Influência de agentes protetores na prevenção da erosão extrínseca ou intrínseca : estudos in vitro e in situ

Abstract

Considering the decline in the prevalence of caries and periodontal diseases in society, there is greater tooth longevity. Thus, non-carious cervical lesions have been observed with greater frequency. Therefore, products that enable the reduction of tooth wear, with easy access and daily use, are ideal alternatives for reducing the loss of mineralized tissue. This thesis consists of three papers that aim, respectively: (1) verify the preventive effect of three commercial AmF, AmF/SnF2 or SnF2-containing dentifrices through an erosive/abrasive model on human dentin; (2) investigate the effect of Mg(OH)2 present in commercial dentifrices in preventing the erosion of enamel by extrinsic and intrinsic acids, as well as, the influence of the number of experimental days in erosion progression; (3) evaluate in situ the action of Mg(OH)2 and NaF in prevention of intrinsic erosion on human enamel. In Articles 1 and 2, were conducted in vitro models, randomized, blind, cyclic, in which the specimens were subjected to the process of de- and remineralization. In Article 1, the erosion was simulated by intrinsic acid, while in Article 2, was intrinsic and extrinsic acids. In Article 1, was added the process of abrasion for toothbrushing. For both studies, the cycle was repeated three times daily for 5 days. In Article 3, the study was in situ, randomized, double-blind, crossover in three phases of five days each, with the participation of 18 volunteers who wore palatal appliances containing 2 blocks of human enamel treated with different toothpastes: control (0 ppm F), Mg(OH)2 (2%) and NaF (1450 ppm F). The specimens were subjected to erosion by immersion them in a cup containing 0.01 M hydrochloric acid (pH = 2) for 60 seconds, 4 times a day, in predetermined times. Then, the volunteers brushed their teeth for 25 seconds with the device in the mouth, and the dilution dentifrice/saliva was rinsed mouthwash for 60 seconds. The alterations caused in specimens of all articles were evaluated by hardness and/or stylus profilometry. Data were tested using ANOVA (p <0.05). The Tukey test was used when required, in cases in which ANOVA revealed difference statistically significant. The results showed that in the article 1, AmF/SnF2 or SnF2 significantly reduced (p <0.05) the loss of dentin surface after erosion/abrasion. In Article 2, Mg(OH)2 or NaF-containing dentifrices were effective in reducing demineralisation caused by citric acid 0.05 M (p <0.001) compared to control. However, none prevention was observed for simulation of intrinsic acid, for both products. The results of the article 3 showed that tested dentifrices reduced the loss of surface enamel (p = 0.021). However, these products not present remineralizing effects (p = 0.349). Thus, it is concluded that dentifrices containing stannous fluoride or magnesium hydroxide are effective in performing some protective effect on the dental substrate after action of acids exogenous or endogenous.