Quantitative evaluation of lip symmetry in functional asymmetry.
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The objectives of this study were to quantitate lip symmetry/asymmetry from clinical photographs; to demonstrate that asymmetry due to functional side shifts (functional asymmetry) leading to unilateral crossbites including the canines, results from measurable thinning of the upper lip and thickening of the lower lip on the side of the crossbite when viewed in the intercuspal contact position; and to show that orthodontic treatment aimed at eliminating the functional shift and crossbite would achieve lip symmetry, both visually and quantitatively. The study consisted of 26 patients, who were divided into two groups: a study group of 13 patients (eight females, five males, aged 8-17 years) with a functional asymmetry, and a control group of 13 age- and gender-matched subjects with other forms of malocclusion without functional asymmetry. All patients in the study group exhibited unilateral crossbites including the canines in intercuspal contact position. Digitized images of frontal facial photographs were analysed for upper and lower lip symmetry pre- and post-orthodontic treatment. The upper and lower lips were subdivided into four quadrants and the surface area and length of each quadrant were measured and expressed as a percentage of the total surface area/length of the relevant lip. The degree of asymmetry was obtained by calculating the difference in percentage area or length between the two quadrants of each lip. In the study group, the lower lip quadrant on the shift side was enlarged while the contralateral side was reduced (mean area ratio 59.9 to 40.1 per cent, mean length ratio 53.0 to 47.0 per cent). The upper lip demonstrated differences that were smaller and inverse. The controls showed a small difference between the right and left sides (less than 1 per cent). After treatment, both groups displayed visual and quantitative lower and upper lip symmetry, i.e. an area or length of approximately 50 per cent of each quadrant. In absolute values, the control patients had up to 3 per cent asymmetry in area regardless of treatment. The patients in the study group exhibited mean absolute asymmetry of 9.2 per cent in the upper lip and 19.8 per cent in the lower lip. Asymmetry values in the study group were reduced to approximately 3 per cent post-treatment. The absolute values of asymmetry in length of all patients were up to 2 per cent in the control group regardless of treatment. The subjects in the study group exhibited mean absolute asymmetry of 6.3 per cent in the upper lip and 8.6 per cent in the lower lip. Asymmetry values in the study group were reduced post-treatment to approximately 2 per cent. Although asymmetry in the study group could be quantitated using both parameters (lip surface area and lip length), the surface area parameter proved to be a more sensitive tool for measuring lip asymmetry. (+info)
Unilateral Angle II in functional lateralities.
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The aim of this study was to explore unilateral Angle II-type malocclusion prevalences in functionally true right-sided (TRS) and non-right-sided (NRS) children having one or more left-sided functions (eye, hand, foot). A half cusp sagittal relationship of the upper and lower M1 and Dm2 was determined on dental casts of 1423 young American black and white children in a cross-sectional sample with the mean age of 8.5 years (range 6-12 years). Hand, foot and eye preferences were recorded at the age of 4 years during the Collaborative Perinatal Study. The prevalences of symmetric bilateral Angle I and II and asymmetric unilateral Angle II right and Angle II left cases were compared between TRS and NRS children using Chi-square analysis. In general, unilateral Angle II right occurred in 9 per cent of the population and Angle II left in 6.5 per cent. In moderate non-right sideness (two-thirds of left dominant functions), these proportions were 17 and 3 per cent, respectively, and in true right sidedness 8 and 6 per cent, respectively. TRS subjects were more symmetric (bilateral Angle I or II in 85 per cent of cases) than NRS children (80 per cent), and the differences were statistically significant (P < 0.02). These results highlight the anatomical relationships of structures supporting the occlusion and the symmetry/asymmetry of the neurocranium, cranial base, masticatory apparatus, and probably also the sidedness and the growth-stimulating effect of lateralized jaw function. Based on the results and considering earlier observations on brain asymmetry in functional lateralities, it can be hypothesized that a normal symmetric sagittal occlusal relationship is based on unilateral sagittal compensatory growth to maintain optimal bite, challenging early preventive orthodontic treatment in suspect unilateral Angle II cases. (+info)
Bifid mandibular condyle: case report and etiological considerations.
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Bifid mandibular condyle, usually diagnosed on routine radiographic examination, is described in the literature as a rare entity. Its cause is controversial, and it has no predilection by sex or ethnic background. Dental professionals should have some knowledge of this anatomic abnormality, as well as its implications for function and appropriate treatment modalities, so that they can be alert to this potential diagnosis. This paper reports an unusual case of bifid mandibular condyle with possible traumatic cause, with emphasis on the radiographic and tomographic findings. (+info)
Detecting hemifacial asymmetries in emotional expression with three-dimensional computerized image analysis.
