Stability after vertical subcondylar ramus osteotomy for correction of mandibular prognathism

A cephalometric analysis of the positional changes of the mandible and the upper and lower incisors following vertical subcondylar ramus osteotomy was performed on 80 patients. The patients were prognathic without laterognathism or open bite and all the patients had preoperative orthodontic treatment. 40 patients were operated with an intraoral (IVSO) and 40 with an extraoral approach (EVSO). Both groups showed postoperatively posterior rotation of the mandible, shortening of the posterior facial height, increase in anterior facial height and extrusion of the incisors in both jaws. A significantly greater reduction of posterior facial height was observed in the EVSO-group, but otherwise the 2 groups did not reveal any statistically significant positional differences. The material was sub-divided into 2 groups 1 with (n = 32) and one group without (n = 48) extra skeletal (nasomandibular) fixation in addition to the intermaxillary fixation. Significantly less positional changes of the incisors and less increase of anterior facial height was found in the group with skeletal fixation, but the influence on other skeletal alterations was limited. After release of the intermaxillary fixation, the only difference between the groups was intrusion of the earlier extruded incisors, most pronounced in the group without skeletal fixation.     

Initial intrusion of the molars in the treatment of anterior open bite malocclusions in growing patients

The treatment of the hyperdivergent phenotype and/or anterior openbite is one of the common problems facing orthodontists. The purpose of this study is to present a new appliance (Molar Intruder) for molar intrusion and to determine its effects in the treatment of anterior openbite. The study group comprised 14 patients (eight girls and six boys), with a mean age of 10 years and 7 months. All presented anterior open bite malocclusions between the second premolars. The study was carried out on lateral head films taken before (T1) and after (T2) molar intrusion. Periapical radiographs, study models, and standard photographs of all the patients were also obtained before and after molar intrusion. The paired sample t-test was used to determine the differences between the parameters. The average treatment time with the Molar Intruder was five months. The mean intrusion of maxillary and mandibular molars was 1.86 mm and 1.04 mm, respectively. Maxillary incisors extruded 0.54 mm with a labial tipping of 1.46 degrees and overbite increased by 4.00 mm. The mandibular plane angle was decreased by 1.57 degrees, and the anterior face height was decreased by 1.86 mm on average. The mandible showed a counterclockwise rotation, the chin moved forward, and the posterior facial height/anterior facial height ratio was increased. Anterior openbites of the patients were significantly rehabilitated at the end of the intrusion period, simplifying further orthodontic treatment.     

辽宁地区成人深覆(牙合)患者颌面部硬组织形态特征的CBCT研究

目的:探讨成人深覆患者的牙性和骨性结构特征.方法:纳入符合标准的160 份CBCT资料,其中深覆组80 例,正常对照组80 例,利用Mimics 17.0三维重建软件建模,得出点、线、面的三维数据,采用配对样本t检验进行统计分析.结果:骨性特征中,下颌平面角、上下颌聚散角和颅下颌三角,深覆组均比正常对照组降低,而下颌升支长度、后面高、上面高以及后面高与前面高的比值,深覆组比正常对照组大,下面高以及下面高分别与前面高和上面高的比值,深覆组比较小.牙性特征中,上下颌中切牙的轴倾角,深覆组比正常对照组小,而Spee曲线深度,深覆组明显增大.上颌中切牙萌出长度和下颌第一磨牙萌出长度在2 组间增减趋势相反,前者在深覆组增大,而后者在深覆组减小.结论:下颌骨的逆时针旋转以及Spee曲线的加深和后面高的增大是促使深覆形成的重要因素.     

