Prospective Clinical Evaluation of Cercon^TM Premolar and Molar FPDs

Objective: 3- and 4-unit molar and premolar Cercon^TM FPDs are prospectively evaluated regarding their clinical survival rates. The evaluation focuses on 1) stability of zirconia cores; 2) durability of veneering ceramics, and 3) applicability of luting with ZnO phosphate cement.

Methods: Between January 2001 and September 2005, 75 patients were restored with 99 FPDs. 51 specimens (group A) were veneered with an experimental ceramic. Since 2002, 48 restorations (group B) were veneered with Ceram-S^TM, all luted with ZnO phosphate cement. Average observation time of all units: 50 months.

Results: 1 core fracture occurred and caused total loss. A chipping of the veneering material was observed in 9 cases of group A, and at 4 specimens of group B. All were adjusted by polishing. Loss of retention was observed in 9 cases, 6 could be reinserted, 3 FPDs (group A) were lost due to secondary caries caused by unfastening. 1 additional loss in group A was induced by secondary caries, 2 were sealed with composite fillings. One marginal carious lesion was also recorded in group B, it was sealed with an adhesive filling. In group B, 1 loss of vitality occurred. 2 restorations failed due to biological complications. 7 specimens were declared total losses, 8 drop-outs due to no-shows were recorded. 62 of 99 inserted FPDs are in situ without any clinical post-treatment. The survival rate (Kaplan-Meier) is 89.3% (group A, 61 months) and 100 % (group B, 38 months).

Conclusions: The main complications are fractures of the veneering ceramics and retention losses (not due to faulty preparations) which mainly occurred in the mandible (8:1). It is therefore recommended to carefully gauge a conventional luting for FPDs in the posterior region of the lower jaw.