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Paper text:
contemporary restorative dentistry relays on the durable adhesive joint for long survival of composite restorations .
although etch and rinse adhesives are considered the gold standards , they are technique sensitive .
thus , isolation of the working field via rubber dam application is a prime requisite .
unfortunately , contamination of the adherent with saliva or blood represents a problem in adhesive dentistry .
this occurs when rubber dam isolation is encroached in deep subgingival areas and while managing children with copious salivation .
when contamination of the bonding site occurs , several consequences take place as postoperative sensitivity , caries recurrence , discoloration , and restoration dislodgement . with two - step etch and rinse adhesives ,
most studies were directed toward contaminant - removing options of etched substrate while scanty focused on cleansing treatments if contamination occurred at subsequent stages .
ari et al . reported that contamination should be avoided regardless the affected step to avoid a reduction in bond strength t. park and lee suggested that blot drying of saliva could retain passable bond strength to etched dentin .
contrary researchers suggested that rinsing off the contaminant , particularly blood , although improved the bond strength , could not regain uncontaminated values .
this study conducted to assess saliva and blood effect on etch and rinse adhesive and to evaluate cleansing treatments via micro - shear bond strength ( sbs ) and scanning electron microscope ( sem ) .
the null hypothesis tested that no effect of postcontamination cleansing treatments on bonding to dentin at different stages .
adper single bond ( sb ) plus ( hema , bis - gma , vitrebond copolymer , ethanol / water , photo - initiator ) and nanofilled filtek z250 composite ( 3 m espe , st .
the crowns mounted horizontally in molds of 15 mm diameter and 18 mm height , using self - curing resin with labial surfaces upward .
surfaces were ground flat using diamond disc ( komet , rock hill , usa ) in low speed under water to expose superficial dentin then polished using carbide paper 600-grit to obtain uniform smear layer .
specimens were randomly grouped ( n = 12/group . ) according to contaminated step and sub - grouped according to cleansing treatments [ table 1 and figure 1 ] .
all specimens , except group a , were troughed inciso - cervically into two halves .
each mesial half received fresh human saliva ( s ) collected from the same donor 2 h after breakfast , while the distal half received fresh venous blood ( b ) collected with a disposable needle from the same donor .
plastic tubes 5-fr ( feeding tube , integral medical products , china ) with 0.7 mm diameter and 2 mm height , were mounted on the dentin surface .
the composite was packed into each tube under gentle pressure over cellophane strip then light - cured according to manufacturers guidelines using elipar ii unit ( 3 m espe , st .
each half received two tubes away by at least 3 mm whereas group a received two microcylinders only .
all specimens were stored for 24 h in an incubator at 37c and 100% humidity .
treatments at different bonding steps diagram depicting experimental protocol among the test groups the plastic tubes were removed using sharp blade then each specimen was screwed to the lower fixed compartment of testing machine ( lrx - plus ; lloyd instruments ltd . , uk ) with 5 kn load . a loop wire , 0.014 in , wrapped around each microcylinder flushing with the resin - dentin interface and aligned with the loading axis of the machine upper movable compartment .
a shearing load applied to each assembly at 0.5 mm / min crosshead speed until failure .
failures classified as adhesive if occurred at the interface , cohesive as observed within dentin substrate or composite resin , and mixed when adhesive and cohesive fractures detected simultaneously . two representative specimens per group were examined .
specimens were gold sputtered under vacuum ( ladd sputter coater , bal - tec , scd005 , germany ) then examined under sem ( philips , holland ) . the data were analyzed using spss ( version 16.0 ) software package ( spss inc . , chicago , il , usa ) with significance level set at p  0.05 .
one - way anova evaluated cleansing treatments effects and tukey 's post hoc test for multiple comparisons . the impact of saliva or blood contaminants assessed using independent t - test .
specimens were randomly grouped ( n = 12/group . ) according to contaminated step and sub - grouped according to cleansing treatments [ table 1 and figure 1 ] .
all specimens , except group a , were troughed inciso - cervically into two halves .
each mesial half received fresh human saliva ( s ) collected from the same donor 2 h after breakfast , while the distal half received fresh venous blood ( b ) collected with a disposable needle from the same donor .
plastic tubes 5-fr ( feeding tube , integral medical products , china ) with 0.7 mm diameter and 2 mm height , were mounted on the dentin surface .
the composite was packed into each tube under gentle pressure over cellophane strip then light - cured according to manufacturers guidelines using elipar ii unit ( 3 m espe , st .
each half received two tubes away by at least 3 mm whereas group a received two microcylinders only .
all specimens were stored for 24 h in an incubator at 37c and 100% humidity .
the plastic tubes were removed using sharp blade then each specimen was screwed to the lower fixed compartment of testing machine ( lrx - plus ; lloyd instruments ltd . , uk ) with 5 kn load . a loop wire , 0.014 in , wrapped around each microcylinder flushing with the resin - dentin interface and aligned with the loading axis of the machine upper movable compartment .
a shearing load applied to each assembly at 0.5 mm / min crosshead speed until failure .
failures classified as adhesive if occurred at the interface , cohesive as observed within dentin substrate or composite resin , and mixed when adhesive and cohesive fractures detected simultaneously .
specimens were gold sputtered under vacuum ( ladd sputter coater , bal - tec , scd005 , germany ) then examined under sem ( philips , holland ) .
the data were analyzed using spss ( version 16.0 ) software package ( spss inc . , chicago , il , usa ) with significance level set at p  0.05 .
one - way anova evaluated cleansing treatments effects and tukey 's post hoc test for multiple comparisons . the impact of saliva or blood contaminants assessed using independent t - test .
table 3 presents group b cleansing treatments where re - etching showed the highest sbs .
