Effects of treatment with a combined maxillary protraction and chincap appliance in skeletal Class III patients with different vertical skeletal morphologies

Several cephalometric studies and case reports have described the effects of treatment with a maxillary protraction appliance (MPA) and chincap appliance. The purpose of this investigation was to identify differences in the response to treatment with a combined MPA and chincap in skeletal Class III patients with different vertical skeletal morphologies: short- (low mandibular plane angle) and long- (high mandibular plane angle) face types. The cephalograms used in this study were of 42 Japanese girls at the beginning of treatment (T0, mean age 10.1 years) and at removal of the appliance (T1, mean age 11.5 years). The subjects were divided into two groups (short and long face) according to the inclination of the mandibular plane at T0. Total anterior face height, upper and lower face height, occlusal plane, and gonial angle were significantly larger in the long-face group at T0. In both groups, significant increases in SNA, maxillary size (A'-Ptm'), and ANB were noted during treatment. Compared with the long-face group, the short-face group showed greater forward displacement and size increment of the maxillary body, while there were no significant differences in changes in mandibular size or position between the two groups. These results indicate that the vertical dimensions of the craniofacial skeleton are important factors in the orthopaedic effects of a MPA and chincap and the prognosis for skeletal Class III patients.     

236例不同骨性畸形磨牙颊舌向角度关系的研究

目的 评估不同骨性畸形患者磨牙的颊舌向角度关系,旨在为预置矫治器的选择、治疗计划的制定及并发症的预防提供理论依据及临床参考。方法 选取2016—2017年南京医科大学附属口腔医院正畸科就诊的236例患者(男88例,女148例)的锥形束CT资料进行测量分析,评估第一磨牙的颊舌向角度在不同矢状向及垂直向骨性畸形中有无差异。结果 矢状向骨性畸形中,骨性Ⅲ类患者的上颌第一磨牙颊舌向角度较骨性Ⅰ类、Ⅱ类患者的更大,骨性Ⅱ类患者的下颌第一磨牙颊舌向角度较骨性Ⅰ类、Ⅲ类患者的更大,差异有统计学意义。不同垂直骨面型患者的角度差异也较大,高角患者的上颌第一磨牙颊舌向角度较均角、低角患者的更大,但下颌第一磨牙的颊舌向角度较其他两组更小,差异显著。ANB角度的大小与上颌磨牙的颊倾度呈负相关,而与下颌磨牙的颊倾度呈正相关。结论 随着矢状向骨性畸形的差异增大,骨性Ⅱ类患者上颌磨牙有舌侧倾斜的趋势,下颌磨牙有颊侧倾斜的趋势,骨性Ⅲ类患者相反,这一定程度上代偿了骨骼畸形的横向不调。在治疗不同骨性错牙合时,应考虑这些因素以避免临床并发症的发生。     

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.     

A cephalometric comparison of black open-bite subjects and black normals

Orthodontic surveys of the adolescent and adult population of the United States have shown that the incidence of anterior open bite is three to four times higher in blacks than in whites. A cephalometric comparison of black subjects with and without an open bite was used to identify skeletal and dental differences between the two groups. Statistically significant differences were found in the vertical skeletal dimensions and incisor proclination. The open-bite group had a significantly longer anterior lower facial height and total facial height. The mandibular plane was rotated down relative to the cranial base and Frankfort plane and gonial angle was increased in the open-bite sample. There were small differences between the open bite and non-open-bite groups in the cranial base angle and the overbite depth indicator of Kim. No significant differences were found in the skeletal anteroposterior dimensions or dental vertical development. The vertical skeletal pattern and the greater degree of dental proclination differentiated black patients with an anterior open bite from those without.     

