pH Change Following Smear Layer Removal and Final Rinse with 95% Ethyl Alcohol Using Calcium Hydroxide Medicament or BC Sealer

Abstract

Introduction: An in vitro investigation of pH change at the external root surface after final rinse of 95% ethyl alcohol using Ultracal XS, Calasept Plus, or obturation with BC sealer. Methods: 80 single rooted extracted human teeth were decoronated with a standardized root length of 15mm. All root were instrumented to size F4 using the ProTaper Gold file system. Defects were made on the facial and lingual root surfaces to remove cementum. Teeth were then randomized into treatment groups based on medicament used and final rinse with or without ethanol. Negative controls received no medicament. Full wax control groups received medicaments but were completely sealed with wax. After final rinses roots were filled with Ultracal XS, Calasept Plus, or BC sealer. Negative controls received no medicaments. Roots were sealed at coronal and apical ends using two layers of sticky wax and were placed in a 4mL lab vial containing 2mL of sterile saline. pH was measured days 0,1,2,4,7,9,12,16,22,28. Tooth roots were sectioned and remaining dentin thickness (RDT) was measured to correlate RDT and pH values. A multiple linear regression model was used to estimate the effects of medicament, ethanol, interaction of medicament and ethanol, as well as a continuous variable of RDT. Pairwise comparisons were completed to establish differences within groups. Results: It appears that ethanol may have an effect on the rate of pH change in the Calasept Plus group. Trends towards a faster rise in pH were noted in both ethanol positive calcium hydroxide groups. BC sealer maintained a pH higher than negative controls for the first 12 days before dropping to baseline levels. RDT was found to affect pH levels, with greater thicknesses correlating to lower pH values. Maximum pH values were reached between days 12-16 after which a decline was noted in each group, indicating a replenishing of medicament may be necessary to maintain pH levels at the external root surface.