one third of impacted maxillary canines are positioned labially or within the alveolus, and two thirds are located palatally [6]. In another study [7], Ericson and Kurol reported that, 50% of the 156 ectopically positioned canines were in a palatal or distopalatal position, 39% in a buccal or distobuccal position, and 11% apical to the adjacent incisor or between the roots of the central and lateral incisors. Maxillary canine impactions occur twice as often in females than in males [8] and only 8% of canine impactions are bilateral [9].

## **3. Developmental considerations**

Maxillary canines develop lateral to the priform fossa and have a longer and difficult path of eruption than any other tooth through they reach their final position in occlusion. Coulter and Richardson [10] stated that in three planes of space, maxillary canines travel almost 22 mm from their position at the age of 5 years to their position at 15 years. At the age of 3 maxillary canine is high in the maxilla, with its crown directed mesially and lingually. At the age of 8 it angulates medially with its crown lying distal and slightly buccal to the lateral incisor [11]. Also at this stage the canine normally migrates buccally from a position lingual to the root apex of its deciduous precursor, however, if it cannot make this transition from the palatal to the buccal side, it remains palatally impacted [12]. Maxillary canines follow a mesial path until it reaches the distal aspect of the lateral incisor root and gradually uprights to a more vertical position by moving towards the occlusal plane guided by the lateral incisor root. However, maxillary canines often erupt into the oral cavity with a marked mesial inclination [13]. If the lateral incisors are congenitally missing, the canine may erupt in a mesial direction until it comes into contact with the distal aspect of the central incisor root and erupts into the lateral incisor space [14]. Consequently, the roots of the lateral incisors play an important role in the guidance of upper permanent canines [15].

Table 1 shows the calcification and eruption timing of the maxillary canines according to Brand and Isselhard [16].

**Table 1.** Calcification and eruption timing of the maxillary canines

The mean eruption age for the maxillary canine is approximately 1 year earlier in females (10.98 years) than in males (11.69 years) [17]. Hurme [17] suggested that if maxillary canine has not appeared by the age of 13.1 in males or by 12.3 in females, the eruption may be considered late.

## **4. Etiology of impacted canines**

Eruption is a tightly coordinated process, regulated by a series of signaling effects between the dental follicle and the osteoblast and osteoclast cells found in the alveolar bone [18]. A wide variety of localized, systemic and genetic reasons may cause disruption in eruption process, ranging from delayed eruption to a complete failure of eruption [19]. Systemic reasons include endocrine deficiencies, febrile diseases, and irradiation. There is not only one etiology to explain the occurrence of a majority of impactions or either the localization of impaction occuring labially or palatally [20]. Environmental factors may cause impaction during the long, tortuous eruption path of a canine. The primary causes of impacted canines are localized conditions and result of one or a combination of following factors [21]:

Approximately one third of impacted maxillary canines are positioned labially or within the alveolus, and two thirds are located palatally [6]. In another study [7], Ericson and Kurol reported that, 50% of the 156 ectopically positioned canines were in a palatal or distopalatal position, 39% in a buccal or distobuccal position, and 11% apical to the adjacent incisor or between the roots of the central and lateral incisors. Maxillary canine impactions occur twice as often in females than in males [8] and only 8% of canine impactions are bilateral [9].

Maxillary canines develop lateral to the priform fossa and have a longer and difficult path of eruption than any other tooth through they reach their final position in occlusion. Coulter and Richardson [10] stated that in three planes of space, maxillary canines travel almost 22 mm from their position at the age of 5 years to their position at 15 years. At the age of 3 maxillary canine is high in the maxilla, with its crown directed mesially and lingually. At the age of 8 it angulates medially with its crown lying distal and slightly buccal to the lateral incisor [11]. Also at this stage the canine normally migrates buccally from a position lingual to the root apex of its deciduous precursor, however, if it cannot make this transition from the palatal to the buccal side, it remains palatally impacted [12]. Maxillary canines follow a mesial path until it reaches the distal aspect of the lateral incisor root and gradually uprights to a more vertical position by moving towards the occlusal plane guided by the lateral incisor root. However, maxillary canines often erupt into the oral cavity with a marked mesial inclination [13]. If the lateral incisors are congenitally missing, the canine may erupt in a mesial direction until it comes into contact with the distal aspect of the central incisor root and erupts into the lateral incisor space [14]. Consequently, the roots of the lateral incisors play an important role in the

