Prediction of contact points and pressures against canal walls of NiTi rotary files by virtual modeling and finite elements analysis

Aim The objective of this study was to predict contact points and pressure distribution against canal walls when using NiTi rotary instruments by FEM virtual simulation. Methodology ProTaper Next (PTN) X1 and ProTaper Universal (PTU) S2 were compared. Canal configuration was based on an in vitro testing device. The in vitro canal and file geometries were replicated with computer aided design (CAD) software. CAD geometries (geometrical model) were imported and discretized (numerical model). The typical material model of dentine and MWire alloy was applied. The numerical models of the device and file geometries were used for finite element analysis (FEA). Experimental data from PTN X1 and PTU S2 were used to set-up the material parameter in the numerical model. Stress histories on the root canal contact points patterns due to the PTN X1 and PTU S2 were compared. Results The pressure distribution against canal walls was mainly influenced by the geometry of the file. The material of the file did not affect significantly the results. The PTN X1 was associated with a pressure 80% lower than PTU S2. Conclusions The pressure distribution against canal walls may be predicted by FEA. Virtual design, testing and analysis of file geometries could save considerable time and resources during instrument development.