the carious process usually progresses as a series of exacerbations and remissions that are characterized by periods of high production of acid that are responsible for the dissolution of the hard tissues of the tooth . if allowed to proceed untreated , it results in the progressive destruction of the tooth and eventual infection of the dental pulp .
carious dentin has been identified by two layers of soft dentin , the outer carious layer is infected unremineralizable with irreversible deteriorated collagen fibers , with no odontoblastic processes , insensitive and therefore , should be removed .
the inner carious layer is uninfected , remineralizable with reversibly denatured collagen fibers , alive with living odontoblastic processes , sensitive , and so should be preserved .
caries detector dyes have been developed to further help the diagnosis and removal of dental caries , by differentiating between infected and affected dentin .
the dye stains only the infected outer carious dentin.[24 ] dye usage allows dentists to perform an ideal cavity preparation for adhesive restorations . to ensure that all carious dentin has been removed , use of dye is indicated as the last step in tooth preparation .
the bonding mechanism for current adhesive agents is based on the acid removal of the smear layer and demineralization of the underlying dentin , which leaves an exposed collagen network .
the application of hydrophilic primers followed by the adhesive , which encapsulate this collagen network and form a resin impregnated layer or hybrid layer .
few reports are available in literatures regarding the effect of caries detection dye on the bond strength of sound and carious affected dentin .
the present study has been designed to evaluate the influence of caries detection dye on the in - vitro tensile bond strength of adhesive materials to sound and carious affected dentin .
materials along with their composition used in the present study are summarized in table 1 .
materials and their composition used in the study forty freshly extracted ( both carious and non - carious ) human mandibular molar teeth were selected for this study .
the samples were stored in normal saline at room temperature until they were subjected to the experimental procedure . for carious affected dentin
, twenty samples with coronal caries extending approximately halfway through the dentin were used in this study .
the buccal carious surface was ground parallel to the long axis of the tooth to expose a flat surface of normal dentin surrounding the carious lesion .
the buccal enamel was grinded with the help of carborundum disc , made smoothened by the sand paper ( silicon carbide , 220 - 600 grit ) and washed copiously with distilled water . to obtain carious affected dentin , grinding was performed using combined criteria of visual examination and staining with caries detector dye ( kurary , japan ) as described that is the dentin was hard to an explorer and no longer stained bright red with caries detector dye [ figure 1 ] .
flow chart showing distribution of samples into groups the samples in group - a ( n=20 , control group ) were without application of caries detection dye on both sound and carious affected dentin surfaces .
the samples in group - b ( n=20 , experimental group ) were with application of caries detection dye on sound and carious affected dentin surfaces .
the control and experimental group were further divided into two subgroups a1 and a2 and b1 and b2 with 10 samples in each as shown in the following flowchart .
buccal surface of each sample was exposed from acrylic resin block . in control subgroups ,
dentin surfaces were etched with 37% phosphoric acid gel for 15 sec while in experimental subgroups all samples were etched after application of caries detection dye . after etching , it was rinsed with spray water and dried leaving a moist dentin surface for application of the bonding agent .
the adhesive resin ( single bond ) was applied in a single layer on the sound and carious affected dentin surface as per the manufacturer 's instruction and photo cured for 10 sec using qth light source ( 3 m curing light 2500 ) .
a plastic cylindrical mould with a internal diameter of 3 mm and length 4 mm was placed atop the bonded surface . a flexible orthodontic wire to be used during testing procedure
the composite resin was build up in increments and each layer was cured for 20 sec .
after complete curing , the plastic mold was easily removed with the help of tweezers .
debonding procedure was performed in tension on instron universal testing machine at a crosshead speed 0.5 mm / min .
after testing , the fracture mode of each specimen was determined visually under 5x magnification .
forty freshly extracted ( both carious and non - carious ) human mandibular molar teeth were selected for this study .
the samples were stored in normal saline at room temperature until they were subjected to the experimental procedure . for carious affected dentin
, twenty samples with coronal caries extending approximately halfway through the dentin were used in this study .
the buccal carious surface was ground parallel to the long axis of the tooth to expose a flat surface of normal dentin surrounding the carious lesion .
the buccal enamel was grinded with the help of carborundum disc , made smoothened by the sand paper ( silicon carbide , 220 - 600 grit ) and washed copiously with distilled water . to obtain carious affected dentin
, grinding was performed using combined criteria of visual examination and staining with caries detector dye ( kurary , japan ) as described that is the dentin was hard to an explorer and no longer stained bright red with caries detector dye [ figure 1 ] .
flow chart showing distribution of samples into groups the samples in group - a ( n=20 , control group ) were without application of caries detection dye on both sound and carious affected dentin surfaces .
the samples in group - b ( n=20 , experimental group ) were with application of caries detection dye on sound and carious affected dentin surfaces .
the control and experimental group were further divided into two subgroups a1 and a2 and b1 and b2 with 10 samples in each as shown in the following flowchart .
buccal surface of each sample was exposed from acrylic resin block . in control subgroups ,
dentin surfaces were etched with 37% phosphoric acid gel for 15 sec while in experimental subgroups all samples were etched after application of caries detection dye .
after etching , it was rinsed with spray water and dried leaving a moist dentin surface for application of the bonding agent .
the adhesive resin ( single bond ) was applied in a single layer on the sound and carious affected dentin surface as per the manufacturer 's instruction and photo cured for 10 sec using qth light source ( 3 m curing light 2500 ) .
