Quantifying normal head form and craniofacial asymmetry of elementary school students in Taiwan.

BACKGROUND: Defining three-dimensional (3D) normal craniofacial morphology in healthy children could provide craniofacial surgeons a reference point to assess disease, plan surgical reconstruction, and evaluate treatment outcome. The purposes of this study were to report normal craniofacial form and quantify craniofacial asymmetry of healthy children in Taiwan by implementing the 3D stereophotogrammetry technique. METHODS: Healthy Taiwanese elementary school children (n = 652) aged 6-12 years with no known craniofacial anomaly were recruited. After the 3dMD scanning procedure, 32 landmarks were manually placed on the 3D cranial images. Thin plate spline algorithm based on landmarks and closest point matching was applied to deform a symmetric 3D template into the scale of each scanned images. Skull asymmetry and facial asymmetry were calculated using 3dMD vultus and MATLAB. Average head shape models were also presented. RESULTS: Overall, the mean head transverse width, height, anteroposterior length, and circumferences were 163.02, 220.79, 179.07, and 526.55 mm, respectively. On average, the skull asymmetry and facial asymmetry were 2.47 ± 1.26 mm and 0.96 ± 0.53 mm, respectively, with no significant (all p > 0.05) differences found when comparing males and females. In the average head shape model, certain craniofacial areas on the right side were found to be more protruded than those on the left side. CONCLUSIONS: This study shows that the baseline craniofacial form of the Taiwanese elementary school children is asymmetric with a tendency of more protrusion of the head on the right side.

Radiographic features associated with temporomandibular joint disorders among African, White, Chinese, Hispanic, and Indian racial groups.

CONTEXT: Various radiographic features have been associated with temporomandibular joint disorders (TMDs); however, these characteristics have not been compared among different racial groups. AIMS: To radiographically evaluate and compare craniofacial patterns and condylar findings suggestive of TMD among African, White, Chinese, Hispanic, and Indian racial groups. SETTINGS AND DESIGN: This multicenter retrospective study used data from three private orthodontic practices and a University Orthodontic Clinic. SUBJECTS AND METHODS: Panoramic and lateral cephalometric radiographs were collected from 250 subjects who were equally divided into five racial groups: Africans, Whites, Chinese, Hispanics, and Indians. All radiographs were initial records from patients seeking orthodontic treatment. Linear and angular cephalometric measurements were used to evaluate and compare cephalometric characteristics associated with TMD among groups. Panoramic radiographs were analyzed to compare the presence of condylar abnormalities and antegonial notching among groups. STATISTICAL ANALYSIS USED: One-way analysis of variance, followed by Tukey's test. RESULTS: African and Chinese groups had the smallest mean cranial base measurements, while the Indians had the largest. The mean Y-axis value was significantly larger in the Chinese group compared with the other groups. Increased mandibular plane angles were seen in the Chinese and African patients, compared with subjects from other groups. The mean percentage of condylar anomalies was higher in the Chinese subjects compared with all other groups. CONCLUSIONS: Chinese patients presented with more radiographic features suggestive of TMD, whereas the Indians showed the least, compared with subjects from the White, Black, and Hispanic racial groups.

Craniofacial asymmetry as a marker of socioeconomic status among undocumented Mexican immigrants in the United States.

This study examines levels of fluctuating asymmetry (FA) in Mexican residents, U.S. residents, and undocumented border crossers (UBCs) from Mexico to the United States. Craniofacial structures develop symmetrically under ideal circumstances; however, during periods of developmental stress random deviations from perfect symmetry, or FA, can occur. It is hypothesized that the UBC sample would represent individuals of a lower socioeconomic status (SES) who experienced higher stress levels during development, and that these individuals would consequently have higher levels of FA. Three-dimensional cranial landmarks were collected from 509 individuals representing the three resident groups. Geometric morphometric methods were used to calculate an FA score for each individual. The FA score provides a distance measure that is a scalar measure of the magnitude of FA in each individual. The results show that the difference in the means of the FA scores between UBCs and U.S. residents is 0.43 (p = 0.02), with UBCs showing significantly higher levels of FA compared to U.S. residents. Moreover, Mexican residents' FA levels are intermediate between and not significantly different from the other two samples. These results suggest that levels of FA may prove useful for reconstructing individuals' social and economic circumstances, and that craniofacial asymmetry provides a suitable biological marker for analyzing differences in SES among different groups.

