in spite of the various benefits provided by orthodontic treatment , the retentive 
 surfaces of the appliance make them difficult to clean and are directly responsible for 
 food and biofilm accumulation
. imbalances such as gingivitis , gingival hyperplasia and 
 caries may occur during orthodontic treatment , especially when patients do not cooperate with regard 
 to performing the recommended cleaning protocols . in this context
, there is an increase 
 in the acidogenic bacterial populations , such as streptococcus mutans 
 and lactobacillus sp in the plaque and saliva .
the set 
 formed by retentive niches , added to the deficient oral hygiene and a diet rich in 
 fermentable carbohydrates also favors the increase in the candida 
 albicans population in the oral cavity , particularly if there is caries 
 activity .
there are reports in the literature that microorganisms of the oral microbiome adhere 
 firmly to resin materials .
it is also known that components present in the matrix of 
 adhesive materials may accelerate bacterial growth , increasing the levels of pathogens 
 extremely harmful to tissues . 

therefore , the ideal bonding material must be capable of withstanding salivary 
 biochemistry , constant changes in ph , different temperatures , and especially the 
 resident oral microbiota .
thus , the importance must be pointed out of maintaining 
 essential properties , such as : hardness , roughness and fluoride release capacity , since 
 these are intimately related to the retention of microorganisms and the maintenance of 
 oral health . in view of the biofilm - composite interaction , which is capable of 
 negatively altering the surfaces of materials for orthodontic bonding , these must have 
 adequate resistance and antimicrobial activity .
fluoridated bonding materials have been inserted outstandingly in orthodontics because 
 of their fluoride release capacity , irrespective of the patients ' cooperation . 
 nevertheless , it is important to point out that these materials are recommended as 
 supplementary to and not as substitutes for conventional prophylactic 
 alternatives , since their 
 anticariogenic capacity is still being widely discussed . in view of the context
presented , the aim of this study 
 was to evaluate the microbial inhibition capacity of three orthodontic bonding 
 materials , and their fluoride release in vitro .
thus , the hypothesis 
 considered in the present study was that bonding materials play a biological influence 
 to orthodontic treatment outcomes .
the capacity of the material to release fluoride and 
 prevent microbial contamination can be noted in the prevention and maintenance of the 
 integrity of the oral tissues .
to conduct the study , three materials extensively applied in bonding orthodontic 
 accessories were selected : transbond xt ( xt group ) , a traditional light 
 cure adhesive ( 3 m unitek , monrovia , ca , usa ) , transbond plus color 
 change ( plus group ) , a moisture tolerant light cure adhesive ( 3 m unitek , monrovia , 
 ca , usa ) and fuji ortho lc ( fuji group ) , a resin reinforced glass 
 ionomer cement ( gc america corporation , tokyo , japan ) ( figure 1 ) . for fabricating the specimens with standardized 
 dimensions , a prefabricated teflon matrix with perforations measuring 5 mm in 
 diameter and 2 mm in thickness was used .
the materials were manipulated in accordance 
 with the manufacturers ' instructions and then inserted into the matrix in a single 
 increment , applying the pressure required for producing specimens with smooth 
 surfaces ( figure 2 ) .
light polymerization was 
 performed for 40 seconds on each surface , using a halogen light with 550 
 mw / cm ( foto optilight ld max , gnatus - 50/60 hz , ribeiro preto , sp , 
 brazil ) , with the active tip of the equipment touching directly on the glass 
 slides .
groups of materials used in the study and their respective chemical 
 compositions , in accordance with the manufacturers ' specifications sequence of specimen preparation : ( a ) devices used for fabrication ( teflon 
 matrix , polyester strip and glass slide ) ; ( b ) specimen surfaces with smoothness 
 and mirror brightness obtained immediately after removal from the matrix microbiologic analyses were performed in two stages .
