current restorative techniques are associated with the bonding characteristics of 
 resin - based materials . contemporary dentin bonding agents contain a chemically balanced 
 combination of hydrophilic ( i.e. hema , bpdm , penta ) and hydrophobic monomers ( i.e. 
 bis - gma , udma ) that intrinsically permeate the wet dentin surface . in 
 addition , the dentin bonding agents contain solvents , known to be essential components 
 for establishing adequate dentin - resin interface . solvents are responsible for carrying 
 these resin monomers throughout the collagen fibrils of the dentin substrate after the 
 etching step . in these dental adhesives , this characteristic complex blend of 
 hydrophilic / hydrophobic ingredients , water and solvents makes the adhesives prone to 
 phase separation , which may impair their bonding effectiveness . in order to 
 allow the mixing of these kinds of monomers , and also to avoid the phase separation 
 between them , volatile organic solvents , such as ethanol and acetone , are added in the 
 formulation of adhesives . these solvents facilitate the evaporation of 
 water from the wet dentin , ensuring an increased monomer infiltration into the 
 demineralized dentin , thus improving the physical - chemical interaction with the tooth 
 substrate . the solvent evaporation before the photoactivation of an adhesive system is regarded as 
 being of paramount importance to increase the effectiveness of the bonding 
 procedure . the adhesive system is placed and exposed while it is in 
 a liquid state and is relatively low in viscosity . this lowered viscosity may lead to 
 enhanced radical mobility , and thus higher conversion values . for a durable , long - term sealing of dentin the residual water or organic solvents is claimed to be 
 responsible for producing localized areas of incomplete monomer polymerization . thus , the monomer conversion and the 
 extent of polymerization might vary throughout the hybrid layer , which could cause 
 significant differences in the quality of the interpenetrating network at different 
 locations . a direct 
 correlation between the extent of polymerization of the adhesive films and their 
 permeability has been found . in 
 addition , water is responsible for the chemical decomposition , such as oxidation and 
 hydrolysis of the resin matrix . 
 however , the water uptake is not only dependent upon the presence of residual solvent , 
 but is also dependent upon the hydrophilicity of these materials . therefore , the aim of the present study was to evaluate the influence of solvent 
 evaporation on the water sorption , solubility , and net water uptake ( sum of water 
 sorption and solubility ) of specimens immersed in water and mineral oil , and also on the 
 nanoleakage pattern of contemporary adhesive systems . the hypotheses tested were : ( i ) 
 the solvent evaporation would reduce the net water uptake ; ( ii ) the water sorption and 
 solubility parameters will be similar , irrespective of the immersion media ; and ( iii ) 
 the nanoleakage of the adhesives tested would be reduced when the solvents are 
 evaporated . in this in vitro study , the assessments of water sorption and 
 solubility of adhesive specimens immersed in water and mineral oil were performed 
 according to the factors : ( 1 ) adhesive system , at four levels : i- clearfil s3 bond 
 ( cs3 ) - a one - step , self - etching adhesive - , ii- scotchbond universal adhesive ( sbu ) 
 - a universal adhesive - , iii- clearfil se bond ( cse ) - a two - step , self - etching 
 adhesive - , iv- optibond solo plus ( op ) - a two - step , total - etching adhesive ; ( 2 ) 
 adhesive protocol : i- evaporated , ii- non - evaporated ; and ( 3 ) immersion media , at two 
 levels : i- water , and ii- mineral oil . for comparative reasons , only specimens of the 
 " bond " component of cse were fabricated . the net water uptake , i.e. , the sum of water 
 sorption and solubility , was also calculated . the composition of the adhesive systems 
 is described in figure 1 . in order to support 
 the results , composition , manufacturers and batch numbers of the adhesives used mdp : methacryloyloxydecyl dihydrogen phosphate ; bisgma : bisphenol - a 
 glycidyldimethacrylate ; hema:2-hydroxyethylmethacrylate forty - eight disc - shaped specimens of each material ( except for cse ; n=24 ) were 
 prepared for each storage condition ( water and mineral oil ) . for the specimen 
