Evaluation of the absolute marginal discrepancy of zirconia-based ceramic copings

Abstract

Statement of problem: Marginal fit is an important factor for the long-term success of ceramic restorations; however, it is difficult to compare results from studies on marginal accuracy of zirconium oxide-based restorations that used various computer-assisted systems, because different methods were used to obtain the data.

Purpose: The purpose of this study was to analyze the effect of different manufacturing techniques on the marginal adaptation of zirconia ceramic copings.

Material and methods: An extracted mandibular first premolar was prepared for a complete coverage restoration and subsequently duplicated 40 times in a liquid crystal polymer (LCP). Ceramic copings (n=10) were fabricated on the LCP models using the following systems: glass-infiltrated zirconia-toughened alumina (In-Ceram Zirconia) and yttrium cation-doped tetragonal zirconia polycrystals (In-Ceram YZ, Cercon, and Procera Zirconia). The absolute marginal discrepancy of the cores was assessed by using an image analysis system. The data were analyzed using 1-way ANOVA and Scheffé's test (α=.05).

Results: The mean marginal openings were 29.98 ± 3.97 μm for the In-Ceram Zirconia group, 12.24 ± 3.08 μm for the In-Ceram YZ group, 13.15 ± 3.01 μm for the Cercon group, and 8.67 ± 3.96 μm for the Procera group. Significant differences were found among the 4 systems (P<.05).

Conclusions: The marginal accuracy achieved for the 4 zirconia-based ceramic crown systems analyzed was within the range of clinical acceptance (120 μm).