Effect of the ultrasonic insertion technique on the seating of composite inlays.

The seating of MOD composite inlays was determined before and after cementation with one of three cements of different viscosities. The seating was determined by measuring the axial discrepancy. Inlays were seated by strong finger pressure or by the ultrasonic insertion (USI) technique. The axial discrepancy of luted inlays varied between 115 microns and 472 microns. The axial discrepancy of inlays luted with finger pressure increased with the viscosity of the cement (Duo Cement < Twinlook < Sono-Cem). Inlays luted with the cement of lowest viscosity (Duo Cement) had seating values of similar magnitude irrespective of seating procedure. As compared with luting by finger pressure, use of the USI technique improved the seating of inlays luted with Twinlook and Sono-Cem (the cement of highest viscosity) to such an extent that the values of seating were of the same magnitude as those of inlays luted with Duo Cement. Consequently, the seating of inlays cemented with the USI technique did not depend on the viscosity of the cement.