Aesthetic All-ceramic Restorations. CAD-CAM System

Restorations requirements are resistant, lasting, precise, functional and aesthetic. All-ceramic has been developed for more than a century and has several possibilities for the elaboration of metal free restorations of maximum aesthetic. First all-ceramic restorations emerged in 1903, and contained a high percentage of feldspat (60%), silica (25%) and fluxes (Land, 1886, 1903). Later, in 1965, their reinforced ceramics with alumina appeared (McLean & Hughes, 1965; McLean, 1974-1976) where the glass matrix of the porcelain is spread with crystals to improve resistance but, actually, aesthetics is affected due to opacity increase. Therefore, to reconcile the aesthetic requirements and the resistance, a thin alumina coping, similar to a metal core, over which a veneering ceramic is put, began to be used (Chiche & Pinalt, 1994).

The strengthening of the porcelain can be done by four methods: i) Metal strengthening (Brukl & Ocampo, 1987); ii) Strengthening by high resistance ceramic crystals spread and vitreous matrix elasticity; iii) Ceramic strengthening by low glass fusion and iv) Strengthening by glass crystallization (Castellani, 1990).