a plastic cylindrical mould with a internal diameter of 3 mm and length 4 mm was placed atop the bonded surface . a flexible orthodontic wire to be used during testing procedure
the composite resin was build up in increments and each layer was cured for 20 sec .
after complete curing , the plastic mold was easily removed with the help of tweezers .
debonding procedure was performed in tension on instron universal testing machine at a crosshead speed 0.5 mm / min .
tensile bond strength of each group was calculated in mpa . after testing , the fracture mode of each specimen
tensile strength is significantly higher in sound dentine from carious affected dentine in control subgroups as well as experimental subgroups 
 [ table 3 ] . the mean value of tensile strength within control group and experimental group anova table for tensile strength in subgroups since 
f is highly significant hence there are significant difference in tensile strength of with and without application of dye in experimental and control group .
there are significant differences between the control subgroups ( a1 vs a2 ) and experimental subgroups ( b1 vs b2 ) in tensile strength values .
( p<.001 ) [ table 4 ] . comparison of tensile strength between control ( without application of caries detection dye ) and experimental subgroup ( with application caries detection dye )
caries- detector dyes have proven to be useful in the identification and removal of carious dentin .
these agents made from basic fuschin in a propylene glycol base reliably stain only the dentin that is infected with bacteria and irreversibly demineralized without staining the affected dentin .
therefore , the presence of stain reliably determines the part of dentin to be removed .
early formulations of the caries detector included a 5% basic fuchsin solution in propylene glycol as a solvent ; however , it was replaced with 1% acid red 52 solution in the same solvent as a substitute dye because fuchsin is believed to be carcinogenic .
studies demonstrated that dentin containing less than 10000 cfu / mg was normally not disclosed by the fuschin dye , whereas counts of greater than 550,000 cfu /mg dentin were readily stained .
this suggests that the dye can be used to approximate the bacterial load of the dentinal surface because a certain bacterial mass apparently needs to be present before the dye is absorbed by the dentin .
the mechanism by which caries disclosing agents selectively stain only carious , irreversibly demineralized dentin has been determined .
both basic fuchsin and acid red stain the collagen fibers exposed by the bacteria caused dentin demineralization process .
the results of this study show that the mean value of tensile bond strength of single bond was higher in the control subgroup than experimental subgroups which can be explained as that caries - affected dentin contain some substances that interfere with free radical generation or propagation , leading to improper polymerization of resins in such dentin .
the peritubular dentin matrix of caries - affected dentin , which take up much more toluidine blue stain and exhibit more intense metachromasia than normal peritubular dentin , suggests the presence of mucopolysaccharides or glycoprotiens . these molecules may interfere with resin wetting of fine porosities within both intertubular and peritubular dentin and/or
fusayama et al , observed affected dentin to have turbid , transparent and subtransparent zones .
there is limited information on the structure of these zones as well as conflicting evidences about their properties .
general perception is that transparent dentin is sclerotic and hypermineralized due to tubular occlusion which might act as a barrier to penetration of primers and bonding agents .
although the adhesive resin may have followed the primer , it may not have copolymerized well with the primer .
thus the adhesion of resins to caries - affected dentin may be inferior to that of normal dentin , due to weaker collagen and/or weaker resin even though most of the tubules in such dentin are filled with mineral deposits .
these intratubular crystals are not well - packed and are softer than well - packed apatite even through they are more acid - resistant.[1015 ] in relation to the influence of dyes on the adhesion of filtekz250 , the decrease in the bond strength may be due to dye solution remaining in sound and affected dentin as mentioned in other studies .
single bond is an adhesive that needs to have close contact with the dentin substrate to produce the desired bond strength .
dye remaining trapped in dentin may adversely affect the wetting of dentin by materials , thereby decreasing micromechanical retention of these materials .
it was observed that despite the application on sound dentin and carious affected dentin , caries - detecting dyes , even after being rinsed and acid etched , were not completely removed , as evidenced by some samples with sound tissue remaining lightly colored which might have influenced the results .
within the limitation of the present study , it is concluded that the tensile bond strength was higher in sound and carious affected dentin in both control and experimental group without application of caries detection dyes than that with the application of caries detection dyes .
 objectives : the objective of this study was to evaluate the influence of caries detection dye on the in - vitro tensile bond strength of adhesive materials to sound and carious affected dentin.materials and methods : forty healthy and carious human molars were ground to expose superficial sound dentin and carious affected dentin . 
 caries detector dye was applied to sound and carious affected dentin and rinsed . 
 subsequently the dentin was etched with 37% phosphoric acid and rinsed leaving a moist dentin surface . 
 the adhesive ( single bond ) was applied in single layers and light cured . a posterior composite ( filtek z 250 ) 
 were used to prepare the bond strength specimens with a 3 mm in diameter bonding area . 
 control and experimental groups were made with and without application of dye respectively . 
 each group includes both sound and carious affected dentin . 
 after 24 hour immersion in distilled water , tensile bond strength ( mpa ) was measured using an instron testing machine.results:analysis of variance ( anova ) was used to evaluate the data . 
 the tensile bond strength were significantly less in experimental subgroup than control subgroups.conclusion:the tensile bond strengths were higher in sound and carious affected dentin without application of caries detection dyes . 
INTRODUCTION
MATERIALS AND METHODS
Experimental groups
RESULTS
DISCUSSION
CONCLUSION