Strength comparison of anterior teeth restored with ceramic endocrowns vs custom-made post and cores

The aim of the study was to compare strength of the anterior teeth restored with ceramic endocrowns versus custom-made post and core.

The investigation used the finite element analysis. Three 3-D models of maxillary central incisor were created: model A-tooth restored with metal post and core with ceramic crown; model B-tooth with leucite ceramic endocrown; model C-tooth with lithium disilicate ceramic endocrown. Each model was subjected to a 100N force applied at a distance of 5mm from the incisal edge, at the angle of 130° to the long axis of the tooth. The modified von Mises failure criterion was used to evaluate the strength of the dentin, ceramic and resin cement, and Huber-Mises-Hencky failure criterion for cast alloy. Contact stresses in the cement-tissue adhesive interface were calculated.

The lowest stresses occurred in the anterior tooth restored with custom post and core (model A). The mvM stress of 47.5MPa concentrated in leucite ceramic endocrown (model B) and its value was close to the tensile strength of this material. The maximal mvM stresses in the lithium disilicate ceramic endocrown (model C) were 4 times lower than tensile strength of this material. In all cases contact stresses in the adhesive interface under restorations did not exceed the resin cement bond strength to dentin.

Leucite ceramic endocrowns in incisors may fracture during physiological loading. Endocrowns made of lithium disilicate ceramic are resistant to failure. Posts and prosthetic crowns are still recommended for anterior teeth restorations.