Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns
Beleidy, M., Ziada, A. (2019). Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns. EKB Journal Management System, 65(Issue 3 - July (Fixed Prosthodontics, Dental Materials, Conservative Dentistry & Endodontics)), 2779-2793. doi: 10.21608/edj.2019.72676
Marwa Beleidy; Ahmed Ziada. "Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns". EKB Journal Management System, 65, Issue 3 - July (Fixed Prosthodontics, Dental Materials, Conservative Dentistry & Endodontics), 2019, 2779-2793. doi: 10.21608/edj.2019.72676
Beleidy, M., Ziada, A. (2019). 'Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns', EKB Journal Management System, 65(Issue 3 - July (Fixed Prosthodontics, Dental Materials, Conservative Dentistry & Endodontics)), pp. 2779-2793. doi: 10.21608/edj.2019.72676
Beleidy, M., Ziada, A. Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns. EKB Journal Management System, 2019; 65(Issue 3 - July (Fixed Prosthodontics, Dental Materials, Conservative Dentistry & Endodontics)): 2779-2793. doi: 10.21608/edj.2019.72676

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, Page 2779-2793  XML PDF (2.1 MB)
Document Type: Original Article
DOI: 10.21608/edj.2019.72676
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Authors
Marwa Beleidyorcid 1; Ahmed Ziadaorcid 2
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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