Anterior skeletal fixation as an adjunct to oblique sliding osteotomy of the mandibular ramus. A cephalometric study

Positional changes of the mandible and upper and lower incisors were studied by means of cephalometric analysis after oblique sliding osteotomy for the correction of mandibular prognathism. In addition to intermaxillary fixation, skeletal fixation between the anterior nasal spine and the chin was used. The patients were followed up for 18 months after surgery. During the fixation period no increase in anterior facial height was observed and at 18 months this had decreased by 2.2 mm. Nevertheless, there was an increase in the mandibular plane angle by 3.8 degrees which mainly occurred during the fixation period. The posterior facial height decreased by 4.0 mm. As to the changes of the incisors these varied between individuals, but the mean values were small. Anterior skeletal fixation prevented increase in anterior facial height and seemed to limit the posterior shortening of the mandible and the extrusion of the mandibular incisors. However, the benefits remained rather limited.     

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.     

Displacement of the mandible after removal of the intermaxillary fixation following oblique sliding osteotomy

In an earlier study (Rosenquist et al., 1985) on oblique sliding osteotomy in 14 patients, operative repositioning and postoperative displacement of the mandible during intermaxillary fixation were presented. In the present stereometric study on the same patients displacement of the mandible after removal of the intermaxillary fixation is presented. A continuous anterior and a minor initial cranial translation and an anterior rotation of the mandible were found. Proclination of both upper and lower incisors was recorded. Correlations were found between operative repositioning and postoperative displacement of the mandible after removal of the intermaxillary fixation. Possible relapse mechanisms are discussed.     

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.     

Skeletal fixation versus skeletal relapse

The use of skeletal fixation was evaluated for skeletal stability during the period of intermaxillary fixation following a modified sagittal split ramus osteotomy for mandibular prognathism. A combination of bilateral maxillary peralveolar wires and circummandibular wires in the canine region was used for the fixation. One group of patients with this method of fixation (S group) and a second group without the fixation (C group) were compared cephalometrically. Statistically significant differences existed in the amount and pattern of relapse; the fixation produced a significant effect on retention of the corrected chin position. As a consequence, downward and backward rotation of the distal fragment of the mandible and compensatory incisor extrusion were notably controlled. However, upward shift of the posterior end of the distal fragment occurred persistently even in the S group, causing considerable intrusion of the posterior teeth in comparison with the C group. This seems to indicate that tension, probably exerted by the pterygomasseteric sling, is important in postoperative skeletal instability.     

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.     

Skeletal and dental effects of a mini maxillary protraction appliance

The aim of this study was to evaluate the skeletal and dentoalveolar changes achieved by a modified protractor in growing skeletal and dental Class III patients and to compare these changes with normal growth in a Class I untreated control group. The study group consisted of 25 patients (11 girls, 14 boys; mean age 11.74 +/- 1.81 years). The control group was composed of 20 patients (15 girls, five boys; mean age 11.89 +/- 1.08 years). The Class III patients were treated with a bonded acrylic cap splint type expander and a modified maxillary protractor until a positive overjet was achieved. The mean observation period was 0.65 years. Changes in study and control groups and differences between the groups were analyzed statistically. The results showed that protraction appliance produced a significant positive improvement in maxillo-mandibular relations. The forward movement of the maxilla was significant in treated Class III patients, but a slight difference was present between the two groups regarding maxillary rotation. The effective length of the maxilla was significantly increased in the Class III patients. The mandible was positioned backward, and posterior rotation of the mandible was significant in the treatment group. There was a significant increase in lower anterior facial height of treated Class III patients. The dentoalveolar measurements showed that the maxillary incisors proclined and the mandibular incisors significantly retroclined in the Class III group. A modified maxillary protractor treatment is effective for correcting skeletal Class III malocclusion.     

