Posterior Monolithic Zirconia Single Crowns – A Two-year Critical Clinical Evaluation

Objectives: Monolithic zirconia has become a common material for manufacturing single crowns. By combining a minimal tooth reduction with good esthetic results, this material offers an alternative to classic metal ceramic crowns. However, there is a limited number of clinical studies investigating the clinical performance of these restorations. Therefore, aim of this prospective cohort study was to evaluate the clinical performance of posterior monolithic zirconia single crowns (MZSC) two years after insertion.
Methods: A total of 30 posterior MZSC were inserted. The crowns were evaluated and inspected at baseline and 1, 3, 6, 12 and 24 months after insertion. The clinical and occlusal situation, any biological or technical complications and occlusal changes on the crowns and opposite jaw were documented using documentation forms, intraoral photographs and impression casts. A descriptive data analysis took place and a significance level of a=0.05 was set, while a p-value <0.001 represented high significance.
Results: Thirty patients received a MZSC (14 premolars, 16 molars). At the two-year follow-up 26 crowns were examined representing a drop-out of 13.3%. One biological complication (vertical root fracture) was recorded. No other biological or technical complications were detected. Signs of abrasion in the opposite jaw and MZSC as well have been noticed in some cases.
Conclusions: Posterior MZSC seem to have a good middle-term clinical performance offering a promising alternative to conventional metal ceramic crowns. However, the positive long-term performance of these restorations will still have to be evaluated. Signs of abrasion in the opposite jaw and crowns will have to be observed and evaluated further.