Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns | ||
| Egyptian Dental Journal | ||
| Article 35, Volume 65, Issue 3 - July (Fixed Prosthodontics, Dental Materials, Conservative Dentistry & Endodontics), July 2019, Pages 2779-2793 PDF (2.1 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/edj.2019.72676 | ||
| Authors | ||
| Marwa Beleidy1; Ahmed Ziada2 | ||
| 1Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, October 6th University, Giza, Egypt. | ||
| 2** Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, Benisuef University, Benisuef, Egypt. | ||
| Abstract | ||
| Statement of the problem: The wide use of digital dentistry in fixed prosthodontics using 3D printers and CAD/CAM in fabricating crowns and partial fixed dental prosthesis created a need for more information about their marginal gap and internal fit. Purpose: This study aimed to evaluate the effect of fabrication technique using CAD/CAM manufactured and heat pressed lithium dislicate crowns made from milled wax and 3D printed resin patterns on their marginal gap and internal fit. Material & Methods: A total of 50 prepared mandibular first molar resin models were used and divided into two main groups according to their fabrication phase: Patterns group and fully fabricated crowns group. Patterns group was subdivided into milled wax patterns (W) (n=10) and 3D printed resin patterns (P) (n=10). Fully fabricated crowns group was subdivided according to fabrication technique of lithium disilicate crowns into: Machinable ceramics (M), using IPS e-max CAD blocks (n=10), Pressable ceramics (Pw), using IPS e-max press ingots following wax milling (n=10) and Pressable ceramics (Pp), using IPS e-max press ingots following 3D resin printing (n=10). All patterns and ceramic crowns were cemented with Rely-X self-adhesive resin cement. Marginal and internal adaptations were measured using SEM at 300 × magnification. Kruskal-Wallis and Wilcoxon signed-rank tests were applied to compare between the groups. Data were presented as median and range values. The significance level was set at P ≤ 0.05. Results: P group showed a significant higher median total marginal gap of 111.4 μm (80.8-139.7) than W group of 51.3 μm (45.1-57.8) before heat pressing. While M group showed the significant highest median marginal gap of 138.4 μm (83.4-191.8) and no significant difference between heat pressed groups (Pw and Pp) (P ≤ .05). Regarding changes after heat pressing, Pw group showed no significant decrease, while Pp group showed a significant decrease in median total marginal gap. For internal fit, there was no significant difference between the pattern groups (W and P) before heat pressing (P ≤ .05). After heat pressing, Pp group showed the significantly highest median gap of 195 μm (138.9-441.5) with no significant difference between M and Pw groups (P ≤ .05). Pw group showed a significant decrease in median gap, and Pp group showed no significant decrease after pressing (P ≤ .05). Conclusions: Heat pressed lithium disilicate glass ceramic crowns produced from CAD/CAM waxing or resin 3D printing techniques resulted in better marginal and fit accuracy than CAD/CAM. 3D printed resin patterns yielded internal fit values higher than other groups, but with promising clinical acceptability. Clinical implications: Both the additive and subtractive production for patterning phase before heat pressing allow clinical acceptability in terms of marginal and internal adaptation when a single unit posterior ceramic lithium disilicate crown is fabricated. | ||
| Keywords | ||
| 3D printing; CAD/CAM; Heat pressed; Marginal gap and Internal fit | ||
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