Marginal adaptation of lithium disilicate ceramic crowns cemented with three different resin cements.

Abstract

The cementation process and cementation materials have an influence on the marginal adaptation of restorations. The gap could be affected by thermal and mechanical loading (TCML). The computerized x-ray microtomography (μCT) method offers the possibility of measuring the marginal gap without destruction of the restoration. The aim of this study was to evaluate the marginal gap (MG) and the absolute marginal discrepancy (AMD) before and after TCML. Thirty-nine human premolars were prepared for full ceramic crowns made of lithium disilicate. The crowns were cemented by three different resins-Panavia F 2.0, Variolink II, and Relyx Unicem. The MG and AMD were evaluated by μCT before and after TCML. Panavia F 2.0 had the lowest MG (before 118μm-after TMCL 124μm) and AMD (before 145μm-after TMCL 154μm), followed by Relyx Unicem (MG: before 164μm-after TCML 155μm; AMD: before 213μm-after TMCL 209μm) and Variolink II (MG: before 317μm-after TMCL 320μm; AMD: before 412μm-after TMCL 406μm). The differences were statistically significant before and after TCML. Rather than TCML, it appeared the resin cement was responsible for differences between the MG and AMD before and after TCML. μCT is an accurate technique for assessing cemented restorations. Panavia F 2.0 has the lowest MG and AMD before and after TCML. The resin material that features a three-step protocol (Variolink II) produced higher MG and AMG values than the Panavia or Relyx Unicem varieties with less or no intermediate steps at all.