Effect of Le Fort III osteotomy on mandibular growth in patients with Crouzon and Apert syndromes

Midface advancement by Le Fort III osteotomy is a common procedure in craniofacial surgery. However, little data exist concerning the effect of midface advancement on mandibular growth. This is a retrospective study of 38 patients from two craniofacial centers who had Le Fort III osteotomy. The aims of this investigation were to document the size and shape of the mandible in Crouzon and Apert syndromes and to determine the effect on these parameters of downward and forward movement of the midface. The syndrome patients had increased gonial angle, increased MP-SN, increased ramus height, and increased ratio of ramus height to body length when compared with normal standards. Patients operated during growth and those operated when growth was completed had similar mandibular size and shape indicating that Le Fort III osteotomy had no measurable effect on these parameters. Inclination of the mandible to the anterior cranial base was increased by the operation and remained unchanged during the follow-up period. The results of this study indicate that the size and morphology of the mandible are similar in Crouzon and Apert syndromes. The pattern of growth is more vertical in the syndrome patients than in normals. Le Fort III osteotomy in growing children does not result in altered mandibular size and shape despite backward rotation of the mandible as a result of midface advancement.     

Is the mandible intrinsically different in Apert and Crouzon syndromes?

Relative mandibular prognathism is an observed finding in Apert and Crouzon syndromes. This imbalance in the facial profile is generally attributed to the diminished growth of the maxilla, thereby increasing the disparity between maxilla and mandible with increasing age. What is not known is whether the mandible is, indeed, normal. Previous work by Kreiborg with Crouzon syndrome led to the conclusion that the mandible, although somewhat smaller, grew in a "normal" pattern. Our own observations, which used a greater variety of mandibular measurements on patients with both Apert and Crouzon syndromes, corroborated Kreiborg 's conclusions but go further to suggest a syndrome-specific mandibular malformation. Ramal height was found equal to the norm and sometimes greater. Mandibular body length was significantly shorter, thereby producing a distinctly different ramus/body length ratio, particularly in older patients. These findings become significant in the planning of reconstructive procedures. They also raise the question as to whether the shape of the mandible is genetic in origin or is an adaptation to the increasing derangements of the cranial base, maxilla, and occlusion observed with maturation in these patients. The possibility of interactive genetic and environmental factors affecting growth of the mandible emerges from the data.     

Papilledema in patients with Apert, Crouzon, and Pfeiffer syndrome: prevalence, efficacy of treatment, and risk factors

Patients with syndromic craniosynostosis are at risk for elevated intracranial pressure because of various physiologic and anatomic abnormalities. The aims of this study were to determine the prevalence of papilledema in syndromic craniosynostosis, to evaluate the results of the treatment, and to examine the risk factors.This is a retrospective study on 84 patients with Apert, Crouzon, or Pfeiffer syndrome. Papilledema was defined as blurring of the margins of the optic disk. The association between clinical symptoms, beaten-copper pattern on skull radiograph, ventricular dilatation on computed tomography scan, and papilledema was assessed.Papilledema was present in 51% of the patients. No relation between specific clinical symptoms and papilledema was found. The significant associations were complex craniosynostosis, exorbitism, and ventricular dilatation.The prevalence of papilledema in patients with Apert, Crouzon, or Pfeiffer syndrome is high, not only before cranial decompression but also after vault expansion. Annual fundoscopy is recommended to screen for papilledema. We consider that early decompressive surgery (within the first year of age) prevents the development of papilledema and, most likely, elevated intracranial pressure.     

A longitudinal study of dental arch morphology in children with the syndrome of Crouzon or Apert

The aim of this study was to compare changes in dental arch morphology between patients with Crouzon syndrome or Apert syndrome and controls. Children between 4 and 14 yr of age with Crouzon syndrome (n = 40) or Apert syndrome (n = 28) were compared with non‐syndromic controls (n = 457) in terms of arch widths, depths, and length dimensions. Multilevel statistical modeling techniques were used to evaluate changes over time. Dental arch dimensions were found to be smaller in patients with Crouzon syndrome or Apert syndrome compared with control subjects. Maxillary intercanine width for patients with Apert syndrome were increased, whilst other arch width variables showed no change. Patients with Crouzon syndrome showed increases in maxillary intercanine width, whilst intermolar width showed no change over time. Dental arch dimensions in syndromic patients were thus found to be consistently smaller than in control subjects between 4 and 14 yr of age, implying that patients with Crouzon syndrome and Apert syndrome had a diminished growth potential.     

