In vitro marginal fit of three all-ceramic crown systems

Abstract 

Statement of problem

Studies on marginal discrepancies of single restorations using various systems and materials have resulted in statistical inferences that are ambiguous because of small sample sizes and limited numbers of measurements per specimen.

Purpose

The purpose of this study was to compare the marginal adaptation of single anterior restorations made using different systems.

Material and methods

The in vitro marginal discrepancies of 3 different all-ceramic crown systems (Celay In-Ceram, conventional In-Ceram, and IPS Empress 2 layering technique), and a control group of metal ceramic restorations were evaluated and compared by measuring the gap dimension between the crowns and the prepared tooth at the marginal opening. The crowns were made for 1 extracted maxillary central incisor prepared with a 1-mm shoulder margin and 6-degree tapered walls by milling. Thirty crowns per system were fabricated. Crown measurements were recorded with an optical microscope, with an accuracy of ±0.1 μm, at 50 points spaced approximately 400 μm along the circumferential margin. The criterion of 120 μm was used as the maximum clinically acceptable marginal gap. Mean gap dimensions and standard deviations were calculated for marginal opening. The data were analyzed with a 1-way analysis of variance (α=.05).

Results

Mean gap dimensions and standard deviations at the marginal opening for the incisor crowns were 87 ± 34 μm for control, 83 ± 33 μm for Celay In-Ceram, 112 ± 55 μm for conventional In-Ceram, and 46 ± 16 μm for the IPS Empress 2 layering technique. Significant differences were found among the crown groups (P<.05). Compared with the control group, the IPS Empress 2 group had significantly smaller marginal discrepancies (P<.05), and the conventional In-Ceram group exhibited significantly greater marginal discrepancies (P<.05). There was no significant difference between the Celay In-Ceram and the control group.

Conclusion

Within the limitations of this study, the marginal discrepancies were all within the clinically acceptable standard set at 120 μm. However, the IPS Empress 2 system showed the smallest and most homogeneous gap dimension, whereas the conventional In-Ceram system presented the largest and more variable gap dimension compared with the metal ceramic (control) restoration.