Since the introduction of crown software for Cerec, it has been possible to produce full-ceramic crown restorations. Despite the excellent material quality of industrially made ceramic blocks and the good clinical long-term success of these ceramics in inlay- and onlay preparations, extended preparation with high loss of dental tissue is incident to crown restorations, which may endanger the vitality of the respective tooth.
The aim of this experimental study was to determine the residual dentin thickness after preparation of an extended circular shoulder in the molar and premolar region. On extracted human molars and premolars, 1.2-mm-wide circular shoulders with rounded inner edges were prepared, and the thickness of the residual dentin wall was measured under a microscope.
Using this preparation method, it was found that only the group of maxillary molars showed an average residual dentin thickness of more than 0.7 mm. Mandibular premolars exhibited an average residual dentin thickness of 0.46 mm at the thinnest site. The residual dentin on maxillary premolars was slightly thicker (0.54 mm). On mandibular molars, residual dentin was measured at 0.62 mm. Remaining dentin thickness was not influenced by the presence or absence of carious lesions.