Le Fort III external midface distraction: surgical outcomes and skeletal stability

A retrospective study on the stability of Le Fort III midface advancement with distraction in craniofacial dysostosis. Twenty-six surgical procedures for midface advancement were performed between 2000 and 2009. Subjects were 14 consecutive patients who underwent Le Fort III osteotomy with midface advancement using a rigid external distraction device (Synthes) in the Dep of Maxillo-Facial Surgery of the University "Sapienza" of Rome. In this study, 8 patients (n = 3 females, n = 5 males) affected by craniofacial dysostosis (Crouzon, n = 5; Apert, n = 3; Pfeiffer syndrome, n = 1; and other, n = 1) were selected on the basis of age and radiologic documentation. The mean age at the time of the procedure was 8.6 years, and all the patients had at least 1 year of follow-up after distraction.The radiologic documentation of each case was composed of posteroanterior and lateral cephalograms preoperatively (T1), at the time of removal of the distractor device (T2), and at follow-up (T3).The average latency period before activation of the distractor was 5 days. The device was activated on an average of 15 mm (range, 7-22 mm) as recorded on the device at a rate of 1 mm/d. Activation period ranged from 7 to 15 days, and the consolidation period was 8 to 12 weeks.Seven anatomic landmarks and 5 cephalometric measurements were identified on the lateral cephalograms at each of the 3 time periods. The cephalograms underwent digital analysis via Dolphin imaging digitalization software by 2 operators independently. The displacement of each identified landmark was recorded and examined in relation to their position at each time point.Cephalometric analysis revealed stability of Le Fort III midface advancement during follow-up. However, bone growth after midface advancement is limited, and as reported in the literature, almost no spontaneous growth is present because of the intrinsic nature of malformations. Patients treated in the growing age benefit from midface advancement, with resolution of exophthalmos, ocular bulb exposure, airway impairment, and good aesthetic outcome.     

Cephalometric analysis of craniofacial morphology and growth in unrepaired isolated cleft palate patients

ObjectiveThe aim of this study is to analyze the craniofacial morphology in patients with unrepaired isolated cleft palate (UICP) at childhood, adolescence and adulthood, in order to assess the influence of nonsurgical factors on the craniofacial growth in these patients.Material and methodsLateral and posteroanterior cephalograms of 106 non-syndromic UICP patients and 102 normal matched controls were obtained and analyzed. Patients and controls were divided into three subgroups: children (5–7 years), adolescents (12–14 years), and adults (>18 years).ResultsUICP patients in childhood showed a shortened cranial basal length; reduced bony nasopharyngeal height; short maxillary depth and height with a posterior positioned maxilla and an increased width of the nasal cavity, maxilla and orbit; and a shortened mandibular length and height. UICP patients in adulthood showed a normal nasopharyngeal and mandibular morphology. However, the patients in this subgroup still showed a shortened cranial basal length, and short maxillary depth and anterior height with increased width of the nasal cavity, maxilla and orbit.ConclusionsCraniofacial morphology and growth in patients with UICP were significantly affected by nonsurgical factors. Growth of the cranial base and upper face were absolutely reduced, while growth of the bony nasopharynx and mandible were only postponed.     

Craniofacial dysostosis syndromes: stages of reconstruction

The term "craniofacial dysostosis" is used in a general way to describe syndromal forms of craniosynostosis. These disorders are characterized by sutural involvement that not only includes the cranial vault but also extends into the skull base and midfacial skeletal structures. Craniofacial dysostosis syndromes have been described by Carpenter, Apert, Crouzon, Sathre-Chotzen, and Pfeiffer. Although the cranial vault and cranial base are believed to be the regions of primary involvement, there is also significant impact on midfacial growth and development. In addition to cranial vault dysmorphology, patients with these inherited conditions exhibit a characteristic "total midface" deficiency that is syndrome specific and must be addressed as part of the staged reconstructive approach.     

