Clinical evaluation of monolithic zirconia multiunit posterior fixed dental prostheses

Abstract

Statement of problem: Monolithic zirconia restorations have been evaluated with in vitro studies, but limited clinical evidence of their longevity and reliability is available.

Purpose: The purpose of this clinical study was to evaluate the clinical performance of posterior multiunit glazed monolithic zirconia fixed dental prostheses.

Material and methods: A total of 20 participants received 33 monolithic posterior zirconia fixed dental prostheses (Zolid white; Amann Girrbach AG) with minimally invasive preparations. Bilaterally supported fixed dental prostheses with a connector area of at least 9 mm² were luted with resin-modified glass ionomer cement. The clinical evaluations were performed after 1 week, 6 months, and then annually after completion of the treatment. The biologic outcomes were evaluated by assessing the pocket depth, attachment level, plaque control, bleeding on probing, caries, and tooth vitality. Esthetics and the functional performance of the prostheses (color match, cavosurface marginal discoloration, anatomic form, marginal adaptation) were evaluated as per the rating scales of Cvar and Ryge. An analysis of survival was made by using the Kaplan-Meier method.

Results: After 39.8 ±16.7 months of observation, the overall survival rate of the monolithic zirconia multiunit posterior prostheses was 93.9%. No caries were found on the abutment teeth, signs of gingivitis were noted in 1 participant after 24 months, and increased probing depths of the abutment teeth were detected in 5 prostheses (15.1%). No loss of retention was detected. Two prostheses had to be replaced: 1 because of a biologic complication and 1 because of a technical complication. The remaining 31 prostheses received Alfa scores for marginal adaptation, cavosurface marginal discoloration, and caries. Twenty-seven (87.1%) prostheses were rated as Alfa and 4 (12.9%) as Bravo for anatomic form. The color match was noted as Alfa in 15 (48.3%) prostheses, and 16 (51.6%) were rated as Bravo.

Conclusions: Monolithic zirconia restorations demonstrated a reliable treatment option after medium-term clinical use for the replacement of missing posterior teeth.