Enamel erosive Remineralization and demineralization considering different times of salivary action and intraoral appliances: In situ study

Author(s)

Fernanda Lyrio Mendonça

• Document type: Master's Dissertation
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2015-04-10

Examining board members

Daniela Rios Honório; Marilia Afonso Rabelo Buzalaf; Juliano Pelim Pessan

• Advisor: Daniela Rios Honório

Abstract

The protective potential of saliva has been described as an important factor that influences the pathogenesis of dental erosion. The aim of this study was to evaluate in situ the remineralizing effect of saliva on initial erosion lesions and the protective effect of saliva in relation to erosive enamel desmineralization, using palatal and mandibular appliances in different times of salivary exposure (30 min, 1h, 2h e 12h). This study consisted of two subprojects, each one with a sample size of 20 volunteers. In subproject I, after initial surface hardness evaluation, enamel blocks were demineralized in vitro (hydrochloric acid 0.01 M for 30 seconds), selected and randomly assigned between two types of appliances. Four blocks were placed on the palatal device and two blocks for the mandibular appliance (2 aplliances per volunteer / right and left). In the in situ phase, the volunteers were instructed to use the palatal and mandibular appliances for 12 hours, so that after every predetermined period of time, the enamel blocks were removed from the appliances for immediate evaluation of surface hardness (remineralization surface hardness). In subproject II, enamel blocks were selected using initial surface hardness and randomized among the volunteers according to factors time (30 min, 1h, 2h, and 12h) and types of intrabucal aplliance (palatal and mandibular). A control group with enamel blocks not subjected to salivary effect was also used. In in situ phase, the volunteers used intrabucal appliances with two enamel blocks in the palatal appliance (1 appliance per volunteer) and one block in each mandibular appliance (2 aplliances per volunteer / right and left). Imeddiatelly after use in each phase, the enamel blocks were desmineralized and the surface hardness was assessed. The data were analyzed using two-way ANOVA and Tukey test subproject I; Kruskal-Wallis and Tukey test subproject II, considering p<0.05. In subproject I, was observed a significant difference (p <0.0001) between 30 minutes and 2 hours, which showed no difference comparing to 12 hours. There was no significant difference in hardness recovery between specimens kept in the maxilla and mandibula. In subproject II, no significant difference was seen between the types of intraoral appliances. However, when times were compared, there was no difference between 30 minutes and 2 hours, which showed no difference compared to the 12 hours. Significant difference was found when the periods of 2 hours and 12 hours were compared with the control group (without exposure to saliva), for both, palatal and mandibular aplliances. Therefore, regardless of the type of appliance, 2 hours of salivary exposure showed remineralizing potential, as well as promoted some level of protection in relation to erosive enamel demineralization, and increased enamel exposure to saliva (12 hours) did not increase these effects. (AU)

• FAPESP's process: 13/15765-2 - Erosive remineralization and demineralization of enamel considering different times of salivary action and intraoral devices: in situ study
• Grantee: Fernanda Lyrio Mendonça
• Support Opportunities: Scholarships in Brazil - Master