Prediction of post-treatment outcome after combined treatment with maxillary protraction and chincap appliances

The aims of this study were to identify differences in the initial skeletal morphology between successful and unsuccessful groups and to establish a novel method for predicting the final outcome of treatment with a maxillary protraction appliance (MPA) and chincap. The cephalograms used in this study were taken from 32 Japanese girls (mean age 10.2 years) with a Class III malocclusion at the beginning of treatment with an MPA and chincap (T1), at removal of the appliance (T2), and during the final post-treatment period (T3). The subjects were divided into two groups according to the treatment outcome at T3. Lower face height (ANS-Me), total face height (N-Me), ratio of face height (ANS-Me/N-ANS), maxillary position, mandibular plane and gonial angle at T1 were all significantly larger in the unsuccessful group, compared with the successful group. Discriminant analysis indicated that lower face height and gonial angle were significant determinants for distinguishing between the two groups at T1. From T1 to T2, while the anterior displacement of the maxilla was almost the same in the two groups, SNB decreased by 1.6 degrees in the successful group and 0.4 degrees in the unsuccessful group. After orthopaedic treatment, a second phase of treatment with a multibracket system was performed (T2 to T3). From T2 to T3, SNA increased by 0.4 degrees in the successful group and decreased by 0.7 degrees in the unsuccessful group. These results indicate that the vertical dimensions of the craniofacial skeleton are important for predicting the prognosis of skeletal Class III patients treated with a MPA and chincap and that the discriminant formula established in this study is effective in predicting the final treatment outcome.     

Long-term effect of the chincap on hard and soft tissues.

The short- and long-term effects of the chincap used in combination with a removable appliance to procline upper incisors were analysed cephalometrically in 23 patients with Class III malocclusions. The overall changes were compared with growth changes in a closely matched control sample of untreated Class III patients. There was no evidence that the chincap retarded growth of the mandible. During treatment, there was an increase in mandibular length and facial height. The lower incisors retroclined and the upper incisors proclined. The incisor relationship was corrected. Soft tissue changes included an increase in nasolabial angle and improvement in soft-tissue profile, including the nose. Skeletal post-treatment changes included further mandibular growth associated with an increase in angle SNB and Wits measurement. Facial height also increased significantly. The Class I overjet was maintained, although slightly diminished. The soft tissue nose, upper and lower lip, and chin moved anteriorly, and the nasal tip and chin moved inferiorly. At the end of the study period there were no significant skeletal or soft tissue differences between the treated and control groups. The only significant contrasts were in the overjet and the overbite. Chincap therapy combined with an upper removable appliance to procline the upper incisors is effective in producing long-term correction of the incisor relationship by retroclination of lower incisors, proclination of upper incisors, and redirection of mandibular growth in a downward direction. The direction of growth at the chin is maintained subsequent to treatment, as are the changes in incisor inclination, although in diminished form. There are corresponding improvements in the soft tissue profile.     

Comparison of the effects of monoblock and twin-block appliances on the skeletal and dentoalveolar structures.

Functional appliances, which are used in the early treatment period of skeletal Class II malocclusions, induce the forward displacement of the mandible by altering the postural activity of the muscles and causing some changes in both skeletal and dentoalveolar structures. The purpose of this investigation was to evaluate the differences between monoblock and twin-block appliances. Two treatment groups composed of 26 growing patients with skeletal and dental Class II, Division 1, malocclusions, were compared to an untreated control group of 13 patients with the same morphologic characteristics and growth rate. These groups were matched according to their age, sex, and vertical and sagittal skeletal cephalometric and dental characteristics. Monoblock was worn by the subjects for 16 hours/day, whereas twin-block was worn 24 hours/day, even while eating. Patients of the control group were followed without any intervention. Treatment effects were identified with a conventional cephalometric analysis. The findings of this study revealed that by using these different functional appliances, the stimulation of the growth of the lower jaw and the correction of Angle Class II relationship were achieved. In the twin-block group, the mandibular plane angle and gonial angle increased, although a decrease in the degree of overbite occurred. In the monoblock group, upper incisors demonstrated a greater degree of retrusion. However, within the twin-block group, the lower incisors showed a greater degree of proclination.     

