[Three-dimensional finite element analysis of one-piece computer aided design and computer aided manufacture involved zirconia post and core].

OBJECTIVE

To analyze the biomechanics trait of one-piece computer aided design and computer aided manufacture (CAD/CAM) zirconia post and core by the Three-dimensional finite element.

METHODS

The Three-dimensional finite element models of three upper central incisors restored with one-piece CAD/CAM zirconia post and core (group 1), refabricated zirconia post and hot-pressed porcelain core (group 2), and cast gold alloy post and core (group 3) were built by geometry method respectively. 100 N vertical loading through the central incisor models long axis and 100 N loading along directing at an angle of 45° with the models long axis were used to imitate the central incisor stress state in biting and mandible physiological protraction movement.

RESULTS

Under vertical loading, the restored teeth without dentin ferrule, the maximum Von-Mises stress value of the tooth root in group 1 was the least(11.02 N), which was the largest (13.17 N)in group 2. The stress became weaker from the upper to the lower of the tooth root. The maximum Von-Mises stress value of the tooth root, post and core became smaller while the restored teeth with the 2.0 mm high dentin ferrule. Under directing at an angle of 45° loading, without the design of dentin ferrule in the restored teeth, the maximum Von-Mises stress value of the post and core in group 1 was the greatest(20.45 N), while that stress of post and core in group 3 was the smallest(13.61 N). With 2.0 mm high dentin ferrule design in the restored teeth, the tooth root stress became weaker. The maximum Von-Mises stress value of the tooth root was the greatest (14.10 N) in group 3, but which was the lowest (13.38 N) in group 1.

CONCLUSION

The results of the Three-dimensional finite element analysis infers that one-piece zirconia post and core restoration is more beneficial to disperse the bite force than the prefabricated zirconia post and the cast gold alloy post and core. The one-piece of zirconia post and core is good to protect the teeth and keep the restoration intact.