Twin-block矫治Ⅱ类错He 12例分析

目的：定量评价双He垫矫治器(Twin-block)对生长期安氏Ⅱ类Ⅰ分类错He患者的颌骨及牙槽骨的影响。方法：12例10～12岁安氏Ⅱ类错He患者，用Twin-block进行矫治，治疗结果与11例未经治疗的10～12岁安氏Ⅱ类错He患者比较。观察时间为12个月。采用团体t检验进行组间比较。结果：Twin-block治疗组，覆盖和磨牙关系均得到改善，覆盖的减小主要是由于上切牙的远中移动，及下颌骨的向前生长；磨牙关系的矫正，下颌骨的生长与牙槽骨的变化各占50％作用。下颌骨长度(Ar-Gn)比对照组增加2．29mm，后面高(Ar-Go)与前下面高(ANS-Me)均有增加，分别为2．28mm与2．58mm，未观察到不利的垂直向生长。结论：Twin-block能有效减小前牙覆盖，矫正磨牙关系，改善软组织侧貌。并增强Ⅱ类错He患者下颌骨的生长。     

Relapse following mandibular advancement with dental plus skeletal maxillomandibular fixation

This study examines the short-term stability of the mandible following mandibular advancement surgery in which skeletal suspension wires were used in addition to dental maxillomandibular fixation. Twenty adults underwent sagittal ramus osteotomies. No concomitant surgical procedures were performed. Maxillomandibular fixation consisted of wiring between the upper and lower orthodontic brackets and circummandibular wires connected to the piriform aperture or anterior nasal spine wires for eight weeks. Cephalograms were analyzed during this period to evaluate skeletal stability. A statistically insignificant mean horizontal relapse of 8.9% was found at pogonion during the period of fixation. Significant vertical intrusion of the anterior mandible occurred, however, with a mean superior movement of pogonion of 0.83 mm (P less than or equal to 0.05). Dental changes noted were uprighting of the maxillary incisors and flaring of the mandibular incisors. In comparison with the results of other studies in which dental maxillomandibular fixation was used alone, the results of this study indicate that the use of skeletal suspension wires is advantageous in the prevention of horizontal skeletal relapse.     

Intraoral or extraoral approach in oblique sliding osteotomy of the mandibular ramus. A cephalometric study

Positional changes of the mandible after oblique sliding osteotomy of the mandibular rami were investigated by means of cephalometric analysis. The patient material comprised 40 patients. Twenty patients were operated upon using an extraoral approach and 20 were operated on using an intraoral approach. The patients were followed up with lateral cephalograms for 18 months after operation. In both groups, a posterior rotation of the mandible took place during the fixation period. This rotation gave a further retro-displacement of gnathion and a shortening of posterior facial height. The incidence of patients with considerable posterior rotation of the mandible was higher in the intraoral than in the extraoral group. The difference between the means of the changes in the mandibular plane angle (dEO = 4.9 degrees, dIO = 6.3 degrees) of the groups was, however, not statistically significant. Nor was there any significant difference in relapse between the two groups after release of the fixation.     

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目的了解排除了自然生长因素后,Twin—block矫治器治疗青少年安氏Ⅱ^1错（牙合）引起的硬组织改变,从而更为真实、准确地评价该矫治器的矫治效能。方法于2008年9月至2010年9月在河北医科大学附属口腔医院正畸科门诊选择30例手腕骨片为FG—G期的安氏Ⅱ^1下颌后缩患者。治疗组15例,平均年龄11．5岁,采用Twin—block矫正器治疗,平均治疗及保持时间14个月;对照组15例,平均年龄11岁,作为自然生长对照,平均观察时间13个月。对治疗及观察前后头颅X线侧位片的32项硬组织项目进行Pancherz测量分析,评价矫治疗效。结果排除了自然生长因素的影响,治疗组在采用Twin—block矫治器矫治后,下颌全长、升支高度及下颌体长分别净增加了4．95、4．03和1．67mm,SNB角（蝶鞍中心、鼻根点及下齿槽座点所构成的角）增加了2．39°;全面高、下面高及后面高均明显增加,但下颌平面保持稳定;上切牙舌倾、下切牙唇倾。在4．76mm的覆盖减少量和5．22mm的磨牙关系改善中,牙齿效应分别占61％和75％,骨骼效应占39％和25％。结论Twin—block矫治器使发育期安氏Ⅱ^1错（牙合）患者覆（牙合）覆盖、磨牙关系均得到改善,有效促进了下颌骨矢状方向上的生长发育,Ⅱ类骨面型趋于好转。     

Facial growth in females 14 to 20 years of age.

