School of Dentistry, Isfahan University of Medical SciencesJournal of Isfahan Dental Schoolمجله دانشکده دندانپزشکی اصفهان1735-255x111FAjalali139398gregorian20141129Evaluation of pH and calcium ion concentration changes with the use of different calcium hydroxide pastes on external root surfaceبررسی تغییرات pH و غلظت یون کلسیم در محیط اطراف ریشه دندان در موارد استفاده از ناقل های مختلف هیدروکسید کلسیم113FAعلیرضافرهادبهنازبرکتینحجتصادقیآزادهخزایی زادهدانشجوي دندانپزشكي، کمیته پژوهشهای دانشجویی، دانشکده دندانپزشکی، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران. azdkhazaei@gmail.comAlirezaFarhadBehnazBarekatainHojatSadeghiAzadehKhazaei Zadehjalali139398Introduction: Calcium hydroxide is used as an intracanal medicament in endodontics. Its therapeutic effects depend on the dissociation of calcium hydroxide into calcium and hydroxide ions. The aim of this study was to evaluate the pH and calcium ion concentration of three different calcium hydroxide pastes, after 24 hours and 1 week for each vehicle, on the external root surface. Materials and methods: In this experimental study, the crowns of 72 human single-rooted teeth were removed, the canals were prepared and external defects were created on the root surfaces. All the surfaces except the external defects were sealed and the teeth were immersed in normal saline solution. The samples were divided into 6 experimental and 2 control groups. Experimental groups were dressed with calcium hydroxide in combination with: A and B: 0.2% chlorhexidine solution, B and C: 5.25% sodium hypochlorite solution, E and F: distilled water. Calcium ion concentrations and pH of normal saline solution were determined after 24 hours in groups A, C and E, and after one week in groups B, D and F. One-way and two-way ANOVA were used for statistical analysis with SPSS software program (α=0.05). Results: In relation to pH, after 1 week there was a significant difference between groups B and D (p value = 0.013); the effect of time was significant in all the groups except for groups D and C (p value < 0.05). Calcium ion concentration at 24-hour and 1-week intervals was significant for each vehicle (p value < 0.001) but it was not significant between different groups (p value > 0.05). Conclusion: As an intracanal medication, the combination of 0.2% chlorhexidine and calcium hydroxide exhibited significantly higher pH values compared to the combination of 5.25% sodium hypochlorite and calcium hydroxide after one week. Calcium ion concentration increased after 1 week in all the groups; however, there were no significant differences in each group between the two time intervals. Key words: Calcium hydroxide, Sodium hypochlorite, Tooth root.http://www.jids.mui.ac.ir/index.php/jids/article/view/872http://www.jids.mui.ac.ir/index.php/jids/article/download/872/2864