Evaluation And Comparison of Flexural Strength of Two Different Posterior Provisional Crowns Fabricated Using CAD-CAM and 3D Printing: An invitro study
Abstract
Background: Provisional restorations play an important role in fixed prosthodontics in maintaining function, esthetics and protecting prepared teeth until permanent restorations are applied. Digital dentistry is becoming more and more common, and computer-aided design/computer-aided manufacturing (CAD-CAM) milling and three-dimensional (3D) printing are now modern ways to make things. But there is limited comparative research on their flexural strength. The study aimed to assess and compare the flexural strength of posterior provisional crowns made utilizing CAD-CAM milling and 3D-printing technologies. Materials and Methods: Thirty standardized acrylic dies were produced from a master cobalt chromium die and were randomly divided into 2 groups (n = 15). Group A was composed of temporary crowns milled from polymethyl methacrylate (PMMA) via CAD-CAM, and Group B was composed of crowns made of 3D-printed light-polymerized urethane dimethacrylate resin. The specimens were cemented with eugenol-free temporary luting cement and loaded in compression using a universal testing machine (crosshead speed: 1 mm/min) till fracture. Flexural strength was determined in Newton (N). The data were analyzed statistically using Shapiro Wilk test and independent samples t-test. The level of significance was established at p < 0.05. Results: The mean flexural strength of CAD-CAM milled provisional crowns (1633.33 ± 391.09 N) was greater than 3D-printed provisional crowns (1452.00 ± 406.08 N). However, the difference between groups was not statistically significant (t = 1.246, p = 0.223). The values of flexural strength in both groups were higher than the typical posterior masticatory forces, showing good mechanical performance. Conclusion: Flexural strength of CAD-CAM milled and 3D printed temporary crowns was clinically acceptable. CAD-CAM crowns had a greater mean fracture resistance, but the difference was not statistically significant, justifying the clinical use of both digital fabrication processes for posterior provisional restorations....