(PO29) Creating Precision-Milled Simulated Double-Curved Root Canals in Bovine Dentin

Abstract: Standardized models to study chemo-mechanical root canal preparation in a clinically relevant substrate are elusive. The aim of this project was to develop a standardized double-curved root canal model in bovine dentin using high-precision computer numerical control (CNC) milling. CNC milling was used to recreate a simulated root canal from a standard resin training block (Endo Training Bloc S-Shape) in longitudinally sectioned bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. The roots were embedded in methacrylate for sectioning and reassembly. The natural root canal was cut out from the longitudinal sections, and the dentin surfaces were flat polished. Subsequently, the average S-shaped root canal identified previously was milled into one root half, and half of the access funnel in each of the two halves. Using an open-source image manipulation program (GIMP), geometrical data were obtained. Optical overlays were analyzed and compared between the simulated resin canals and CNC-milled counterparts in the bovine dentin. Superimposed images showed that S-shaped simulated root canals in the resin blocks varied considerably in terms of their length and curvature, while the milled canals in the bovine root dentin were highly similar. CNC milling allows for the creation of standardized geometrical forms of root canals in bovine dentin. The resulting models offer a high level of reproducibility in canal geometry for future studies of chemo-mechanical root canal instrumentation. <.u>