骨性Ⅲ类错颅面结构及发育的性别差异

目的：探讨和分析骨性Ⅲ类错颅面形态结构及生长发育的性别差异。方法：选择骨性Ⅲ类错患者154例,男女分别分为恒牙初期和恒牙期2组,拍摄治疗前头颅定位侧位片行X线头影测量分析,采用独立样本t检验进行4组之间的比较分析。结果：男性颅底、上颌、下颌、前面高和后面高的线距均显著大于女性;恒牙期女性Y轴角小于男性。从恒牙初期到恒牙期,男性后颅底、下颌长和垂直面高增长显著;女性前颅底、上颌长、下颌长、前下面高和后面高均有显著增长,上下颌的矢状不调（ANB和NA-PA）加重,下颌平面角明显减小。结论：骨性Ⅲ类错的颅面形态及发育存在明显性别差异,临床治疗计划的制定和预后的评估应考虑男女的不同。     

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)     

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。     

Evaluation of the effects of temporomandibular joint disk displacement and its progression on dentocraniofacial morphology in symptomatic patients using lateral cephalometric analysis

The aim of this study was to evaluate the effects of disk displacement (DD) and its progression on dentocraniofacial morphology in symptomatic patients and compare the results with asymptomatic volunteers. Skeletal and dental Class I female patients with DD, diagnosed using magnetic resonance imaging (MRI) and lateral cephalometric analysis were included in the study. Subjects were grouped as follows: control group with bilateral normal disk position (group 1, n=12), unilateral DD with reduction (group 2, n=16), bilateral DD with reduction (group 3, n=26), unilateral DD without reduction (group 4, n=12), and bilateral DD without reduction (group 5, n=8). Thirty-two (32) cephalometric variables were measured, and statistically significant differences were found in 11. Dental and soft tissue measurements did not reveal any differences, but variables related to the mandible showed statistically significant differences. Progression of DD was associated with an increase in all angular measurements related to vertical skeletal relationships and articular angle and a decrease in the ratio of posterior face height to anterior face height indicating clockwise rotation of the mandible. Similarly, the height of ramus was decreased with the progression of DD. The results of this study demonstrated that the presence of DD in skeletal Class I female patients effects facial morphology, and its progression makes the differences more significant and remarkable. These results emphasize the importance of early diagnosis and treatment in the management of DD.     

磨牙前倾弯治疗前牙开(牙合)畸形的临床效果评价

目的 开拾畸形在临床治疗上难度较大，治疗方法较单一、局限、疗程长、矫治效果不确定，本文目的在于了解应用前倾弯矫治前牙开He时的矫治效果。方法 对5例前牙开He的患者应用前倾弯进行矫治，通过分析矫治前后X线头颅定位侧住片，评价前倾弯在矫治前牙开He畸形的效果。结果 发现矫治过程中，第一磨牙明显近中倾斜；矫治前后全面高、前后面高有显著性变化；上颌切牙至腭平面、下颌切牙至下颌平面的垂直距离明显增加；下颌第一磨牙至下颌平面的角度明显变大，说明在矫治后上下切牙伸长并向舌侧移动。结论 前倾弯治疗开He主要是通过前牙的伸长和舌侧移动来达到建立覆He的目的，而后牙不仅不能直立，而且会更加近中倾斜，从而使He平面不能改变，而使开He的矫治效果不稳定。     

Dental-skeletal dimensions in growing individuals with variations in the lower facial height

The dental and skeletal dimensions of individuals with Class I skeletal pattern in puberty were compared. Eighty patients with Class I malocclusion were selected, independent of the vertical relations (overbite) of the incisors. The sample was divided into 3 groups: normal, short and excessive lower anterior face height, based on facial proportions. The dental and skeletal measurements of the 3 groups were compared among themselves. In the angular measurements, the results showed no correlation in the mandibular plane angle. In the linear measurements, the mandibular length was significantly greater in the group of patients with short lower anterior face height, with a positive correlation among the three groups. The dentoalveolar heights of the incisors had a positive correlation among the three groups in relation to the lower anterior face height, showing that they are responsible for its variation.     

