Gravimetric Analysis (Dentin) Gravimetric Analysis (Enamel) Potential Erosive Effect of Commercially Available Mouthrinses on Enamel and Dentin Delgado AJ1, Quesada A2, Rodriguez L2, Behar-Horestein 3, Su Y3, Wynkoop B1, Dilbone DA1 1 Department of Restorative Dental Sciences, College of Dentistry, University of Florida, Gainesville , 2 DMD Student, College of Dentistry, University of Florida, Gainesville, 3 Department of Community Dentistry, College of Dentistry, University of Florida #1546 OBJECTIVE Objective: To asses and compare the pH values and the titratable acidity of different commercially available mouthrinses and to evaluate the erosive potential on enamel and dentin by gravimetric analysis.   METHODS & MATERIALS Mouthwashes: Listerine Total Care, Listerine Ultra Clean, Crest Pro-health, Scope Classic, Listerine Original, ACT pH Analysis: Performed for 6 commercially available over-the-counter mouthrinses using a calibrated pH meter. For each bottle, the pH was recorded five times, resulting in 25 measurements per brand. The pH meter was calibrated with buffer solutions with pH of 4.0, 7.0 and 10.0 before recording a new measurement. The pH value was recorded when the meter obtained a stabilized value. Between each recording the meter probe was rinsed with de-ionized water (pH 7.06) and dried with air, to buffer the glass-electrode sensor. All recordings were made at room temperature of 23 degrees Celsius. Titratable Acidity The TA was then measured by adding 1.0-mL of NaOH to each beverage until the pH reached 7.0. The amount of base (m/mol) required to reach a neutral pH was recorded and then calculated. If there was a solution that presented a pH value of ≥ 7 this part of the experiment was omitted. Gravimetric Analysis: Freshly extracted molars crown/roots were collected. Each root was sectioned at the CEJ. The coronal and apical portions of the specimens were sealed with a self-etching dentin bonding agent to avoid influx of the solution into the pulp chamber. The specimens were then dried and weighed on a calibrated analytical balance to obtain a baseline recording. The specimens were then submerged in 5 ml of solution of each of the mouthwashes for 24 hours, 48 hours, 96 hours, 1 week, and 2 weeks with measurements performed at each interval after drying the specimens as previously described. The solutions were renewed at each interval. RESULTS pH Analysis Titratable Acidity Gravimetric Analysis (Dentin) Gravimetric Analysis (Enamel) LTC: Listerine Total Care, LUC: Listerine Ultra Clean, CPH: Crest Pro-health, SC: Scope Classic, LAO: Listerine Original, ACT: ACT In order to verify the distribution of the data, the Shapiro Wilk test was performed. All data set (pH, TA, dentin and enamel loss) presented non-normal distribution and therefore non-parametric test was used (Spearman correlation). The association between: pH and TA was considered significant (p= 0.002). pH and dentin loss was considered significant (p= 0.048). pH and enamel loss was not considered significant (p= 0.6297). TA and dentin loss was considered significant (p= 0.0051). TA and enamel loss was not considered significant (p= 0.6157). CONCLUSIONS Most of the mouthwashes tested reported an acidic pH value except Crest Pro-Health. Listerine Antiseptic Original and Listerine Antiseptic Ultra Clean reported the highest titratable acidity (TA). Dentin tooth loss is associated with high titratable acidity and low pH. There was not significant loss of enamel with the mouthwashes tested.