摘要
目的用三维有限元方法分析钴铬合金铸造三臂卡环固位臂在摘取时的应力分布,探讨3种宽度固位臂可放置的最大倒凹深度,为可摘局部义齿的设计和制作提供参考。方法以下颌第二磨牙为基牙,建立基牙和3种宽度固位臂的三维有限元模型,设定固位臂宽厚比为3:1,设计卡臂尖和固位臂中部进入基牙的倒凹深度不同,在固位臂中部施加动态位移载荷(以3 mm/s 速度,使卡环向上产生3 mm 的位移),计算固位臂从基牙上摘取时的接触受力。采用的统计学方法为直线相关与回归分析和两条回归直线的比较。结果固位臂的最大应力与卡臂尖进入基牙的倒凹深度呈正相关关系,与固位臂中部1/3进入基牙的倒凹深度无明显相关性。当卡臂尖进入基牙的倒凹深度相同时,随固位臂宽度的增大,固位臂最大应力的增加有统计学意义(P<0.01)。1.8、1.6和1.4 mm 3种宽度的钴铬合金固位臂可放入基牙的最大倒凹深度分别为0.25 mm、0.30 mm 和0.35 mm。结论当宽厚比一定时,固位臂越宽,卡臂尖可进入基牙的最大倒凹深度越小。为防止固位臂永久变形,应根据卡臂尖进入基牙的倒凹深度选择不同宽度的固位臂。
Objective To analyze the stress distribution on cast retentive clasp arms in dislodging denture, and to discuss the deepest undercuts of the second mandibular premolar （abutment） for cobaltchromium alloy cast clasps with different widths. Methods Three-dimensional finite element models of the abutment with different depths of undercuts and retentive arms with different widths were set up. Dynamic displacement load （3 mm/s） was exerted on the middle of the retentive arms to analyze the stress in retentive arms while they were being removed from the abutment. Results The peak stress in retentive arms was positively correlated to the undercuts displaced by clasp tips, and those were not obviously related to the undercuts displaced by the middle of retentive arms. When width/thickness of retentive arms was 3, the increase of peak stress of retentive arms with similar locations of clasp tips was significantly related to the increase of the arm width. The deepest undercuts of the second mandibular premolar for cobalt-chromium alloy cast retentive arms with different widths of 1.8 mm, 1.6 mm, and 1.4 mm were 0. 25 mm, 0. 30 mm, and 0. 35 mm respectively. Conclusions When width/thickness of the retentive clasp arm is fixed, the wider the arm is, the smaller depth it should be placed on the undercut of abutment. Retentive clasp arms with different widths should be placed on different depths of undercuts in order to prevent their permanent deformation.
出处
《中华口腔医学杂志》
CAS
CSCD
北大核心
2007年第5期276-279,共4页
Chinese Journal of Stomatology
关键词
牙修复体固位
牙科卡环
三维有限元
Dental prosthesis retention
Dental clasps
Three-dimensional finite element
