Lower incisor extraction in orthodontic treatment.

The extraction of a single mandibular incisor can be employed as a compromise treatment of certain malocclusions, if the end result fulfills the requirements for a healthier dentition which is functionally and esthetically harmonized in relation to the surrounding structures. Indications, contraindications, and the procedure of treatment have been presented. Class I malocclusions with normal maxillary dentition and good buccal interdigitation in which there is severe lower anterior crowding are the best cases for this procedure, provided that the lower anterior arch length deficiency is greater than 4 to 5 mm. and the anterior tooth ratio is more than 83 mm. In conditions exhibiting a deep overbite pattern, reduction of the mandibular anterior unit should be avoided. Furthermore, I do not regard mandibular incisor extraction as a routine orthodontic procedure but, instead, consider it to be an almost last resort measure since it involves the most important stabilizing area of occlusion.     

Lower incisor extraction in orthodontic treatment. Four clinical reports

Four different clinical cases in which the treatment plan finally selected included the extraction of one lower incisor and reduction of upper anterior tooth width.     

正畸拔除下颌切牙矫治病例的回顾性分析

目的探讨各类拔除下颌切牙进行矫治的适应证选择和矫治特点。方法采用回顾性研究的方法,对17例由于各种原因需拔除单个下颌切牙或还需配合拔除其它牙齿进行矫治的病例进行分析。其中伴有下切牙拥挤的成人轻、中度III类错病例拔除单个下颌切牙矫治;前牙深覆盖的成人安氏Ⅱ类Ⅰ分类病例拔除上颌两个第一双尖牙及一个下中切牙矫治;由于上颌两个侧切牙过小引起Bolton指数不调病例拔除一个下颌切牙矫治;均采用直丝弓矫治技术,通过头影测量分析,比较治疗前后的改变情况。结果病例矫治时间为19～26个月,17例病例治疗结束后拔牙间隙均全部关闭,前牙覆覆盖关系正常,后牙咬关系良好。软组织侧貌得以改善。结论拔除下颌切牙矫治在诊断设计时应权衡利弊,严格控制适应证,在治疗过程中注重相应矫治技术与方法的应用,以获得良好、稳定的矫治效果。     

Lower incisor and second molar extraction in Class III treatment

Although not fully accepted as routine orthodontic therapy, second molar and lower incisor extraction is well documented in the literature. The following cases show how both procedures can be used successfully to simplify the treatment of Class III malocclusion, while preserving the facial profile.     

中切牙外伤拔除的正畸治疗

目的 探讨正畸拔除上颌单侧中切牙矫治模式的可行性及临床治疗的要点.方法 从40例切牙外伤正畸病例中,选出患者19例.其中安氏Ⅰ类错（牙合）10例,安氏Ⅱ类错（牙合）7例,安氏Ⅲ类错（牙合）2例;男16例,女3例,平均年龄14.5岁,均存在牙量与骨量不调需拔牙矫治病例.所有患者采取拔除外伤中切牙及其它三个象限第一前磨牙模式进行矫治.矫治后对临床资料做回顾性的研究,并进行临床疗效评价.结果 19例患者均取得较好的治疗效果,矫治后拔牙间隙关闭,前牙覆（牙合）覆盖正常,中线基本正中,侧貌得到改善.采用治疗前后配对t检验方法,发现牙性指标4项：U1-NA（27.5°至23.3°）、L1-NB（36.4°至32.5°）、L1-MP（97.2°至93.5°）角度减少,表示上下中切牙的倾斜度减小,U1-L1（11.83°至124.4°）角度增加,表示上下中切牙的凸度减少;软组织指标2项：上唇凸点-E线距（Ls-E）从3.5mm减小到1.2mm、下唇凸点-E线距（Li-E）从4.1mm减少到1.5mm,差异均有统计学意义（P＜0.05）.结论 遵循个体化原则,用Bolton指数指导设计和有效支抗控制,非常规拔牙模式矫治,能够达到预期目的.     