Cephalometric evaluation of patients with anterior open-bite

Cephalometric evaluations of the skeletal pattern of 30 patients with anterior open-bite malocclusion were compared to those of 30 individuals with a normal overbite. The posterior/anterior face height ratio (PFH/AFH) was the only skeletal characteristic statistically different in the two groups. The other cephalometric measurements were not found to be statistically different in the malocclusion and normal overbite groups (SN-GoGn, SN-PP, gonial angle, LFH/AFH ratio), indicating that there is no skeletal origin in the group with anterior open-bite in this study.     

Early treatment of vertical skeletal dysplasia: the hyperdivergent phenotype.

This cephalometric study evaluated an early nonextraction treatment approach for patients with severe vertical skeletal dysplasia and maxillary transverse constriction. Thirty-eight patients, 8.2 years (+/- 1.2 years) of age, were treated for 1.3 years (+/- 0.3 years) with lip seal exercises, a bonded palatal expander appliance, and a banded lower Crozat/lip bumper. The bonded palatal expander functioned as a posterior bite-block and was fixed in place throughout treatment. Patients with poor masticatory muscle force (79%) wore a high-pull chincup 12 to 14 hours per day. A control group was matched for age, sex, and mandibular plane angle. Treatment changes for chincup and other patients were not significantly different. Overall, treatment significantly enhanced condylar growth, altered it to a more anterosuperior direction, and produced "true" forward mandibular rotation 2.7 times greater than control values. Posterior facial height increased significantly more in patients than in controls, and the maxillary molars showed relative intrusion. In treated patients, articular angle increased, gonial angle decreased, and the chin moved anteriorly twice as much as in controls. Treatment also led to increased overbite and decreased overjet. Maxillary and mandibular expansion did not cause the mandibular plane angle to increase. The 16 patients with openbite malocclusions exhibited a 2.7 mm increase in overbite and inhibition of growth in anterior lower facial height. The aggregate of individual changes demonstrates a net improvement, indicating this treatment approach may be suited for hyperdivergent patients with skeletal discrepancies in all 3 planes of space.     

The relationship between mandibular morphology and apical root curvature in man

Two samples of individuals, a low-angle group and a high-angle group, were selected on the basis of the inclination of the lower border of their mandible, defined by the mandibular plane angle (ML/SNL) in profile radiographs. Apical root curvature of mandibular first and second premolars and molars on panoramic radiographs was compared between the two groups and related to mandibular morphology. In the low-angle group most teeth had more distally curved roots than in the high-angle group. Significant differences were found for the first premolars on both sides (p less than 0.001, p less than 0.05), the right second premolars (p less than 0.05) and the distal root of left first molars (p less than 0.05). Correlations were calculated between root curvature and two variables reflecting mandibular morphology, the mandibular plane angle and the gonial angle. The strongest associations were found between the first premolar roots and the gonial angle (rs = -0.75, p less than 0.001 and rs = -0.56, p less than 0.01, for right and left sides respectively). The association between mandibular morphology and root curvature is probably indirect, caused by tooth migration during root formation.     

Long-term effects of chincap therapy on skeletal profile in mandibular prognathism

The purpose of this study was to investigate the long-term changes in the skeletal Class III profile subsequent to chincap therapy. The sample consisted of 63 Japanese girls who had skeletal Class III malocclusions before treatment. All underwent chincap therapy from the beginning of treatment. The duration of chincap therapy varied but averaged 4 1/2 years. The samples were divided into the following three groups according to their ages when chincap therapy was started: A group that started at 7 years of age (n = 23), a group that started at 9 years of age (n = 20), and one that started at 11 years of age (n = 20). The data were derived from lateral cephalometric head films, taken serially at the ages of 7, 9, 11, 14, and 17 years. Skeletal facial diagrams were constructed by X-Y coordinates of representative cephalometric landmarks. The data were analyzed statistically. The results of the present study were as follows: (1) The mandible showed no forward growth during the initial stages of chincap treatment in all three groups. (2) Patients who had entered treatment at 7 and 9 years of age appeared to show a catch-up manner of mandibular displacement in a forward and downward direction before growth was completed. (3) There was no statistical difference in the final skeletal profile between the group that had entered treatment at age 7 and the one that had entered at age 11. In conclusion, the skeletal profile was greatly improved during the initial stages of chincap therapy, but such changes were often not maintained thereafter. This finding indicated that chincap therapy did not necessarily guarantee positive correction of skeletal profile after complete growth.     

