Fracture Strength of Interim CAD/CAM and Conventional Partial Fixed Dental Prostheses

• Published in: Journal of prosthodontics Vol. 30; no. 8; pp. 720 - 724
• Main Authors: Sadid‐Zadeh, Ramtin, Zirkel, Cory, Makwoka, Seteven, Li, Rui
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-10-2021
• Subjects: Chewing; Dentistry; Mandible; Mechanical properties; Polymethylmethacrylate; Prostheses; Prosthetics
• ISSN: 1059-941X; 1532-849X
• DOI: 10.1111/jopr.13325

Purpose
 To compare the fracture strength of three‐unit provisional partial fixed dental prostheses (FDPs) fabricated by an indirect‐direct technique from poly(methylmethacrylate) (PMMA) through digital and conventional workflows, and FDPs fabricated by a direct technique using Bisacryl (BisA) and externally reinforced BisA.
Materials and Methods
 Forty partially edentulous typodonts with a missing mandibular left first molar and standard preparations on mandibular left second premolar and molar were used to fabricate three‐unit provisional FDPs. Two materials and two techniques were used to fabricate a total of forty provisional FDPs: (1) BisA; (2) BisA reinforced with glass fiber strips [BisA‐GFR]; (3) conventionally fabricated PMMA shell relined with PMMA [C‐PMMA]; (4) CAD/CAM fabricated PMMA shell relined with PMMA [CAD/CAM‐PMMA]. Provisional FDPs were then luted onto the preparations using a temporary cement. Specimens were mounted onto a chewing simulator; 20,000 cycles of 70 N forces were applied under 25°C distilled water. Specimens were then loaded to fracture using a universal testing machine (The Dillion Quantrol TC2i; Mecmesin) with a crosshead speed of 2 mm/min. One‐way ANOVA, followed by Tukey post hoc test, was used to assess the effect of production technique on the fracture strength of the provisional FPDs (α = 0.5).
Results
 Mean fracture strengths recorded for the CAD/CAM‐PMMA, C‐PMMA, BisA, and BisA‐GFR groups were 520 N, 448 N, 245 N, and 169 N, respectively. PMMA groups had significantly (p < 0.0001; F = 24.40) higher fracture strength compared to Bisacryl groups.
Conclusion
 When high occlusal forces are expected, provisional FDPs fabricated with PMMA using the indirect‐direct technique are recommended, irrespective of CAD/CAM or conventional workflow.