The effect of occlusal morphology of implant-supported prosthesis, support configuration, and build angulation on the number of isolated islands in a 3D printing slicing software.

Abstract

Purpose: To evaluate the impact of posterior occlusal morphology, build angulation, and support configuration on the occurrence of isolated islands in a three-dimensional (3D) printing slicing software when printing a full arch implant-supported prosthesis.

Materials and methods: Three maxillary implant-supported full-arch prostheses were designed with similar intaglio and anterior teeth and different posterior morphology based on cusp angulations, including shallow (10°), medium (20°), and steep (33°). Each digital file was transferred to slicing software and nested in different angulations (0°, 15°, 30°, 45°, and 90°), and supports were created using different configurations (thin, standard, and thick). The sliced file from each configuration was evaluated for the presence of isolated islands of print where the printed material was left unsupported. The effect of independent variables and number of isolated islands, time to print, number of layers, and volume of the resin to print were analyzed with a three-way ANOVA test with a significance level set at 5%.

Results: The mean number of isolated islands (minimum 0 and maximum 11.9) in the slicing software was significantly affected by all three investigated variables (p < 0.05). Steep occlusal morphology reduced the chance of developing islands after slicing. The standard and thick support configuration reduced the number of islands when compared with the thin support configuration. In terms of build angulation, 0° resulted in the highest number of islands, and 90° build angulation resulted in no islands. Increasing the thickness of support and steeper cusp angulation significantly increased the amount of resin required to print (p < 0.05). Increasing the build angulation significantly increased the time to print, number of layers, and amount of resin to print (p < 0.05).

Conclusions: Slicing software can produce isolated unsupported areas that have the potential to cause print failure of a full arch implant-supported prosthesis. Based on the present findings, shallower posterior occlusal anatomy, thinner supports, and 0° build angulation increased the chance of developing isolated islands in a slicing software.