PDF(Pubmed)
Abstract：
BACKGROUND: The infrazygomatic crest mini-screw has been widely used, but the biomechanical performance of mini-screws at different insertion angles is still uncertain. The aim of this study was to analyse the primary stability of infrazygomatic crest mini-screws at different angles and to explore the effects of the exposure length (EL), screw-cortical bone contact area (SCA), and screw-trabecular bone contact area (STA) on this primary stability.
METHODS: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation.
RESULTS: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05).
CONCLUSIONS: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.
METHODS: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation.
RESULTS: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05).
CONCLUSIONS: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.
摘要：
背景：下颌骨脊微型螺钉已被广泛使用，但微型螺钉在不同插入角度下的生物力学性能仍不确定。本研究的目的是分析不同角度下颌棘微型螺钉的主要稳定性，并探讨暴露长度（EL）的影响，螺钉-皮质骨接触面积（SCA），和螺钉-骨小梁接触面积（STA）在这个主要的稳定性。
方法：将90块合成骨分配到9个组，以交叉组合的角度沿八孔牙龈和近端方向插入微型螺钉。SCA,STA,EL,和侧向拉出强度（LPS）测量，并分析了他们的关系。然后从六个新鲜的尸体头部以最佳和较差的角度将十二个微型螺钉插入上颌骨，并测量相同的生物力学指标进行验证。
结果：在合成骨试验中，LPS，SCA,STA,EL和EL与眼周方向的角度显着相关（rLPS=0.886，rSCA=-0.946，rSTA=0.911，rEL=-0.731；所有P<0.001）。在尸体验证测试中，在LPS中观察到显著差异(P=0.011)，SCA(P=0.020),STA（P=0.004），和EL（P=0.001）之间的不良角度和最佳角度在occusgival方向。STA与LPS呈正相关（rs=0.245[合成骨试验]和r=0.720[尸体验证试验]；两者均P<0.05）。
结论：颌下骨嵴微型螺钉的主要稳定性与咬合牙龈成角度相关。STA显着影响下颌骨骨微型螺钉的主要稳定性，但SCA和EL没有。
方法：将90块合成骨分配到9个组，以交叉组合的角度沿八孔牙龈和近端方向插入微型螺钉。SCA,STA,EL,和侧向拉出强度（LPS）测量，并分析了他们的关系。然后从六个新鲜的尸体头部以最佳和较差的角度将十二个微型螺钉插入上颌骨，并测量相同的生物力学指标进行验证。
结果：在合成骨试验中，LPS，SCA,STA,EL和EL与眼周方向的角度显着相关（rLPS=0.886，rSCA=-0.946，rSTA=0.911，rEL=-0.731；所有P<0.001）。在尸体验证测试中，在LPS中观察到显著差异(P=0.011)，SCA(P=0.020),STA（P=0.004），和EL（P=0.001）之间的不良角度和最佳角度在occusgival方向。STA与LPS呈正相关（rs=0.245[合成骨试验]和r=0.720[尸体验证试验]；两者均P<0.05）。
结论：颌下骨嵴微型螺钉的主要稳定性与咬合牙龈成角度相关。STA显着影响下颌骨骨微型螺钉的主要稳定性，但SCA和EL没有。
