Mandibular Ramus Height Research Articles

Unilateral bimaxillary vertical elongation by maxillary distraction osteogenesis and mandibular sagittal split ramus osteotomy: a case report

Maxillary canting and vertical shortening of the unilateral mandibular ramus height is common in cases of severe facial asymmetry. Normally, mandibular distraction osteogenesis (DO) with horizontal osteotomy at the ascending ramus is used for vertical lengthening of the mandibular ramus to correct facial asymmetry with an absolute shortened ascending ramus. In this case report, vertical lengthening of the ascending ramus was performed successfully with unilateral DO and sagittal split ramus osteotomy (SSRO), where the posterior part of the distal segment can be distracted simultaneously in an inferior direction with maxillary DO, resulting in a lengthening of the medial pterygoid muscle. This case describes the acquired unilateral mandibular hypoplasia caused by a condylar fracture at an early age, which resulted in abnormal mandibular development that ultimately caused severe facial trismus. The treatment of this case included two-stage surgery consisting of bimaxillary distraction osteogenesis for gradual lengthening of the unilateral facial height followed by secondary orthognathic surgery to correct the transverse asymmetry. At the one year follow-up after SSRO, the vertical length was maintained without complications.

Editor's Comment and Q&A: Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

Introduction The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Methods Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Results Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. Conclusions The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors. The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

Prevalence of mandibular asymmetries in growing patients

The aim of the present study was to determine the prevalence of mandibular asymmetries during the mixed dentition in growing children. For this purpose, a retrospective study was designed where various measurements were performed on the right and left sides of the mandible of panoramic radiographs of 327 children (males: 169; females: 158), 8-12 years old. Four linear measurements, mandibular ramus height, ramus width, corpus height, and corpus length, and two angles, mandibular gonial (Go) and mandibular condyle (Co), and the developmental stage of the permanent lower second molar were analysed. All measurements were adjusted for the magnification factor. The final data were then processed for the asymmetry index (AI) to determine the severity of the asymmetries and statistically analysed by Wilcoxon paired tests at the 95 per cent level of confidence. A moderate-to-severe mandibular asymmetry for the linear dimensions when both sides of the mandible were contrasted was found in more than a half of the sample. There was also a high prevalence of moderate and severe asymmetries when comparing Go and Co angles on both sides of the mandible. No differences were observed in the developmental stage of the lower permanent second molar between either side. There was a high prevalence of both dimensional and angular mandibular asymmetries in the studied population.

Meta-analysis of skeletal mandibular changes during Frankel appliance treatment

The purpose of this study was to perform a meta-analysis of articles to verify the mandibular changes produced by the Fränkel-2 (FR-2) appliance during the treatment of growing patients with Class II malocclusions when compared with untreated growing Class II subjects. The literature published from January 1966 to January 2009 was reviewed with search engines. A quality analysis was performed. The effects on primary end points were calculated with random-effect models. Heterogeneity was assessed using Q statistic and investigated using study-level meta-regression. A total of nine articles were identified. The quality of the studies ranged from low to medium. Meta-analysis showed that the FR-2 was associated with enhancement of mandibular body length [0.4 mm/year 95 per cent confidence interval (CI) 0.182-0.618], total mandibular length (1.069 mm/year, 95 per cent CI 0.683-1.455), and mandibular ramus height (0.654 mm/year, 95 per cent CI 0.244-1.064). A consistent heterogeneity among studies was found for all the considered linear measurements. The FR-2 appliance had a statistically significant effect on mandibular growth. Nevertheless, the heterogeneity of the FR-2 effects, the quality of studies, the differences in age, skeletal age, treatment duration, and the inconsistent initial diagnosis seem to overstate the benefits of the FR-2 appliance. An evidence-based approach to the orthodontic outcomes of FR-2 appliance is needed, by selecting and comparing groups of children with the same cephalometric characteristics with and without treatment.