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Emotions are expressed more clearly on the left side of the face than the right: an asymmetry that probably stems from right hemisphere dominance for emotional expression (right hemisphere model). More controversially, it has been suggested that the left hemiface bias is stronger for negative emotions and weaker or reversed for positive emotions (valence model). We examined the veracity of the right hemisphere and valence models by measuring asymmetries in: (i) movement of the face; and (ii) observer's rating of emotionality. The study uses a precise three-dimensional (3D) imaging technique to measure facial movement and to provide images that simultaneously capture the left or right hemifaces. Models (n = 16) with happy, sad and neutral expressions were digitally captured and manipulated. Comparison of the neutral and happy or sad images revealed greater movement of the left hemiface, regardless of the valence of the emotion, supporting the right hemisphere model. There was a trend, however, for left-sided movement to be more pronounced for negative than positive emotions. Participants (n = 357) reported that portraits rotated so that the left hemiface was featured, were more expressive of negative emotions whereas right hemiface portraits were more expressive for positive emotions, supporting the valence model. The effect of valence was moderated when the images were mirror-reversed. The data demonstrate that relatively small rotations of the head have a dramatic effect on the expression of positive and negative emotions. The fact that the effect of valence was not captured by the movement analysis demonstrates that subtle movements can have a strong effect on the expression of emotion. (+info)
Unilateral posterior crossbite and chin deviation: is there a correlation?
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A retrospective study evaluating the clinical discernment of chin deviations in general, and especially in relation to unilateral posterior crossbite (UPXB), was carried out to determine whether (1) there is a correlation between UPXB and clinically discernible chin deviation, (2) there are differences between the judgement of professional dental observers and laymen, (3) visual assessment of chin deviation compares well with computer-assisted assessment and (4) how large a chin deviation should be before it is noticed. The experimental group consisted of 72 patients (30 males and 42 females, average age 14.5 years) with a UPXB. A control group of 72 subjects without a UPXB was matched for age and sex. In addition, one computer-designed face was added with chin deviations of 0, 2, 4, 6 and 8 mm to the left. The full-face slides of all subjects were shown twice, with an interval of 2 weeks, to an audience of seven orthodontists, ten dental students and five laymen judging by eye. A computer-assisted assessment was carried out by one observer, in order to create a standardized comparison to visual scoring. Inter-observer examination of visual scoring showed moderate agreement (kappa = 0.48). When comparing the computer-assisted and visual scores, the intra-class correlation coefficient (ICC) was 0.87. There were no major differences between professional observers and laymen, although the latter gave significantly more responses in the direction opposite to the crossbite. In 70.3 per cent (on average) of the subjects with a crossbite, a deviation in the same direction as the crossbite was noticed visually. The majority of the observers observed a chin deviation of at least 4 mm. (+info)
The relationship between sexual dimorphism in human faces and fluctuating asymmetry.
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Previous studies have found both support and lack of support for a positive relationship between masculinity and symmetry, two putative signs of mate quality, in male faces. We re-examined this relationship using an explicit measure of facial fluctuating asymmetry, as well as other measures of asymmetry, and measures of facial masculinity/femininity. We also used ratings of these traits for faces. Further, we examined the relationship between facial sexual dimorphism and body asymmetry. We found no significant correlations between facial masculinity and any of our measures of asymmetry or ratings of symmetry in males. Facial femininity was not consistently associated with facial symmetry in females, but was associated with body symmetry. Therefore, for females, but not males, facial femininity and body symmetry may reflect similar aspects of mate quality. We also examined the relationships between trait ratings and measurements. Our results provide validation of our ability to measure aspects of asymmetry that are perceived to be symmetrical, and aspects of sexual dimorphism that are perceived as feminine in females and masculine in males. (+info)
Prenatal diagnosis of hemifacial microsomia and ipsilateral cerebellar hypoplasia in a fetus with oculoauriculovertebral spectrum.
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Oculoauriculovertebral spectrum, or Goldenhar syndrome, is characterized by varying degrees of prevalently unilateral underdevelopment of craniofacial structures (orbit, ear, mandible) and spinal anomalies. We report the prenatal ultrasonographic diagnosis made at 24 weeks' gestation in a family with a negative history. The prenatal diagnosis was suspected due to the presence of marked hemifacial microsomia and moderate ipsilateral cerebellar hemisphere hypoplasia in the absence of facial clefting. (+info)
Treatment of hemifacial microsomia in a growing child: the importance of co-operation between the orthodontist and the maxillofacial surgeon.
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The treatment of patients with hemifacial microsomia (HM) always requires an interdisciplinary approach including at least maxillofacial surgery and orthodontics. Co-operation not only within the team, but also with the patients and their family is essential in order to achieve the best results. In the case history of the 10-(1/2) year old female patient reported here, three surgical interventions (two with costo-chondral bone grafts) and a 3-year orthodontic treatment have taken place. A harmonious facial and occlusal result was finally reached. (+info)