- 學位論文
植體支持之陶瓷燒附牙冠的底部金屬設計對陶瓷破折強度之影響
The strength of porcelain in different metal substructure designs for implant-supported PFM crown
摘要
製作人工植體支持的固定式贗復物時，經常會受到齒槽骨寬度的限制，以致植體直徑與其上牙冠正常的尺寸差距甚大，因而常造成贗復物陶瓷層厚度過厚，因此導致陶瓷破裂以致贗復物失敗的比例較傳統牙齒支持固定式贗復物為高。 關於固定式陶瓷牙冠的理論及材料特性，研究者曾提出不同底部金屬的設計。但卻鮮有實際實驗來證明其改善效果。 故本實驗目的，在比較人工植體支持的固定式陶瓷牙冠，不同底部金屬的設計，對於其上的陶瓷抗破折強度之影響。 實驗按底部金屬的設計，分成最薄金屬厚度型、傳統型及wrinkling design，三種不同的底部金屬設計。每組6個，按標準的技工流程製作，每組6個試件，以牙科用低金合金，鑄造出底部金屬後，用常用的牙科陶瓷瓷粉，燒附以完成固定式陶瓷牙冠的製作。 固定試件於施力夾具，以2 Hz，200 N垂直力，作用於牙冠的頰側功能性咬頭（functional cusp）三十萬次模擬口內咬合，再以萬用材料測試機，測試其破裂時，最大的抗破折強度。用SEM觀察及分析其斷裂面。 三組的最大抗破折強度依序分別為：111.13 kgw，236.1 kgw，188.63 kgw。經由one-way ANOVA及Tukey test，三組間有非常顯著差別（p < 0.001）。傳統型的抗破折強度最強，最薄金屬厚度型強度最弱。 斷面皆有底部金屬的曝露。在掃描式電子顯微鏡觀察下，呈階梯狀紋路。反之，未做疲乏模擬的試件，斷裂面呈不規則斷面，顯著不同。 由本研究的結果可以得知，傳統型有最佳的強度，過厚的陶瓷層最容易減低牙冠的抗破折強度。wrinkling design在本實驗中，和傳統型的差距在統計上呈顯著的差別。至於其理論上，提供陶瓷更佳支持的效果，則需更進一步的證實。
並列摘要
The fabrication of PFM ( porcelain-fused-to-metal crowns ) supported by dental implant is usually limited by the width of the edentulous ridge. As a result, ceramic fracture occurs more frequently in implant-supported than tooth-supported ones due to the great thickness of porcelain. Based upon theories as well as the quality of such material, scholars have come up with many different designs of the metal substructure. However, little evidence and experiment show improvement. The purpose of this study is to compare the fracture resistance of the implant-supported PFM crowns with different designs through the examination of fatigue of occlusal simulation. There are three different submetal structure designs discussed in my study: the thinnest metal thickness design, the traditional design, and the wrinkling design. Under the standard dental technical procedure, each design with 6 samples is cast with low gold alloy and then sintered on dental porcelain. Samples are fixed on the clamp before simulating oral biting ( 2Hz, 200N, 3 x 105 times ) on the distobucccal cusp with vertical force takes place. Then, the maximum porcelain fracture loading resistance is tested, and the fracture surface of each sample is analyzed. The maximum loading of the three designs mentioned above is respectively as followed: 111.13 kgw, 236.1 kgw, and 188.63 kgw. After one-way ANOVA analysis and Tukey test analysis, the maximum loading of the three designs is very significant in statistic (p<0.001). The traditional design has the highest fracture resistance, while the thinnest metal thickness design has the lowest fracture resistance. All fracture surfaces with metal exposed are noticed. Under SEM, they present a step-like crack line. On the other hand, those samples without fatigue test present irregular surface. This result shows an absolute difference. As my study shows, the traditional design provides the highest fracture resistance. The improper thickness of porcelain is an obvious risk which would result in PFM crown fracture. As for the wrinkling design, it is statistically significant from the traditional design. Further study about its theories of better support providing to ceramic is needed.