Evaluation of mandibular morphology in different facial types

The purpose of this study was to evaluate mandibular morphology in different facial types using various parameters. This study was conducted on lateral cephalograms of a total of 110 subjects, which included 55 males and 55 females between the age of 18-25 years having a mean of 22.3 years for males and 21.5 years for females. The sample was divided into normodivergent, hypodivergent, and hyperdivergent subgroups based on Jarabak's ratio. Symphysis height, depth, ratio (height/depth) and angle, antegonial notch depth, ramal height and width, mandibular depth, upper, lower, and total gonial angle, and mandibular arc angle were analyzed statistically and graphically. It was found that the mandible with the vertical growth pattern was associated with a symphysis with large height, small depth, large ratio, small angle, decreased ramus height and width, smaller mandibular depth, increased gonial angle, and decreased mandibular arc angle in contrast to mandible with a horizontal growth pattern. Sexual dichotomy was found with mean symphysis height and depth in the female sample being smaller than in the male sample, but symphysis ratio was larger in the female sample; males having greater ramus height and width, mandibular depth than females. The mandible seemed to have retained its infantile characteristics with all its processes underdeveloped in hyperdivergent group.     

Sagittal and Vertical Growth of the Jaws in Class II, Division 1 and Class II, Division 2 Malocclusions during Prepubertal and Pubertal Development

AIM: The aim of the present study was to evaluate the sagittal and vertical development of the jaws in Class II, Division 1 (II/1) and Class II, Division 2 (II/2) malocclusions. In addition, facial morphology was to be investigated in probands with these malocclusions. PROBANDS AND METHODS: Maxillary and mandibular development was investigated with reference to lateral cephalograms of orthodontically untreated probands from the Belfast Growth Study at 7, 9, 11, 13 and 15 years of age. Moreover, development of facial width was assessed from the associated posteroanterior cephalograms, with radiographic magnifications being corrected in both the lateral and the posteroanterior cephalograms. A Class II/1 group (n = 17) and a Class II/2 group (n = 12) were compared with two control groups: a group with good occlusion (n = 18) and a Class I group (n = 37). RESULTS AND CONCLUSIONS: With respect to the sagittal position of the maxilla, no significant differences between the Class II groups and the controls were found. In the Class II/1 group, mandibular retrognathism was observed. The posterior position of the mandible present at 15 years of age had been present even at 7 years of age, and growth increments in the Class I and Class II/1 subjects were similar. In the Class II/2 groups no uniform pattern with respect to mandibular position was found. With respect to vertical development, a deficit in lower anterior facial height was found in the Class II/2 groups. In addition, between 7 and 15 years of age, growth increments in lower anterior facial height were significantly smaller in the Class II/2 subjects than in the controls. Furthermore, the Class II/2 groups displayed a more euryprosopic facial form on average. The cause of this characteristic facial morphology was the vertical deficit in lower anterior facial height. Overall, however, the broad variability and the small sample sizes, in particular of the Class II/2 groups, in the present study have to be seen as limitations.     

Cranial base,maxillary and mandibular morphology in Down syndrome

Objective:To test the null hypothesis that there is no difference between craniofacial measurements of individuals with Down syndrome (DS) and normal controls.Materials and Methods:A cephalometric analysis including additional landmarks and measurements to study specific craniofacial features was undertaken on pretreatment cephalograms of 25 patients with DS (12 male, 13 female; mean age 15.1 years) treated at The Hospital for Sick Children, Toronto. Measurements were compared with those from cephalograms of racial groups age and gender matched, normal, Class I children, available from the Burlington Growth Center. Data were analyzed using paired t-tests.Results:Large reductions were measured in the size and spatial relationships of craniofacial structures in the DS group. The greatest differences included a larger cranial base angle; reduced elevation of sella from FHP; reduced anterior and posterior cranial base lengths; reduced anterior and posterior face heights; smaller maxilla with reduced anterior basal and apical dimensions; and smaller mandibular ramus, body and symphyseal dimensions and proclined symphysis. Maxillary incisors were severely proclined and undererupted, while mandibular incisors were undererupted. Alveolar heights were reduced. Anterior open bite was frequently noted. Maxillary and mandibular planes exhibited forward rotation patterns, promoting overclosure. Mandibular hypoplasia was less severe than cranial base and maxillary hypoplasia. Hypodontia of one or more permanent teeth was found in 92% of the sample.Conclusions:The null hypothesis was rejected. Significant hypoplasia in endochondral, mesodermal, and ectomesenchymal derived structures of the cranium and face in subjects with DS was clearly evident. More severe platybasia than previously reported was found.     

