The accuracy and fit of rests of conventional (analogue) and CAD/CAM removable partial denture frameworks: a cross-sectional study

Abstract

Introduction: The objective of this study was to compare the fit and accuracy of removable partial denture (RPD) framework rests fabricated through two different manufacturing techniques: conventional casting and digital workflow with CAM printing by selective laser sintering (SLS). The comparison is based on analyzing standard tessellation (STL) data and aims to determine which fabrication technique results in a more accurate fitting rest. Aim: This study compared the fit and accuracy of rests of conventional and 3D-printed RPD frameworks. Materials and methods: A cross-sectional study was conducted in which a maxillary metal RPD framework was designed for a Kennedy class III modification 1. The master model was scanned and used to compare the fit and accuracy of RPD frameworks. A total of forty models (conventional and digital) and frameworks were fabricated using chrome-cobalt. The frameworks were categorized into four groups based on the fabrication method: group 1, lost-wax technique (conventional technique); group 2, lost-wax technique on a resin model; group 3, CAD-printing; and group 4, CAD-printing from stone models. All the frameworks were scanned and digitized, and the gap distances at the cingulum and occlusal rest areas of the framework and the scanned master model were measured. ExoCAD was used to superimpose the STL files of the frameworks onto the STL files of the models and the distance between the two was recorded in mm.