pH and Erosive Potential of Commonly Used Oral Moisturizers

Purpose: To measure the pH values of commonly used oral moisturizers and to evaluate their erosive potential using a gravimetric analysis. Materials and Methods: A pH analysis was performed for seven commercially available oral moisturizers using a calibrated pH meter. The pH recording was repeated three times, from three different bottles each of the same product. The gravimetric analysis was performed by submerging human dentin blocks in 5 ml of each of the moisturizers for a total of 2 weeks, with gravimetric measurements made at baseline, 24 hours, 48 hours, 96 hours, 1 week, and 15 days. Tap water was used as positive control and citric acid as the negative control. The erosive potential was descriptively analyzed, and a Spearman correlation coefficient was used to assess the relationship between the erosive potential and the pH values. Results: The average pH values are as follows: Oasis, 6.3, Bioténe Moisturizing Mouth Spray, 6.1, CTx2 Spray, 9.1, Mouth Kote, 3.0, Thayer's, 6.3, Bioténe Oral Balance, 6.6, Rain, 7.1, tap water 6.99, and citric acid 1.33. The results (% of tooth structure lost) of the gravimetric analysis were as follows: Mouth Kote, 9.6%, Bioténe Moisturizing Mouth Spray, 4.6%, Oasis, 3.2%, Thayer's, 2.0%, Bioténe Oral Balance, 0.0%, Rain, 0.0%, CTx2 Spray, 0.0%, tap water 0.0%, and citric acid 18.8%. There was a significant negative correlation between the pH values and the erosive potential (r_s = -0.73; P ≤ 0.0001). Conclusions: There is large variation in the composition and pH values of commonly used oral moisturizers, and there is a strong correlation between pH values and erosive potential of commonly used oral moisturizers. Clinical Significance: Patients with dry mouth are at increased risk for erosion and root caries. Oral moisturizing agents are often prescribed for patients with hyposalivation to be used as needed for symptomatic relief. This study shows that there is large variation in the pH values and erosive potential of commonly used oral moisturizing agents.