a desinfeco das superfcies de dentina  desejada desde que no haja interferncia na adeso dos agentes adesivos . testar a hiptese nula de que a resistncia adesiva no  afetada pela aplicao prvia de uma soluo desinfetante de iodo . o esmalte oclusal destes dentes foi removido , e sobre as superfcies planas de dentina expostas foi aplicada da soluo desinfetante de iodo a 2% ( i2dds ) , que permaneceu sobre a superfcie por 20 s e foi lavada por 20 s com gua deionizada . sobre as superfcies desinfetadas foram aplicados um dos seguintes sistemas adesivos ( n=3 ) : single bond ; prime & bond nt ; clearfil se bond ; opti - bond plus . os grupos controle ( n=3 ) no tiveram a supeficie de dentina tratada com i2dds antes dos precedimentos adesivos . em todos os grupos , aps hibridizao da dentina , foi construda uma " restaurao " de resina composta com cerca de 4 mm de espessura . aps 7 dias de armazenagem em gua destilada , os dentes foram secionados de modo a originarem espcimes a serem submetidos ao teste de microtrao ( palitos ) . anlise estatstica para comparao dos dados foi realizada pelo teste t de student (  = 0,05 ) . de forma geral , os grupos experimentais ( tratados com i2dds ) apresentraram resistncia adesiva significativamente menor do que os respectivos grupos controle ( p<0.05 ) , exceo se fez apenas para o grupo p&bi2 que no diferiu significativamente de seu grupo controle p&bc ( p>0.05 ) . assim , a hiptese nula deve ser rejeitada para os adesivos a base de etanol e / ou a base de gua , mas aceita para o adesivo a base de acetona . o uso da soluo experimental de iodo previamente  realizao dos procedimentos adesivos afetou a efetividade da unio  dentina apenas quando do emprego de sistemas adesivos a base de etanol e / ou gua . incomplete removal of bacterially contaminated dentin or enamel associated with caries is a potential problem in restorative dentistry . bacteria can remain in the smear layer or in dentinal tubules , and can potentially multiply . studies6,7 indicate that residual bacteria might proliferate from the smear layer beneath restorations , allowing toxins to diffuse to the pulp , resulting in irritation and inflammation3 . it is argued that microorganisms that are present in the cavity walls can not be removed by the use of water spray or by the effect of restorative materials containing disinfecting agents8 . therefore , the adjunctive use of antibacterial solutions after cavity preparation may be considered as an important tool on reducing the potential for both microorganism growth and hypersensitivity2 . a 2% iodine disclosing / disinfecting solution ( i2dds ) has been used to disclose and kill bacteria in plaque , hence working as " toilet " for caries removal4 . based on this bactericidal effect , i2dds could be an appropriate agent to clean and disinfect dentin and enamel substrates prior to restorative procedures . however , a potential problem of using disinfectant solutions before bonding restorative procedures could be an interference with the ability of hydrophilic monomer resins to wet , diffuse and polymerize in situ into dentin substrates . due to the lack of information about i2dds application as a disinfectant agent applied prior to adhesive restorations , this study tested the null hypothesis that the adhesive bond strengths obtained via microtensile method11 are not affected whenever i2dds is used prior to application of a range of bonding systems . the occlusal enamel was removed perpendicular to the long axis of the tooth using a slow - speed saw ( buehler isomet low speed saw with buehler diamond wafering blade - series 20 hc diamond , no 114215 , buehler , usa ) to expose a flat dentin surface that was subsequently finished using 600-grit silicon paper ( buehler , phoenix beta polisher and grinder ) . in all experimental groups , the dentin surfaces were treated using an i2dds ( table 1 ) for 20 seconds and then rinsed for 20 seconds followed by the application of self- or total etching adhesive systems , therefore generating five bonding groups ( 3 teeth per group ) as listed below : sbi2 : single bond ( 3m - espe co , usa ) p&bi2 : prime & bond nt ( dentsply , usa ) sei2 : clearfil se bond ( kuraray co , japan ) optbi2 : opti - bond ( kerr co , usa ) in the control groups ( 3 teeth per group ) , the disinfectant solution was not applied and the groups were defined as sbc , p&bc , sec , and optbc for respective adhesive systems . the adhesive agents were applied and photo - activated ( curing light 2500 , 3m-3350 granada ave . n oakdale , mn 55128 , usa ) according to the manufacturers ' directions . following adhesive application , a 4-mm resin restoration was built up on the bonded surface using z 100 composite ( 3m- espe , st . paul , mn 55144 , usa ) in increments of not more than 1.5 mm . all teeth were then aged for a period of 7 days in water at 37c . after aging , the specimens were cross - sectioned perpendicular to the adhesive interface with a slow - speed saw ( buehler isomet low speed saw with