 fabrication , adhesive systems were dispensed into a silicon mold ( 5.0 mm in diameter 
 x 0.8 mm in thickness ) . for solvated adhesives ( sbu , cs3 , op ) , oil / water - free 
 compressed air was gently blown for 30 s at a distance of 10 cm to facilitate the 
 solvent evaporation ( e ) . for the non - solvated adhesive ( cse bond ) , the drying step 
 was not performed . as an air spray is recommended to optimize solvent 
 evaporation , care was taken 
 to be gently applied to avoid oxygen incorporation in the adhesive specimens . in 
 addition , care was also taken to carefully remove all visible air bubbles entrapped 
 in the adhesive specimens , and a polyester strip was placed over the adhesive and 
 covered with a glass slide . the specimens were photoactivated using a qth light 
 ( demetron lc , 450 mw , demetron research corp . , danbury , ct , usa ) for 40 s with a 
 power density of 550 mw / cm . the specimens were then carefully removed 
 from the mold and photoactivated for additional 40 s. water sorption and solubility tests were based on the 4049 iso standard , with the 
 exception of the specimen 's dimensions ( 5.0 mm in diameterx0.8 mm in thickness ) . after 24 h , the specimens were placed in a desiccator device containing silica gel 
 and stored at 37c . the specimens were repeatedly weighed on an analytical balance 
 ( ag204 , mettler - toledo , columbus , oh , usa ) every 24 h , until a constant mass 
 ( m1 ) was obtained ( i.e. a mass in which variation amounted to less than 
 0.2 mg within any 24 h period ) . the thickness and diameter of the specimens were measured at three different points 
 to the nearest 0.01 mm using a digital caliper , and these measurements were used to 
 calculate the volume ( v ) of each specimen ( in mm ) . specimens were then 
 individually placed in test tubes ( eppendorf vials ) containing 1.5 ml of distilled 
 water ( ph 7.2 ) at 37c for 7 days . half of the specimens ( n=12 ) were placed in sealed 
 glass vials containing 1.5 ml of a chemically - inert mineral oil ( nujol , liquid 
 petrolatum , sigma - aldrich co. , saint louis , mo , usa ) . these specimens were tested as 
 controls in parallel with the specimens immersed in distilled water . the storage time interval of up to 7 days had passed , the tubes were removed from the 
 oven and left to equilibrate at room temperature for 30 min . the specimens were then 
 washed in running water , gently wiped with a soft absorbent paper , weighed by means 
 of an analytical balance ( m2 ) , and returned to vials containing 10 ml of 
 fresh distilled water or oil . following the further 7 days of storage , the specimens 
 were dried inside a desiccator containing fresh silica gel and weighed daily until a 
 constant mass ( m3 ) was obtained ( as previously described ) . the initial 
 mass determined after the first desiccation process ( m1 ) was used to 
 calculate the change in mass after each fixed - time interval of the 7 days of storage . changes in mass were plotted against the storage time in order to obtain the kinetics 
 of water sorption for the entire period of water storage . the water sorption ( ws ) and 
 solubility ( sl ) over 7 days of water storage were calculated by means of the following formulae : where m1 refers to the initial dry constant mass ( mg ) prior to immersion in water ; 
 m describes the mass ( mg ) 
 after water immersion at various time periods ; m is the mass ( mg ) after drying the specimens that had reached 
 their maximum water sorption ; and v refers to the specimen volume in mm . net water uptake ( % ) was also calculated as the sum of water sorption and solubility . data were analyzed by three - way anova ( with factors including " adhesive system " , 
 " adhesive protocol " , and " immersion media " ) and tukey 's post - hoc 
 test for multiple comparisons , at a preset alpha of 5% . for the nanoleakage pattern investigation , six additional disc - shaped specimens were 
 prepared for the solvated adhesive systems , and three discs were made for cse . in 
 order to investigate the influence of the solvent incorporated into adhesive systems 
 on the nanoleakage , the specimens were stored in distilled water for 7 days and then 
 placed in an ammoniacal silver nitrate solution for 24 h. after that , the specimens 
 were rinsed thoroughly in distilled water and immersed in a photo developing solution 
 for 8 h under a fluorescent light to reduce silver ions into metallic silver 
