Hydroxyl ion diffusion through intact and resorbed roots at various time intervals

INTRODUCTION: The purpose of this study was to investigate root surface pH changes over a period of 4 weeks following treatment with calcium-hydroxide dressing of intact and resorbed roots. MATERIALS & METHODS: The canals of 30 single-rooted teeth were instrumented with ProTaper rotary files and randomly divided into 2 experimental groups of 14 each, and one control group with two samples. To simulate external resorption in group 2 and control, two defects were made on the buccal and lingual mid-root surfaces of each tooth with a diamond bur (1×1mm). Teeth were then submerged in 20% sulfuric acid for 4 days. Canals of 14 intact teeth in group 1, and 14 resorbed teeth in group 2 were filled with calcium hydroxide Ca(OH)(2) while canals of resorbed teeth in control group were filled with saline. All teeth were then placed in a glass vial containing 15mL of deionized water (pH≈7). The pH of water was measured at 0 and 1, 4, 7, 10, 14, 21 and 28 days using pH microelectrode. Independent t-test and repeated measured ANOVA analyzed the data. RESULTS: Except a mild decline at 7days and 14days, the average pH values showed increased during the time periods of this study. Day 28 showed the maximum pH average value in both groups (7.67-7.72) (P<0.05). Significant increase of pH values were detected at different time intervals compared with the baseline time (P<0.05). CONCLUSION: Diffusion of hydroxyl ions was similar in both resorbed and intact roots. In both groups pH values were significantly higher than the baseline pH at the various times.