Scanning electron microscopic study of the in situ effect of salivary stimulation on erosion and abrasion in human and bovine enamel

Daniela Rios,Heitor Marques Honório,Ana Carolina Magalhães,Alberto Carlos Botazzo Delbem,Marília Afonso Rabelo Buzalaf,Salete Moura Bonifácio Da Silva,Maria Aparecida De Andrade Moreira Machado

doi:10.1590/s1806-83242008000200007

Abstract

This in situ study investigated, using scanning electron microscopy, the effect of stimulated saliva on the enamel surface of bovine and human substrates submitted to erosion followed by brushing abrasion immediately or after one hour. During 2 experimental 7-day crossover phases, 9 previously selected volunteers wore intraoral palatal devices, with 12 enamel specimens (6 human and 6 bovine). In the first phase, the volunteers immersed the device for 5 minutes in 150 ml of a cola drink, 4 times a day (8h00, 12h00, 16h00 and 20h00). Immediately after the immersions, no treatment was performed in 4 specimens (ERO), 4 other specimens were immediately brushed (0 min) using a fluoride dentifrice and the device was replaced into the mouth. After 60 min, the other 4 specimens were brushed. In the second phase, the procedures were repeated but, after the immersions, the volunteers stimulated the salivary flow rate by chewing a sugar-free gum for 30 min. Enamel superficial alterations of all specimens were then evaluated using a scanning electron microscope. Enamel prism core dissolution was seen on the surfaces submitted to erosion, while on those submitted to erosion and to abrasion (both at 0 and 60 min) a more homogeneous enamel surface was observed, probably due to the removal of the altered superficial prism layer. For all the other variables--enamel substrate and salivary stimulation -, the microscopic pattern of the enamel specimens was similar.

Highlights

The incidence of dental caries has declined in developed countries[1] followed by the increase of other dental lesions, such as pathological tooth wear.[2]
An acidic attack leads to demineralization and softening of the tooth surface, and to a decrease in the wear-resistance of the tooth surface, rendering it more susceptible to the effects of mechanical abrasion, such as those offered by tooth-brushing.[8,9,10]
For the uncoated surfaces submitted to erosion only, enamel prism core dissolution was seen (Figures 2.B and 2.C), while for those submitted to erosion subjected to abrasion a more homogeneous enamel surface was observed (Figures 2.D, 2.E and 2.F), probably due to the removal of the superficial altered prism layer

Summary

Introduction

The incidence of dental caries has declined in developed countries[1] followed by the increase of other dental lesions, such as pathological tooth wear.[2] In clinical situations, tooth wear can involve attrition, abrasion and erosion simultaneously. Erosion is defined as the loss of dental hard tissue resulting primarily from non-bacterial chemical attack, usually involving acidic substances (foods and soft drinks).[5,6,7] An acidic attack leads to demineralization and softening of the tooth surface, and to a decrease in the wear-resistance of the tooth surface, rendering it more susceptible to the effects of mechanical abrasion, such as those offered by tooth-brushing.[8,9,10] Because these erosive and abrasive processes are usually observed in the mouth, efforts have been made to elucidate how erosive/abrasive lesions can be prevented

Methods

Results

Conclusion