The objective of this study was to determine the magnitude and the direction of postpubertal mandibular and maxillary facial growth in females. The sample consisted of 37 untreated subjects who had Class I skeletal and dental characteristics and whose lateral cephalograms were taken at 14, 16, and 20 years of age. Mandibular growth was determined to be significant for the age periods of 14 to 16 years and 16 to 20 years. Overall mandibular growth as measured from Co-Gn was approximately twice that of the overall maxillary growth as measured from Co-A. Correlation analysis revealed a statistically significant relationship between the estimates of incremental mandibular growth from either articulare or condylion. The mandibular growth rate was found to be twice as large for age period 14 to 16 years as for age period 16 to 20 years. The increase in posterior vertical face height was slightly more than the increase in anterior vertical face height. The mandibular plane angle decreased 1.1 degrees during the age period of 14 to 20 years, suggesting a tendency for a closing rotation of the mandible. Mandibular incisors appeared to tip labially with advancing age. Although variable, the potential for significant maxillary and mandibular facial growth in females during late adolescent has been demonstrated.     

Components of adult class III malocclusion

To identify the skeletal and dental relationships of adults who have class III malocclusion, lateral cephalograms of 302 adult patients who had a class III molar and cuspid relationship were traced. Ninety-four of the patients had had presurgical orthodontic treatment and 208 had not. The tracings were digitized, and the following sets of measures were analyzed: maxillary skeletal position; maxillary dentoalveolar position; mandibular dentoalveolar position; and mandibular skeletal position. In addition, the mandibular plane angle and lower anterior facial height were measured as an indicator of vertical facial dimensions. None of these values demonstrated significant gender differences except lower anterior facial height; therefore, the subjects were treated as a group. Although there was considerable variation among patients, the most common combination of variables was a retrusive maxilla, protrusive maxillary incisors, retrusive mandibular incisors, a protrusive mandible, and a long lower facial height.     

双颌前突畸形正畸治疗后颅面硬组织变化的研究

目的研究正畸治疗对双领前突患者硬组织矢状及垂直向的影响。方法对24例广东籍双领前突患者在拔除4个第一双尖牙后,采用标准方丝弓矫治技术进行矫治,并对矫治前后硬组织侧貌的变化进行分析。结果 ①上下领骨间关系无明显变化,上下前牙突度和倾斜度明显减小。②前后面高明显增加,但前后面高间的比值及反映下领平面倾斜度的MP-FH无明显变化。③上下磨牙高度随前后面高的增加而明显增加。④上前牙高度明显增加,下前牙高度明显减小。结论双领前突畸形正畸治疗中垂直向及矢状向支抗可得到较好控制。     

Skeletal and dental changes with nonextraction Begg mechanotherapy in patients with Class II Division 1 malocclusion

This prospective cephalometric study was undertaken to assess the mode and magnitude of Class II correction with nonextraction Begg mechanotherapy in growing children. The sample comprised subjects with similar malocclusion and age range (9-12 years) who were specifically selected for nonextraction Begg mechanotherapy. Cephalograms were analyzed to assess the skeletal, dental, and soft tissue changes that occurred after correction of the molar relationship, the overjet, and the overbite during the 9-month treatment period. The results revealed a significant improvement in the anteroposterior jaw relationship, suggested by the significant reduction in the ANB angle (1.62 degrees ) and in Wits AO-BO (1.42 mm). The mandibular length increase of 0.56 mm suggests that the Class II elastics used in nonextraction Begg mechanotherapy had a minimal stimulatory effect on mandibular growth. There was a significant increase in the anterior and posterior facial heights and the ramal height. Almost all of the dental changes were significant. The most striking feature were a significant retraction and extrusion of the maxillary incisors and proclination and intrusion of the lower incisors accompanied by extrusion of the mandibular molars. The maxillary incisors extruded by 1.64 mm under the influence of the undesirable downward component of the Class II elastic forces. The major contribution to overjet and molar correction was predominantly dentoalveolar.     

