Confocal laser scanning reflection microscopy applied to the remineralization studies in incipient caries lesions

Abstract

To evaluate through roughness parameters measurement the penetration of calcium phosphate stabilized by casein phosphopeptides (CPP-ACP) in the subsurface zone of the incipient caries lesions known in dentistry as white spot lesion (WSL). To our knowledge, there is no data about roughness parameters to evaluate the demineralization-remineralization process in the body of the lesion. WSL was generated in vitro in 10 dental samples and sectioned in half of them (longitudinal section). CPP-ACP was applied on the WSL (3 minutes daily for 60 days). Roughness parameters (Rp and Ra) were measured on the longitudinal section with a laser scanning confocal microscope in the reflection acquisition mode (CLSRM), either in the WSL or sound enamel, before and after applying CPP-ACP. CLSRM is a non-contact method able to detect small irregularities more precisely due to the small spot of laser illumination (0.5 μm). Mixed linear models were carried out, using the treatment as a fixed factor and the tooth as a random factor (significance level 5%). Rp and Ra values in WSL area before applying the remineralization protocol (WSL pre) were significantly higher than in the sound enamel of the same samples. After applying CPP-ACP, Rp and Ra values decreased significantly with respect to the WSL pre and were similar to the values of these parameters in sound enamel. roughness parameters were used as an indirect way to measure the porosity of WSL at subsurface level. The decrease of these parameters could be interpreted as the remineralization of WSL by the ability of CPP-ACP to penetrate the body of the lesion. Clinical significance: WSL is characterized by the loss of minerals from the enamel and an increase in porosity at the subsurface level. The effectiveness of remineralizing substances would be determined by their ability to penetrate the body of the lesion and reduce porosity.