The influence of masticatory hypofunction on developing rat craniofacial structure

The purpose of this study was to use botulinum neurotoxin type A (BoNT/A) selectively to evaluate the influence of localized masticatory atrophy and paresis on craniofacial growth and development. 60 growing rats, 4 weeks old, weighing approximately 120g, were randomly divided according as follows (Long-Evans, N=15 per group): I (Mb+Tns); II (Mns+Tb); III (Mb+Tb); IV (Mns+Tns), where Mb or Tb is the BoNT/A-injected masseter or temporalis muscles (1.0U/muscle, 2.5ml) and Mns or Tns is the saline-injected muscles (2.5ml). After 7 weeks, the mature rats were killed, the muscles dissected and mean muscle mass recorded. Anthropometric cranial, maxillary and mandibular measurements were taken from the dried skulls. Changes in animal weight during the growth period were not statistically significant. The mean masticatory muscle mass was smaller for the BoNT/A-injected muscles of Mb and Tb. Anthropometric measurements of bony structures inserted by masseter and temporalis muscles revealed a significant treatment effect. The measurements showed a facial morphology typical of a dolichofacial profile: short upper face accompanied by a long lower face with an extended mandibular length and ramus height and constricted bicoronoidal and bigonial widths. The results suggest that induction of localized masticatory muscle atrophy with BoNT/A alters craniofacial growth and development.

Influence of experimental hemi-occlusion on mandibular morphology and internal structure in growing rabbit

We induced experimental hemi-occlusion in growing rabbits to investigate the effect of masticatory laterality on the morphology and internal structure of the mandible. Three-dimensional morphometric data from micro-CT were used to compare changes in mandibular morphology and internal structure. Rabbits in the experimental group were placed under general anesthesia and their left maxillary and mandibular molars cut as far as the cervical area using a rabbit molar cutter. Thereafter, the teeth were cut once every 2 weeks. Rabbits were kept until they were 17 weeks old. For morphometric analysis of the mandible, we measured mandibular body length, mandibular length, mandibular ramus height and gonial angle. To analyze cancellous bone structure, we measured total volume, cancellous bone volume, cancellous bone volume density, trabecular thickness, trabecular number, trabecular separation, and trabecular spacing. Mandibular ramus height and gonial angle were significantly greater on the occlusal side in the experimental group than on the non-occlusal side. Cancellous bone volume density, trabecular thickness and trabecular number were significantly greater on the occlusal side in the experimental group than on the non-occlusal side, whereas trabecular separation and trabecular spacing were significantly lower on the occlusal side. The results indicate that differences in mechanical stimuli during the growth phase resulting from masticatory dysfunction or parafunction affect the morphology and internal structure of the mandible.

Soft tissue facial morphometry in subjects with Moebius syndrome

Moebius syndrome is a congenital facial palsy associated with the impairment of ocular abduction. The three-dimensional characteristics of the facial soft tissues of 12 male and 14 female subjects [3-52 yr of age (mean age + standard deviation: 17 + 14 yr)] were measured using a non-invasive, computerized system; facial volumes, areas, angles, and distances were computed and compared with those obtained in reference subjects of the same age and gender. When compared with reference subjects, patients with Moebius syndrome had a more prominent and hyperdivergent face in the sagittal plane, a smaller and more prominent upper facial third; a smaller middle facial width; a smaller nose; smaller mandibular volume, depth, corpus length, and ramus height; and a more posterior positioned mandible, with a less prominent chin. In conclusion, patients with Moebius syndrome had a tendency towards a skeletal Class II pattern. These morphological variations may be the combined effect of a general alteration of the motor and sensitive facial nerves, including the trigeminal nerve, and of a maldevelopment of the brainstem.

Further evidence for an association between mandibular height and the growth hormone receptor gene in a Japanese population

Craniofacial morphology has a significant genetic component. It has recently been reported that single nucleotide polymorphisms (SNPs) in the growth hormone receptor gene (GHR) are associated with mandibular height. To confirm these findings, we genotyped SNPs in healthy Japanese subjects, about 1.7 times the number analyzed in previous reports. By using 5 SNPs in exon 10 of the GHR, we studied the relationships between genotypes and craniofacial linear measurements. The allelic frequencies in a multi-ethnic population (Han Chinese, African American, European American, and Hispanic) were also observed. There was a significant association between SNPs and mandibular ramus height (P = 0.029), confirming our previous report of an association between polymorphism P561T and mandibular ramus height. Moreover, the SNP, C422F, was in linkage disequilibrium with P561T. Subjects with genotype CC of polymorphism P561T and genotype GG of polymorphism C422F had significantly greater mandibular ramus height than those with genotypes CA and GT. Four of the 5 SNPs were found almost exclusively in Asians, with the frequencies in other populations extremely small. Our results indicate that the GHR polymorphisms P561T and C422F are associated with mandibular ramus height in Japanese population and suggest that the SNPs of the GHR associated with the Japanese are likely to be different in other ethnic groups. This might partly explain the differing craniofacial morphology among different ethnicities.

