【作者】 刘茜；

【导师】 段银钟；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2007， 硕士

【摘要】 安氏Ⅱ类错牙合是一种常见的错牙合畸形,据报道Ⅱ类错牙合在我国青少年中的发病率约为23%。其临床表现主要为上颌或上牙弓前突,下颌或下牙弓后缩,前牙深覆盖深覆牙合,颏唇沟深陷,磨牙尖牙是远中关系。根据不同的病因可分为牙性Ⅱ类错牙合与骨性Ⅱ类错牙合。目前国内外学者,常使用远移磨牙的矫治方法纠正牙性Ⅱ类错牙合,通过远移磨牙提供的间隙纠正磨牙和尖牙的远中关系。目前国内对于拔除个别磨牙提供间隙远移磨牙的研究很少,在临床实践中我们发现拔除上颌第二磨牙后远移磨牙,不仅可以减轻远移磨牙的阻力,还能促进第三磨牙的萌出,减少复发。这与传统观念中的远移磨牙有所区别,应该引起我们足够的重视。目的:本课题通过对牙性Ⅱ类错牙合患者,在上颌第二磨牙不同状态时使用口外弓进行上颌第一磨牙的远中移动,对比第二磨牙萌出前,萌出后,以及拔除后远移磨牙效果,分析各自的作用特点。并对拔除上颌第二磨牙后远移上颌第一磨牙矫治Ⅱ类错牙合的临床疗效进行评价,为今后临床应用此方法的适应证选择和临床矫治原则提供依据。实验方法及结果:实验一:选取牙性安氏Ⅱ类错牙合患者35例(男19女16),分为三组:拔除上颌第二磨牙组(G1) 12例,上颌第二磨牙未萌组13例(G2);上颌第二磨牙已萌组10例(G3)。通过对头颅侧位定位片上13项指标的分析测量,使用LSD-t检验对比三组在磨牙远移效果,以及磨牙、前牙在三维方向上的移动。统计结果表明:拔除上颌第二磨牙组远移速度最快、磨牙远中倾斜最小。三组的磨牙远移速度分别为拔除组0.96±0.29mm/m、未萌组0.79±0.39mm/m、已萌组0.61±0.40mm/m,第一磨牙远中倾斜度分别为0.58±1.00、1.80±1.57、0.12±1.09均有显著性差别、未萌组面高度增加显著大于其他两组。而上颌第二前磨牙近中移动量、伸长量,上前牙轴倾度、突度变化等三组均无显著性差异实验二:单侧拔除上颌第二磨牙后矫治Ⅱ亚类的错牙合,选取牙性Ⅱ类错牙合患者15名,(男8女7)平均18.4岁,均拔除单侧上颌第二磨牙,采用方丝弓矫治技术,口外弓200g/侧力值远移第一磨牙,观察磨牙远移效果,磨牙远移总量平均为3.25mm,总时间平均为3.05月,远移速度平均为0.96mm/m,观察磨牙远移前后面部软硬组织12项指标的变化,对各项指标进行配对t检验,结果显示1-NA、Ls-E、Li-E、Cm-Sn-Ls、A’Ls-FH、A’Ls-B’Li矫治后比矫治前均有减小,具有统计学意义。牙弓对称性也得到明显改善。结论:拔除第二磨牙后使用口外弓远移上颌第一磨牙的病例,可获得较大的磨牙远移距离、远移速度、以及较短的疗程,效果优于上颌第二磨牙萌出前远移磨牙。同时磨牙远移提供更充足的间隙内收前牙,口外支抗不但不会破坏侧貌外形,反而能够改善唇部软组织外形。在掌握拔除第二磨牙的适应证的前提下,以及第三磨牙位置预测可萌出到正常位置时,使用拔除上颌第二磨牙后远移上颌第一磨牙不失为矫正Ⅱ类错牙合患者的有效方法,可在临床工作中逐步推广应用。更多还原

【Abstract】 ClassⅡmalocclusion is one of the most common malocclusion in china. The incidence of ClassⅡmalocclusion in Chinese juvenile is reported to be 23%. The specific characteristics of classⅡmalocclusion can include a protrusion of the maxillary or upper dental arch, a retrusion of the mandible, deep overjet and overbite, incongruous profile, and distal malocclusion of the first molars and canines. According to etiopathology, it can be classified into 2 types: dental and skeletal malocclusion. Since last century, the method of distalizating maxillary molar has become an important and effective technique to correct Class2 dental malocclusion and moderate space deficiency. Recently there are lots of researches about the different methods of molar distalization and the efficacy of each different method. The study of distalizing molar after the maxillary second molar extraction is rare to report. But in clinical analysis we discovered that maxillary second molar extraction not only can make molar distalization more efficient but also facilitate the eruption of the third molar and decrease the relapse. ObjectiveThe study was conducted to examine the clinical effect and the peculiarity of distalizing maxillary first molar after maxillary second molar extraction. comparing the effect of three different positions of the maxillary second molar. And provide theoretical foundations for clinical indication and treatment principle. Methods and resultsPart 135 patients with ClassⅡmalocclusions were divided into 3 groups, all patients treated by distalization of maxillary molar were collected. LSD t-test was used to compare the 13 different indexes including cephalometric indexes, incisor and molar changes of pretreatment and posttreatment.The results show that there are statistically significant differences in the velocities of molar distalization are 0.96±0.29mm/Mo、0.79±0.39mm/Mo、0.61±0.40mm/Mo, and the distal tipping of maxillary first molar are 0.12±3.09°,0.58±4.57°,1.80±5.00°, there are no statistically significant differences in distalization of maxillary second premolar, intrusion of upper incisors, and extrusion of molars.Part 215 sub-ClassⅡpatients (8 boys and 7 girls)with permanent dentition were chosen, and were treated by distalization of maxillary molar after maxillary second molar extraction ClassⅡside with headgear using the force of 200g . Matched t-test was conducted to compare 12 indexes of cranio-facial hard and soft tissue changes of pretreatment and posttreatment.The statistical result shows that the therapy time of ditalizing maxillary first molar is 3.05Mo, the velocity is 0.96mm/Mo,and the 1-NA, Ls-E, Li-E, Cm-Sn-Ls, A’Ls-FH, A’Ls-B’Li all reduced compared to pretreatment. It is statistical significant differences.ConclusionDistalization of maxillary first molar after maxillary second molar extraction can spend shorter therapy time but achieve more space. Obviously this method is more efficient than distalize molar before maxillary second molar eruption. Headgear guarantee the anchorage, so can provide the space to intrude the incisors. Distalizing maxillary first molar after maxillary second molar extraction is an efficient method for correcting ClassⅡmalocclusion.更多还原