The korean journal of orthodontics (대한치과교정학회지)

The Korean Association Of Orthodontists (대한치과교정학회)
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Optimization of orthodontic microimplant thread design

교정용 마이크로 임플란트의 나사산 디자인 최적화

  • Kim, Kwang-Duk (Department of Orthodontics, School of Dentistry, Kyungpook National University) ;
  • Yu, Won-Jae (Department of Orthodontics, School of Dentistry, Kyungpook National University) ;
  • Park, Hyo-Sang (Department of Orthodontics, School of Dentistry, Kyungpook National University) ;
  • Kyung, Hee-Moon (Department of Orthodontics, School of Dentistry, Kyungpook National University) ;
  • Kwon, Oh-Won (Department of Orthodontics, School of Dentistry, Kyungpook National University)
  • 김광덕 (경북대학교 치의학전문대학원 교정학교실) ;
  • 유원재 (경북대학교 치의학전문대학원 교정학교실) ;
  • 박효상 (경북대학교 치의학전문대학원 교정학교실) ;
  • 경희문 (경북대학교 치의학전문대학원 교정학교실) ;
  • 권오원 (경북대학교 치의학전문대학원 교정학교실)
  • Received : 2010.01.04
  • Accepted : 2010.06.09
  • Published : 2011.02.28
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Abstract

Objective: The purpose of this study was to optimize the thread pattern of orthodontic microimplants. Methods: In search of an optimal thread for orthodontic microimplants, an objective function stability quotient (SQ) was built and solved which will help increase the stability and torsional strength of microimplants while reducing the bone damage during insertion. Selecting the AbsoAnchor SH1312-7 microimplant (Dentos Inc., Daegu, Korea) as a control, and using the thread height (h) and pitch (p) as design parameters, new thread designs with optimal combination of hand p combination were developed. Design soundness of the new threads were examined through insertion strain analyses using 3D finite element simulation, torque test, and clinical test. Results: Solving the function SQ, four new models with optimized thread designs were developed (h200p6, h225p7, h250p8, and h275p8). Finite element analysis has shown that these new designs may cause less bone damage during insertion. The torsional strength of two models h200p6 and h225p7 were significantly higher than the control. On the other hand, clinical test of models h200p6 and h250p8 had similar success rates when compared to the control. Conclusion: Overall, the new thread designs exhibited better performance than the control which indicated that the optimization methodology may be a useful tool when designing orthodontic microimplant threads.

교정용 마이크로 임플란트는 나사산을 매개수단으로 한 인접골 압박으로 골내 고정력을 얻는다. 그러므로 충분한 고정력을 얻기 위해서는 나사산이 크면 유리하다. 그러나 몸체에서 차지하는 나사산의 부피비율이 과도하면 이는 코어(core) 직경을 감소시켜 파절위험성을 증대시킬 뿐 아니라, 식립 시 나사산이 골을 지나치게 압박, 인접골에 골개형 장애를 일으켜 임플란트를 이완시키는 원인이 될 수도 있다. 따라서 마이크로 임플란트의 안정성은 그 나사산 디자인이 치밀골 특성과 조화를 이루어야 한다. 본 연구에서는 $Absoanchor^{(R)}$ SH1312-7 (Dentos Inc., Daegu, Korea) 모델을 비교모델로 선택, 몸체와 나사산 사이즈의 조화를 이루기 위한 최적화 해석을 실행하였다. 나사산의 높이(h)와 피치(p)를 디자인 변수로 하여 임플란트 안정성 증대, 식립 시 골 과부하 감소, 파절강도 증대를 목표로 목적함수 SQ(Stability Quotient)를 설정, 해석함으로써 4가지의 다른 h, p 조합을 갖는 나사산을 디자인하였다. 4종의 실험모델과 비교모델에 대해 3D 유한요소법을 이용한 임플란트 식립모사 해석으로, 식립 시 예상되는 골 과부하 영역을 비교하였으며(self tapping과 self drilling의 두 식립 방식에 대해), 또한 실험모델의 실물(prototype)을 가공, 토오크 파절 시험을 실시하였다. 평가결과, 실험모델은 비교모델에 비해 식립 시 인접골 과부하 영역을 덜 발생시켰으며, 파절강도는 더 높게 관찰되었으며, 이로써 나사산 디자인 최적화에 사용된 SQ의 타당성을 확인할 수 있었다.

Keywords

Acknowledgement

Supported by : 중소기업청

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