Evaluation of objective and subjective treatment outcomes in orthodontic cases treated with extraction of a mandibular incisor

Objectives:To analyze changes in occlusal characteristics following mandibular incisor extractions (MIE), to determine the usefulness of wax setups in treatment planning MIE cases and to compare the pre- and posttreatment dental attractiveness between MIE cases and nonextraction (NE) controls.Materials and Methods:The Peer Assessment Rating (PAR) Index was used to score pre- and posttreatment dental casts of MIE cases (n = 14) and matched NE controls (n = 14). Occlusal characteristics were evaluated on diagnostic wax setups and posttreatment casts. Attractiveness of pre- and posttreatment cases judged on intraoral photographs of cases (n = 6) and controls (n = 6) were rated by 76 dental students and 10 laypeople using visual analogue scales (VAS).Results:The difference in PAR score reduction (%) between the MIE and NE groups was not significant. Between the wax setup and posttreatment casts, there were moderate correlations in overjet, overbite, and right canine classification. There was no significant difference in pre- and posttreatment change in VAS scores (%) for attractiveness between the MIE (49.8 ± 4.3 [S.E.]) and control groups (40.8 ± 4.3 [S.E.]). However, there was a significant difference (P = .000) between the observer groups.Conclusions:There were no significant differences in the treatment outcomes of orthodontic cases treated with MIE or NE, indicating that MIE is a valid treatment option. A wax setup is moderately correlated with posttreatment results. Both laypeople and dental students rated posttreatment dental attractiveness higher than pretreatment in MIE and NE groups. Dental students tended to be more critical than laypeople in their ratings.     

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。     

Mandibular incisor stability after orthodontic treatment in the upper arch

The aim of this study was to observe longitudinally the anterior region of the lower jaw when treating only the upper jaw. A comparison was made between a group of 35 children treated with extraction of the maxillary first premolars and a fixed appliance in the upper jaw and a control group of 19 untreated children. The treatment group was studied with plaster models on five occasions: before treatment, at the end of active treatment, at the end of retention, after one year out of retention and at the last registration, in total over about a seven year period. Cephalometric registrations were made before treatment and at the last registration. The control group was studied with plaster models and lateral head films during a period of nine years and their age at the last registration was the same as for the treatment group. The space loss in the anterior region of the lower jaw increased from a mean of 0.4 mm (s.d. 0.82) to 2.5 mm (s.d. 1.52) in the treatment group and from 0.1 mm (s.d. 0.16) to 0.5 mm (s.d. 0.81) in the control group: an extra space loss of 2.0 mm for the treatment group. The main increase was registered during treatment and after retention. Subjective ranking of the plaster models from the final registrations according to the amount of crowding in the lower anterior region also showed a significant difference between the treatment group and the control group, the treatment group showing the largest of crowding. In cases where maxillary protrusion is treated by extraction in the maxilla only, stabilization of the lower arch with fixed orthodontic appliances seems justified.     

Relationship between dental crowding and mandibular incisor proclination during orthodontic treatment without extraction of permanent mandibular teeth

Objective:To examine changes in mandibular incisor proclination and protrusion resulting from alleviation of crowding.Materials and Methods:Records of 96 patients from a private practice treated without extractions or interproximal enamel reduction in the mandibular arch were included. Pre- and post-treatment cephalograms and models were examined to determine changes in incisor proclination, protrusion and crowding.Results:For every millimeter of crowding alleviation, increases in incisor proclination (ΔIMPA) and protrusion (ΔL1 to A-Pog) of 0.5° and 0.2 mm, respectively, were found, on average. High variability was calculated for both linear variables (that can be reduced by incorporating other variables by multilinear regression).Conclusions:For every millimeter of crowding alleviated, 0.5° of proclination and 0.2 mm of protrusion are expected. Our results indicate that proclination is mulifactorial and cannot be explained solely by the amount of crowding alleviated during orthodontic treatment. These results may be a useful guiding principle rather than a prognostic tool.     

正畸治疗中拔牙矫治的临床分析

目的：分析拔牙矫治疗在临床中的应用情况，了解拔牙理念对拔牙比例的影响。方法：选择1995年－2000年400例恒牙期错He病例分为两组（1995年－1997年为第一组，1998年－2000年为第二组）进行统计分析。结果：第一组拔牙比例是50．0％，第二组组拔牙比例是38．8％，安氏Ⅱ^1类错He拔牙比例较其他类型的错He高，两组分别是69．8％和68．8％，双尖牙的拔除占总拔牙数的百分比最高，两组分别为95．9％和94．3％。结论：1995年－2000年拔牙比例发生较大变化，拔牙比例减少主要受矫治理念的影响。     

倒位埋伏阻生上中切牙的临床矫治探索

目的 探索倒位埋伏阻生上颌中切牙的矫治方法,以提高临床矫治效果和保留更多的倒位阻生牙.方法对8例患者的9颗倒位埋伏阻生的上中切牙采用开拓间隙、手术开窗牵引、固定人工支点协助调向、排齐、反向控根等方法进行矫治.结果9颗倒位阻生的上中切牙中,有8颗经过15～30个月的矫治达到正常位置,牙齿稳定,功能正常.剩余1颗因牵引15...