Abstract:

Objective

To investigate the effects of three types of tooth preparation methods on fracture load and mode of fired porcelain veneer complexes （PVCs）.

Methods

Human maxillary central incisors were collected and randomly divided into four groups. In the first three groups， teeth were prepared according to the three recommend tooth preparation methods （Type I， Type L， and Type U） respectively. Prepared teeth were restored with fired porcelain veneers， then bonded with adhesive resin luting system. 10 teeth were remained intact and used as controlled group. Fracture loads were recorded with a mechanical testing machine.Statistical analysis was made with SPSS for Windows.

Results

Mean fracture loads in groups of Type I， L， U and the control group were as follows： 278.61N ± 73.86N（n=9），295.17N ± 71.76N（n=9），303.42N ± 96.87N （n=8），332.29N ± 60.06N（n=10）. No significant difference was found among the fracture loads of the three PVC groups and the controlled group （P ＞0.05）， but there was significant difference in the tooth fracture mode among the three PVC groups and the controlled group （P ＜0.05）.

Conclusions

When loading point is located in tooth structure， the fracture resistance of PVCs with all the three types of tooth preparations are comparable to the natural teeth. Fired porcelain veneer can change the biomechanical behavior of the nature tooth.

Key words: Fracture load, Fracture mode, Tooth preparation, Lminate veneer