Comparative evaluation of materials used for the temporary crowns

Abstract

Background: Temporary crowns are provisional prosthetic restorations used until the final crown is fixed. An ideal temporary crown must simultaneously meet biological, mechanical, aesthetic, and functional requirements. These materials include polymethyl methacrylate (PMMA) and bis-acrylic composites. CADCAM technologies have emerged in recent years through the milling of resin blocks. Objective of the study: To investigate the mechanical and aesthetic properties of different materials used for the fabrication of temporary dental crowns. Material and methods: The types of prostheses used were PMMA dental crowns fabricated by computeraided design and manufacturing (CAD/CAM) technique and bis-acrylic crowns by the conventional method. The study was conducted on 13 patients, aged between 18 and 70. Quality was evaluated based on marginal adaptation, gingival bleeding, color, structural integrity, discomfort, and decementation. Results: Marginal openings were significantly more frequent with the conventional method (12.28%) compared to CAD/CAM (3.50%). There were 8 reported cases (14.03%) of fracture in traditional crowns compared to 2 cases (3.50%) in CAD/CAM. The incidence of decementation was almost double for the traditional method (17.54% vs. 7.01%). Milled PMMA achieves maximum scores of 100% in all aesthetic categories: translucency, color stability, polishability, and stain resistance. Bis-acrylic shows lower stain resistance (73.33%), tending to absorb dyes more rapidly. Conclusions: Milled PMMA (CAD/CAM) has superior mechanical properties, with increased fracture resistance, dimensional stability, and high-quality aesthetic finish. Precise adaptation reduces gingival irritation and offers a more natural feel compared to bis-acrylic resins. Bis-acrylic resins are easier to use but less precise and resistant.