 grains . the stained specimens were then profusely water - rinsed in tap 
 water , mounted in aluminum stubs , dehydrated in silica gel for 2 h , and then 
 submitted to carbon evaporation ( scd 050 , balzer union ag , balzers , lichtenstein ) . a 
 qualitative analysis of the nanoleakage patterns was performed using a scanning 
 electron microscope ( sem - phenom - world , eindhoven , the netherlands ) , operating in 
 back - scattering electron mode with an accelerating voltage of 15 kv . the nanoleakage 
 patterns were classified as follow : type i - moderate silver uptake ; or type ii - 
 severe silver uptake . in this in vitro study , the assessments of water sorption and 
 solubility of adhesive specimens immersed in water and mineral oil were performed 
 according to the factors : ( 1 ) adhesive system , at four levels : i- clearfil s3 bond 
 ( cs3 ) - a one - step , self - etching adhesive - , ii- scotchbond universal adhesive ( sbu ) 
 - a universal adhesive - , iii- clearfil se bond ( cse ) - a two - step , self - etching 
 adhesive - , iv- optibond solo plus ( op ) - a two - step , total - etching adhesive ; ( 2 ) 
 adhesive protocol : i- evaporated , ii- non - evaporated ; and ( 3 ) immersion media , at two 
 levels : i- water , and ii- mineral oil . for comparative reasons , only specimens of the 
 " bond " component of cse were fabricated . the net water uptake , i.e. , the sum of water 
 sorption and solubility , was also calculated . the composition of the adhesive systems 
 is described in figure 1 . in order to support 
 the results , composition , manufacturers and batch numbers of the adhesives used mdp : methacryloyloxydecyl dihydrogen phosphate ; bisgma : bisphenol - a 
 glycidyldimethacrylate ; hema:2-hydroxyethylmethacrylate forty - eight disc - shaped specimens of each material ( except for cse ; n=24 ) were 
 prepared for each storage condition ( water and mineral oil ) . for the specimen fabrication , adhesive systems were dispensed into a silicon mold ( 5.0 mm in diameter 
 x 0.8 mm in thickness ) . for solvated adhesives ( sbu , cs3 , op ) , oil / water - free 
 compressed air was gently blown for 30 s at a distance of 10 cm to facilitate the 
 solvent evaporation ( e ) . for the non - solvated adhesive ( cse bond ) , the drying step 
 was not performed . as an air spray is recommended to optimize solvent 
 evaporation , care was taken 
 to be gently applied to avoid oxygen incorporation in the adhesive specimens . in 
 addition , care was also taken to carefully remove all visible air bubbles entrapped 
 in the adhesive specimens , and a polyester strip was placed over the adhesive and 
 covered with a glass slide . the specimens were photoactivated using a qth light 
 ( demetron lc , 450 mw , demetron research corp . , danbury , ct , usa ) for 40 s with a 
 power density of 550 mw / cm . the specimens were then carefully removed 
 from the mold and photoactivated for additional 40 s. water sorption and solubility tests were based on the 4049 iso standard , with the 
 exception of the specimen 's dimensions ( 5.0 mm in diameterx0.8 mm in thickness ) . after 24 h , the specimens were placed in a desiccator device containing silica gel 
 and stored at 37c . the specimens were repeatedly weighed on an analytical balance 
 ( ag204 , mettler - toledo , columbus , oh , usa ) every 24 h , until a constant mass 
 ( m1 ) was obtained ( i.e. a mass in which variation amounted to less than 
 0.2 mg within any 24 h period ) . the thickness and diameter of the specimens were measured at three different points 
 to the nearest 0.01 mm using a digital caliper , and these measurements were used to 
 calculate the volume ( v ) of each specimen ( in mm ) . specimens were then 
 individually placed in test tubes ( eppendorf vials ) containing 1.5 ml of distilled 
 water ( ph 7.2 ) at 37c for 7 days . half of the specimens ( n=12 ) were placed in sealed 
 glass vials containing 1.5 ml of a chemically - inert mineral oil ( nujol , liquid 
 petrolatum , sigma - aldrich co. , saint louis , mo , usa ) . these specimens were tested as 
 controls in parallel with the specimens immersed in distilled water . the storage time interval of up to 7 days had passed , the tubes were removed from the 
 oven and left to equilibrate at room temperature for 30 min . the specimens were then 
 washed in running water , gently wiped with a soft absorbent paper , weighed by means 