firstly , the antimicrobial 
 activity of the materials was evaluated by means of spectrophotometry ( quantitative 
 aspect ) . for this ,
18 specimens were prepared , divided in duplicate for each tested 
 microorganism . with regard to the qualitative aspect of analyses , after fabricating one control 
 specimen for each material ( baseline ) , the initial surface ( contamination - free ) 
 record
after evaluation on the 
 spectrophotometer , one specimen per microorganism was randomly selected from each 
 group , to be submitted to a sem analysis to verify microbial growth on its surfaces 
 after contamination , and therefore , the inherent antimicrobial potential of each 
 material . for each specimen evaluated by the sem , various images were obtained in 
 order to contemplate a large scanning area .
the following strains were used in the experiment : s. mutans ( atcc 
 25175 ) , l. casei ( atcc 4646 ) and c. albicans ( atcc 
 10231 ) , kept in bhi broth ( brain heart infusion , himedia , so paulo , sp , brazil ) . 

initially , the bhi broth contaminated with the microorganisms of choice ( positive 
 control ) was placed into 24 well plates , interspersed with wells containing sterile 
 medium ( negative control ) and inoculated medium in conjunction with the specimens 
 that would have their antimicrobial capacity tested .
the quantity of cells in the 
 experiment was standardized in order to attain the desired concentration of 
 5x10 cells 
 per well ( 500 l ) .
the plates were incubated in an oven at 37c , 
 and the plate with s. mutans , was placed in an anaerobic jar .
after 
 24 h , the optical density ( od ) readout of each well was taken , starting by 
 calibrating the spectrophotometer to 550 nm ( beckman coulter du 530 
 spectrophotometer , fullerton , ca , usa ) by taking the sterile medium readout . the 
 inoculated medium readout consisted of the positive control of growth for each 
 microorganism .
to obtain the percentage of microbial growth inhibition of the different groups 
 studied , the following equation was used , with : ( m ) mean of optical 
 densities of each material tested ; ( c ) positive control of growth : % 
 growth inhibition = 100-(m / c)x100 .
in addition to quantifying the antimicrobial activity by spectrophotometry , the 
 specimens were analyzed by sem , in order to visualize the microbial proliferation on 
 the surface of each studied material . to obtain the initial record of the material 
 surfaces ( baseline ) , one specimen from each group was prepared on aluminum stubs , and 
 gold sputtered for examination by scanning electron microscopy ( jeol - jsm ; 5800lv , 
 tokyo , japan ) .
a voltage of 30 kv and low vacuum mode ( 45 pa ) was used . immediately 
 after the quantitative analysis of the antimicrobial activity
, one specimen 
 per microorganism from each group was randomly selected and fixed 
 stored in 2.5% glutaraldehyde and 0.1 m cacodylate buffer .
after 2 h , the specimens 
 were removed , washed with pbs ( phosphate buffered saline ) solution and dried .
next , 
 they were gold sputtered to obtain the final records under conditions similar to the 
 initial ones .
various records of each specimen were obtained with the goal of 
 extensive scanning of the surface .
6 specimens were prepared for each group ( xt , 
 plus , fuji ) , totaling 18 specimens .
after each specimen was removed from the teflon 
 matrix , its base and lateral surfaces were sealed with sticky wax , and it was 
 adequately identified , thus only the surface area of 19.62 mm remained 
 exposed . for each specimen ,
15 tubes of the eppendorf type , previously 
 washed for ionic decontamination , were filled with 1.5 ml of ultrapure water .
the 
 eppendorf tubes corresponded to the 15 predetermined time intervals of 
 fluoride release , with variation from 1 hour to the 14 day , identified 
 as follows : 1 h , 1 d , 2 d , 3 d , 4 d , 5 d , 6 d , 7 d , 8 d , 9 d , 10 d , 11 d , 12 d , 13 d 
 and 14 d. during this cycle , the tubes were kept in a microbiologic oven at 37c , 
 separately in receptacles which were named xt , plus and fuji .
the daily time when the specimens were moved into their new tubes was standardized . 