buehler diamond wafering blade - series 20 hc diamond , no 11 - 4215 , lake bluff , il , usa ) under copious water , to produce a series of squared beams of approximately 0.8-mm per side and 8-mm length . each beam was attached to the flat grips of a special jig ( bencor multi - t , bencor , calgary , alberta , australia ) using cyanoacrylate cement ( krazy glue gel , advanced formula- elmer 's products , inc , usa ) and loaded to failure under tension at a crosshead speed of 12.7 mm / min using a testing machine ( model tsd 500 , chatillon - ametek , agawam , ma 01001 , usa ) . the cross - sectional areas of all specimens were measured individually , after bond testing , using a digital caliper ( mitutoyo , 20 - 1 sakado , kawasaki , kanagawa 213 , japan ) , and this value was used to calculate the bond strength . the mean tensile bond strength ( mtbs ) data were converted to mpa , and comparison between experimental and control groups of the different bonding systems were performed by student - t tests . the mode of failure of each specimen was determined using stereomicroscope ( sxz - illb 100 , olympus optical , co , ltd , japan ) and classified as cohesive in resin composite , adhesive cohesive in dentin and mixed.11 pre - testing failures due to handling and cutting procedures prior testing were not considered as a zero value for statistical analysis . a separated group of dentin substrates were prepared following the same protocol of application of i2dds with and without etching step and then observed in the sem ( jeol - jms 5400 scanning microscope , tokyo , japan ) to evaluate whether there was a change on the dentin substrate after the application of i2dds . a drop of either an ethanol and/or water - based or acetone - based adhesive formulation was added to a drop of glycerol and observed under a stereomicroscope ( sxz- illb 100 , olympus optical , co , ltd , japan ) to ascertain whether there could be a phase separation between the two agents . means and standard deviations of the bond strength for all groups are shown in table 2 . in general , experimental groups ( previously treated with i2dds ) showed significantly lower bond strength values when compared with their respective controls ( p<0.05 ) . an exception was the p&bi2 , which did not significantly differ from its control p&bc ( p>0.05 ) . mixed failure was found in approximately 75% of bond test specimens for both control and iodine groups , respectively . adhesive failure in dentin was observed in 16.6% of controls and 23.4% of iodine treated specimens summed across all tested groups . this slight increase of adhesive failure mode for the iodine groups might be related to the possible presence of remnants of glycerol after application and rinsing of i2dds . residual glycerol may be responsible for the decrease ( p>0.05 ) of mtbs of water and/or ethanol based bonding agents . cohesive mode of failure either in dentin of resin was observed in 8.3% of tested specimens in control groups and 4.3% of all tested specimen of iodine groups . figure 1 shows the effects of adding either an ethanol and/or water - based or acetone - based adhesive formulation to a drop of glycerol . the ethanol and/or water - based adhesive depict a phase separation , while the acetone adhesive is miscible with glycerol . when i2dds was applied to dentin surface before etching , fewer opened - tubules were observed in the dentin , compared to the etched only dentin surface ( figure 2 ) . this suggests that residual glycerol or iodine affects on the smear layer or collagen reduces the acid dissolution of the dentin surface . during clinical procedures , prepared dentin surfaces may be contaminated with saliva , blood , and microorganisms8 . saliva and blood contamination has been shown to reduce resin to dentin bond strengths , depending greatly upon adherent surface condition5 . however , no bacteria were found when the cavity was cleaned with a microbiocidal fluoride solution and leakage was eliminated1 . these observations suggest that prepared surfaces need to be cleaned to eliminate bacteria2 before lining , cementation , and restoration . using disclosing and/or disinfectant solutions on dentin before application of adhesive systems could potentially interfere with the ability of adhesive to micromechanically bond to the dentin , and consequently reduce bond strength . in 2002 , wahl , et al.13 tested the effect of different disinfectant rinses ( distilled water as a control ; water with 3.5 ppm iodine ; water 3.0 ppm sodium hypochlorite ; water with 2% ethanol ; water contaminated with 610 cfu / ml of e. coli bh5 ) applied following acid etching of dentin . they observed that the disinfectant water rinse had no significant effect on the shear bond strength of resin - dentin bonds . they also concluded that further work was needed to evaluate the effect of antimicrobial agents on adhesive bond strength of various adhesive systems ( alcohol / water based and/or acetone based ) . wahl 's group13 employed shear