Treatment of condylar hypoplasia with distraction osteogenesis: a case report.

This report describes the surgical-orthodontic treatment procedures of a patient with condylar hypoplasia. Condylar hypoplasia is a major factor in any facial abnormality in a growing child. This case report describes a patient with a facial anomaly with an acquired unilateral condylar hypoplasia. His asymmetry was corrected by using functional therapy for the correction of muscle tonus and distraction osteogenesis for lengthening the mandibular ramal height. Fixed orthodontic appliances were used for conventional orthodontic therapy and final occlusal adjustment.

Association of the growth hormone receptor gene polymorphisms with mandibular height in a Korean population

Growth hormone receptor gene ( GHR) is one of the likely candidates for determining morphological traits, because GH is a key regulator of bone growth. The genetic association of GHR in exon 10 with mandibular ramus height has been found in different populations, Japanese and Chinese. On the other hand, two common isoforms of GHR, one full-length ( fl-GHR) and the other lacking the extracellular domain encoded by exon 3 ( d3-GHR), are associated with differences in responsiveness to GH. The purpose of this study involving 159 Korean subjects was to study the associations between a GHR polymorphism ( d3/fl- GHR) that results in genomic deletion of exon 3 and craniofacial morphology, and to study the associations between GHR genotypes in exon 10 and craniofacial morphology. Moreover, the allelic frequencies in a multi-ethnic population (24 Han Chinese, 24 African-Americans, 24 European-Americans, and 24 Hispanics) in a GHR polymorphism ( d3/fl- GHR) were compared in this study. The five craniofacial linear measurements (cranial base length, maxillary length, overall mandibular length, mandibular corpus length, and mandibular ramus height) obtained from lateral cephalograms were examined as craniofacial morphology. We found that the d3/fl- GHR polymorphism had no association for any measurements, and a statistically significant association ( P = 0.024) between the GHR polymorphisms P561T and C422F in exon 10 and mandibular ramus height. Neither SNPs besides P561T and C422F polymorphisms in exon 10 nor the measurements besides mandibular ramus height have statistically significances. Both derived alleles at P561T and C422F SNPs were highly associated with only one haplotype, haplotype-4 in Korean population. As quantitative haplotype association, the results showed a significant difference in mandibular ramus height between individuals having one haplotype-4 and others without haplotype-4 ( P = 0.028). Moreover, we found that the d3/fl- GHR polymorphism showed diverse frequency in different population. Regarding GHR genotypes in exon 10, the present study mostly reflected the results obtained for a Japanese population, although our current study does not replicate the correlation between the I526L polymorphism of GHR and mandibular ramus height as was reported in a previous study of Han Chinese. The results of the present study suggest that the GHR exon 10 SNPs, not d3/fl- GHR, contribute to changes in the mandibular ramus height of Koreans.

Evaluation of skeletal and surgical factors related to relapse of mandibular setback surgery using the bioabsorbable plate

This study was to evaluate the stability of the bioabsorbable plate used in the orthognathic surgery for patients with prognathic mandibles and to evaluate the relapse tendency after surgery and the factors affecting the relapse. The sample consisted of 30 subjects (14 males and 16 females) who underwent bilateral sagittal split ramus osteotomy (BSSRO) for mandibular setback using the poly-l/dl-lactide plate system (Biosorb FX), Linvatec Biomaterials Ltd., Tampere, Finland). The lateral cephalometric radiographs of each subject were taken pre-operatively within 1 month (T0), post-operatively within 1 month (T1), and post-operatively between 4 and 10 months (T2) and skeletal changes were analyzed with V-Ceph (CyberMed), Seoul, Korea) software. The changes between T1 and T2 were evaluated with a paired t-test to estimate the stability of the surgery. The post-operative changes of mandibular body length and ramus height were used for a K-means clustering analysis to separate subjects into either the less changed (LC), or the more changed (MC) group. The two groups were compared with T0 and the surgical changes (T1-T0) using the t-test. Significant relapse after surgery was shown in vertical measurements but not in the horizontal plane measurements. The MC group showed significantly more vertical operative changes than the LC group independent of horizontal measurements. Usage of a bioabsorbable plate in mandibular setback surgery could provide stable fixation in the horizontal dimension, but also may allow an increase of vertical relapse due to the increase in vertical dimension post-operatively.

