Attempt to modify the chemical model of enamel demineralization used in microinvasive dentistry

Introduction
Developments in minimally invasive dentistry result both in the advancement of methods used in early diagnosis and of the therapy of carious lesions.

Objectives
The aim of the study is to compare the efficiency of the demineralization process (which caused artificial caries lesions) controlled with a chemical model on the surface of enamel of extracted healthy human teeth. Two demineralizing solutions were used: one based on methylenehydroxydiphosphonate (MHDP) and another based on methylenediphosphonate (MDP).

Material and methods
The material (16 healthy human teeth) was divided into two parts, and exposed to two acidic solutions (MHDP or MDP): 3 mM calcium chloride dihydrate, 3 mM dipotassium phosphate, 50 mM acetic acid and either 6 µM MHDP or 6 µM MDP. Both solutions had an established pH of 5 (with a constant temperature of 37°C, and a constant composition). Then the specimens were dissected along their long axis, and prepared for scanning electron microscopy.

Results
The analysis showed no statistically significant quantitative changes in calcium and phosphorus at the measurement points a and β in both groups (MHDP and MDP). Results obtained in area S for both groups showed smaller discrepancies of Ca and P values, which suggests that the course of decalcification obtained at a distance of 60 µm down the surface area is similar in both groups. Moreover, the variance of the content of phosphorus and calcium is always lower in the samples with the MHDP formulation.

Conclusions
Use of MDP instead of MHDP in the buffer bath does not change properties of the environment which affect its ability to cause artificial caries lesions in hard tissues of teeth.