Factors of human skeletal craniofacial morphology.

Thirty cephalometric measurements representing craniofacial depth, height, and width were obtained from lateral and posterior rediographs of 66 boys, 8 years of age. A multivariate factor analysis was performed on these measurements in an effort to locate specific areas of variability within the craniofacial complex. Twelve uncorrelated factors were extracted which account for 91% of the total variance and these were identified as: 1) retrognathic facial type, 2) anterior dentoalveolar height, 3) maxillary body length, 4) cranial base and facial width, 5) mandibular ramus height, 6) anterior maxillary body height, 7) mandibular length, 8) cranial vault height, 9) vertical position of the condyles, 10) cranial vault and clivus length, 11) bigonial width, and 12) cranial vault width.     

The craniofacial complex in 45,X/46,XX females

Fourteen Finnish 45,X/46,XX females were compared with population female and male controls, and in addition, nine of them were compared with their first-degree female relatives. Linear and angular measurements were made from standardized lateral cephalograms of patients and normal population controls from the “Kvantti” study series. In both comparisons the results indicated that craniofacial dimensions in 45,X/46,XX females were smaller than those in population female and male controls. The general metric pattern was similar to that observed in relation to the tooth crowns of 45,X/46,XX females. Several of their craniofacial proportions and plane angles differed from those of normal women: shorter anterior and posterior cranial bases and a flatter cranial-base angle, a sagittally shorter maxilla and a sagittally shorter mandible with an enlarged ramus:corpus length ratio, posterior rotation of the mandible and a tendency to bimaxillary retrusion. It is suggested that the reduction of X-chromosomal genetic material in 45,X/46,XX females results in smaller craniofacial dimensions than in normal females, with substantial effects on dimensional ratios and especially plane angles of the cranial base.     

Longitudinal intermaxillary relationships in class III malocclusions with low and high mandibular plane angles

OBJECTIVE: To analyze the sagittal, vertical, and transverse relationships of the maxilla and mandible in Japanese girls with Class III malocclusions with different inclination of mandibular plane. MATERIALS AND METHODS: This longitudinal study utilized serial posteroanterior and lateral cephalograms of 56 untreated subjects from the age of 8 years until the age of 14 years (low mandibular plane angle group: n = 20; average mandibular plane angle group: n = 15; high mandibular plane angle group: n = 21). Sagittal and vertical growth was analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms. RESULTS: There was no significant difference in intermaxillary sagittal relationships among the three groups from age 8 until 14. On the other hand, there were significant changes in the vertical and transverse intermaxillary relationships during this period. When comparing the three groups at the same age, there were significant differences in vertical and transverse intermaxillary relationships in some ages, whereas no significant difference was found in sagittal relationships in any ages. CONCLUSIONS: The inclination of mandibular plane might play a role in anticipating changes in vertical and transverse intermaxillary relationships from 8 until 14 years of age.     

Transverse growth of the maxilla and mandible in untreated girls with low, average, and high MP-SN angles: A longitudinal study

INTRODUCTION: The purpose of this study was to investigate maxillary and mandibular transverse growth in untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18. METHODS: Eighty-one untreated white girls with low (< or = 27 degrees , n = 16), average (> 27 degrees to < 37 degrees , n = 41), and high (> or = 37 degrees , n = 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and Burlington Growth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6 to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements were converted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). RESULTS: At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, and this trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate of increase for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups. Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateau was reached for the high-angle group. For the low- and average-angle groups, mandibular growth continued from ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). CONCLUSIONS: Vertical facial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth of the maxilla and the mandible.     