Influência da proporção entre as alturas do ramo mandibular e dentoalveolar posterior na inclinação do plano mandibular

OBJETIVO: avaliar a existência de correlação entre a proporção da altura do ramo mandibular (AR) com a altura dentoalveolar posterior total (ADAPT) e a inclinação do plano mandibular (PM). MÉTODOS: dois examinadores avaliaram 81 telerradiografias laterais de pacientes, com idades a partir de 18 anos, do arquivo do curso de especialização em Ortodontia e Ortopedia Facial da Faculdade de Odontologia da UFBA. As radiografias foram digitalizadas, os pontos marcados e as medidas obtidas através do programa Radiocef 1.0. Mediu-se a inclinação do plano mandibular para caracterizar o padrão vertical da face e dividir as radiografias em três grupos: grupo de face normal (GN), de 22º a 28º, de face curta (GC), menor que 22º, e de face longa (GL), maior que 28º. A inclinação do plano palatino serviu como critério de exclusão, sendo que valores abaixo de -2,5° ou acima de 3,5º foram excluídos. Desta forma, 46 telerradiografias laterais totalizaram a amostra. RESULTADOS: a AR diferiu entre GC e GL, porém não houve diferença estatisticamente significante para as alturas dentoalveolares posteriores. Houve baixa correlação entre a AR e a ADAPT nos grupos, no entanto, a correlação da proporção entre essas alturas com a inclinação do PM mostrou-se estatisticamente significante e negativa. CONCLUSÃO: este é um fator a ser levado em consideração na avaliação do PM, quando do diagnóstico e tratamento das displasias verticais dentofaciais.

Hemimandibular elongation: treatment and long‐term follow‐up

To study long-term changes in the mandibular asymmetry of patients with hemimandibular elongation (HE) treated with two-phase surgical orthodontic approach. Descriptive clinical study. Private practice setting. Seven (six females) out of 47 diagnosed and treated patients for severe mandibular asymmetry were included with the following criteria: diagnosis of HE based on clinical, radiological and single photon emission computed tomography bone scintigraphic studies, good quality orthopantomograms (OPT) available at six time-points, two-phase surgical treatment (high condylectomy, HC, and orthognathic surgery, OS) and measurements of maximal mouth opening (MMO) available. Mandibular ramus height and corpus length were measured on OPTs at six time-points. Ratios between the affected/non-affected sides were calculated. All patients had progression of mandibular asymmetry before any operation, which finding together with the scintigraphy resulted to the decision to perform HC. Thereafter ramus and corpus asymmetry decreased compared with the initial measurements. After OS, stable symmetry of corpuses and alignment of skeletal and dental midlines were obtained. MMO reduced on average 50% after HC, regained 20% after OS and recovered almost totally at the last follow-up. High condylectomy to stop excessive growth and OS to correct facial asymmetry is considered successful and necessary treatment for patients with HE. MMO can well recover after surgical traumas. Orthodontists should consider mandibular asymmetry as abnormal and need for surgical treatment if asymmetry is progressive and the ratio between affected/non-affected sides approaches 10%.

Longitudinal growth changes in untreated subjects with Class II Division 1 malocclusion

The purpose of this longitudinal study was to compare the craniofacial growth changes in untreated subjects with Class II Division 1 malocclusion with those in subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development, as defined by a biological indicator of individual skeletal maturity (cervical vertebral maturation method). The Class II Division 1 sample consisted of 17 subjects (11 boys, 6 girls). The Class I sample also consisted of 17 subjects (13 boys, 4 girls). The lateral cephalograms of the subjects in both groups were analyzed at 6 consecutive stages of development, from CS1 through CS6. The statistical comparisons of the growth changes in the study groups were performed with Mann-Whitney U tests. Craniofacial growth in subjects with untreated Class II malocclusion is essentially similar to that in untreated subjects with normal occlusion at all developmental intervals, with the exception of significantly smaller increases in mandibular length (P <0.001) at the growth spurt (interval CS3-CS4) and during the overall observation period (intervals CS1-CS6). Class II dentoskeletal disharmony does not tend to self-correct with growth in association with worsening of the deficiency in total mandibular length and mandibular ramus height.