 of an analytical balance ( m2 ) , and returned to vials containing 10 ml of 
 fresh distilled water or oil . following the further 7 days of storage , the specimens 
 were dried inside a desiccator containing fresh silica gel and weighed daily until a 
 constant mass ( m3 ) was obtained ( as previously described ) . the initial 
 mass determined after the first desiccation process ( m1 ) was used to 
 calculate the change in mass after each fixed - time interval of the 7 days of storage . changes in mass were plotted against the storage time in order to obtain the kinetics 
 of water sorption for the entire period of water storage . the water sorption ( ws ) and 
 solubility ( sl ) over 7 days of water storage were calculated by means of the following formulae : where m1 refers to the initial dry constant mass ( mg ) prior to immersion in water ; 
 m describes the mass ( mg ) 
 after water immersion at various time periods ; m is the mass ( mg ) after drying the specimens that had reached 
 their maximum water sorption ; and v refers to the specimen volume in mm . net water uptake ( % ) was also calculated as the sum of water sorption and solubility . data were analyzed by three - way anova ( with factors including " adhesive system " , 
 " adhesive protocol " , and " immersion media " ) and tukey 's post - hoc 
 test for multiple comparisons , at a preset alpha of 5% . for the nanoleakage pattern investigation , six additional disc - shaped specimens were 
 prepared for the solvated adhesive systems , and three discs were made for cse . in 
 order to investigate the influence of the solvent incorporated into adhesive systems 
 on the nanoleakage , the specimens were stored in distilled water for 7 days and then 
 placed in an ammoniacal silver nitrate solution for 24 h. after that , the specimens 
 were rinsed thoroughly in distilled water and immersed in a photo developing solution 
 for 8 h under a fluorescent light to reduce silver ions into metallic silver 
 grains . the stained specimens were then profusely water - rinsed in tap 
 water , mounted in aluminum stubs , dehydrated in silica gel for 2 h , and then 
 submitted to carbon evaporation ( scd 050 , balzer union ag , balzers , lichtenstein ) . a 
 qualitative analysis of the nanoleakage patterns was performed using a scanning 
 electron microscope ( sem - phenom - world , eindhoven , the netherlands ) , operating in 
 back - scattering electron mode with an accelerating voltage of 15 kv . the nanoleakage 
 patterns were classified as follow : type i - moderate silver uptake ; or type ii - 
 severe silver uptake . mass variation curves for the 12 days of immersion in water are presented in figure 2 . the statistical analysis revealed that 
 only the factor " adhesive protocol " was significant ( p=0.01 ) . the solvent evaporation 
 procedure had no effect on the water sorption and solubility of the adhesives 
 ( p=0.21 ) , irrespective of the storage media . when mass gain ( i.e. water sorption ) and 
 mass loss ( i.e. solubility ) of adhesive disks were plotted against time , non - solvated 
 adhesive cse was determined to have the lowest water sorption ( figure 2 ) . cse adhesive also presented significantly lower means 
 of sl ( -2.9 g / mm ) ( p<0.05 ) . when the ws and sl were compared as a 
 function of the storage media , the net water uptake means varied from 5.4 to 24.6% 
 among the adhesive systems ( table 1 ) and were 
 determined to be significantly lower for the cse bond ( 5.4% ) . all the adhesives 
 stored in water presented a time - dependent increase in water sorption and solubility , 
 whereas the adhesives stored in mineral oil presented lower sorption and solubility 
 means ( figure 2 ) . in spite of the variation in 
 mass as a function of the time , cse was the only adhesive to present similar weight 
 after the desiccation process in comparison to that obtained at m1 ( figure 2 ) . changes in mass of the adhesive systems tested in the water sorption / solubility 
 test . op - optibond solo plus , cs3 - clearfil s bond , and sbu 
 - scotchbond universal adhesive as a function of the solvent evaporation 
 ( non - evaporated - n ) or evaporated solvents - e ) water sorption ( ws ) , solubility ( sl ) and net water uptake of the adhesives 
 tested values are meansd ( n=12 ) g / mm different upper case letters for rows and lower case letters for columns : 
 significant ( p<0.05 ) water sorption is given in absolute terms ( g / mm ) and in relative 