the specimens were manipulated with tweezers and they had been delicately dried with 
 absorbent paper before they were reinserted into the sequence of the cycle . as the 
 changes occurred , the solutions in which the specimens had been immersed were sent 
 for laboratory analysis .
it should be pointed out that the ultrapure water was the 
 renewed vehicle , since the same specimen was kept from the beginning to the end of 
 the experiment .
the purpose of this was to identify the daily fluoride release 
 capacity , by exhaustion of this same material throughout the cycle . during the 
 experiment , no ionic supplement
the ultrapure water was 
 renewed in an attempt to eliminate any possible saturation of the medium .
this study generated a total of 270 accumulated fluoride release readouts , performed 
 by ion chromatography ( dx 80 ion analyzer , dionex , sunnyvale , ca , usa ) , in order to 
 perform the separation and determination of fluoride content in each solution .
before 
 the readouts , the ion chromatograph was calibrated with 5 specific patterns , these 
 being : 1- ultrapure water ; 2- pattern 1 ( f concentration=0.02 mg / l ) ; 3- 
 pattern 2 ( f concentration=0.2
the 
 data obtained were transferred and processed by an integrator , automatic module 
 dionex 4400 that promotes complete automation of the system .
the time that elapsed 
 for specific determination of the desired ion was approximately 12 minutes for each 
 1.5 ml sample of ultrapure water .
the percentage of growth inhibition data for each specimen of the xt , plus and fuji 
 groups obtained in the microbiologic analysis , as well as the fluoride release tests , 
 were submitted to the analysis of variance anova and tukey test in the spss 17.0 
 software ( statistical package for social sciences , spss inc . ,
the 
 difference between the means was considered significant when values of p<0.05 were 
 obtained .
to conduct the study , three materials extensively applied in bonding orthodontic 
 accessories were selected : transbond xt ( xt group ) , a traditional light 
 cure adhesive ( 3 m unitek , monrovia , ca , usa ) , transbond plus color 
 change ( plus group ) , a moisture tolerant light cure adhesive ( 3 m unitek , monrovia , 
 ca , usa ) and fuji ortho lc ( fuji group ) , a resin reinforced glass 
 ionomer cement ( gc america corporation , tokyo , japan ) ( figure 1 ) . for fabricating the specimens with standardized 
 dimensions , a prefabricated teflon matrix with perforations measuring 5 mm in 
 diameter and 2 mm in thickness was used .
the materials were manipulated in accordance 
 with the manufacturers ' instructions and then inserted into the matrix in a single 
 increment , applying the pressure required for producing specimens with smooth 
 surfaces ( figure 2 ) .
light polymerization was 
 performed for 40 seconds on each surface , using a halogen light with 550 
 mw / cm ( foto optilight ld max , gnatus - 50/60 hz , ribeiro preto , sp , 
 brazil ) , with the active tip of the equipment touching directly on the glass 
 slides .
groups of materials used in the study and their respective chemical 
 compositions , in accordance with the manufacturers ' specifications sequence of specimen preparation : ( a ) devices used for fabrication ( teflon 
 matrix , polyester strip and glass slide ) ; ( b ) specimen surfaces with smoothness 
 and mirror brightness obtained immediately after removal from the matrix
firstly , the antimicrobial 
 activity of the materials was evaluated by means of spectrophotometry ( quantitative 
 aspect ) . for this ,
18 specimens were prepared , divided in duplicate for each tested 
 microorganism . with regard to the qualitative aspect of analyses , after fabricating one control 
 specimen for each material ( baseline ) , the initial surface ( contamination - free ) 
 record
after evaluation on the 
 spectrophotometer , one specimen per microorganism was randomly selected from each 
 group , to be submitted to a sem analysis to verify microbial growth on its surfaces 
 after contamination , and therefore , the inherent antimicrobial potential of each 
 material .
for each specimen evaluated by the sem , various images were obtained in 
 order to contemplate a large scanning area .
the following strains were used in the experiment : s. mutans ( atcc 
 25175 ) , l. casei ( atcc 4646 ) and c. albicans ( atcc 
 10231 ) , kept in bhi broth ( brain heart infusion , himedia , so paulo , sp , brazil ) . 

