Susceptibility of deciduous and permanent enamel to erosion in vitro

Objectives: The aim of this study was to compare the difference in susceptibility of deciduous and permanent enamel to demineralization by soft drinks in vitro. Methods: Fleshly extracted human premolars and deciduous incisors without caries and cracks were used. Teeth were cleaned and the dental root and pulp were removed. Two enamel samples of each permanent crown and one enamel sample of each deciduous crown were prepared. The samples were ground with 600-2000 grit waterproof abrasive paper and let the buccal / labial / lingual surface parallel to the bottom. All samples were divided into four groups: coca cola group (A), lemonade group (B), orange juice drink(C) and control group (D). The samples were discontinuously immersed into four different solutions respectively for two minutes each time, and six times per day, totally 7 days at room temperature. The surface micro-hardness (SMH) was measured and the surface morphology under Scanning Electronic Microscope (SEM) and Atomic Force Microscope (AFM) were observed before and after erosion. Results: The baseline SMH of deciduous enamel(295.1604±22.3220) was lower than that of permanent enamel(329.65±16.0294), but the decrease of SMH in permanent enamel was significantly lower than that of deciduous enamel (P<0.001). Although the SMH decreased in both permanent and deciduous enamel, there was no statistically significant decrease in deciduous (P>0.05). For permanent enamel, the decreases of SMH in group A and group C were significantly different from the control, but there was no statistical significance between the other groups. The SEM and AFM showed related morphological changes of dental enamel before and after erosion, but there was no particular morphological difference between the deciduous and permanent enamel, as well as the four groups. Conclusions: The study showed that the permanent enamel was more susceptible than deciduous enamel to different soft drinks.