 terms ( % ) to provide comparisons to literature values which include both 
 expressions c 57.1 g / mm=0.5710 mg / mmx100 5.71 mg/100 
 mm=5.7 % [ malacarne , et al . ( 2006 ) ] d net water uptake is the sum of water sorption and solubility ( % ) the nanoleakage patterns of the adhesives investigated are illustrated in figures 3 and 4 . representative sem micrographs of the adhesives after 7 days of storage 
 in water are presented in figure 3 . the 
 solvated adhesives showed similar nanoleakage patterns ( moderate silver uptake - type 
 i ) after evaporation , whereas a more intense nanoleakage was noted for the 
 non - evaporated ones ( severe silver uptake - type ii ) ( figure 3 ) . the non - solvated adhesive cse presented a nanoleakage pattern 
 ( type i ) similar to that observed for the solvated adhesives when the solvents were 
 evaporated ( figure 4 ) . the adhesive sbu showed 
 higher silver uptake when the evaporation was not performed in comparison with that 
 observed for both op and cs3 . nanoleakage of the adhesives optibond solo plus ( op ) , clearfil s 
 bond ( cs3 ) , and scotchbond universal adhesive ( sbu ) with the solvent 
 non - evaporated ( n ) or evaporated ( e ) after 7 days of water storage . the more 
 intense silver uptake is evident for the non - evaporated groups nanoleakage of clearfil se bond ( cse ) after 7 days of water storage mass variation curves for the 12 days of immersion in water are presented in figure 2 . the statistical analysis revealed that 
 only the factor " adhesive protocol " was significant ( p=0.01 ) . the solvent evaporation 
 procedure had no effect on the water sorption and solubility of the adhesives 
 ( p=0.21 ) , irrespective of the storage media . when mass gain ( i.e. water sorption ) and 
 mass loss ( i.e. solubility ) of adhesive disks were plotted against time , non - solvated 
 adhesive cse was determined to have the lowest water sorption ( figure 2 ) . cse adhesive also presented significantly lower means 
 of sl ( -2.9 g / mm ) ( p<0.05 ) . when the ws and sl were compared as a 
 function of the storage media , the net water uptake means varied from 5.4 to 24.6% 
 among the adhesive systems ( table 1 ) and were 
 determined to be significantly lower for the cse bond ( 5.4% ) . all the adhesives 
 stored in water presented a time - dependent increase in water sorption and solubility , 
 whereas the adhesives stored in mineral oil presented lower sorption and solubility 
 means ( figure 2 ) . in spite of the variation in 
 mass as a function of the time , cse was the only adhesive to present similar weight 
 after the desiccation process in comparison to that obtained at m1 ( figure 2 ) . changes in mass of the adhesive systems tested in the water sorption / solubility 
 test . op - optibond solo plus , cs3 - clearfil s bond , and sbu 
 - scotchbond universal adhesive as a function of the solvent evaporation 
 ( non - evaporated - n ) or evaporated solvents - e ) water sorption ( ws ) , solubility ( sl ) and net water uptake of the adhesives 
 tested values are meansd ( n=12 ) g / mm different upper case letters for rows and lower case letters for columns : 
 significant ( p<0.05 ) water sorption is given in absolute terms ( g / mm ) and in relative 
 terms ( % ) to provide comparisons to literature values which include both 
 expressions c 57.1 g / mm=0.5710 mg / mmx100 5.71 mg/100 
 mm=5.7 % [ malacarne , et al . ( 2006 ) ] d net water uptake is the sum of water sorption and solubility ( % ) representative sem micrographs of the adhesives after 7 days of storage 
 in water are presented in figure 3 . the 
 solvated adhesives showed similar nanoleakage patterns ( moderate silver uptake - type 
 i ) after evaporation , whereas a more intense nanoleakage was noted for the 
 non - evaporated ones ( severe silver uptake - type ii ) ( figure 3 ) . the non - solvated adhesive cse presented a nanoleakage pattern 
 ( type i ) similar to that observed for the solvated adhesives when the solvents were 
 evaporated ( figure 4 ) . the adhesive sbu showed 
 higher silver uptake when the evaporation was not performed in comparison with that 
 observed for both op and cs3 . nanoleakage of the adhesives optibond solo plus ( op ) , clearfil s 
 bond ( cs3 ) , and scotchbond universal adhesive ( sbu ) with the solvent 
 non - evaporated ( n ) or evaporated ( e ) after 7 days of water storage . the more 