Orthodontic treatment of openbite and deepbite high-angle malocclusions.

The aim of the investigation was to assess the effect of orthodontic treatment on dentoskeletal morphology in children with openbite and deepbite high-angle malocclusion. Subjects (n = 54) in the mixed dentition with a hyperdivergent mandibular plane angle (high-angle, NSL/ML > or =40 degrees) were surveyed. Pre- and posttreatment lateral roentgenographic cephalograms were analyzed. Subjects were divided into three subgroups according to the amount of pretreatment overbite: < 0 mm = insufficient/no compensation (openbite); 0-4 mm = acceptable compensation (normal overbite); >4 mm = overcompensation (deepbite). Pretreatment, 20% of the high-angle cases exhibited insufficient dentoskeletal compensation (overbite <0 mm), and 35% displayed overcompensation (overbite >4 mm). Influences of habits such as lip sucking and tongue-thrust swallowing were more common in the openbite group. No major difference in treatment approach could be found between subgroups. In 82% of the openbite group and 90% of the deepbite group, overbite was corrected by orthodontic treatment. The mandibular plane angle was unaffected in both groups. The mechanisms of overbite correction differed between groups. The openbite group exhibited a significant decrease in interjaw-base angle. Increases in anterior and posterior dentoalveolar heights were comparable. The deepbite group showed no significant changes in skeletal morphology. The increase in dentoalveolar height was approximately twice as large posteriorly as anteriorly. The majority of children (80%) with high-angle morphology had a positive pretreatment overbite, thus exhibiting compensation of jaw-base hyperdivergency. Orthodontic treatment of high-angle malocclusions did not influence the mandibular plane angle in openbite or deepbite cases. Overbite correction was accomplished by tipping the maxilla downward anteriorly in openbite subjects, and by controlling incisor eruption in deepbite subjects.     

成人Ⅱ~1类错垂直骨面型特征的头影测量分析

目的:利用头影测量分析成人安氏Ⅱ1类错颅面结构的垂直向特征。方法:选取福建籍安氏Ⅱ1类错成人患者100例,男46例(高角12例,均角14例,低角20例),女54例(高角16例,均角24例,低角14例)。拍摄头颅定位侧位片,导入Winceph软件进行测量。结果:①高角组后颅底长较均角、低角组缩短。低角组颅底相对逆时针旋转,高角组相对顺时针旋转。②随下颌平面角的增大,下颌垂直向发育大于水平向发育。低角组腭平面呈逆时针旋转。③上面高占前面高比例三组间无差异。④随着下颌平面角减小,上下前牙牙槽高度逐渐减低。上下颌磨牙段牙槽骨高度三组间无差异。三组间平面倾斜度不同,高角组顺时针旋转,低角组逆时针旋转。结论:安氏Ⅱ1类错机制复杂,表现出复杂的形态学差异。不同下颌平面角组之间有不同的垂直向特征表现。     

Morphological evaluations in skeletal Class III malocclusion requiring maxillofacial surgery using orthognathic surgical analysis

