A STRUCTURAL-ANALYSIS OF APPROXIMAL ENAMEL CARIES LESIONS AND SUBJACENT DENTIN REACTIONS

The present study examines the correlation between caries lesions in e namel and the corresponding dentin reactions in proximal tooth surface s with lesions ranging from enamel lesions to cavitations without dent in exposure. Using quantitative imbibition technique, the highest degr ee of tissue porosity, irrespective of lesion activity, was always not ed along a Central-Traverse (CT), which followed the direction of the rods from the deepest point of penetration to the surface. The conical shape of approximal enamel lesions can thus be seen as the result of systematic variations in porosity along the rods determined by the spe cific interproximal environment. The initial dentin reaction, related to the enamel lesion approaching the enamel-dentin junction (EDJ), was seen as a local dentin translucency where the CT crossed the EDJ. Res ults from histomorphometric analyses revealed that, when the enamel le sions reached the EDJ, brownish discoloration in the dentin never exce eded the histologic contact area between the enamel lesion and the EDJ . In relation to the less advanced parts of the individual enamel lesi on, the dentin responded with formation of translucent dentin. These r eactions did not occur beyond an area determined by lines in the direc tion of the rods from the peripheral part of the enamel lesion towards the EDJ. The results did not support the view that dentin caries spre ads along the enamel-dentin junction. The peripheral dentin translucen cy is therefore generated by stimuli transmitted along the rods of the less advanced parts of the enamel lesions.