正畸拔除四个第二双尖牙治疗牙列轻中度拥挤及前突

目的探讨牙列轻中度拥挤病例拔除四个第二双尖牙矫治后,对侧貌突度的改善情况。方法:牙列轻中度拥挤病例共17例,均拔除四个第二双尖牙进行矫治,对治疗前后的头颅侧位片及模型进行测量和比较。结果矫治后齿槽座的位置、大小、骨骼矢状向的变化均无统计学差异(P>0.05),维持了原有的上下基骨关系;IMPA 角、U1-PP 角分别减少了4.6°和12.16°,前面高 AFH 增加了2.10 mm,差异有统计学意义(P<0.05);FMIA 角平均增大了5.21°、Z 角平均增大4.15°,后面高 PFH(mm)平均增加了4.30mm、面高比 FHI 平均增加了5.62%,矫治前后此四项指标的差异也有统计学意义(P<0.01)。结论轻中度拥挤的临界病例,当侧貌协调或前突不严重时,拔除第二双尖牙矫治既能有效地解除拥挤,又能维持或改善软组织侧貌突度。     

132例拔除四个双尖牙正畸病例的临床分析

本文回顾总结了１３２例拔除四个双尖牙正畸的病例，其中男４０例，女９２例，年龄范围为９～３４岁，临床分析的结果是因Ⅱ°─Ⅲ°牙列拥挤而拔牙的占总数４７％，因前牙反伴上前牙拥挤而拔牙的占３０％，在拔除四个双尖牙的１２种模式中，拔除的９２例，占拔牙总数的７０％，对各种拔牙模式的选择，作者认为主要与磨牙的关系密切相关。     

下颌第二双尖牙拔除后牙齿自行调整的研究

本研究以１５名恒牙期安氏Ⅱ类病人作为研究对象，下牙弓均拔除第二双尖牙，拔牙时的平均年龄为１３．４岁。拔牙后上颌即开始方丝弓矫正器治疗，下牙弓牙齿自行调整，平均观察６．６个月。通过拔牙前后的牙　模型测量及计算机Ｘ线头影测量对比分析发现，下牙弓拔牙间隙明显减小，下前牙直立，下颌磨牙前移，下牙弓拥挤度减小。本研究结果表明：下牙弓自行调整期间牙齿的移动情况对于第二双尖牙拔除的安氏Ⅱ类病人的治疗有益。     

拔除第二双尖牙矫正病例He颌面的垂直向变化

目的评价安氏Ⅰ类错He畸形患者，特别是下颌平面角较大的患者拔除第二双尖牙矫正后He颌面的垂直向变化，尤其是下颌平面的旋转变化。方法24例覆He正常或较浅且下颌平面角大于均值的安氏Ⅰ类错He患者(骨性与牙性均为Ⅰ类)拔除第二双尖牙，应用直丝弓技术完成矫治，25例符合同样标准的患者由不拔牙矫正完成。对所有病例治疗前后的头颅侧位片进行描图和手工测量，比较拔牙组与非拔牙组He颌面垂直向的变化。结果对拔牙和非拔牙两组患者的头影测量结果进行的统计学比较发现，除下磨牙的伸长量拔牙组大于非拔牙组外，两组患者问He颌面垂直向的变化并无统计学意义的差别。结论第二双尖牙的拔除并不一定意味着下颌平面角的减小，对于高角前牙开He倾向病例选择拔除第二双尖牙后，在矫正过程中仍需注意对后牙的垂直向控制。     

口腔正畸与颌面部美学

口腔正畸是一门基于美学的临床应用学科,通过调整牙齿移动以及颌骨关系来协调鼻唇颏的相互关系。正畸医生需要在术前对患者的面部软组织正貌和侧貌进行充分的分析,了解可能存在的颌面部对称性、水平向、垂直向问题,可能的影响因素（增龄性变化和代偿性变化对面部形态的影响）以及在牙齿正畸时给颌面部形态带来的变化,以引导矫治方案的设计与正畸治疗的实施,有效提高正畸临床的效果,本文将以正畸医生视角对指导正畸方案设计的美学评价作一综述。     

拔除第二前磨牙在正畸治疗中的应用

在正畸治疗中,对于某些牙列拥挤不很严重,面型尚可的病例,拔除第二前磨牙是一种行之有效的方法。本文从拔除第二前磨牙理论的提出、发展历史、适应证以及拔除第二前磨牙后牙移动规律以及颅颌面组织的结构变化等作一综述。     

拔除4个第一双尖牙正畸治疗满意病例Bolton指数的测量研究

目的　明确拔除 4个第一双尖牙对Bolton指数的影响以及对咬合关系的影响。方法　选取 4 3例拔除 4个第一双尖牙和 36例不拔牙治疗结果满意的病例 ,测量治疗后模型的牙齿宽度 ,计算比较其Bolton指数的差异 ;并计算不拔牙组在模拟拔除 4个第一双尖牙后的Bolton指数。结果　 1 拔除 4个第一双尖牙治疗满意的病例其全牙比小于不拔牙组 ,其差别具有显著统计学意义 (P <0 .0 0 1)。 2 不拔牙治疗满意的病例在模拟拔除 4个第一双尖牙后的全牙比亦小于未拔牙之前 (P <0 .0 0 1) ,与实际测量的拔牙组的全牙比没有统计意义上的差别 (P =0 .94 )。结论　拔除 4个第一双尖牙病例治疗后的全牙比小于不拔牙病例。拔牙后Bolton指数的变化对最终理想咬合关系影响不大     