The effects of extraction and nonextraction treatment on the mandibular position

Decisions on extraction of teeth as an aid in orthodontic treatment depend on dental and skeletal discrepancies concerning sagittal and vertical relationships. The purpose of this study was to assess the effects of extraction and nonextraction procedures on the posterior rotation of the mandible and the position of gnathion. Forty-eight nonextraction patients and seventy-three extraction patients treated in the orthodontic department were selected. The patients were from 11 to 15 years old, with a mean age of 12 years 2 months. The lateral cephalometric radiographs taken before and after treatment were traced and measured. Eleven variables reflecting the mandibular rotation were selected on the basis of factor analysis. Before treatment, total arch circumferential discrepancy and the 11 selected measurements showed significant differences between the extraction and nonextraction groups. In the extraction group, the lower anterior facial height was larger, ramus height was smaller, and the difference between vertical position of both maxillary and mandibular first molars and posterior facial height was greater than in the nonextraction group. Consequently, the mandible showed posterior rotation and was in retruded position in the extraction group. In the nonextraction group, the type of force application had no significant effect on the changes in skeletal and dental measurements. In the extraction group, however, the type of force application had a significant effect (p less than 0.05) on the changes in total anterior facial height, the horizontal distance of the maxillary first molar to a perpendicular line to the S-N plane passing through point S, the vertical distance of the maxillary molar to the S-N plane, the vertical distance of the maxillary and mandibular first molars to the S-N plane, the difference between the vertical position of the first molars and posterior facial height, and the difference between the vertical position of the first molar and vertical height of the ramus. In the group in which high-pull face-bow headgear was used, the extraction/nonextraction procedures had a significant effect (p less than 0.05) on the changes in angle ANB, total anterior facial height, anterior lower facial height, and the difference between anterior and posterior facial height.(ABSTRACT TRUNCATED AT 400 WORDS)     

Changes in Vertical Tooth Position and Face Height Related to Long Term Anterior Repositioning Splint Therapy

This study evaluates whether extended full-time wear of a partial coverage mandibular anterior repositioning splint (MORA) causes intrusion of posterior teeth and determines the effect on jaw position. Sixty-four patients from two private orthodontic practices were studied using cephalometric radiographs to measure vertical change in position of the anterior and posterior teeth and the mandible. The splint wear time ranged from a minimum of one half year to a maximum of 4.8 years, with a mean of 1.33 years. No significant change was recorded in the distance from the mandibular molar to the mandibular plane. On average, the maxillary incisor and maxillary molar extruded about 1 mm, while the mandibular molar was unchanged and the mandibular incisor intruded about 0.6 mm. Posterior face height increased an average of 1.6 mm, and anterior face height increased an average of 2.7 mms. In 20% of the patients, intrusion of the mandibular molars of 1 mm or more occurred. In 41%, extrusion of the maxillary incisors of 1 mm or more was noted. Intrusion of the upper molars or extrusion of the lower incisors occurred in only 5% of the patients. The data indicates that only a very small proportion of patients having long term splint therapy using the MORA have clinically significant molar intrusion. Change in mandibular position was expressed in a vertical increase in posterior and anterior face height. Only very small changes occurred in antero-posterior position.     