initially , the bhi broth contaminated with the microorganisms of choice ( positive 
 control ) was placed into 24 well plates , interspersed with wells containing sterile 
 medium ( negative control ) and inoculated medium in conjunction with the specimens 
 that would have their antimicrobial capacity tested .
the quantity of cells in the 
 experiment was standardized in order to attain the desired concentration of 
 5x10 cells 
 per well ( 500 l ) .
the plates were incubated in an oven at 37c , 
 and the plate with s. mutans , was placed in an anaerobic jar .
after 
 24 h , the optical density ( od ) readout of each well was taken , starting by 
 calibrating the spectrophotometer to 550 nm ( beckman coulter du 530 
 spectrophotometer , fullerton , ca , usa ) by taking the sterile medium readout . the 
 inoculated medium readout consisted of the positive control of growth for each 
 microorganism . to obtain the percentage of microbial growth inhibition of the different groups 
 studied ,
the following equation was used , with : ( m ) mean of optical 
 densities of each material tested ; ( c ) positive control of growth : % 
 growth inhibition = 100-(m / c)x100 .
in addition to quantifying the antimicrobial activity by spectrophotometry , the 
 specimens were analyzed by sem , in order to visualize the microbial proliferation on 
 the surface of each studied material . to obtain the initial record of the material 
 surfaces ( baseline ) , one specimen from each group
was prepared on aluminum stubs , and 
 gold sputtered for examination by scanning electron microscopy ( jeol - jsm ; 5800lv , 
 tokyo , japan ) . a voltage of 30 kv and low vacuum mode ( 45 pa ) was used . immediately 
 after the quantitative analysis of the antimicrobial activity ,
one specimen 
 per microorganism from each group was randomly selected and fixed 
 stored in 2.5% glutaraldehyde and 0.1 m cacodylate buffer .
after 2 h , the specimens 
 were removed , washed with pbs ( phosphate buffered saline ) solution and dried .
next , 
 they were gold sputtered to obtain the final records under conditions similar to the 
 initial ones .
various records of each specimen were obtained with the goal of 
 extensive scanning of the surface .
for the fluoride release analysis , 6 specimens were prepared for each group ( xt , 
 plus , fuji ) , totaling 18 specimens . after each specimen
was removed from the teflon 
 matrix , its base and lateral surfaces were sealed with sticky wax , and it was 
 adequately identified , thus only the surface area of 19.62 mm remained 
 exposed . for each specimen ,
15 tubes of the eppendorf type , previously 
 washed for ionic decontamination , were filled with 1.5 ml of ultrapure water .
the 
 eppendorf tubes corresponded to the 15 predetermined time intervals of 
 fluoride release , with variation from 1 hour to the 14 day , identified 
 as follows : 1 h , 1 d , 2 d , 3 d , 4 d , 5 d , 6 d , 7 d , 8 d , 9 d , 10 d , 11 d , 12 d , 13 d 
 and 14 d. during this cycle , the tubes were kept in a microbiologic oven at 37c , 
 separately in receptacles which were named xt , plus and fuji .
the daily time when the specimens were moved into their new tubes was standardized . 

the specimens were manipulated with tweezers and they had been delicately dried with 
 absorbent paper before they were reinserted into the sequence of the cycle .
as the 
 changes occurred , the solutions in which the specimens had been immersed were sent 
 for laboratory analysis .
it should be pointed out that the ultrapure water was the 
 renewed vehicle , since the same specimen was kept from the beginning to the end of 
 the experiment .
the purpose of this was to identify the daily fluoride release 
 capacity , by exhaustion of this same material throughout the cycle . during the 
 experiment , no ionic supplement
the ultrapure water was 
 renewed in an attempt to eliminate any possible saturation of the medium .