正畸治疗中磨牙的拔除和保留(三十)——拔除第二磨牙的矫治设计

目的:总结主动或被动拔除第二磨牙矫治病例的特点.方法:统计35例拔除第二磨牙病例,男12例,女23例,年龄12～43岁,平均17.8岁.均采用直丝弓矫治器矫治.结果:矫治周期7～28个月,平均16.7个月.矫治结束时均达到尖牙和磨牙的中性关系,前牙覆(牙合)覆盖正常,牙根平行,软组织侧貌协调.结论:设计拔除第二磨牙是我们拔除磨牙设计理念的首选,可以兼顾牙弓前后段的问题,有效地实现保留28个牙齿的设计思想.     

拔除第二双尖牙矫正病例(牙合)颌面的垂直向变化

目的　评价安氏 I类错畸形患者,特别是下颌平面角较大的患者拔除第二双尖牙矫正后颌面的垂直向变化,尤其是下颌平面的旋转变化。方法　24 例覆正常或较浅且下颌平面角大于均值的安氏 I类错患者(骨性与牙性均为 I类)拔除第二双尖牙,应用直丝弓技术完成矫治,25 例符合同样标准的患者由不拔牙矫正完成。对所有病例治疗前后的头颅侧位片进行描图和手工测量,比较拔牙组与非拔牙组颌面垂直向的变化。结果　对拔牙和非拔牙两组患者的头影测量结果进行的统计学比较发现,除下磨牙的伸长量拔牙组大于非拔牙组外,两组患者间颌面垂直向的变化并无统计学意义的差别。结论　第二双尖牙的拔除并不一定意味着下颌平面角的减小,对于高角前牙开倾向病例选择拔除第二双尖牙后,在矫正过程中仍需注意对后牙的垂直向控制。     

拔除上颌中切牙的正畸治疗分析

目的:探讨拔除上颌中切牙进行矫治的疗效和治疗特点。方法:选择拔除上颌中切牙进行矫治的患者9例,男4例、女5例,开始治疗年龄平均17.2岁。拔除双侧上颌中切牙和下颌2颗第一前磨牙者5例;拔除单侧上颌中切牙及对侧第一前磨牙和下颌2颗第一前磨牙者4例。进行治疗前后Bolton指数、X线头影测量和临床疗效分析。结果:所有患者均取得了良好的疗效。治疗前预测Bolton指数前牙比和全牙比分别为80.14%和91.31%;治疗后分别为78.68%和90.28%。X线头影测量分析治疗前后U1-NA(mm)、U1-NA、L1-NB(mm)、L1-NB、U1-SN、L1-MP、UL-E、LL-E的值减小(P<0.05)。结论:根据Bolton指数分析,进行个体化设计,拔除双侧上颌中切牙或单侧上颌中切牙及对侧第一前磨牙和下颌2颗第一前磨牙进行正畸治疗,可以获得良好的疗效。     

早期远移磨牙矫治上颌第二前磨牙阻生的临床研究

目的:探讨远中移动上颌第一磨牙,结合直丝弓矫治伴有第二前磨牙阻生的II类错畸形的有效性。方法:选取处于替牙晚期、上颌中重度拥挤的24例患者,采用活动矫治器单侧或双侧远移上颌第一磨牙,开辟间隙并进行第二期固定矫治;统计学分析治疗前后的X线头影测量结果,评估临床疗效。结果:上颌第一磨牙平均远中移动4.5 mm,两侧磨牙和尖牙达到I类关系,上颌前牙唇倾度增加。结论:早期远中移动上颌第一磨牙并结合直丝弓技术可促进第二磨牙正常萌出。     

Root canal treatment of mandibular second premolar with four root canals: a case report

The importance of an accurate diagnosis of the morphology of the root canal system is a prerequisite for successful root canal treatment and has been emphasized throughout the literature. Root canal morphology of premolar teeth, either maxillary or mandibular, and the discrepancies between first and second premolars, have been investigated and reported. A case report is presented of the root canal treatment of a mandibular second premolar with four root canals. As far as the reviewed literature revealed, up to three root canals in mandibular premolars have been reported. No previous report of a similar case of four root canals in a mandibular premolar was found.     

