A comparison of two in vitro methods for assessing the fitting accuracy of composite inlays

Composite inlays were fabricated in standardised cavities cut into aluminum and perspex blocks using a computer controlled milling process. Four materials were used to construct the inlays. These were fabricated using an indirect technique following the manufacturers' recommendations, where applicable. In addition, for one of the composites, the fabrication procedures were modified. The fitting accuracy of the restorations was assessed by taking elastomeric impression wash replicas of the luting space and by examination of sectioned restored units using image analysis. The former method indicated significantly reduced fitting accuracy when either use of die spacer or secondary curing was omitted from restoration construction resulting in incomplete seating. The sectioning technique indicated that more factors appeared to significantly reduce fitting accuracy including bulk packing, alteration in curing time, omission to die spacer and the final polishing procedure. This method also provided more specific information concerning sites of premature contact. One material gave rise to significantly greater film thicknesses using both methods of assessment. No direct correlation was found between the two techniques of fit evaluation but both methods taken together provided complementary information.