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.     

Extreme dentoalveolar compensation in the treatment of Class III malocclusion

The orthodontic treatment of an adult patient with a skeletal Class III malocclusion, increased anterior facial height, negative overjet, and bilateral posterior crossbite is presented. Treatment options included mandibular first premolar or third molar extractions with dentoalveolar compensation or combined surgical-orthodontic treatment. Mandibular third molar extraction with dentoalveolar compensation was the treatment choice. Biofunctional brackets, with accentuated lingual crown torque on the maxillary incisors and accentuated buccal crown torque on the mandibular incisors, were used. The anterior crossbite was corrected with intermaxillary elastics from the palatal aspect of the maxillary incisors to the labial aspect of the mandibular incisors. Class III elastics moved the maxillary teeth mesially and assisted in retruding the mandibular teeth. Patient compliance with the elastics was excellent, and satisfactory dentofacial esthetics were achieved. This treatment protocol has rigorous indications, and it is not a routine plan. The mechanotherapy and the pros and cons of this approach are discussed.     

Craniofacial parameters of Syrian children with β‐thalassemia major

Abstract Aim: To investigate cephalometric craniofacial parameters (skeletal and dental) of β‐thalassemic‐major patients and to compare findings with a group of healthy patients in the same age group. Methods: Fifty‐one Syrian thalassemic‐major patients aged 8–12 years were recruited. Lateral cephalometric radiographs were taken. Linear and angular cephalometric measurements were recorded and compared with Syrian controls (n = 50) in the same age group. Results: Thalassemic patients, when compared with controls, showed significant retrognathia in the mandible (reduced sella [mid‐point of sella turcica]–nasion [most anterior point on the frontonasal suture] B‐point [deepest point on the concavity of the mandibular profile between the alveolar crest and the point of the chin] angle, and decreased sella–nasion–pogonion [most anterior point on the bony chin] angle, P < 0.0001), a significant decrease in ramus height (articulare–gonian = 36.51 ± 3.87 mm, P < 0.0001). They also exhibited a significant class II skeletal pattern (P < 0.0001) and a convex facial profile as the nasion A‐point (deepest point on maxillary profile between the anterior nasal spine and the alveolar crest) pogonion angle and maxillomandibular A‐point–nasion P‐point angle increased. They also showed a highly‐significant decrease in the total posterior facial height (sella gonion [most posterior, inferior point on the angle of the mandible] = 64.24 ± 5.73 mm, P < 0.0001) and significant increase in the total anterior facial height (N–Me = 110.78 ± 6.66 mm, P = 0.009) when compared to controls. Conclusion: Thalassemic patients exhibited a skeletal class II malocclusion, retrognathia of the mandible, a short height of the ramus, an increase in anterior facial height, and a decrease in posterior facial height.     

前牙覆(牙合)相关因素的研究

目的 :探讨不同类型错牙合畸形中与前牙覆牙合相关的多种因素。方法 :恒牙期错牙合 14 4例 ,其中 ,I类骨骼型 74例 ,II类 70例。在自然头位下摄取头颅定位侧位片。以覆牙合值为因变量 ,分析前牙覆牙合与其他头影测量参数的相关关系 ,并建立以覆牙合值为因变量的多元回归方程。结果 :I类骨骼型组多元回归分析显示 ,前牙覆盖、后面高及上切牙高度值越大 ,或下面高及下磨牙高度距离值越小 ,前牙覆牙合越深 ;在II类骨骼型组 ,前牙覆盖、上下切牙角及下切牙倾斜度值越大 ,或下颌角及上磨牙高度值越小 ,前牙覆牙合越深。 2个方程分别能解释 75 .8%和 62 .3 %的前牙覆牙合值的变化。其中 ,前牙覆盖值对前牙覆牙合最具影响。结论 :与前牙覆牙合相关的X头影测量参数包括牙性的和骨性的 ,这些参数相互补偿 ,其中 ,前牙覆盖值对维持正常且稳定的前牙覆牙合起着最重要的作用。     

Surgical versus orthodontic correction of skeletal Class II malocclusion in adolescents: effects and indications.