Fluctuating asymmetry of the normal facial skeleton.

The purpose of this study was to produce reliable estimations of fluctuating facial asymmetry in a normal population. Fifty-four computed tomography (CT) facial models of average-looking and symmetrical Chinese subjects with a class I occlusion were used in this study. Eleven midline landmarks and 12 pairs of bilateral landmarks were digitized. The repeatability of the landmark digitization was first evaluated. A Procrustes analysis was then used to measure the fluctuating asymmetry of each CT model, after all of the models had been scaled to the average face size of the study sample. A principal component analysis was finally used to establish the direction of the fluctuating asymmetries. The results showed that there was excellent absolute agreement among the three repeated measurements. The mean fluctuating asymmetry of the average-size face varied at each anthropometric landmark site, ranging from 1.0mm to 2.8mm. At the 95% upper limit, the asymmetries ranged from 2.2mm to 5.7mm. Most of the asymmetry of the midline structures was mediolateral, while the asymmetry of the bilateral landmarks was more equally distributed. These values are for the average face. People with larger faces will have higher values, while subjects with smaller faces will have lower values.

A comparative study of fluctuating asymmetry in Chinese families with nonsyndromic cleft palate.

OBJECTIVE: To compare the asymmetry displayed by Chinese patients with nonsyndromic cleft palate (NSCP), their unaffected parents, and a control population. METHOD: With rigorous inclusion criteria, a total number of 675 individuals with NSCP, 675 parental pairs of these patients, and 650 control individuals were involved in this case-control study. Size-adjusted fluctuating asymmetry (FA) scores were calculated by data on 10 variables. Analysis of variance was used for a three-way comparison of patients/gender-matched parents/gender-matched controls. RESULTS: A significant increase in FA for ear length (p<.05) was noted in NSCP patients when compared with their gender-matched parents. A significant increase in FA for ear length and palpebral fissure width (p<.05) was observed in NSCP patients when compared with the gender-matched control population. A significant increase in FA for palpebral fissure width (p<.05) was detected in parents of NSCP patients when compared with a gender-matched control population. CONCLUSION: Our results indicated that, when compared with a gender-matched control population, patients with NSCP show significantly increased FA in both ear length and palpebral fissure width, but the parents of patients with NSCP show significantly increased FA only in palpebral fissure width. In general, these characteristics seem to be more distinct in male individuals.

Midface augmentation using bony segments obtained from sagittal splitting angle ostectomy in asians.

BACKGROUND: Asians characteristically have flat or broad and round facial features. These characteristics are primarily attributable to enlarged and widened jawbones, impressive muscles associated with mastication, and a zygomatic arch involving the masseter. Their faces appear flat, with midface regression in the center. This regression is often combined with a narrow nasolabial angle and a depressed alar base and cheeks. METHODS: Between June of 1999 and March of 2002, 32 patients underwent facial contouring surgery for prominent mandible angles and subsequent rhinoplasty. After bilateral prominent mandible angle modification, midface augmentation was accomplished using bony segments obtained from sagittal splitting angle ostectomy. The bony fragments were inserted via an intraoral approach into the paranasal area, trimmed, and then reshaped with an osteotome. RESULTS: Of these 32 patients (31 women and one man), 47 percent were in their thirties. The amount of reduction of the distance between mandible angles on the frontal view, the extent of protrusion of the paranasal area on the profile view, and the degree of patient satisfaction were the primary areas of postoperative evaluation. Complications included one wound infection and two cases of wound dehiscence. All but two patients were satisfied with their results. CONCLUSIONS: Satisfactory aesthetic results were obtained with a one-stage modification of the mandible angles and advancement of the midfacial area. The advantages included the absence of any additional costs and a low infection rate. None of the disadvantages of an autologous transplant were present, and the procedure yielded aesthetically superior results. The authors advocate this method.

Spectrum and management of dentofacial deformities in a multiethnic Asian population.