 intense silver uptake is evident for the non - evaporated groups nanoleakage of clearfil se bond ( cse ) after 7 days of water storage the first hypothesis that the solvent evaporation procedure would reduce the net water 
 uptake was not accepted . in the present study , the tested adhesives showed different 
 amounts of net water uptake , which was not dependent on the evaporation of the solvent . although the ws and sl means varied among the experimental groups , no significant 
 difference was observed among the groups , irrespective of the storage media . in a 
 previous study , higher solvent 
 eliminations were only observed when the drying air temperature was raised for adhesives 
 in comparison to non - evaporated groups . the net water uptake , which represents the sum of water sorption / solubility 
 parameters , has been claimed to reliably estimate the capacity of 
 polymers to absorb water . it has been pointed out that simply evaluating 
 the increase in mass of the specimens stored in water is not the correct way of 
 assessing their water sorption . hydrophilic methacrylate polymers exhibit a spatial heterogeneity in which some parts 
 are densely cross - linked and some parts are loosely cross - linked , representing a 
 variable density of cross - links . in 
 this way , there may be a dynamic process when resin - based materials are stored in water 
 that interferes in the mass of these materials . thus , there may be a 
 simultaneous infiltration of water into the materials while unreacted monomers and 
 low - molecular - weight polymers may be leached out . in this way , the mass 
 variation as a result of both an increase in mass due to water penetration and a 
 decrease in mass as a function of the elution of low - molecular - weight material has been 
 advocated . the storage of the specimens in mineral oil exhibited significantly lower ws and sl when 
 compared to that of the specimens stored in water . when the ws and sl were compared 
 among the adhesive groups , no significance was observed among the groups , irrespective 
 of the evaporation of the solvents . in addition , no significance was observed for the 
 non - solvated adhesive ( cse bond ) concerning the means exhibited by the experimental 
 groups . thus , the second hypothesis , which anticipated that there would be no difference 
 in the ws and sl parameters when the immersion media were compared , was rejected . it has 
 been demonstrated that when specimens were immersed in oil , no water to challenge the 
 interfaces existed , which decreased the silver impregnation to a minimum 
 amount . it has been pointed 
 out that the storage in oil might have removed residual water from the resin - dentin 
 interfaces . even though water is barely solubilized by the mineral oil in addition , in the absence of 
 water , less silver uptake may occur . many factors may affect the water sorption and solubility of contemporary dentin - bonding 
 systems . moisture diffuses into polymers at different degrees depending on a number of molecular 
 and microstructural aspects : ( 1 ) polarity of the molecular structure , presence of 
 chemical groups capable of forming hydrogen bonds with water ; ( 2 ) degree of 
 crosslinking ; ( 3 ) presence of residual monomers ; and ( 4 ) crystallinity of the polymer 
 ( well - defined crystallites are inaccessible to water ) . according to these factors , the mechanism of water 
 diffusion can be summarized in two main theories : ( 1 ) free - volume theory , according to 
 which water diffuses through voids within the polymer , and ( 2 ) interaction theory , 
 according to which water binds to specific ionic groups of the polymer chain . in this case , it was reported that 
 the amount of water sorption and solubility of adhesive polymers increased 
 proportionally to their hema concentrations . in another study , it 
 was pointed out that monomers are heteroatom polymers , having carbon and oxygen or 
 nitrogen in their backbones and that the presence of certain groups , such as ester , 
 urethane , and ether linkages , as well as hydroxyl groups are hydrolytically 
 susceptible . despite their 
 relative hydrophilicity , the resultant polymer formed may absorb water to a potentially 
 damaging extent . moreover , the solvents are probably another factor regarding the extent of water 
 sorption and solubility . solvents also contribute to an exacerbation of the 
 hydrophilicity of the adhesives . 