A case of unusual anatomy: a mandibular second premolar with four canals

AIM: The aim of this case report is to describe conventional root canal treatment on a mandibular second premolar with four canals. SUMMARY: The pulp of a mandibular second premolar had become irreversibly inflamed, probably as a result of bacterial microleakage from a carious lesion. The general dental practitioner had initiated root canal treatment, but due to procedural difficulties referred the case. Conventional root canal treatment was then performed with magnification. Preparation was undertaken in a crown-down manner using balanced force hand instrumentation with flexible K-type files and files of Greater Taper. The root canals were obturated with vertically condensed gutta-percha technique. KEY LEARNING POINTS: Good illumination and magnification are vital during root canal treatment. Crown-down preparation using the balanced force technique with flexible files makes instrumentation easier and prevents many of the procedural errors that can occur with filing techniques. Greater Taper instruments made of nickel-titanium are sufficiently flexible to be used in complex curved canals and obviate the need for step-back flaring of the apical preparation. Vertical compaction of warm gutta-percha may simplify the obturation of complex root canal systems. When the technical difficulty of a procedure exceeds the expertise of the practitioner, specialist referral may be required.     

Long-term follow-up of delayed development of maxillary right second premolar with inversely positioned corresponding primary molar

Impaction is defined as a condition in which a tooth fails to erupt within a normal range of functional position. The condition is generally found in permanent teeth, while impaction of primary teeth is considered to be uncommon. We previously presented a rare case of delayed development of a maxillary right second premolar with an inversely positioned corresponding primary molar identified in a girl aged 10 years and 4 months. In the present report of the same patient, we show transitional changes in location and developmental stage of the affected permanent tooth and impacted primary tooth noted during periodical examinations over a 5.5 year period. At 13 years and 2 months, the root of the permanent tooth began to develop, after which the root extended to half of the entire length at 15 years and 3 months. At the most recent examination conducted at 15 years and 9 months, the permanent successor had emerged into the oral cavity and the impacted primary molar maintained a similar position close to the inferior wall of the maxillary sinus without any symptoms. Throughout the observation period, the dental age of the maxillary right second premolar was calculated to be approximately 3 to 4 years behind those of the other second premolars. Our findings in the present case led us to consider that careful observation of the developmental stage of an unerupted permanent tooth is important, while no intervention is required before confirming tooth development as the patient grows, even if the dental age of the corresponding tooth is much later than the ages of other teeth.     

Changes in facial profile during orthodontic treatment with extraction of four first premolars

The present study was designed to evaluate soft tissue profile changes after the orthodontic treatment of class I bimaxillary dentoalveolar protrusion in adult cases. Pre- and post-treatment cephalograms of 20 Caucasian female class I bimaxillary dentoalveolar protrusion patients were selected from private practice. All of them were treated by extraction of four first premolars, and banded and bonded by 022 × 028 standard edgewise technique. t-Test was used to analyze pre- and post-treatment cephalograms. This study showed that upper and lower lip protrusions were decreased respectively 2.7 ± 2.9 mm (p < 0.001) and 2.8 ± 2.8 mm (p < 0.001). The mean changes of upper and lower lip thickness and length, as well as nasolabial and labiomental angles were not significant. Significant positive correlation was found between changes of maxillary and mandibular incisors with changes in upper lip (r_UI = 0.70, p < 0.001, r_LI = 0.59, p < 0.006) and the lower lip positions (r_UI = 0.64, p < 0.002, r_LI = 0.72, p < 0.001). By using stepwise regression it was found that a ratio of 0.63:1 was obtained between upper lip retraction and maxillary incisor retraction and a ratio of 0.62:1 was obtained between lower lip retraction and mandibular incisor changes. This study concluded that, a strong correlation exists between anterior tooth retraction and the position of both lips.     

Comparison of achieved and predicted tooth movement of maxillary first molars and central incisors: First premolar extraction treatment with Invisalign

Objectives:To compare achieved and predicted tooth movements of maxillary first molars and central incisors in first premolar extraction cases treated with Invisalign.Materials and Methods:The present study included 30 patients who received maxillary first premolar extraction treatment with Invisalign. The actual posttreatment model was registered with the pretreatment model on the palatal stable region and superimposed with the virtual posttreatment model. Achieved and predicted tooth movements of maxillary first molars and central incisors were compared using paired t-test. Linear mixed-effect model analyses were used to explore the influence of age (adolescents vs adults), attachment (G6-optimized vs 3-mm vertical, 3-mm horizontal, and 5-mm horizontal), and initial crowding on the differences between predicted and achieved tooth movement (DPATM).Results:First molars achieved greater mesial tipping, mesial translation, and intrusion than predicted. Central incisors achieved less retraction and greater lingual crown torque and extrusion than predicted. Adolescents showed greater DPATM in the mesiodistal translation of first molars and labiolingual translation of central incisors and smaller DPATM in the occlusogingival translation of the first molars and crown torque of the central incisors than adults. The 3-mm vertical attachment group showed greater DPATM in the mesiodistal translation of the first molars vs the G6-optimized attachment group. Initial crowding had an inverse correlation with DPATM in angulation and mesiodistal translation of the first molars.Conclusions:First molar anchorage control and central incisor retraction were not fully achieved as predicted in first premolar extraction treatment with Invisalign. Age, attachment, and initial crowding affected the differences between predicted and achieved tooth movement.