this study generated a total of 270 accumulated fluoride release readouts , performed 
 by ion chromatography ( dx 80 ion analyzer , dionex , sunnyvale , ca , usa ) , in order to 
 perform the separation and determination of fluoride content in each solution . before 
 the readouts ,
the ion chromatograph was calibrated with 5 specific patterns , these 
 being : 1- ultrapure water ; 2- pattern 1 ( f concentration=0.02 mg / l ) ; 3- 
 pattern 2 ( f concentration=0.2
the 
 data obtained were transferred and processed by an integrator , automatic module 
 dionex 4400 that promotes complete automation of the system .
the time that elapsed 
 for specific determination of the desired ion was approximately 12 minutes for each 
 1.5 ml sample of ultrapure water .
the percentage of growth inhibition data for each specimen of the xt , plus and fuji 
 groups obtained in the microbiologic analysis , as well as the fluoride release tests , 
 were submitted to the analysis of variance anova and tukey test in the spss 17.0 
 software ( statistical package for social sciences , spss inc . ,
the 
 difference between the means was considered significant when values of p<0.05 were 
 obtained .
table 1 shows the results obtained in the 
 microbiologic test , specifying the activity of the materials in relation to the 
 microorganisms analyzed , with respect to the microbial growth and inhibition .
results of microbiologic analysis of specimens , specifying : mean optical 
 densities ( od ) of positive controls for each group of microorganisms ( od 
 control ) , values obtained in duplicate for each material tested ( od1 , od2 ) , 
 mean and standard deviation ( sd ) , and percentage of microbial growth inhibition 
 ( % ) different letters express statistically significant values ( p<0.05 ) , 
 being a > b > c   to evaluate the microbiologic action of materials against s. mutans 
 and l. casei , it was shown that only the plus presented a 
 significant reduction in growth ( p<0.05 ) . with regards to action against 
 c. albicans , the materials showed significant differences among 
 them ( p<0.05 ) , with emphasis on the plus , since it was the material that presented 
 significant inhibition potential against the fungus ( p<0.001 ) .
the sem photomicrographs shown in figure 3 ( 1a , 
 2a , 3a ) reveal the images of the negative control specimen surfaces from the xt , plus 
 and fuji groups , respectively .
images 1b and 3b denote s. mutans 
 growth on xt and fuji specimens , in this order . visually , the greatest microbial 
 growth occurred in the fuji group ( 3b ) , whereas the plus group was found to have a 
 contamination - free surface ( 2b ) , which also occurred in image 2c , in which no 
 l. casei was observed on the surface of the specimen from the 
 plus group .
images 1c ( xt ) and 3c ( fuji ) also point out microbial growth , which was 
 more expressive in the fuji group .
lastly , it is possible to visualize great 
 c. albicans proliferation on the fuji surface ( 3d ) , followed by 
 xt ( 1d ) and plus ( 2d ) , although insignificantly on the latter .
scanning electron microscopy photomicrographs showing the surfaces of tested 
 materials : ( 1 ) xt group , ( 2 ) plus group and ( 3 ) fuji group ( columns ) ; ( a ) 
 baseline , negative control , ( b ) s.mutans , ( c ) 
 l.casei and ( d ) c.albicans ( lines ) the fluoride release data during the 14 days of the experiment are shown in table 2 , and are expressed comparatively in 
 figure 4 .
one observes that the fuji was the 
 most outstanding material for fluoride release , especially in the first 24 hours , 
 followed by the plus and xt , respectively .
although the latter characteristically 
 does not release fluoride , the rates found were very low and insignificant , being 
 directly related to the accuracy of the technique .
on the tenth day of the cycle , the 
 values obtained for the fuji and plus were similar ( p>0.05 ) .
mean * ( standard deviation ) of fluoride release in ppm of the bonding materials 
 ( n=6 ) during the 15 time intervals * means followed by different letters differ statistically at the level of 
 significance of 0.05 ( comparison in column for the same time analyzed , being 
 a > b > c ) .  
quantity of fluoride in ppm released by each material during the time intervals 
 evaluated throughout the study
table 1 shows the results obtained in the 
 microbiologic test , specifying the activity of the materials in relation to the 
 microorganisms analyzed , with respect to the microbial growth and inhibition .