Fronto-facial monobloc distraction in syndromic craniosynostosis. Three-dimensional evaluation of treatment outcome and facial growth

The objectives of this study were to investigate the treatment effect and stability of fronto-facial monobloc distraction osteogenesis. Five consecutive patients who underwent monobloc distraction were included (aged 4.8-18.4 years). Three patients had Crouzon syndrome, one had Apert syndrome, and one had Pfeiffer syndrome. The evaluation included clinical records, serial cephalograms for at least 1-year follow up (average 24.6 months). The treatment and post-treatment changes were measured. The intracranial volume, upper airway volume and globe protrusion were calculated from CT before and after treatment. After distraction, the supraorbital region was advanced 15.3mm forward, the midface demonstrated forward advancement of 17.7 mm, 22.1mm and 23.1mm at orbitale, anterior nasal spine and A point, respectively. The downward movement was 2-3mm at maxillary level. The intracranial volume increased 11%; the upper airway volume increased 85% on average. Globe protrusion reduced 3.7 mm on average, which was 20% of underlying skeletal movement. Facial growth demonstrated forward remodelling of the supraorbital region, mild downward but no further forward growth of the midface. Monobloc distraction is effective for relieving related symptoms and signs through differential external distraction at different vertical levels of the face.     

Dentocraniofacial morphology of 12 Japanese subjects with unilateral cleft lip and palate with a severe Class III malocclusion: a cephalometric study at the pretreatment stage of surgical orthodontic treatment.

OBJECTIVE: The present study clarifies the dentocraniofacial morphology of patients with cleft lip and palate (CLP) with severe Class III malocclusion prior to surgical orthodontic treatment. METHODS: The sample was 12 Japanese male subjects with repaired complete unilateral CLP (surgical CLP group; 21.2 +/- 1.92 years in mean age). Two sets of patients without CLP Class III malocclusion, consisting of 19 male subjects treated by surgical orthodontic treatment (surgical Class III group; 23.4 +/- 6.35 years in mean age) and 14 male subjects treated by nonsurgical orthodontic treatment (nonsurgical Class III group; 18.7 +/- 3.49 years in mean age) were used as controls. Analyses were performed using lateral and posteroanterior (P-A) cephalograms. RESULTS: (1) The surgical CLP group showed significantly smaller values for overjet, SNA angle, and inclination of the maxillary incisor as compared with those of the surgical and nonsurgical Class III controls. The values of SNB, mandibular effective length, and ramus height in the surgical CLP group were significantly smaller than those of the surgical Class III group but were similar to those of the nonsurgical Class III group. (2) The mandible and the upper and lower dental arches deviated laterally toward the cleft side. The displacement of the mandible was correlated with that of the maxilla. These results show that CLP patients who required surgical orthodontic treatment had a characteristic dentocraniofacial morphology, compared to controls without CLP with Class III malocclusion.     

A longitudinal three-dimensional evaluation of the growth pattern in hemifacial microsomia treated by mandibular distraction osteogenesis: a preliminary report

This study analyzed in three dimensions the longitudinal growth pattern of young patients with hemifacial microsomia (HFM) before and after mandibular distraction osteogenesis (DO). Six individuals with HFM (five boys and one girl; age at distraction, 12.5 +/- 2.4 years) were treated with similar procedures (surgery, type and direction of distraction, no functional orthodontic treatment before and after DO). Two individuals who did not undergo DO until late in their growth were used to compare growth patterns. In addition, one individual besides the six previously chosen sample in whom no DO was performed was also used to compare longitudinal growth patterns. Lateral and posteroanterior (PA) cephalograms were utilized preoperatively, spanning a period of 9 years. Computerized three-dimensional models were constructed from the lateral and PA cephalograms using a vector intercept algorithm. In the comparison group, for a period of 8 years on the affected side, the ramus height, body length, and total mandibular length increased at an average rate of 1.3, 1.9, and 3.0 mm per year respectively. On the unaffected side, the ramus height increased by 2.1 mm per year, 1.9 mm in the body, and 2.9 mm per year in total mandibular length. On average, the gonial angle on the affected side was increased by 1 deg per year, yet decreased by 1 deg per year on the unaffected side. The proportions between the affected to the unaffected side were maintained. In the six individuals 18 months after DO, it was found that the ramus height was reduced by 1.0 mm, whereas the body was found to resume its growth with a faster rate on the distracted side, maintaining its proportion. Angular changes demonstrated closing of the gonial angle on both the unaffected (0.5 deg) and distracted (3.5 deg) sides. Observed in three dimensions were the following: (1) On average, unoperated patients with isolated HFM tend to maintain their asymmetrical facial proportions and do not worsen substantially with time. (2) Different treatment effects were seen on the ramus, body, and total length of the mandible: changes in body length > ramus height > total length. (3) Eighteen months after DO, the correction was stable but with some degree of settling back from the initial overcorrection (< 5%). (4) Eighteen months after DO the mandibular body was found to have greater growth than the ramus. (5) Evaluating changes in three dimensions provides an improved understanding of the growth pattern and distraction effects on the mandible and its structural components. (6) Additional studies on the effect of mandibular distraction on other conditions involving mandibular deformities are required. In addition, the effect of various distractor devices should also be evaluated. Three-dimensional evaluation is recommended for improved accuracy.     

