Comparison of internal fit between implant abutments and cast metal crowns vs laser-sintered crowns

A common problem related to cemented single crowns is the internal misfit, which may cause inadequate retention, especially when seated on the implant abutment. The aim of this study was to compare the internal fit of Co-Cr crowns using a traditional lost-wax casting technique from laser-sintered Co-Cr alloy crowns.

Twelve metallic crowns per each technique were fabricated. The effect of the thickness of cement, originated internal gap was evaluated. Crowns were cemented on the implant abutments with resin cement, and the internal fit of crowns was measured at five areas with an optical microscope. The data were analyzed, and the means were compared with a t-test (p<0.05).

The internal gap width measurements for the laser-sintered group (min. 52.19 ± 11.61 μm and max. 140.01 ± 31.84 μm) indicated the presence of a significantly closed internal gap compared to the crowns obtained through the lost wax method (min. 65.50 ± 9.54 μm and max. 313.46 ± 48.12 μm).

The fit of the metal crown likely varies with the fabrication technique. The use of techniques that enable the adjustment of crown parameters, such as the laser sintering technique, maintains the desired fit between casting and implant abutments.

This study investigated which technique affects the internal fit of cemented implant-supported crowns, comparing the use of lost wax casting and laser-sintered metal dental alloys. The results of this study indicate that the use of laser-sintered crowns can improve for crown accuracy.