Micro-CT Evaluation of Ceramic Inlays: Comparison of the Marginal and Internal Fit of Five and Three Axis CAM Systems with a Heat Press Technique.
Abstract: Objectives: The purpose of this in vitro study was to evaluate the marginal and internal adaptation of CAD/CAM lithium disilicate inlay restorations fabricated by two milling systems (Five and Three axis), and a heat press technique. Materials and Methods: Fifteen PMMA models of typodont premolar tooth #12 (Kilgore International Inc., Coldwater, MI) with an MOD cavity preparation were fa... read morebricated. Lithium disilicate inlay restorations were obtained by three different fabrication techniques and were fitted to their single respective die (n=45). Groups were as follows: Group 1, E4D three axis milling system (n=15), Group 2, Tizian Cut 5 five axis milling system (n=15), Group 3, conventional heat press technique (n=15). Evaluation of the marginal and internal gaps was performed by the X-ray microtomography (mCT) (Nikon Metrology, Inc., Americas). Marginal gap (MG), occlusal marginal gap (OMG), proximal marginal gap (PMG), gingival marginal gap (GMG), absolute marginal discrepancy (AMD), axial internal gap (AIG) and occlusal internal gap (OIG) were evaluated at 120 different points for each inlay. The data were analyzed using repeated measures ANOVA. Pairwise comparisons were conducted for post-hoc testes with the use of the Bonferroni correction to adjust for multiple comparisons (alpha=0.007). Results: The heat press group demonstrated significantly smaller mean values amongst all outcomes compared to the CAD/CAM groups except for the gingival marginal gap location, where there was no statistically significant difference between the groups in the ANOVA (P = .042). Within the CAD/CAM groups, the five-axis group showed significantly lower occlusal marginal gap mean value (51.08 ± 12.46 microns) compared to the three-axis group (79.93 ± 19.41 microns; P < .001), and lower axial internal gap mean value (104.98 ± 14.05 microns) compared to the three-axis group (143.56 ± 12.44 microns; P < .001). There was no significant difference found between the five-axis and the three-axis groups' absolute marginal discrepancy, marginal gap, proximal marginal gap and occlusal internal gap locations (P > 0.007). Conclusion: Within the limitations of this in vitro study, different fabrication techniques affected the marginal fit and internal adaptation of ceramic inlay restorations. The heat press group gave the best results for marginal and internal adaptation; however, in every group, 100% of samples were within the clinically acceptable marginal gap limit of 100 microns. Among the CAD/CAM groups, the five-axis had better AIG and OIG values compared to the three-axis values.
Thesis (M.S.)--Tufts University, 2014.
Submitted to the Dept. of Other.
Advisor: David Bardwell.
Committee: Samer Khayat, Hiroshi Hirayama, Ala Ali, and Matthew Finkelman.
Keyword: Dentistry.read less