Components of adult Class II open-bite malocclusion

In an effort to identify the frequency and distribution of the dental and skeletal components of adult Class II malocclusion with and without open-bite, 124 adults, half of whom had an anterior open-bite, were evaluated. Significant differences (P less than 0.05) between the open-bite and non-open-bite groups were found for the following measurements: the posterior maxilla exhibited vertical excess in the open-bite group; the maxillary occlusal plane was less steep in the open-bite group; the mandibular occlusal plane was more steep in the open-bite group; the gonial angle was higher in the open-bite group; the mandibular plane angle was higher in the open-bite group; the mandibular ramus was positioned in a more downward and backward (clockwise) location in the open-bite group; the total and lower anterior facial height were increased in the open-bite group; and the mandible was less protrusive in the open-bite group. No significant intergroup differences were noted in the cranial base, the anteroposterior position of the maxilla or of the upper and lower incisors, the palatal plane, posterior facial height, mandibular ramus height, or mandibular body length. The results of this analysis indicate that the average Class II open-bite malocclusion is characterized by aberrations in both the maxilla and the mandible. Therapy, therefore, may frequently require surgical intervention in both jaws to successfully correct this deformity.     

Effects of a magnetic appliance in functional Class III patients

The aim of this study was to determine the effects of a magnetic appliance in functional Class III patients. Standardized lateral head cephalograms and hand-wrist films of 10 subjects (mean age nine years seven months) were taken. These records were repeated after a period of one year, and the serial films were compared to determine the direction of facial growth as the control group. After this observation period, the magnetic appliance was placed in the 10 patients for approximately 9.4 months. The significant findings showed a posterior rotation of the mandible (x = 2.1 +/- 0.7 degrees), increased overjet (x = 4.8 +/- 0.3 mm), decreased overbite (x = -3.7 +/- 0.7 mm), protrusion of the upper incisors (x = 6.2 +/- 1.2 degrees), retrusion in the lower incisors (x = -0.6 +/- 0.3 degrees), reduced SNB angle (x = -1.8 +/- 0.8 degrees), increased ANB angle (x = 1.9 +/- 0.3 degrees), and an increased mandibular plane angle (x = 2.1 +/- 0.7 degrees). The results of this study indicate that the primary effect of magnetic appliance was the increase in the posterior rotation of the mandible.     

Comparative study of the Fr?nkel (FR-2) and bionator appliances in the treatment of Class II malocclusion.

The purpose of this investigation was to compare the dentoalveolar and skeletal cephalometric changes produced by the Fr?nkel (FR-2) and bionator appliances in persons with Class II malocclusion. Lateral cephalograms were available for 66 patients of both sexes, who were divided into 3 groups of 22. The control group included untreated Class II children, with an initial mean age of 8 years 7 months; they were followed without treatment for 13 months. The FR-2 appliance group had an initial mean age of 9 years; those children were treated for a mean period of 17 months. The bionator group initially had a mean age of 10 years 8 months; on average, they were treated for 16 months. The results demonstrated no significant changes in maxillary growth during the evaluation period. Both appliances showed statistically significant increases in mandibular growth and mandibular protrusion, with greater increases in patients treated in the bionator group. Both experimental groups showed an improvement in the maxillomandibular relationship. There were no significant changes in growth direction, while the bionator group had a greater increase in posterior facial height. Both appliances produced similar labial tipping and protrusion of the lower incisors, lingual inclination, retrusion of the upper incisors, and a significant increase in mandibular posterior dentoalveolar height. The major treatment effects of bionator and FR-2 appliances were dentoalveolar, with a smaller, but significant, skeletal effect.     

