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目的 :分析金属烤瓷全冠面中央及边缘的瓷耐压强度 ,探讨临床常见崩瓷现象。材料与方法 :利用离体左上第一磨牙常规制作无尖金属烤瓷全冠 2 0枚 ,随机分 2组 ,一组置 5mm直径球形压头于面中央 ,另一组同样压头置于面近颊尖处 ,于LJ5 0 0型拉力机上匀速 (10mm/min)加压 ,记录瓷崩裂时的载荷值并作统计分析。结果 :面中央受力组瓷层全部碎裂 ,平均载荷 3.0 5 2KN ,面近颊尖处受力组其瓷层呈片块状剥脱 ,与临床崩瓷现象相似 ,平均载荷 1.335KN ,仅为前组的44 %。两组最大载荷比较差异有显著性 (p <0 .0 1)。结论 :面边缘的瓷层为金属烤瓷全冠的结构薄弱区 ,是崩瓷现象最易发生处。临床上应采取必要措施重点防范。
OBJECTIVE: To analyze the compressive strength of porcelain at the center and edge of the porcelain crown, and to explore the common phenomenon of porcelain collapse. MATERIALS AND METHODS: A total of 20 non-pointed porcelain crowns were routinely prepared using the first left upper molar isolated from the body. They were randomly divided into two groups. One group consisted of a 5 mm diameter spherical indenter at the center of the face and the other group with the same pressure head Noodles close to the buccal cusps, LJ5 0 0 pulling machine uniform (10mm / min) pressure, record the value of cracking load porcelain and make statistical analysis. Results: The porcelain layer in the central stress group was all fragmented with an average load of 3.05 2KN. The porcelain layer of the near-buccal force group showed a lump-like exfoliation, similar to the clinical collapse phenomenon. The average load was 1.335KN, Only 44% of the previous group. The maximum load difference between the two groups was significant (p <0.01). CONCLUSION: The porcelain layer on the edge of porcelain face is the structural weak area of metal crown, which is the most prone to collapse porcelain. Clinic should take the necessary measures to focus on prevention.