Figure 6.

Quantifying the depth of penetration of lactic acid within the dentin tubules and beneath the exposed surface. The depth of degradation (D) is identified in the micrographs of (a) and (b). a) representative micrograph of the microstructure beneath the tensile surface of a beam after 1k cycles. b) representative micrograph of the microstructure beneath the tensile surface of a beam after one million cycles of loading. Note the cracks within the partially demineralized tubule lumens (white arrows). c) average depth of degradation (with standard deviation) assessed over different periods of evaluation.