The purpose of this study was to establish a Japanese standard norm for orthognathic surgical analysis to be used in clinical applications and to clarify maxillofacial morphological characteristics in skeletal Class III malocclusions requiring orthognathic surgery. The materials were pretreatment lateral cephalometric radiographs in the relaxed lip posture from 50 subjects with skeletal Class III malocclusions diagnosed as requiring orthognathic surgery. The control group consisted of 50 subjects with normal occlusion and well-balanced faces. Detailed cephalometric measurements were recorded and analyzed statistically. The skeletal, dental, and soft tissue measurements from the normal group did not reveal any marked differences between the sexes. The Class III group exhibited a more retrognathic maxilla and prognathic mandible, a steeper mandibular plane, a more prominent chin, and a larger lower facial height in the skeletal measurements; a significant lingual inclination of the mandibular incisor in the dental measurement; and a more concave profile with prognathic mandible, a larger lower facial height, a more acute nasolabial angle and chin in the soft tissue measurements. We suggest that this analysis can be clinically useful in diagnosis, treatment planning, and posttreatment evaluation for orthognathic surgical cases who are Class III patients.     

An analysis of complete and incomplete overbite in class II division 1 malocclusions (an analysis of overbite incompleteness)

A retrospective cephalometric study of Class II Division 1 malocclusions was carried out. Sixty patients with complete overbites were compared with another group of 60 matched in every respect, with the exception of having incomplete overbites. All patients were in the permanent dentition stage and aged between 10 and 14 years. An incomplete overbite was related to vertical variation in the skeletal pattern. This was demonstrated by greater anterior lower facial height, greater gonial angle, and steeper mandibular plane inclination. Incisor alveolar heights and molar heights did not vary between the groups. No differences between groups were noted for the degree of overjet reduction achieved during treatment, or in post retention relapse of overbite and overjet.     

Craniofacial growth in untreated skeletal Class I subjects with low, average, and high MP-SN angles: A longitudinal study

Sixty-eight (36 male and 32 female) untreated skeletal Class I subjects with low (< or = 27 degrees ), average (>27 degrees - <37 degrees ), and high (> or = 37 degrees ) mandibular plane (MP-SN) angles were selected from the Bolton-Brush and 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 boys and girls at age 9, the low-angle groups exhibited significantly larger SNA angle, SNB angle, facial taper, PFH, PFH:AFH, and ramus height, and the high-angle groups showed significantly larger ANS-Me and gonial angle. From ages 9 to 18, all the male and female low-, average-, and high-angle groups showed an increase in SNA and SNB angles, and PFH:AFH, and a decrease in ANB angle, convexity (more flattened face), MP-SN angle, and gonial angle (mandibular forward rotation). The dental measurements showed few changes with growth in all groups. In terms of skeletal measurements from ages 9 to 18, similar growth changes were found between the sexes in most angular measurements, but males had larger values in linear measurements than females.     

Skeletal and dental effects of serial extractions performed with or without maxillary expansion—A retrospective controlled study

Objectives

The study aimed to compare severe crowding treatment's skeletal and dental effects by serial extractions or maxillary expansion and serial extractions in the mixed dentition phase.

Setting and Sample Population

The retrospective controlled study included lateral cephalograms of 78 subjects aged 8.5 ± 1.4 years, 52 consecutively treated because of severe crowding, and 26 untreated controls matched for baseline age and observational period.

Methods

Subjects were clustered according to the treatment modality, either serial extraction (EX) or expansion and extraction (EXP-EX) group. Sagittal and vertical skeletal as well as dental cephalometric parameters were assessed at baseline and after the eruption of all permanent posterior teeth, and group comparisons were performed.

Results

Both treatment modalities significantly affected the vertical skeletal parameters in terms of decreasing the mandibular and occlusal plane inclination and increasing the facial height index. A distinct treatment effect on the gonial angle was observed, with a significant decrease in its superior part observed in both extraction groups. The annualized changes in the superior part of the gonial angle significantly differ (P = .036) between the Control (−0.04 ± 0.6), EX (−0.44 ± 0.6) and EXP-EX (−0.34 ± 0.5) groups. Upper and lower incisor inclination did not change significantly in any of the groups; however, the interincisal angle at follow-up was significantly smaller in the Control compared with both treated groups.

