Clinical Significance
Zirconia restorations cause twice the degree of wear on the opposing natural teeth that is seen between natural teeth that are opposed. Both gender and nightly muscle activity level appeared to influence this wear.
Because they are desired by patients as a metal-free, tooth-colored, and biocompatible material, zirconia ceramics are being used increasingly in prosthetic dentistry. These ceramics have excellent mechanical properties but are prone to chipping unless they are properly modified. Computer-aided design/computer-aided manufacturing (CAD/CAM) monolithic zirconia restorations with proper translucency are becoming a popular choice, but concerns also attend their use. In particular, the increased
The 20 patients received 20 monolithic zirconia full molar crowns. Vinylpolysiloxane impressions were prepared after the crown incorporation and after 6, 12, and 24 months of use to analyze wear. Occlusal contact area wear of the crowns, their natural antagonists, and two contralateral natural antagonists, which served as controls, was determined using plaster replicas and a three-dimensional (3D) laser-scanning device. The differences were compared statistically and when the factors of patient
Four subjects were lost to follow-up; two had new fillings in the antagonistic teeth, one reference tooth was altered by grinding, and the casts of the fourth subject could not be analyzed.
Mean vertical loss at 2 years was 46 μm for enamel opposed by zirconia crowns, with a maximum of 151 μm. Mean vertical loss was 19 and 26 μm for enamel opposed by natural antagonists, with a maximum of 75 and 115 μm. Mean vertical loss for the zirconia crowns was 14 μm, with a maximum of 60 μg.
The differences
Over the course of 2 years, monolithic zirconia restorations produced significantly greater wear on the antagonistic natural teeth than unrestored teeth did. The mean and maximum vertical losses for zirconia were about twice what was found for natural teeth. Clinical Significance Zirconia restorations cause twice the degree of wear on the opposing natural teeth that is seen between natural teeth that are opposed. Both gender and nightly muscle activity level appeared to influence this wear.
Stober T, Bermejo JL, Schwindling FS, et al: Clinical assessment of enamel wear caused by monolithic zirconia crowns. J Oral Rehabil 43:621-629, 2016
Reprints available from T Stober, Dept of Prosthodontics, Heidelberg Univ Hosp, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; e-mail: [email protected]