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Adaptation accuracy of milled lithium disilicate crowns: A 2D and 3D microCT analysis
Bruna N De Freitas1, Bruna S H Tonin1, Ana P Macedo1
1Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Objective:
Evaluate the effects of the scanning techniques and the crystallization in the internal and marginal adaptation of milled lithium disilicate crowns by two techniques computer microtomography analysis.
Materials And Methods:
Sixteen polyurethane teeth prepared for a complete crown were divided into two groups according to the scanner method (n = 8): indirect (IND), dental stone models were scanned with laser-surface scanner, and direct (DIR), digital typodont creates with an intraoral scanner. Internal and marginal gap were evaluated by micro-computed tomography (microCT). The replica technique (RT) was applied for analysis of total volume (TV) and marginal volume (MV) gap in microCT. The data showed normal distribution (Shapiro-Wilk test). One-way ANOVA (scanner techniques) with repeated measures (crystallization) was performed. Multiple comparisons were performed with Bonferroni adjustment (α = .05).
Results:
The axial gap showed a significant difference between the times (P = .017) for lower values after crystallization. The vertical marginal gap presented a significant difference in times for higher value after crystallization (P = .001). The marginal horizontal gap IND was greater than DIR after crystallization (P = .001) and IND before lower than after crystallization. For TV was not significant difference and MV in DIR was reduction (P = .002) after crystallization.
Conclusion:
Crystallization changes the relationship between the crown and tooth, reducing internal gap and preventing the adequate fit in indirect and direct scanning.
Clinical Significance:
The measure gap under technological methodology is useful for adjust clinical parameters prosthetic in the CAD/CAM and the applicability of the new possibilities of analysis.
