An investigation of craniofacial asymmetry using the serial twin-study method

Mulick, James F.

doi:10.1016/0002-9416(65)90165-x

Cited by 48 publications

(20 citation statements)

References 43 publications

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“…In contrast, skeletal Class III patients generally exhibit greater growth and also may be more likely to be affected by postnatal, environmental influences because of the relatively longer jaw growth period. Previous studies 5,6,25,26 have discussed possible causes of facial laterality. Most have concluded that environmental influences were the most likely cause.…”

Section: Discussionmentioning

confidence: 99%

Asymmetry of the Face in Orthodontic Patients

Haraguchi

Iguchi

Takada

2008

The Angle Orthodontist

165

116

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Objective: To investigate the laterality of the normal asymmetry of the human face, examining differences in laterality in relation to sex, growth stage, and skeletal classification. Materials and Methods: A total of 1800 Japanese subjects (651 males and 1149 females; mean age, 15 years 3 months; range, 4 years 2 months to 59 years 11 months) were selected. Individuals in the sample were categorized according to sex, one of three growth stages, and one of three skeletal patterns. Differences in length between distances from the points at which ear rods were inserted to the facial midline and the perpendicular distance from the soft-tissue menton to the facial midline were measured on a frontal facial photograph. Subjects with a discrepancy of more than 3 standard deviations of the measurement error were categorized as having left-or right-sided laterality. Results: Of subjects with facial asymmetry, 79.7% had a wider right hemiface, and 79.3% of those with chin deviation had left-sided laterality. These tendencies were independent of sex, age, or skeletal jaw relationships. In this regard, during pubertal growth, the proportion of subjects with wider right hemiface decreased (P Ͻ .0001), whereas the proportion of those with a wider left hemiface increased (P Ͻ .01), despite a consistent tendency for right-sided dominance. Conclusion: These results suggest that laterality in the normal asymmetry of the face, which is consistently found in humans, is likely to be a hereditary rather than an acquired trait.

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Section: Discussionmentioning

confidence: 99%

Asymmetry of the Face in Orthodontic Patients

Haraguchi

Iguchi

Takada

2008

The Angle Orthodontist

165

116

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“…As already suggested by Galton in 1875 (1), twins constitute a unique tool to discriminate between the effects of 'nature' (heredity) and 'nurture' (environment). Comparison of characteristic conditions between mono-(MZ) and dizygotic (DZ) twins can also be used efficiently to obtain heritability estimates (2)(3)(4). Heritability is the percentage of the phenotypic variation explained by genetic factors.…”

Section: Introductionmentioning

confidence: 99%

A quantitative genetic study of cephalometric variables in twins

Carels¹,

Cauwenberghe²,

Savoye³

et al. 2001

Clinical Orthodontics and Research

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This study aimed at determining the relative genetic and environmental impact on a number of well-known cephalometric variables in twins. In order to find a clue in the heritability pattern of some dentofacial characteristics and on the expected limits of the therapeutic impact on the dentofacial subparts they are representing. Cephalograms were collected from 33 monozygotic and 46 dizygotic twins, who did not undergo any orthodontic treatment. Nineteen linear and four angular variables were selected all representing a different definite subpart of the dentofacial complex. The reproducibility of the measurement of most of the linear variables was very high. A genetic analysis using model fitting and path analysis was carried out. First, data were checked on the fulfilment of the conditions for genetic analysis in twins reared together. The results show that the genetic determination is significantly higher for vertical (72%) than for horizontal (61%) variables. As far as the genetic component is concerned, all variables selected seem to be inherited by additive genes, except for mandibular body length, which was determined by dominant alleles. Sex differences in genetic determination were found for the anterior face height, showing a significantly higher genetic component for boys (91%) than for girls (68%). For the angular measurements, no genetic influence was found: only environmental influences common to both members of each pair could be demonstrated.

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“…Direct measures on dry skulls (Woo, 1931;Lundström, 1961;Berge and Bergman, 2001;Rossi et al, 2003), posteroanterior radiographic analyses (Mulick, 1965;Vig and Hewitt, 1975;Chebib and Chamma, 1981;Peck et al, 1991;Masuoka et al, 2005), direct measures on dental plaster study casts (Chebib and Chamma, 1981), photographs (Ferrario et al, 1993, Quimby et al, 2004 computer tomography (Katsumata et al, 2005), or visual inspection of the face (Sutton, 1968) are used. We developed a method to evaluate hard palate dimensions which has proved to be very accurate, with excellent reproducibility of landmarks, less time-consuming, allowing angular measures to be done with the same exact landmarks used to establish distances for linear measures (Moreira et al, 2006).…”

Section: Discussionmentioning

confidence: 97%

“…Because the skulls have different sizes, from fetus to adult ages, right-left side differences obtained were converted into a percentage of asymmetry index (Mulick, 1965) as described by the following formula (Rossi et al, 2003):…”

Section: Methodsmentioning

confidence: 99%

“…When lateral asymmetry is excessive, it may lead to abnormal dental function and alter facial aesthetics. The correction of asymmetry of dental or skeletal origin is the main aim and one of the most challenging goals not only for orthodontics (Mulick, 1965;Kronmiller, 1998;Sheats et al, 1998) but also for oral and plastic surgeons. Studies with anteroposterior cephalometric radiographs show that children (Vig and Hewitt, 1975) and adults (Peck et al, 1991) with aesthetic faces have some different levels of skeletal asymmetries, which may be undetectable by visual inspection.…”

Section: Introductionmentioning

confidence: 99%

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Palatal asymmetry during development: An anatomical study

et al. 2008

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The purpose of this study was to evaluate hard palate asymmetry during development. The palates of 248 dry skulls were photographed and evaluated digitally. The skulls were divided into seven groups: fetus, newborn, infant, child, adolescent, adult, and aged. Linear measures were obtained from great palatine foramen (GPF) to incisive fossa (INC) and to posterior nasal spine (PNS). Angular measures were obtained from the former landmarks plus the point on sutures intersection between maxillary and palatine bones. Asymmetry was evaluated intra and intergroups. All skulls showed some degree of right-left asymmetry in the hard palate. Regardless of hard palate asymmetry, none of the right-left side differences was statistically significant. For the intergroups assessment, none of the asymmetry index means were statistically different. The posterior part of palate (PNS x GPF) measures was more asymmetric than the anterior part (INC x GPF), showing, respectively, 4.6% and 2.8% of mean asymmetry index. Angular measures showed a more symmetric behavior than the linear ones. Hard palate asymmetry occurs even in the absence of masticatory function, showing that this feature begins early in fetal life and persists through development.

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An investigation of craniofacial asymmetry using the serial twin-study method

Cited by 48 publications

References 43 publications

Asymmetry of the Face in Orthodontic Patients

Asymmetry of the Face in Orthodontic Patients

A quantitative genetic study of cephalometric variables in twins

Palatal asymmetry during development: An anatomical study

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