results of microbiologic analysis of specimens , specifying : mean optical 
 densities ( od ) of positive controls for each group of microorganisms ( od 
 control ) , values obtained in duplicate for each material tested ( od1 , od2 ) , 
 mean and standard deviation ( sd ) , and percentage of microbial growth inhibition 
 ( % ) different letters express statistically significant values ( p<0.05 ) , 
 being a > b > c   to evaluate the microbiologic action of materials against s. mutans 
 and l. casei , it was shown that only the plus presented a 
 significant reduction in growth ( p<0.05 ) . with regards to action against 
 c. albicans , the materials showed significant differences among 
 them ( p<0.05 ) , with emphasis on the plus , since it was the material that presented 
 significant inhibition potential against the fungus ( p<0.001 ) .
the sem photomicrographs shown in figure 3 ( 1a , 
 2a , 3a ) reveal the images of the negative control specimen surfaces from the xt , plus 
 and fuji groups , respectively .
images 1b and 3b denote s. mutans 
 growth on xt and fuji specimens , in this order . visually , the greatest microbial 
 growth occurred in the fuji group ( 3b ) , whereas the plus group was found to have a 
 contamination - free surface ( 2b ) , which also occurred in image 2c , in which no 
 l. casei was observed on the surface of the specimen from the 
 plus group . images 1c ( xt ) and 3c ( fuji ) also point out microbial growth , which was 
 more expressive in the fuji group .
lastly , it is possible to visualize great 
 c. albicans proliferation on the fuji surface ( 3d ) , followed by 
 xt ( 1d ) and plus ( 2d ) , although insignificantly on the latter .
scanning electron microscopy photomicrographs showing the surfaces of tested 
 materials : ( 1 ) xt group , ( 2 ) plus group and ( 3 ) fuji group ( columns ) ; ( a ) 
 baseline , negative control , ( b ) s.mutans , ( c ) 
 l.casei and ( d ) c.albicans ( lines )
the fluoride release data during the 14 days of the experiment are shown in table 2 , and are expressed comparatively in 
 figure 4 .
one observes that the fuji was the 
 most outstanding material for fluoride release , especially in the first 24 hours , 
 followed by the plus and xt , respectively .
although the latter characteristically 
 does not release fluoride , the rates found were very low and insignificant , being 
 directly related to the accuracy of the technique .
on the tenth day of the cycle , the 
 values obtained for the fuji and plus were similar ( p>0.05 ) .
mean * ( standard deviation ) of fluoride release in ppm of the bonding materials 
 ( n=6 ) during the 15 time intervals * means followed by different letters differ statistically at the level of 
 significance of 0.05 ( comparison in column for the same time analyzed , being 
 a > b > c ) .  
quantity of fluoride in ppm released by each material during the time intervals 
 evaluated throughout the study
there has been much discussion about the maintenance of the oral health in patients 
 submitted to orthodontic treatment , such as the formation of initial caries lesions , 
 which even today , is a potential risk . in a study recently conducted with 230 
 individuals ,
71.7% developed from 1 to 12 white spot lesions at the end of treatment , 
 and 69.8% presented adequate oral hygiene conditions at the beginning of orthodontic 
 therapy .
these data are 
 indicative of the importance of instituting a good preventive program in these patients
. 
 should there be clinical signs of disease progression , efforts must be redoubled in an 
 attempt to revert the situation of demineralization .
thus , it is possible to use 
 materials that have fluoride in their composition , with the purpose of helping to 
 prevent caries development .
nevertheless , the action of fluoride as an antibacterial 
 agent is still widely discussed , in spite of it clearly having remineralization 
 potential .
the results obtained demonstrated the greater efficacy of the transbond 
 plus color change as an antimicrobial material , since it showed the best percentages of 
 growth inhibition for all the species evaluated .
the fuji ortho lc 
 presented the most unfavorable result with regards to antimicrobial capacity , however , 
 it showed the greatest fluoride release , which raises questions about the direct 
 relationship of fluoride with microbial growth inhibition . if only fluoride release was 
 responsible for the antimicrobial potential of the material , the fuji , which released 
 the most fluoride in comparison with the other groups with regards to antimicrobial 
 activity , which was not demonstrated in the findings of this research .