Long-term stability of conservative orthodontic treatment in a patient with rheumatoid arthritis and severe condylar resorption

Rheumatoid arthritis is a chronic inflammatory condition that can result in progressive destruction of the articular surfaces of the joints, including the temporomandibular joint. The purpose of this article is to report the conservative correction of a Class II malocclusion in a woman with rheumatoid arthritis. The patient was 32 years 6 months old at the start of treatment. She had a convex profile and a skeletal Class II jaw-base relationship caused by severe condylar resorption. An anterior open bite of -2.0 mm and an excessive overjet of 10.0 mm were observed. Severe crowding was shown in the mandibular incisors. After 8 months of splint therapy, all first premolars were extracted, and 0.018-in preadjusted edgewise appliances were placed in both arches. Class II elastics were used during space closure. After 41 months of active orthodontic treatment, an acceptable occlusion was achieved, and the facial profile was considerably improved. From the cephalometric evaluations, the mandible was rotated counterclockwise, and the mandibular plane angle was significantly decreased. However, the anteroposterior position of the chin was not changed. The condylar resorption was not changed during and after orthodontic treatment. Conclusively, the proper facial profile was maintained, and the occlusion was stable after a 5-year retention period. Our results suggest the possibility of compromised treatment in a Class II malocclusion with an anterior open bite because of rheumatoid arthritis.     

Stability of orthodontic-maxillofacial surgical treatment of anterior open bite deformities]

A sample of 267 patients with maxillary hyperplasia, a Class I or Class II occlusion and anterior open bite, collected from three different institutions, was analysed regarding stability after Le Fort I intrusion osteotomies or bimaxillary osteotomies. Skeletal and dento-alveolar stability of the maxilla, postional changes of the mandible and of incisors were evaluated on cephalometric radiographs. The stability of maxillary arch dimensions after correction of the open bite is measured on dental casts. Patients with anterior open bite, treated with a Le Fort I osteotomy in one-piece or in multi-segments, with or without bilateral sagittal split osteotomy exhibited good skeletal stability of the maxilla. Rigid internal fixation showed better maxillary and mandibular stability than intraosseous wire fixation. Considerable relapse of transverse dimensions, however, was measured after orthodontic and surgical expansion. The mean overbite at the 69 months follow-up was 1.24 mm and lacking of overlap between opposing incisors was present in 19%.     

13名女性自9.5至15.5岁自然生长中下颌骨旋转的研究

目的通过对13名未经正畸治疗的女性个体自9.5至15.5岁拍摄头颅侧位片的重叠研究,探讨面部正常生长发育过程中下颌骨的旋转。方法选择美国密西根大学生长发育中心收集的Dr. Mathews长期追踪观察的13名未经正畸治疗的安氏Ⅰ类高加索人种女性9.5~15.5岁拍摄的头颅侧位片,以种植体作为标志点,重叠并描记所有头颅侧位片。通过Dentofacial Software完成头影测量分析, 采用SPSS 15.0软件对不同年龄段的面部生长变化进行配对t检验。结果高加索人种女性9.5～11.5岁时前下面高、后面高、下颌升支和下颌种植体平面角的变化有统计学差异;11.5～13.5岁时前下面高、后面高、下颌升支的变化有统计学差异;13.5～15.5岁时后面高、下颌平面角、下颌种植体平面角的变化有统计学差异。结论生长发育过程中下颌骨下缘的改建会引起下颌骨的整体旋转。     

Considerations in correction of mandibular protrusion by intra-oral vertical ramus osteotomy

This case report presents a case that underwent orthognathic treatment with intra-oral vertical ramus osteotomy (IVRO). The patient was a 19-year-old female with mandibular protrusion and severe maxillary anterior crowding. The overbite was +0.5 mm and the overjet −1.5 mm. She had orofacial pain and tenderness of the temporomandibular joints (TMJ) and surrounding muscles. The pre-surgical orthodontic treatment included the extraction of the maxillary right lateral incisor, maxillary right second premolar, maxillary left canine, mandibular left second molar and mandibular right second premolar. After 18 months of pre-surgical orthodontic treatment, the left and right sides of the mandible were set back 8 and 6 mm, respectively, via IVRO to improve mandibular protrusion. The total treatment period was 26 months. The patient showed the backward reaction of the mandible, which occurred after release of the maxillo-mandibular fixation. The usage of the Class II elastics during the post-surgical phase to maintain the overjet made the inclination of the maxillary incisors more lingual.