Abstract:

BACKGROUND: Morphology of the shoulder is directly related to the health of patient's abutment and quality of final prosthesis.
OBJECTIVE: To observe the microleakage of porcelain-fused-to-metal of two shoulders by cyclic loading and thermal cycling test.
METHODS: Forty recently extracted molars from patients with periodontal disease, aged 40-50 years, were collected and randomly divided into two groups. The porcelain-fused-to-metals were prepared with the standard prepared criteria, and the shoulders were designed into 120° and 90°. Then the cyclic loading and thermal cycling tests were performed in vitro on the porcelain-fused-to-metal of two shoulders to detect the microleakage.
RESULTS AND CONCLUSION: This study discover that there are significant differences between two groups after cyclic loading and thermal cycling processing, which increased microleakage of porcelain-fused-to-metal with 120° shoulder, and 90° shoulder has the lowest level of microleakage no matter on labial edge or the tongue edge. It demonstrates that 90° shoulder is the best performance to resist microleakage for porcelain-fused-to-metal and 90° shoulder, design can minimize occurrence of secondary caries.