Effect of different salivary exposure times on the rehardening of acid-softened enamel

• Published in: Brazilian oral research Vol. 30; no. 1; p. e104
• Main Authors: Alencar, Catarina Ribeiro Barros de, Mendonça, Fernanda Lyrio, Guerrini, Luísa Belluco, Jordão, Maisa Camillo, Oliveira, Gabriela Cristina de, Honório, Heitor Marques, Magalhães, Ana Carolina, Rios, Daniela
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Pesquisa Odontológica - SBPqO 01.01.2016; Sociedade Brasileira de Pesquisa Odontológica
• Subjects: Adult; Analysis of Variance; Animals; Cattle; Citric Acid - chemistry; Dental Enamel; Dental Enamel - chemistry; Dental Enamel - drug effects; Dentistry; DENTISTRY, ORAL SURGERY & MEDICINE; Female; Hardness Tests; Healthy Volunteers; Humans; Male; Random Allocation; Saliva; Saliva - chemistry; Saliva - physiology; Statistics, Nonparametric; Surface Properties; Time Factors; Tooth Erosion; Tooth Erosion - prevention & control; Tooth Remineralization; Young Adult; Tooth Remineralization; Dental Enamel; Saliva; Tooth Erosion
• ISSN: 1806-8324; 1807-3107; 1807-3107; 1806-8324
• DOI: 10.1590/1807-3107BOR-2016.vol30.0104

This in situ study assessed the effect of different times of salivary exposure on the rehardening of acid-softened enamel. Bovine enamel blocks were subjected in vitro to a short-term acidic exposure by immersion in 0.05 M (pH 2.5) citric acid for 30 s, resulting in surface softening. Then, 40 selected eroded enamel blocks were randomly assigned to 10 volunteers. Intraoral palatal appliances containing 4 enamel blocks were constructed for each volunteer, who wore the appliance for 12 nonconsecutive hours: initial 30 min, followed by an additional 30, and then by an additional 1 hour. For the last additional 10 hours the appliances were used at night, during the volunteers' sleep. Surface hardness was analyzed in the same blocks at baseline, after erosion and after each period of salivary exposure, enabling percentage of surface hardness recovery calculation (%SHR). The data were tested using repeated measures ANOVA and Tukey's test (α = 0.05). Increasing periods of salivary action promoted a progressive increase in the surface hardness (p < 0.001). However a similar degree of enamel rehardening (p = 0.641) was observed between 2 hours (49.9%) and 12 hours (53.3%) of salivary exposure. Two hours of salivary exposure seems to be appropriate for partial rehardening of the softened enamel surface. The use of the intraoral appliance during sleep did not improve the enamel rehardening after erosion.