meansstandard deviation of microshear bond strength values ( mpa ) of contaminated bonding stages meansstandard deviation of microshear bond strength values ( mpa ) of contaminated etching cleansing treatments meansstandard deviation of microshear bond strength values ( mpa ) of contaminated unpolymerized adhesive cleansing treatments meansstandard deviation of microshear bond strength values ( mpa ) of contaminated polymerized adhesive cleansing treatments figure 2 illustrates that predominant failure of group b was adhesive mode while cohesive failure in composite prevailed groups c and d. sem used to understand cleansing treatments effect on substrate topography [ figures 3 and 4 ] .
saliva deposits observed in sb , sb1 , sb3 , c2 and sd ( saliva contamination after adhesive polymerization ) while blood remnants are notable in bb ( blood contamination after dentin etching ) , bb1 , bb3 and bd ( blood contamination after adhesive polymerization ) .
failure mode distribution among the test groups scanning electron microscope photomicrograph of etched dentin substrate ( single bond ) contaminated with saliva , ( bb ) contaminated with blood , ( sb1/bb1 ) rinsing of contamination , ( sb2/bb2 ) re - etching , ( sb3/bb3 ) sodium hypochlorite application .
black arrow points red blood cell ( 1000 ) scanning electron microscope photomicrograph of ( c2 ) alcohol and ( c3 ) acetone effect on contaminated adhesive before its polymerization , ( sd / bd ) saliva or blood contamination of adhesive after polymerization , ( sd3/bd3 ) re - etching , ( sd4/bd4 ) re - etching then rebonding .
black arrows point red blood cells ( 1000 ) scanning electron microscope photomicrograph depicting red blood cells ( 3500 )
micro - shear strength test considered effective for measuring variation in bonding under different conditions .
small specimens allowed several readings from the single tooth and provided harmonious stresses yielding lesser data dispersion .
bonding steps start with etching which selectively decalcify intertubular and peritubular dentin leaving collagen mesh for adhesive impregnation then polymerization .
however , others reported negligible moisture effect ( particularly saliva ) over bonding . the difference attributed to different adhesives composition and experimental design using micro - leakage or diverse loading tests .
chang et al . , and de carvalho mendona et al . , reported that rinsing failed to remove blood due to greater proteins macromolecules contents which resist rinsing and prevent adhesive permeation .
naocl application , for < 60 s , showed fractional reversing of contamination due to its nonspecific proteolytic action which eradicates organic remnants without negatively effecting bonding .
whereby , re - etching regained adequate bonding due to acid denaturation of organic remnants rendering weak affinity to underlying substrate becoming easily washed . when unpolymerized adhesive contaminated , its conversion becomes affected as a result of hydrophilic hema molecules which retain water within the adhesive limiting chain growth during polymerization , producing a plasticizing effect in polymer and oxidation of pendant c = c bonds .
in addition , higher blood viscosity diminish light permeation and adhesive polymerization . according to the present result , acetone application successfully restored bonding strength when contamination affected unpolymerized adhesive .
however , acetone possess additional ability to remove monomer and denature plastics ( polymers ) , accordingly was able to remove contaminated unpolymerized adhesive leaving perspicuous bonding surface .
furthermore , contamination of polymerized adhesive permits glycoproteins adherence to air - inhibited adhesive surfaces forming a physical barrier preventing co - polymerization between adhesive and composite resin . in agreement with furuse et al .
, it was observed that etching of contaminated cured adhesive , created areas devoid from adhesive coverage since etching removed contaminant residue and peeled off adhesive coating [ sd3/bd3 , figure 4 ] .
thus , rebonding after re - etching aided in the refurbishing of patent adhesive for bonding .
therapy , adhesive failures predominated etched contaminated substrate while cohesive mode prevailed affected adhesive stages .

 contamination reduced bonding strength to dentin where blood yielded more negative effect than salivato enhance bonding ; re - etching then rebonding are recommended with contaminated etching or polymerized adhesive while acetone and rebonding with affected uncured adhesives . 
 
contamination reduced bonding strength to dentin where blood yielded more negative effect than saliva to enhance bonding ; re - etching then rebonding are recommended with contaminated etching or polymerized adhesive while acetone and rebonding with affected uncured adhesives .
objectives : to assess the effect of cleansing treatments following saliva and blood contamination at different bonding stages to dentin.materials and methods : labial surfaces of 168 permanent maxillary central incisors were ground flat exposing superficial dentin . 
 specimens were divided into : uncontaminated control ( a ) , contamination after etching ( b ) , contamination after adhesive application ( c ) , contamination after adhesive polymerization ( d ) . 
 groups were further subdivided according to cleansing treatments into : rinsing ( b1 , c1 , d1 ) , re - etching ( b2 , d3 ) , sodium hypochlorite application ( b3 ) , ethyl alcohol application ( c2 ) , acetone application ( c3 ) , rinsing and rebonding ( d2 ) , re - etching and rebonding ( d4 ) . 
 composite microcylinders were bonded to treated substrates and shear loaded micro - shear bond strength ( sbs ) until failure and treated surfaces were examined with scanning electron microscope . 
 debonded surfaces were classified as adhesive , cohesive or mixed failure . 
 the data were analyzed using one - way anova and tukey 's post hoc test.results:the sbs values were ranked as follow ; group b : a > b3 > b2 > b1 > b , group c : a > c3 > c2 > c1 > c , group d : a > d4 > d1 = d2  d3 . 
 debonded surfaces showed adhesive failure in group b while cohesive failure in groups c and d.conclusions:cleansing treatments differ according to bonding step ; re - etching then rebonding suggested if etched substrate or polymerized adhesive were contaminated while acetone application decontaminated affected unpolymerized adhesive .