Maxillary growth following LeFort III advancement surgery in Crouzon, Apert, and Pfeiffer syndromes

This was a cephalometric study of maxillary growth following LeFort III osteotomy in children with Crouzon, Apert, and Pfeiffer (CAP) syndromes. Nineteen children who had undergone LeFort III advancement osteotomies were followed postoperatively for an average of 5.3 years. Data for horizontal and vertical maxillary growth increments were obtained and compared with data of a control group of unoperated CAP children and with normal data. The findings indicate that horizontal maxillary growth following surgical treatment is negligible (less than 0.1 mm/yr), and differs from unoperated CAP children (0.7 mm/yr) and normal children (1.3 mm/yr). Vertical maxillary growth following surgery is identical to that in unoperated CAP and normal children, amounting to 1.3 mm/yr. The LeFort III osteotomy during childhood is a justifiable procedure for physiologic and psychologic reasons. Horizontal maxillary growth, for all practical purposes, is eliminated by this procedure and a subsequent maxillary advancement is invariably required at the completion of growth.     

Effect of low-dose testosterone treatment on craniofacial growth in boys with delayed puberty.

Craniofacial growth was investigated in boys treated with low-dose testosterone for delayed puberty (> 14 years old; testicular volume < 4 ml; n = 7) and compared with controls (12-14 years; n = 37). Cephalometric radiographs, statural height and pubertal stage were recorded at the start of the study and after 1 year. Craniofacial growth was assessed by nine linear measurements. At the beginning of the study, statural height, mandibular ramus length, upper anterior face height, and total cranial base length were significantly shorter in the delayed puberty boys than in the controls. After 1 year, the growth rate of the statural height, total mandibular length, ramus length, and upper and total anterior face height was significantly higher in the treated boys than in the untreated height-matched controls (n = 7). The craniofacial measurements were similar in the treated boys as compared with the controls. These results show that statural height and craniofacial dimensions are low in boys with delayed puberty. Low doses of testosterone accelerate statural and craniofacial growth, particularly in the delayed components, thus leading towards a normalization of facial dimensions.     

成人下颌孔的位置及下颌切迹和下颌支的测量

目的 通过对上海地区成人下颌骨的测量与分析，确定下颌孔的基本位置，并对下颌切迹的宽度、深度和下颌支的高度进行精确测量，旨在为临床提供解剖学参考。方法 取上海地区成人下颌骨，男74例，女79例，以下颌孔最大横径和最大纵径交点为下颌孔中心，测量其至下颌支后缘最近点的水平距离及下颌切迹最凹处的垂直距离，从而确定下颌孔的位置；以下颌切迹最宽处的距离测出下颌切迹的宽度，以下颌切迹最低点至喙突和髁突顶点连线的垂直距离测出下颌切迹的深度；同时测出髁突最高点至下颌角点的直线距离，作为下颌支的高度。结果 下颌孔至下颌后缘和下颌切迹的距离在成年男性平均为16．75mm、24．50mm；成年女性平均为：16．08mm、23．13mm。下颌切迹的宽度和深度在成年男性平均为34．20mm、15．33mm；成年女性平均为32．69mm、14．49mm。下颌支的高度男女平均为：61．62mm、57．19mm。结论 (1)下颌孔至下颌后缘的距离与下颌孔至下颌切迹最凹点的距离在男女间无明显差异。(2)下颌切迹的宽度与深度在男女间无明显差异。(3)下颌支的高度在男女间亦无明显差异。