( 2009 ) in their study , concluded that there is greater microbial adherence to the 
 surfaces of the bonding materials than to the orthodontic appliance accessories , and 
 associated this fact with the free surface energy of these materials .
greater adhesion 
 of s. mutans to the fuji ortho lc was also found than on 
 the composites , corroborating the quantitative and qualitative findings of the study .
it 
 is also known that the surface roughness of materials is directly proportional to the 
 increase in microbial adhesion .
therefore , the fact that glass ionomer 
 cement is a material with low resistance and greater roughness , when compared with 
 composites , also justifies the behavior of the fuji in the present study . with regard to 
 chemical composition
, the fuji ortho lc contains the co - monomer tegdma , 
 described in the literature as being capable of stimulating microbial 
 proliferation .
authors have described the main characteristics of ionomer materials as being 
 anticariogenic and having antimicrobial properties .
the former , is directly related to 
 the preventive and remineralizing potential of fluoride , whereas the latter is 
 associated with the presence of fluoride and aluminum .
however , in this study , neither the fluoride nor 
 aluminum of the fuji ortho lc was shown to be efficient in contributing to 
 microbial reduction and adhesion on its surface .
this denotes the prevalence of the 
 other previously described aspects of these possible benefits .
factors such as the initial ph of the material , hydrophobicity and chemical substances 
 released are also related to antimicrobial activity .
( 2006 ) studied the hydrophobicity of 
 some orthodontic bonding materials , among them the transbond xt and fuji 
 ortho lc , both demonstrating similar hydrophobicity values , and 
 representing the most expressive values in the study .
( 2009 ) , who observed that 
 both the transbond xt and fuji ortho lc exercised no 
 antimicrobial activity , with the fuji having shown the greatest microbial proliferation , 
 corroborating the findings of the present study .
although the cytotoxicity of the material may be related to microbial growth inhibition , 
 it can not be taken as the only justification for the results found in this research , 
 because all the materials tested released substances such as bisphenol a , bis - ema , 
 egdma , tegdma , hema , among others , capable of promoting adverse biologic 
 reactions .
therefore , it would not be conclusive to attribute the 
 bests results found for the plus exclusively to cytotoxicity .
with respect to fluoride release , the majority of studies with the goal of quantifying 
 it use the ion - selective electrode in their methodology , since there is 
 a scarcity of the use of ion chromatography in the literature to proceed with such an 
 analysis .
this technique is frequently used when one desires to obtain the other 
 components in the sample , because of its efficient ion detector system . in the present 
 study ,
the chosen methodology for measuring fluoride ions was shown to be adequate and 
 to have excellent precision because it determined anions and cations at trace 
 levels . during the 15 time intervals of analysis for fluoride quantification ,
in addition to the 
 classic increase in release in the 24 h , there were some moments of slight increase in fluoride release , but 
 no continually decreasing release was verified with the passage of the time considered 
 ( figure 4 ) .
reduction in the quantity of 
 fluoride is explained by the fact that the components of the external layer of the 
 material became exhausted , and were dissolved in the water . with regard to the plus 
 group , the release of fluoride contained within the matrix is a little limited by the 
 resin components that make it difficult to displace . however , since the matrix of the 
 fuji is more sensitive to hydration , there is less limitation of ion 
 displacement .
this justifies 
 the higher values in this group , as well as the more recurrent peaks , in spite of it 
 having been equivalent to the plus on the 10 day of the cycle .
it is possible to associate the initial fluoride release from the surface and the later 
 release from the subsurface of the material matrix .
the initial analog being a 
 " superficial washing " , whereas the release afterwards , said to be late , is allowed 
 through the micropores and from the matrix of the material itself .
other studies have also verified a small quantity of fluoride detectible in the 
 transbond xt , and the better performance of the fuji ortho 
 lc when compared with the transbond plus color change .
the greater fluoride 
 release from resin - modified glass ionomer cements ( rmgic ) is attributed to the acid - base 
 reaction between the aluminosilicate glass powder containing fluoride and polyacid 
 liquid , which results in the release of fluoride ions .
the porosity of 
 the material also has a strong relationship with the quantity of fluoride released , and 
 the greater fluoride release by the fuji in comparison with the composites is therefore 
 justifiable .