Conclusions

Serial extractions and a combination of maxillary expansion and serial extractions have similar significant skeletal effects, mainly affecting vertical cephalometric parameters if performed during the pre-pubertal growth phase.     

Relationship between thoracic, lordotic, and pelvic inclination and craniofacial morphology in adults

OBJECTIVE: To analyze the correlation ratios between the spinal posture (thoracic, lordotic, and pelvic inclination) and the craniofacial morphology. MATERIALS AND METHODS: The sample consisted of 53 healthy adults (32 women, 21 men; mean age 24.6 years). Six angular skeletal measurements (facial axis, mandibular plane angle, inner gonial angle, lower facial height, facial depth, and maxilla position) were determined based on the analysis of lateral head cephalographs. Rasterstereography was used for a precise reconstruction of the back sagittal profile. From the profile parameters, the upper thoracic inclination, the thoracic angle, the lordotic angle, and the pelvic inclination were determined. The correlations to the craniofacial morphology were calculated by means of the Pearson and Mann-Whitney U-test. RESULTS: Significant correlations could be obtained with respect to the facial axis and the lordotic angle, the facial axis and the pelvic inclination, the inner gonial angle and the lordotic angle, the inner gonial angle and the pelvic inclination, the mandibular plane angle and the lordotic angle, the mandibular plane angle and the pelvic inclination, as well as the facial depth and the pelvic inclination. CONCLUSIONS: In the case of postural disorders of the back shape, an interdisciplinary treatment approach seems to be of clinical value. Further prospective studies are necessary to prove how changes in craniofacial parameters can affect the postural balance of an individual.     

骨性Ⅱ类错牙合女性患者上颌磨牙近远中倾斜度的CBCT分析

目的:分析骨性Ⅱ类错牙合女性患者上颌磨牙近远中倾斜情况,以期为临床治疗提供参考。方法:选取骨性Ⅱ类错牙合30例及个别正常牙合10例治疗前CBCT数据,以眼耳平面、腭平面及牙合平面测量上颌磨牙倾斜度,并将患者测量项目与个别正常牙合数据进行单样本t检验。将骨性Ⅱ类高角、均角和低角间进行单因素方差分析,并把不同垂直骨面型间的测量项目与下颌平面角及牙合平面角进行Pearson相关性分析。结果:在FH平面、腭平面及牙合平面为参考平面时,骨性Ⅱ类U6较个别正常牙合更加远中倾斜。以腭平面及FH平面为参考时,骨性Ⅱ类低角组到高角组,U6有远中倾斜趋势。以牙合平面为参考时,U7在高角组到低角组有远中倾斜趋势。结论:为代偿上下颌骨矢状向关系不调,骨性Ⅱ类错牙合U6有远中倾斜。骨性Ⅱ类U6随下颌平面角的增加代偿性远中倾斜,但U7远中倾斜趋势不明显。无论何种骨性Ⅱ垂直骨面型,U6代偿性倾斜移动以维持咬合力沿牙齿长轴传递。     

Protraction of the maxillofacial complex

The purpose of this study was to evaluate the orthopedic effects of reverse headgear therapy in children with skeletal Class III malocclusions. Data based on pretreatment and posttreatment lateral cephalometric radiographs of seven boys and five girls, ages 4 through 14 years, were used. Comparison of the pretreatment and posttreatment cephalograms revealed a significant (p less than 0.05) increase in the SNA angle that indicated the maxilla was positioned farther forward after reverse headgear therapy. Both the maxillary and the mandibular effective lengths increased significantly from pretreatment to posttreatment, as did anterior and posterior total face height. These linear increases are most likely a reflection of growth rather than a direct result of the therapy. There was no significant change in the anteroposterior position of the mandible, although there was a tendency for the mandibular plane angle and the gonial angle to decrease. The results of this study indicate that maxillary protraction with a reverse headgear should be considered an alternative to orthognathic surgery in the treatment of children and adolescents with skeletal Class III malocclusion characterized by maxillary retrognathism.