Table 1 shows the calcification and eruption timing of the maxillary canines according to Brand

The mean eruption age for the maxillary canine is approximately 1 year earlier in females (10.98 years) than in males (11.69 years) [17]. Hurme [17] suggested that if maxillary canine has not appeared by the age of 13.1 in males or by 12.3 in females, the eruption may be considered late.

**3. Developmental considerations**

466 Emerging Trends in Oral Health Sciences and Dentistry

guidance of upper permanent canines [15].

 Calcification and eruption timing of the maxillary canines

and Isselhard [16].

If no physical barrier can be identified, the cessation of eruption of a normally placed and developed tooth germ before emergence is described as primary retention [28]. Generally genetic etiology is related with primary retention [29]. If the teeth becomes impacted due to an obstruction of the eruption pathway such as crowded dental arch, it is defined as secondary retention [28].

The etiology of impacted teeth may depend upon the location of impacted tooth. The exact etiology of palatally displaced maxillary canines is unknown yet hypothesized to be both multifactorial and genetic in origin [30]. Where as buccal canine impaction is result of ectopic migration of the canine crown over the root of the lateral incisor due to crowding or shifting of the maxillary dental midline, causing insufficient space for the canine to erupt [31].

Two main theories have been associated with the occurrence of palatally impacted maxillary canines: the "guidance theory" and the "genetic theory" [2]. According to the guidance theory, the presence of the lateral incisor root with right length and formed at the right time are important variables needed to guide the mesially erupting canine in a more favorable distal and incisal direction. If excessive space exists due to malformed or absent lateral incisor the canine would cross back from the buccal to the palatal side behind the buds of the other teeth [3]. In the clinical observation of Jacoby [32], he stated that 85% of the 40 palatally impacted canines had sufficient space for eruption in the dental arch. He claimed that labially impacted maxillary canine could only be due to arch length deficiency where as palatal impaction due to excessive space in the canine area. In accordance, Al-Nimri and Gharaibeh [33] stated that the presence of an excess palatal width and anomalous lateral incisor may contribute to the etiology of palatal canine impaction. They have also found that palatal canine impaction occurred most frequently in subjects with a Class II division 2 malocclusion. Conversely, McConnell [34] found transverse maxillary deficiency in palatally impacted canine cases. On the other hand, Langberg and Peck [35] observed no statistically significant difference in the anterior and posterior maxillary arch widths between subjects with palatally displaced canines and a comparison sample.

The genetic theory assigns genetic factors as the primary origin of the eruption anomaly of maxillary permanent canines. Palatally impacted canines, such as familial and bilateral occurrence, sex differences, are genetically associated with dental anomalies such as ectopic eruption of first molars, infraocclusion of primary molars, aplasia of premolars and one third molar [36]. Sacerdoti and Baccetti [38] showed that unilateral palatal canine displacement was associated with missing upper lateral incisors where as bilateral canine displacement with agenesis of third molars, indicating the genetic etiology of palatal canine displacement. Peck et al., [37] also found a positive correlation between palatally displaced canines and third molar agenesis.

## **5. Sequelae of canine impaction**

Careful observation of the development and eruption of canines during periodic dental examination of the growing child is essential to prevent potential complications. Shafer et al. [39] suggested the following sequelae for canine impaction:

## **6. Diagnosis of impacted canines**

The diagnosis and localization of the impacted canines is the most important step in the management of impacted canines based on clinical and radiographic examinations.

#### **6.1. Clinical evaluation**

migration of the canine crown over the root of the lateral incisor due to crowding or shifting of the maxillary dental midline, causing insufficient space for the canine to erupt [31].