Color and translucency of milled polymethyl methacrylate crowns on non-tooth-colored interim abutments with different surface treatments

Abstract

Statement of problem: The interim rehabilitation of implants has become a necessity, particularly for those placed in the esthetic regions. However, the optical properties of computer-aided design and computer-aided manufacturing (CAD-CAM) polymethyl methacrylate (PMMA) crowns on interim abutments with different surface treatments are unclear.

Purpose: The purpose of this in vitro study was to investigate the color and translucency of CAD-CAM PMMA crowns when different surface treatments were used on titanium interim abutments.

Material and methods: A maxillary dentate stone cast with a narrow-diameter implant analog at the left lateral incisor site was used. Three titanium interim abutments (blue) were divided into 3 groups according to the surface treatment they received: control (steam cleaning), opaqued (120-μm Al₂O₃ airborne-particle abrasion and opaque application), and airborne-particle abraded (120-μm Al₂O₃). Thirty PMMA crowns (A2 shade) were milled (n=10). The color coordinates of the crown-interim abutment pairs and a shade tab (A2) were measured by using a colorimeter. The color differences (ΔE₀₀) between the crowns and the shade tab and the relative translucency parameter (RTP) values of the crowns were calculated by using the CIEDE2000 formula. One-way ANOVA was used to analyze the ΔE₀₀ and RTP values with subsequent Tukey honestly significant difference tests (α=.05).

Results: The abutment surface treatment significantly affected the ΔE₀₀ of interim crowns from the shade tab (P<.001), but no significant effect was found on RTP (P=.26). The control group had the highest ΔE₀₀ from the shade tab (P≤.011). No significant difference (P=.14) was found between the opaqued and the ΔE₀₀ of the airborne-particle abraded groups from the shade tab.

Conclusions: The surface treatments of interim abutments affected the color of CAD-CAM PMMA crowns, which differed from that of the shade tab. The color of crowns on opaqued or airborne-particle abraded interim abutments was closer to the color of the shade tab. Abutment surface treatments did not affect the translucency of crown-interim abutment pairs.