Confocal laser scanning microscopy versus digital microscopy in the analysis of the marginal adaptation of Tizian overlays

Technological improvements and the progress of new adhesive materials have led to the development of minimally invasive restorations, like overlays; these are also indicated in the treatment of pathological tooth wear caused by bruxism. In this study we evaluated the marginal adaptation of Tizian overlays through two non-invasive methods: digital microscopy and confocal laser scanning microscopy. 12 maxillary first premolars were extracted and prepared for overlays. The Tizian overlays were cemented with Variolonk II (Ivoclar Vivadent). The marginal adaptation of each specimen was analyzed, on all four surfaces, with a digital microscope at 40x to 800x magnification ratio; we also used a confocal laser scanning microscope, at 10x magnification, in Z mode, with 10 μm slices and a resolution of 1020 x 1024. The exposure time per pixel was 8 μs and the wavelength of the laser was set at 405 nm, corresponding to a blue light laser. We concluded that confocal laser scanning microscopy, with its a higher horizontal and vertical resolution with regard to digital microscopy, and with its volumetric reconstructions capability of the sample image, is therefore a more appropriate method for this particular dental field, i.e., to investigate the marginal adaptation of Tizian overlays.