Clinical Performance of Long-span All-ceramic or Metal-ceramic Fixed Partial Dentures on Implants and/or Natural Teeth

Tooth-coloured fixed restorations are becoming increasingly popular with patients and dentists. If high-strength all-ceramics such as zirconia are used as the restoration material, a maximum of two adjacent missing teeth can be replaced with the aid of fixed partial dentures (FPDs). For the replacement of a missing anterior or posterior tooth by FPDs, a very good clinical performance similar to that of metal-based, ceramic-veneered restorations can be expected. However, evidence-based statements on the clinical performance of long-span all-ceramic FPDs are difficult because there are only very few studies on this topic, which are also inhomogeneous with regard to the study conditions. Randomized studies to compare monolithic (consisting only of the high-strength framework material) or partially veneered (weaker veneering ceramics in esthetically relevant tooth areas) all-ceramic and classic (completely veneered) metal-ceramic FPDs are lacking. The aim of the current explorative, prospective, randomized, two-arm clinical interventional study is therefore to compare the clinical performance of long-span FPDs (≥ 4 Pontics) made of monolithic / facially veneered zirconium dioxide with a gold standard (completely veneered cobalt chromium (CoCr)-based FPDs). Forty patients will be recruited. Once all inclusion criteria have been established, including the signed informed consent of the patients informed of the content, effort, advantages and disadvantages of the study, patients are assigned to the two study groups by stratified block randomization (main strata: tooth-supported / (tooth-)implant-supported). After placement of the restorations, follow-up examinations are performed after 1 week (baseline) and after half a year, one year, two years and three years. In addition to the main target criterion (veneering defects), further complications (related to FPDs or supporting tissues / structures) and parameters of oral health are recorded. Depending on the distribution and structure of the data, parametric and non-parametric statistics are used. Group differences with respect to the main target criterion ceramic defects are to be investigated by log-rank and chi-square tests. The significance level is set at α < 0.05. Since this is an explorative study, all p-values are descriptive.