 additionally , another study 
 demonstrated differences in the water sorption of commercial formulations of bonding 
 agents , which indicated the presence of residual solvents as a condition to exacerbate 
 water sorption . this exerts a negative influence on the bonding longevity , as varied 
 resinous monomers are combined into solvents as neat acetone , ethanol , water , or their 
 combination . a previous study also pointed out the fact that the 
 solvent acetone spontaneously evaporates , as its vapor pressure and ebullition 
 temperature are lower than those of other solvent , which results in higher evaporation 
 rate . in the present study , the highest water sorption and solubility means were obtained for 
 solvated adhesive formulations compared to those of cse bond . this may indicate that the adhesive is more 
 suitable to water sorption , which could mask its real solubility . the results 
 demonstrate that the kinetics of water uptake was also material - dependent . thus , the 
 data obtained with the non - solvated adhesive as a parameter for the relationship between 
 water sorption and hydrophilicity suggests that cs3 , op , and sbu present , in fact , more 
 hydrophilic behavior than cse . this is probably due to the solvents present in the 
 composition , i.e. , the rate of 
 water uptake was lower for the less - hydrophilic adhesive cse . the solvated adhesives investigated in the present study utilize the same types of 
 solvents ( water and ethanol ) , which could explain the similar values for net water 
 uptake . although the air - drying had no effect on the net water uptake of the adhesives , 
 residual solvent remaining after the air - drying might produce defects within the 
 polymerized adhesive , which was filled with water molecules during storage . the 
 interpretation of the results was improved by the nanoleakage investigation , in which 
 the silver uptake was significantly increased when the solvated adhesives were not 
 submitted to solvent evaporation prior to storage ( figures 3 and 4 ) , rejecting hypothesis 
 iii . thus , it is possible that the water sorption and silver uptake in the adhesive 
 specimens were possibly due mainly to porous formation of the polymerized adhesive 
 caused by the presence of residual solvents . another important consideration is that all the adhesives tested in the present study 
 contain hema , and residual co - monomer mixtures may be attracted by poly - hema and/or 
 polymers , leading to an increase in the free volume of polymerized adhesive . this 
 promotes an increase in the water sorption into the polymerized matrix , even after 
 air - drying the adhesive prior to immersion in water . this also helps to explain the nanoleakage for the groups in 
 which the solvent was evaporated , as well as for the non - solvated cse ( figures 3 and 4 ) . thus , water molecules diffuse through the porous structure in the adhesive 
 specimens without a mutual relationship with the polar sites of the material . within the limitations of the present study , it can be concluded that although the 
 solvent evaporation related to the adhesive protocol has no influence on the net water 
 uptake of the adhesives evaluated , the nanoleakage was significantly affected for the 
 non - evaporated ones .
objectiveto evaluate the influence of solvent evaporation in the kinetics of water 
 diffusion ( water sorption - ws , solubility - sl , and net water uptake ) and nanoleakage 
 of adhesive systems . 
 material and methodsdisk - shaped specimens ( 5.0 mm in diameter x 0.8 mm in thickness ) were produced 
 ( n=48 ) using the adhesives : clearfil s3 bond ( cs3)/kuraray , clearfil se 
 bond - control group ( cse)/kuraray , optibond solo plus ( os)/kerr and scotchbond 
 universal adhesive ( sbu)/3 m espe . 
 the solvents were either evaporated for 30 s or 
 not evaporated ( n=24/per group ) , and then photoactivated for 80 s 
 ( 550 mw / cm2 ) . 
 after desiccation , the specimens were weighed and stored 
 in distilled water ( n=12 ) or mineral oil ( n=12 ) to evaluate the water diffusion 
 over a 7-day period . net water uptake ( % ) 
 was also calculated as the sum of ws and 
 sl . 
 data were submitted to 3-way anova / tukey 's test ( =5% ) . 
 the nanoleakage 
 expression in three additional specimens per group was also 
 evaluated after ammoniacal silver impregnation after 7 days of water storage under 
 sem . 
 resultsstatistical analysis revealed that only the factor " adhesive " was significant 
 ( p<0.05 ) . 
 solvent evaporation had no influence in the ws and sl of the 
 adhesives . 
 cse ( control ) presented significantly lower net uptake ( 5.4% ) . 
 the 
 nanoleakage was enhanced by the presence of solvent in the adhesives . 
 conclusionsalthough the evaporation has no effect in the kinetics of water diffusion , the 
 nanoleakage expression of the adhesives tested increases when the solvents are not 
 evaporated .