testing while in our work the microtensile bond method 11 was utilized . application of an i2dds prior to adhesive application resulted in reduced microtensile bond strength values for ethanol- and/or water - based adhesive systems and not for the one acetone - based adhesive system tested . ethanol- and/or water - based adhesive systems ( single bond ; clearfil se bond ; and opti - bond plus ) had statistically lower bond strengths ( p<0.05 ) , suggesting that i2dds interferes with the adhesive bond strength . however , the application of i2dds followed by a rinse step and bonding procedures did not have immediate influence on esthetic outcomes of restorations . reduction in bond strength values for ethanol- and/or water - based adhesive agents might be due to the presence of glycerol ( 53% ) in the composition of i2dds . we speculate that remnants of the glycerol " carrier " might be incompletely removed from the dentin substrate after water rinsing ( 20s ) , drying and even etching procedures . glycerol is highly viscous , and is soluble in water only when extensive mechanical mixing occurs . when ethanol and/or water - based adhesive agents were used , residual glycerol might prevent adhesive from diffusing through demineralized dentin surface interfering with hybrid layer formation . phase separation between the water / ethanol adhesive and glycerol might occur during evaporation of these solvents ( figure 1 ) . however , for acetone - based adhesive system used in this study , acetone seemed to be able to diffuse into residual glycerol and allow monomer penetration into demineralized dentin , and thus does not produce a significant difference in bond strength value . this indirectly indicates a plausible basis for bond strength differences , should residual glycerol remain on the surface . the application of i2dds might also lead to variation in the surface demineralization by phosphoric acid etching , suggesting the presence of i2dds remnants on the dentin substrate even after etching procedures . these remnants may limit the etchant to reach the collagen network and thereby work as a barrier for adhesive interlock into dentin , potentially leading to both microleakage and lower bond strengths12 . in 2000 , roberts , et al.10 tested dentin bond strength using four chemical agents developed for the reduction of bacterial contamination in dental treatment water . the authors also observed reduction in dentin bond strength and speculated that this might be caused by essential oils present in these products , which might jeopardize tag formation . it can prevent bacterial growth and consequently diminish the possibility of post - operative hypersensitivity after restorative treatment . to be more conclusive about utilization of i2dds as a disinfectant before adhesive procedures , further studies are warranted to elucidate how bond strength of water- and/or ethanol - based adhesive systems might increase such as rinsing specimen longer than 20 seconds with water to remove any solution residue . investigations into the role of glycerol on lower bond strengths should be pursued by using iodine solutions based upon water alone associated with transmission electron microscopic evaluation ( tem ) . acetone - based adhesive systems seem not to be affected by the application of i2dds prior etching and bonding procedures . the null hypothesis can be rejected for ethanol- and/or water - base adhesives ( p<0.05 ) : single bond , clearfil se bond , and opti - bond plus , in which i2dds application reduces bond strength .
introduction : disinfection of dentin surfaces is desirable so long as it does not interfere with subsequent bonding of adhesive resins.objective:to test the null hypothesis that bond strengths to dentin are not affected by previous application of an iodine disinfecting solution.materials and methods : twenty - four extracted non - carious molars were selected . 
 occlusal enamel was removed producing a flat dentin substrate . 
 test teeth were all treated with 2% iodine disclosing / disinfecting solution ( i2dds ) for 20 sec and rinsed for 20 sec followed by the application of self- or total- etching bonding systems , generating five adhesive groups ( n=3 ) : single bond ; ; prime & bond nt ; clearfil se bond ; opti - bond plus . 
 the control groups ( n=3 per adhesive ) had no disclosing / disinfectant application prior to adhesive application . 
 a 4-mm thick resin restoration was built up on each tooth for microtensile testing . 
 statistical analyses between experimental and control groups were performed by student 's t - test (  = 0.05).results : in general , experimental groups ( previously treated with i2dds ) showed significantly lower bond strength values when compared with their respective controls ( p<0.05 ) , except for group prime & bond i2 that did not significantly differ from its control ( p>0.05).conclusion : acetone - base adhesive systems seem not to be affected by the application of i2dds prior to etching and bonding procedures .