Does functional appliance treatment truly improve stability of mandibular vertical distraction osteogenesis in hemifacial microsomia?

After mandibular unilateral distraction osteogenesis (DO) a gradual reappearance of the vertical asymmetry during growth is observed. A pre- and post-surgical functional-orthodontic treatment was added to our distraction protocol in the attempt to increase long-term stability. In order to evaluate the actual efficacy of such a combined treatment, two samples of children affected by hemifacial microsomia were compared long-term. Ten children were treated by a combined orthodontic-distraction treatment, seven by distraction only. Only the vertical changes in the mandible and maxilla in the panoramic and postero-anterior cephalometric X-rays were measured. All of the patients showed a gradual return of the asymmetry with growth. Occlusal plane correction and, to a much lesser extent, mandibular vertical ramus height correction were better maintained over 5 years post-DO in the orthopaedic group. Although orthopaedic treatment allows for a more stable occlusal plane and for a slower return of the mandibular vertical asymmetry, it has mainly a dento-alveolar effect. Therefore, the decision of applying an orthopaedic treatment associated with distraction, should be taken by surgeon and orthodontist together, considering both the advantages and the disadvantages of this treatment.

Evaluation of the antegonial notch related to the mandibular morphology and the curve of Spee in anteroposterior relation

The aim of this study was to investigate the relationship between the mandibular antegonial notch and the mandibular morphology, and the curve of Spee in anteroposterior skeletal relationship. Pre-treatment lateral cephalograms were obtained from 80(male 34, female 46) adult orthodontic patients and the samples were classified into 3 categories by ANB angle(0°≤ANB&lt; 4° Class I, 4°≤ANB Class II, ANB&lt; 0° Class III). The curve of Spee was measured directly from the pre-treatment mandibular study cast of each patient included in this study. Pearson correlation coefficient test and multiple regression analysis in each group revealed the following results; 1. Antegonial notch depth was positively correlated with hoth lower anterior facial height(ANS-Me) in skeletal Class I, II and III groups and Id-Me height in skeletal Class I and II groups. 2. A statistically significant negative correlation was found between the depth of the antegonial notch and the curve of Spee in the Class III group. 3. Significant relationship was not found between the antegonial notch depth and any of the other cephalometric variables such as mandibular body length(Go-Gn) and ramus height(Co-Go). As antegonial notch depth increased, more vertical growth of the mandible was observed. Antegonial notch can be used as a predictor of vertical mandibular growth in the diagnosis and treatment planning of malocclusion.

Influence of Unilateral Masseter Muscle Atrophy on Craniofacial Morphology in Growing Rabbits

The purpose of the study was to evaluate whether the induction of unilateral masticatory muscle dysfunction can alter the skeletal growth patterns. Twenty-one white male New Zealand rabbits (4 weeks old) were divided into 3 groups of 7 subjects: group 1 served as the control to study normal craniofacial growth. In groups 2 and 3, rabbits were injected with 5 units and 15 units of Botulinum toxin A (BTXA) into the right masseter muscle, respectively. The effect of a neuromuscular blockade of masseteric activity on craniofacial growth was evaluated with 3 samples of serial computed tomography (CT) scans with a slice thickness of 0.625 mm, taken at 4 weeks (base line), 8 weeks (endpoint of prepubertal craniofacial growth), and 24 weeks (after pubertal growth). The ipsilateral mandibular ramus height, zygomatic arch length, and masseteric length did not develop as much as those of the contralateral side after pubertal growth. At age 24 weeks, the masseter muscle volume asymmetry index reached -13.8% (group 2), -18.4% (group 3), and -1.6% for the control group. The ipsilateral side of the hemimandible showed less bone volume after 8 weeks but it showed partially recovered symmetry at 24 weeks. The maxillomandibular incisor midline and transverse molar discrepancies were not evident in any of the groups. The BTXA injection can be an effective method in inducing site-specific muscular hypofunctions so that masticatory muscle-craniofacial bone interaction can be investigated efficiently. The result showed that the unilateral atrophy of the masseter muscle in the growing subjects influenced the morphology of the local skeletal sites. This did not, however, result ultimately in mandibular midline asymmetry or right-left asymmetry in hemimandibular volume after growth. The results imply that alterations in specific masticatory muscle function can be compensated by the growth of other structural components.

