This study evaluated the effect of the addition of 5% calcium chlorite (CaCl2) on pH values in calcium hydroxide pastes (CH), with or without 2% chlorhexidine digluconate (CHX) used as vehicle, in several periods analysis. Polyethylene tubes were filled with CH mixed with water (G1), 2% CHX solution (G2) or gel (G3), or CHX solution  or gel with 5% CaCl2 (G4 and G5, respectively). All tubes were individually immersed in distilled water. After 12, 24 hours, 7, 14 and 28 days, pH value was evaluated directly in water which the tubes were stored. Data were submitted to ANOVA and Tukey tests (α=0.05). In 24 hs and 14 days, pH values were similar to all groups. In 12 hs, the G1 presented lower pH value than other groups except to G4 (p < 0.05), and G4 presented lower pH value than G5 (p < 0.05). In 7 days, G1 presented lower pH value than G4 and G5 (p < 0.05). In 28 days, G1 and G5 presented lower pH values than G2 and G4 (p < 0.05) and among other groups there are no statistical differences (p > 0.05). The pH values increased in long-term analysis to all CH pastes. The association of 5% calcium chloride with 2% CHX solution as vehicle of CH paste provided a pH value increase in relation to CH mixed with distilled water. The CHX gel interfered negatively on pH value in comparison to CHX solution when mixed with CaCl2.

MSc,%Dental%School,%Redentor%School,%Itaperuna%,%RJ,%Brazil*% PhD,%Araraquara%Dental%School%<%Univ%Estadual%Paulista,%Araraquara,%SP,%Brazil**% PhD,%Dental%School,%Rio%Grande%do%Sul%Federal%University,%Porto%Alegre,%RS,%Brazil***% PhD,%Bauru%Dental%School%<%University%of%São%Paulo,%Bauru,%SP,%Brazil****% Correspondence:%miltoncarloskuga@hotmail.com%(KUGA%MC)%|%Received%23%Aug%2013%Received'in'revised'form%30%Aug%2013%Accepted%02%Sep%2013% % % CRESPO,%Mariana%Pires*% KUGA,%Milton%Carlos**% SÓ,%Marcus%Vinicius%Reis***% KEINE,%%Katia%Cristina**% SHINOHARA,%André%Luis****% % % % % % % % EFFECTS'OF'CORONAL'LEAKAGE'ON' CONCENTRATION'OF'HYDROGEN'IONS' AND'CALCIUM'RELEASE'OF'SEVERAL' CALCIUM'HYDROXIDE'PASTES'OVER' DIFFERENT'PERIODS'OF'TIME%% % ABSTRACT' % PURPOSE:% To% evaluate% the% effects% of% coronal% leakage% on% concentration%of%hydrogen%ions%(pH)%and%calcium%release%of%several% calcium% hydroxide% pastes,% over% different% periods% of% time.% MATERIAL' AND' METHODS:% % Fifty% extracted% human% mandibular% central%incisors%(n=10)%were%instrumented%up%to%the%F2%instrument% and% assigned% to% the% following% intracanal% dressing:% G1<% Calen,% G2<% Calen%with%0.4%%chlorhexidine%(CHX),%G3<%Calcium%hydroxide%with% camphorated% paramonochlorophenol% (CPMC)% and% glycerin,% G4<% Calen,% but% temporary% filling% material% maintained% during% all% test% (positive% control)% and% G5<% Root% canal% without% intracanal% dressing% (negative%control).%All%groups%were%immersed%in%distilled%water%for% 7%days.%In%sequence,%the%temporary%filling%materials%were%removed,% except%in%controls%groups.%All%specimens%were%individually%mounted% on% a% specific% device% and% only% its% root% again% immersed% in% distilled% water.% Concentration% of% hydrogen% ions% and% calcium% release% by% calcium%hydroxide%pastes%in%distilled%water%were%evaluated%in%24h,% 7,%14%and%28%days.%The%results%were%submitted%to%ANOVA%test%(p%=% 0.05).% After% 28% days,% root% canals% from% experimental% groups% were% examined% in% SEM.% RESULTS:% G1,% G2,% G3% and% G4% presented% similar% pH% values% and% calcium% release% and% did% not% differ% from% each% other% (p>0.05),% up% to% 7% days.% After% this% time% G1,% G2% and% G3% presented% values% lower% values% than% G4% (p<0.05).% In% SEM% analysis,% calcium% hydroxide% residues% were% observed% in% all% experimental% groups.% CONCLUSIONS:% After% 7% days,% coronal% leakage% decreased% the% concentration%of%hydrogen%ions%and%calcium%ion%release%provided%by% all%calcium%hydroxide%pastes.% ' ' ' ' ' ' KEYWORDS' % Calcium.%Camphorated%parachlorophenol.%Chlorhexidine.% Hydrogen.%Scanning%electron%microscopy.%

Introduction If the restoration, that seal the root canal from oral environment, failed or solubilize, the intracanal dressing could be partially removed, decreasing the efficiency of calcium hydroxide (CH). Objective To evaluate the alkalizing potential and calcium ions release of intracanal residues from different medications, in different periods. Materials and method Human incisors were endodontically instrumented and randomly divided (n=10). The root canals were filled with: G1⎯Calcium hydroxide (CH); G2⎯CH with 0.4% chlorhexidine digluconate (CHC); G3⎯CH with camphorated paramonochlorophenol and glycerin (HPG); G4⎯CH was maintained during all experiment, as positive control group (PC) and G5⎯ No medication was performed in the negative control group (NC). The specimens were immersed in distilled water for 7 days. The intracanal dressing was removed from the experimental groups using F1 instrument (Protaper). The teeth were stored in distilled water for 24 hours, 7, 14 and 28 days. pH value and calcium ions released were evaluated and the data were submitted to ANOVA one-way and Tukey tests. Result All experimental groups presented lower alkalizing potential and calcium ions release than PC (P<0.05). No significant difference was found among the experimental groups, regardless of the period (P>0.05). Conclusion The alkalizing potential and calcium ions release of residues from different intracanal dressing, in different periods, were similar and lower than the positive control group, that the medication was maintained inside the root canal, encouraging the replacement of intracanal dressing when the restoration fail.