To clarify the effects of orthodontic versus surgical treatment and to distinguish more clearly those Class II patients who can be treated successfully with orthodontics alone, we compared three groups of adolescents: forty patients treated successfully with orthognathic surgery, 40 patients treated successfully with orthodontics alone, and 21 patients whose orthodontic treatment was judged to be unsuccessful. Successful surgical treatment was accomplished largely by bringing the mandible forward, but this involved vertically repositioning the maxilla, alone or in combination with advancing the mandible, in 40% of the patients. Successful orthodontic treatment resulted from a combination of retraction of the maxillary incisors and protraction of the mandibular incisors; most of the successfully treated group also had significant vertical growth, and 40% had greater than 2 mm anteroposterior growth. The unsuccessfully treated orthodontic patients initially had greater overjet, more severe mandibular deficiency, and greater anterior facial height than those treated successfully; they also had less retraction of the maxillary incisors and less growth during treatment. In Class II adolescents beyond the growth spurt, surgery is likely to be needed for successful correction of the malocclusion if the overjet is greater than 10 mm, especially if the distance from pogonion to nasion perpendicular is 18 mm or more, mandibular body length is less than 70 mm, or facial height is greater than 125 mm.     

Craniofacial growth in untreated skeletal Class II subjects: A longitudinal study

Eighty-five (45 male and 40 female) skeletal Class II untreated subjects with low (< 27 degrees ), average (27 degrees - 36 degrees ), and high (> 36 degrees ) mandibular plane angles (MP-SN) were selected from the Bolton-Brush and the Burlington Growth Studies. Cephalograms of each subject at ages 9 and 18 were traced, and 28 parameters were measured. The difference in each parameter from ages 9 to 18 was calculated, and comparisons were made between the groups with low, average, and high angles. Results showed that for children at age 9, the high-angle group showed greater convexity, larger Y-axis and gonial angles, and greater anterior facial height, and the low-angle group had larger SNA and SNB angles, and greater posterior cranial base, mandibular body, ramus height, and posterior facial height. From ages 9 to 18, all the low-, average-, and high-angle groups showed a decrease of convexity (more flattened face) and a mandibular forward rotation (decreased MP-SN). The low-angle group displayed significantly more facial flattening and more mandibular forward rotation than did the high-angle group. Moreover, the mandibular incisors became more retroclined in the low-angle group and more proclined in the high-angle group with age. Comparisons between males and females showed similar skeletal growth patterns in angular measurements. However, a significant sex difference was noted in some linear measurements.     

The effect of chin cup therapy on the growth and development of the cranial base and midface

The purpose of this study was to determine how the growth rates of certain cranial base and midfacial points and dimensions were affected by force application to the mandible by the chin cup. Control and treated samples consisting of Japanese girls with skeletal Class III relationships were analyzed. Each sample consisted of lateral cephalometric radiographs taken annually (control group) or semiannually (treated group) from early childhood through adolescence. The control sample was composed of seven persons and the treated sample of ten persons. The subjects of the treated sample were required to wear a chin cup a minimum of 12 hours per day. The total force delivered was 500 g, 250 g per side, and the direction of force was, on average, through the condyle. No other appliances were used. The results of this study indicate that the chin cup causes a closing of the cranial flexure angle N-S-Ba, inhibits posterior growth of the point basion, and imposes a vertical growth tendency on the points nasion and sella. The chin cup significantly inhibits anterior and posterior vertical maxillary growth and growth of upper anterior facial height. Because development of vertical posterior facial height is inhibited more than anterior facial height, a clockwise rotation of the maxilla occurs. The chin cup also causes flaring and a decrease in eruption rate of the maxillary incisors. It has no effect on the eruption rate of the maxillary molars, but accelerates their rate of mesial movement as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)