A longitudinal study of craniofacial growth in idiopathic short stature and growth hormone-deficient boys treated with growth hormone

The aim of this prospective, longitudinal, controlled study is to describe the long-term safety and efficacy of growth hormone (GH) administration on craniofacial morphology in boys with short stature. Forty-six boys, who started GH treatment at the Department of Paediatrics Göteborg Paediatric Growth Research Centre, were consecutively included in the study. Twenty-five boys were classified as growth hormone-deficient (GHD) and 21 as idiopathic short stature (ISS). The patients were injected with 33 (n=31) or 67 (n=15) microg GH/kg body weight/day. The mean age at the start of treatment was 11.8 years [standard deviation (SD) 1.7]. To assess craniofacial growth, standard lateral cephalometric radiographs were obtained at the start of GH treatment, annually during 4 years, and at the end of GH treatment or when growth was less than 1 cm/year. The mean follow-up period was 6.4 years (SD 1.4). Growth changes were compared with boys from a semi-longitudinal reference group of 130 healthy subjects, 7-21 years of age. t-tests for independent and paired samples and multiple regression analysis were applied. Age- and gender-specific standard deviation scores for the cephalometric variables were calculated. Repeated measures analysis of variance was used to identify significant covariates over time, such as low/high GH dose and GHD/ISS and orthodontic treatment. During the study period, eight (out of 40) boys were treated with fixed orthodontic appliances, three with functional appliances (activators), and three with other appliances (plates and lingual arches). During GH treatment period, an overall enhancement in growth of the facial skeleton was observed in boys with short stature. The changes induced by GH yielded a more prognathic growth pattern, a more anterior position of the jaws in relation to the cranial base, and increased anterior rotation of the mandible. The mandibular corpus length and anterior face height of the GH-treated boys were greater at the end of the study compared with the boys in the reference group. No differences in growth response were noted either between the GHD and ISS boys or between those treated with either 33 (low dose) or 67 (high dose) microg GH/kg body weight/day. The only change that remained significantly correlated with orthodontic treatment was the alteration in mandibular ramus height, showing a larger change in the boys who had not undergone orthodontic therapy. The findings of this study demonstrate that GH treatment has a favourable influence on the craniofacial growth pattern of boys with short stature without acromegalic features.

Some mandibular geometry of Eastern Nigerians

Objective: To determine mean values of the mandibular angle, mandibular length and mandibular ramus height in Nigerians of Eastern origin. Methods: A prospective study of 34 prepared mandibular bones of Eastern Nigerians was conducted. The measurements were done using the mandibulometer according to accepted definitions of the different perameters. Results: For the right mandible, the mean mandibular angle was found to be 120.41 °±6.29, mean mandibular length 9.27cm±0.650 and mean mandibular ramus height 5.58cm±0.555. For the left mandible, the correspponding mean values were 120.03°±5.800 for the mandibular angle, 8.83cm±0.830 for the mandibular length and 5.81cm±0.451 for the mandibular ramus height. The Angle/Height ratio for the right mandible was found to be 21.58 and 13.01 respectively, while the corresponding values for the left mandible were found to be 20.66 and 13.50 respectively. These differences were found not to be statistically significant (p Conclusion: Our findings suggest that Nigerians of Eastern origin apparently exhibit a short ramus and a narrow mandibular angle. The implication of this is in the ease of laryngoscopy and intubation for the Eastern Nigerian will need further investigation. Keywords: Mandible, Nigerians, Mandibular height, Mandibular angle, Mandibular length Orient Journal of Medicine Vol. 17 (1&2) 2005: 9-14