[A microscopic evaluation of the marginal adaptation of onlays in gold]

The aim of this in vitro trial was to evaluate the marginal seal and adaptation of gold onlays according to the instrumentation used to prepare the bevels, the quality of margins (as cast vs. polished in the laboratory) and two different finishing procedures (burnishing during or after setting of the cement). For that purpose, 25 freshly extracted human molars were restored with onlays using standardized preparation and fabrication methods. The marginal adaptation of the cemented onlays was evaluated using replicas and scanning electron microscopy. The marginal seal was evaluated on sample sections after a dye infiltration test. In order to improve the marginal fit of gold onlay restorations, it can be recommended to: use diamond burs (Intensiv no. 32 and 37) to prepare the bevels finish and polish restorations in the laboratory except for areas with access to clinically burnish, and polish the margins after setting of the cement.