Three-Dimensional Finite Element Analysis Of Endocrown Restorations

Using the three-dimensional finite element method, this study investigated the stress effects of six different restoration materials on the mandibular first molar after root canal treatment, which was restored with an endocrown. An experimental model of the mandibular first molar restored with an endocrown was established. Six restoration materials were selected, and forces were applied in the vertical direction and at an oblique angle of 45°. The magnitude and distribution of the maximum principal stress and equivalent stress of the restorations, adhesive layer, enamel, and dentin in the six groups of models were analyzed. Under both vertical and oblique loads, the peak values of the equivalent stress and the maximum principal stress both occurred at the occlusal force application point. Among them, the stress peak value at the mesio-buccal cusp was larger than that at other application points. Under vertical load, Lava Ultimate had a more uniform stress distribution compared with other materials. Under oblique load, Lava Ultimate and PEEK had a more uniform equivalent stress distribution. In the Lava Ultimate group, the stress distribution of the endocrown and the remaining dental tissues is more uniform, but the maximum principal stress intensity of the enamel is relatively high under the vertical force. The endocrown made of PEEK material transfers more stress to the remaining dental tissues and fails to better protect the remaining dental tissues.