( 2011 ) observed that rmgics 
 tend to have greater fluoride ion release and recharge capacity , and these ions 
 penetrate precisely into the spaces previously occupied by the fluoride that was 
 released .
it is important to emphasize that the process of matrix erosion is directly 
 related to the diffusion of ions and fluoride release . in spite of the more expressive fluoride release occurring in the first few hours
, one 
 could attribute the rapid formation of calcium fluoride on the enamel surface to this 
 factor , which is of clinical importance in protecting the tooth against 
 demineralization . in a previous study by gorton and featherstone ( 2003 )
, it was proved that irrespective 
 of the antimicrobial potential , the fluoride contained in the fuji ortho 
 lc , used for the bracket bonding , was capable of promoting a cariostatic effect 
 in vivo , when compared with the transbond xt . in view of the above discussion
, the presence of fluoride available to patients 
 submitted to orthodontic treatment is of extreme importance in preventing the appearance 
 of caries lesions , highlighting the 
 bonding material capable of exercising this function . in a similar manner ,
the interesting factor with regards to the 
 antimicrobial activity of the material also refers to the protection against its surface 
 degradation .
the material capable of reducing microbial growth , and particularly 
 microorganism adhesion on its surface , is able to prevent a cycle of deterioration , 
 since bacterial growth on the material is capable of increasing its roughness and 
 accelerating biofilm accumulation .
this study supports the hypothesis that bonding materials can contribute positively to 
 orthodontic treatment outcomes , with an essential role in the maintenance of health and 
 balance in the oral cavity .
the importance is emphasized of the material being able to 
 withstand microbial attacks in order to maintain its integrity and that of the adjacent 
 tissues . in this respect ,
the transbond plus color change was outstanding 
 among the others , and the fuji ortho lc presented less satisfactory 
 results .
however , with regard to the fluoride release capacity , the fuji group 
 guaranteed more expressive results , emphasizing its relevant role in anticariogenic 
 activity .
therefore , one must consider that there is no ideal material , and the choice 
 should be based on scientific findings and clinical experience , respecting the 
 individuality of each case .
 objectivethe aim of this study was to evaluate the antimicrobial and fluoride releasing 
 capacity of 3 bonding materials.material and methodsthirty nine specimens with standardized surface smoothness and dimensions were 
 prepared . 
 the antimicrobial capacity of the materials against s. mutans , 
 l. casei and c. albicans was evaluated by determining 
 the percentage of growth inhibition of these microorganisms in an inoculated 
 medium , obtained by optical density readouts on a spectrophotometer . 
 the potential 
 to interfere in microbial growth on the surface of the studied materials was 
 observed by means of scanning electron microscopy ( sem ) . 
 the fluoride release 
 capacity in ultrapure water for 14 days was analyzed by means of ion 
 chromatography . 
 resultsthe plus group presented the highest percentage of microbial inhibition and the 
 most contamination - free surface . 
 the fuji group presented the best fluoride 
 release capacity.conclusionsthe transbondtm plus color change was the one that presented the best 
 general behavior considering the evaluated aspects . 
INTRODUCTION
MATERIAL AND METHODS
Preparation of specimens
Microbiologic test
Quantitative analysis of antimicrobial activity
Qualitative analysis of antimicrobial activity
Fluoride release analysis
Statistical analysis
RESULTS
Quantitative analysis of antimicrobial activity
Qualitative analysis of antimicrobial activity
Fluoride release analysis
DISCUSSION
CONCLUSION