The erosive effects of some mouthrinses on enamel - A study in situ

Background: There are both anecdotal clinical and laboratory experimental d ata suggesting that low pH mouthrinses cause dental erosion. This evidence is particularly relevant to acidified sodium chlorite (ASC) formulations si nce they have plaque inhibitory properties comparable to chlorhexidine but without the well known local side effects. Aim: Studies in situ and in vitro were planned to measure enamel erosion by low pH mouthrinses. The study in situ measured enamel erosion by ASC, esse ntial oil and hexetidine mouthrinses over 15-day study periods. The study w as a 5 treatment, single blind cross over design involving 15 healthy subje cts using orange juice, as a drink, and water, as a rinse, as positive and negative controls respectively 2 enamel specimens from unerupted human thir d molar teeth were placed in the palatal area of upper removable acrylic ap pliances which were worn from 9 a.m. to 5 p.m., Monday to Friday for 3 week s. Rinses were used 2 x daily and 250 ml volumes of orange juice were imbib ed 4 x daily. Enamel loss was determined by profilometry on days 5, 10 and 15. The study in vitro involved immersing specimens in the 4 test solutions together with a reduced acid ASC formulation for a period of 4 h under con stant stirring; Enamel loss was measured by profilometry every hour. Results: Enamel loss was in situ progressive over time with the 3 rinses an d orange juice but negligible with water. ASC produced similar erosion to o range juice and significantly more than the two proprietary rinses and wate r. The essential oil and hexetidine rinses produced similar erosion and sig nificantly more than water. Enamel loss in vitro was progressive over time, and the order from low to high erosion was reduced acid ASC. ASC, Essentia l oil, and hexetidine mouthrinses and orange juice. Conclusion: Based on the study in situ, it is recommended that low pH mouth rinses should not be considered for long term or continuous use and never a s pre brushing rinses. In view of the plaque inhibitory efficacy of ASC, sh ort- to medium-term applications similar to those of chlorhexidine would be envisaged.