OBJECTIVE: The aim of this retrospective study is to investigate the spectrum and management of dentofacial deformities in a multiethnic Asian community. MATERIALS AND METHODS: Over a period of 3 years (2001 to 2003), 212 patients with dentofacial deformities who had undergone orthognathic surgery in a national tertiary specialist center in Singapore were reviewed. Patients with cleft lip and palate or syndromes were excluded. RESULTS: The mean age (range: 16 to 58 years) of the patients was 24.0 years (SD 6.4) and the ratio of female to male was 1.3:1. The predominant ethnic group was Chinese (91.5%). The majority of the patients had skeletal Class III pattern (68%). Asymmetry was diagnosed in 36% of all cases and in 48% of skeletal Class III cases. Vertical maxillary excess was diagnosed in 21% of all cases and in 47% of skeletal Class II cases. Bimaxillary surgery involving LeFort and bilateral sagittal split osteotomies was performed in 84% of skeletal Class III cases and in 73% of all cases. Segmental osteotomy and genioplasty were performed in 41% of the cases. CONCLUSIONS: The findings suggest that the majority of the patients were young Chinese adults with two-jaw deformities requiring bimaxillary surgeries with genioplasty or segmental osteotomy. This finding may reflect the greater severity of dentofacial deformities in patients in the Asian community.

[Facial anthropometry and aesthetic perception in young italian subjects: their use for orthognatic surgery]. / Antropometria e percezione estetica del volto in un campione di popolazione italiana. Considerazioni ai fini della chirurgia ortognatica.

BACKGROUND: Aesthetic requests of patients undergoing orthognatic surgery have increased over time and represent nowadays the leading subjective motivation for the patient and a major aim of the treatment for the surgeon. In this regard, anthropometric evaluation has considerably improved the diagnostic capacity of the orthodontist and of the surgeon. Aim of the study is to provide the orthognatic surgeon with anthropometric normal values based on a sample of aesthetically pleasant Italian subjects and to discuss the use of a simplified aesthetical analysis in the set-up of the surgical plan and in the evaluation of treatment outcome. METHODS: The present study analyses 94 Italian subjects, by means of anthropometric measurements on photographic images, considering 28 facial proportions and 33 angular values. These figures were compared with the aesthetic judgement provided by 3 common observers and 3 orthodontists. The aesthetic score was attributed on a subjective discrete scale (common observer: above average/average/below average; orthodontist: eumorphic/ dismorphic). Data were also compared with similar evaluations on North-American and African subjects reported in the international literature. RESULTS: This study confirms the sexual dismorphism and the ethnic variability already reported by other Authors and documents specific morphological characters in the Italian population. CONCLUSIONS: The described method appears acceptably simple and consistent for clinical application. Its use in orthognatic surgery may provide objective and reproducible data for evaluating the aesthetic outcome of treatment.

Plagiocefalia cultural y sus posibles alteraciones estrabológicas / Cultural plagiocephaly and possible strabologic complications

Entre los pueblos del México prehispánico, la costumbre de modificar la cabeza de los recién nacidos estuvo muy arraigada y difundida. Estas modificaciones producidas por planos compresores desalineados ocasionaron una deformación cultural asimétrica semejante a la que presentan los pacientes con plagiocefalia, con cambios estructurales en las órbitas, los cuales condicionan cuadros estrabológicos bien establecidos. Se estudiaron 18 cráneos del área maya, todos ellos adultos (10 hombre y 8 mujeres) a los cuales se les realizaron medidas directas e indirectas (rayos X y craneogramas). Como resultados del presente estudio podemos sospechar que las deformaciones culturales asimétricas del cráneo causaron una deformación semejante a la plagiocefalia con cambios en las órbitas que condicionan una distopia vertical importante y como consecuencia de la misma, un cuadro estrabológico de hipertropia en bloque

[The intergroup variability of the indices of asymmetry of the human facial skull]. / Mezhgruppovaia izmenchivost' indeksov asimmetrii litsevogo otdela cherepa cheloveka.

All bilateral sizes of the facial skeleton of Tajik, Khakass and Kazakh skulls have demonstrated an asymmetry. In the three series the greatest values of the asymmetry were obtained for the sizes of the orbital, zygomatic and mandibular areas, the least ones--for the sizes of the upper jaw. Greater sizes were less asymmetrical. The indices of asymmetry of the least sizes of the facial skeleton are characterized by the greatest variability at the intra-group level. The Tajik skulls were considerably different in the degree of asymmetry from both the Khakass and kazakh skulls mainly in the sizes of the upper part of the facial skull. Values of asymmetry of Kazakh and Khakass skulls were similar as a whole.