預成形孔座對於牙植體植入扭矩之影響

近年來，植牙手術已經成為患者治療缺牙的首要選擇，其術後的初期穩定性與骨整合程度皆為影響植牙治療成功率的關鍵，而初期穩定性又會影響後續的骨整合效應，故人工牙植體的初期穩定性方為主要的評估準則。以往有限元素分析於人工牙植體上的研究多半以靜態結構力學來探討螺紋幾何的設計為主，有別於此，本研究乃利用有限元素分析與實際植入試驗來探討預成形孔座對於人工牙植體植入之力學行為，藉以評估人工牙植體與預成形孔座間的匹配性對於植入扭矩以及初期穩定性之影響。研究中選用直徑3.75 mm和長7 mm的Branemark MkⅢ人工牙植體系統作為探討的試驗樣本。首先，將人造假骨試片分別製備2.4 mm、3.0 mm與3.6 mm三組預成形孔座；接著，再將人工牙植體分別植入三組不同的預成形孔座，以測得植入扭矩值作為初期穩定性的評判依據，經過相互驗證實際植入試驗與有限元素分析的結果以確立電腦模擬之準確性與可信度；最後，藉此參數分析並以臨床建議的扭矩值當作標準(35 N-cm至50 N-cm)找出合適的預成形孔座尺寸。根據實際植入試驗的研究結果可得知人工牙植體植入2.4 mm、3.0 mm與3.6 mm的預成形孔座時其植入扭矩值分別為68.2±2.3 N-cm、44.7±2.6 N-cm與11.8±1.5 N-cm；而有限元素分析的結果分別為71.7 N-cm、44.1 N-cm與12.7 N-cm，其最大誤差小於8%。此外，根據上述有限元素分析的結果進行內插運算，得知當植入扭矩值為35 N-cm時的預成形孔座尺寸約為3.2 mm，而在有限元素分析結果中，人工牙植體植入3.2mm預成形孔座的植入扭矩值為35.5 N-cm。因此，本研究成果提出使用直徑3.75 mm的人工牙植體其最適合的預成形孔座尺寸介於3.0 mm至3.2 mm之間，此資訊可以提供臨床醫師執行預成形孔座以及研發新型人工牙植體與相關手術器械之參考依據。

關鍵字

有限元素分析；牙科生物力學；人工牙植體；預成形孔座；植入扭矩；初期穩定性

並列摘要

In recent years, dental implant surgery has become the first choice for edentulous patients. The primary stability and osseointegration are the key points of implant treatment success rate. Moreover, the primary stability will affect the osseointegration effect. So, the primary stability of dental implant is the main factor to be considered. In the past, finite element analysis used in dental implant research was mainly on static structural mechanics in thread geometries. Unlike the previous, this study used finite element analysis and experiment to investigate the mechanical effects of site preparation on dental implant insertion process. In order to evaluate the insertion torque and the primary stability affected by dental implant and site preparation. In this study, Branemark MkⅢ dental implant system (3.75 mm width and 7 mm length) was used in this study. According to the drill sizes, the specimens were grouped into three different dimensions (2.4 mm, 3.0 mm and 3.6 mm). The insertion torque was chosen as the criterion for primary stability. The experiment data was used to verify the finite element analysis results in order to establish the accuracy and credibility. Then the numerical simulation was used to find the sizes of implant site which were in line with the range of clinical recommendations. The insertion torques found from experiments were 68.2±2.3 N-cm (for 2.4 mm site), 44.7±2.6 N-cm (for 3.0 mm site) and 11.8±1.5 N-cm (for 3.6 mm site) respectively. The results of finite element analysis were 71.7 N-cm (for 2.4 mm site), 44.1 N-cm (for 3.0 mm site) and 12.7 N-cm (for 3.6 mm site) respectively, the biggest deviation was smaller than 8%. Furthermore,a torque of 35.5 N-cm was generated when the dental implant was inserted into the 3.2 mm site. It was found in this study that the most suitable site preparation should be between 3.0 mm and 3.2 mm. This information could provide a reference for dentist to choose surgical instruments, and also could be a reference guide for developing new dental implant and corresponding surgical instruments.

並列關鍵字

Finite element analysis ； Dental biomechanics ； Dental implant ； Site preparation ； Insertion torque ； Primary stability

參考文獻

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[2] J. P. Geng, D. W. Xu, K. B. Tan and G. R. Liu, "Finite element analysis of an osseointegrated stepped screw dental implant," The Journal of Oral Implantology, vol. 30, 2004, pp. 223-233.

[3] J. P. Geng, Q. S. Ma, W. Xu, K. B. Tan and G. R. Liu, "Finite element analysis of four thread-form configurations in a stepped screw implant," Journal of Oral Rehabilitation, vol. 31, 2004, pp. 233-239.

[5] D. Bozkaya, S. Muftu and A. Muftu, "Evaluation of load transfer characteristics of five different implants in compact bone at different load levels by finite elements analysis," Journal of Prosthetic Dentistry, vol. 92, 2004, pp. 523-530.

[6] J. Schrotenboer, Y. P. Tsao, V. Kinariwala and H. L. Wang, "Effect of microthreads and platform switching on crestal bone stress levels: a finite element analysis," Journal of Periodontology, vol. 79, 2008, pp. 2166-2172.

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預成形孔座對於牙植體植入扭矩之影響

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