ABSTRACT
OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: Panavia F 2.0 had the lowest MG (before 118 µm-after TMCL 124 µm) and AMD (before 145 µm-after TMCL 154 µm), followed by Relyx Unicem (MG: before 164 µm-after TCML 155 µm; AMD: before 213 µm-after TMCL 209 µm) and Variolink II (MG: before 317 µm-after TMCL 320 µm; AMD: before 412 µm-after TMCL 406 µm). 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. CONCLUSIONS: µCT is an accurate technique for assessing cemented restorations. Panavia F 2.0 has the lowest MG and AMD before and after TCML. CLINICAL RELEVANCE: 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.
