Effect of Palatal Vault Depth on the Trueness of Metal Laser-Sintered and Cast Cobalt-Chromium Removable Partial Denture Frameworks.

Abstract

This in vitro study compared the trueness of removable partial denture cobalt-chromium (Co-Cr) frameworks fabricated by 3D-printed pattern casting and those fabricated by selective laser sintering (SLS) with different palate vault depths. A partially edentulous Kennedy class II mod.1 maxillary model with a deep palatal vault was used, which was modified and duplicated to produce another model with medium palatal vault depth. After model scanning, the partial denture framework was designed using CAD software to fabricate 20 removable partial denture (RPD) frameworks. For each model, two types of frameworks were fabricated. For the 1st type, the 3D-printed resin patterns were formed using a 3D printer, and then casting was performed (AM-cast framework). For the 2nd type, a direct metal laser sintering machine was used for the RPD frameworks fabrication (SLS framework). 3D scanning of fabricated frameworks was performed, and the standard tessellation language (STL) file was superimposed over the STL file from the original design, and the average deviation was recorded. Data were statistically analyzed. Two-way ANOVA test was used, followed by the least significant difference (LSD) for pair-wise comparisons to estimate any significant differences between groups. The RPD frameworks with high palatal vault depth represent larger discrepancies mean value than that with the medium palatal vault depth with a highly significant statistical difference. SLS shows less deviation than AM-cast CO-Cr frameworks with highly significant statistical differences whatever palatal vault depth. RPD metal frameworks fabricated with SLS have better accuracy compared to those fabricated by AM-cast, regardless of the depth of the palatal vault.