Objectives: The purpose of this research was to determine the clinical success rate of a lithia-disilicate-based core ceramic (Ivoclar, Vivadent Corp.) for use in posterior fixed partial dentures (FPDs) as a function of bite force, cement type, connector height, and connector width.

Methods: Thirty ceramic FPD core frameworks were prepared using a hot-pressing technique and a lithia-disilicate-based core ceramic. The maximum clenching force was measured for each patient prior to tooth preparation. Connector heights and widths were measured for each FPD. Patients were recalled yearly after cementation for two years and evaluated using eleven clinical criteria. All FPDs were examined by two independent clinicians and rankings for each criterion were made from 1 to 4 with 4 = excellent and 1 = unacceptable.

The aims of this research were:

1. To test the hypotheses that three-unit fixed partial dentures (FPDs) of a high-strength core ceramic will exhibit good-to-excellent clinical performance (based on 11 evaluative criteria) and that they will adequately resist fracture in posterior situations (excluding third molars) if fabricated with the minimal connector size (4 mm x 4 mm).
2. To test the hypothesis that a reinforced glass ionomer cement (ProTec CEM, Ivoclar, Vivadent), when used to cement core ceramic crowns in posterior FPDs, will be associated with significantly less marginal quality, but similar fracture resistance of the ceramic crowns compared with the marginal quality associated with a dual cure resin cement (Variolink® II, Ivoclar Vivadent AG, Schaan, Liechtenstein).
3. To test the hypothesis that there is no significant difference in tooth sensitivity associated with FPDs cemented with the glass ionomer cement and dual-cure resin cement.