[Finite element analysis of tooth restored with one-piece of computer aided design and computer aided manufacturing zirconia post-core in three different radiuses].

OBJECTIVE

To compare the stress distribution of teeth restored with one-piece of computer aided design and computer aided manufacturing (CAD/CAM) zirconia post-cores in three different radiuses.

METHODS

Constructing the 2D finite element models of the standard maxillary central incisal restored by one-piece of CAD/CAM zirconia post-cores and all ceramic crowns, the radius of post was 1.5 mm, 2.0 mm and 2.5 mm respectively. Two tooth root types with or without the ferrule were constructed and there were 6 models in general. Group 1:100 N force loading to the restored teeth through the long axle of teeth and veritical the incisal edge. Group 2: 100 N inclined force loading beneath the incisal edge 2.0 mm by 45° cross the long axle of teeth in the palate side. The stress distribution characteristic of post-cores and teeth roots were analysed.

RESULTS

In veritical loading, the stress distribution of one-piece of CAD/CAM zirconia post-core with 2.0 mm radius was better distributed than the two others, The stress concentration of teeth roots locate at the root canal wall where the end of the post exists, which increased with the wider radius of the post-core. In 45° inclined loading, the maximum stress of the zirconia post-core and the teeth root was more than three times of which in vertical loading. In post-cores, the stress concentration was in the labia middle 1/3 of the post. In teeth roots, the stress concentration located at the lateral wall in the post end and the area of the apical foramen. The stress of the post-cores and teeth roots was decreasing in the teeth root with a 2.0 mm ferrule.

CONCLUSION

2.0 mm radicus of the one-piece of CAD/CAM zirconia post-core is a better choice in clinic. There should be a conical degree in the teeth roots preparing for one-piece of CAD/CAM zirconia post-core restoration. The force of protrusive movement has a greater influence on the post-core and teeth roots. The area of apical may be apt to break in overloading.