How does variation in lower anterior face height influence perceived attractiveness? A quantitative investigation.

OBJECTIVE: The purpose of this investigation was to undertake an objective and quantitative evaluation of how severity of lower anterior face height (LAFH) variations influences perceived attractiveness. DESIGN: Cross-sectional study SETTING: St George's Hospital, London, UK PARTICIPANTS AND METHODS: The LAFH of an idealized male and female frontal facial image were altered in 2·5 mm increments from -20 to 20 mm (male images) and from -10 to 20 mm (female images), in order to represent reduction and increase in height of this region. These images were rated by a pre-selected group of pre-treatment orthognathic patients (n = 75), clinicians (n = 35) and laypersons (n = 75). OUTCOME MEASURES: Ratings on a seven-point Likert scale. RESULTS: With an increase in LAFH, desire for surgery became significant at 15-16 mm for male faces and 13-14 mm for female faces. With a reduction in LAFH, desire for surgery became significant at -14 to -17 mm for male faces; a smaller reduction of -6 to -8 mm led to a significant desire for surgery for female faces. CONCLUSIONS: The classical vertical facial trisection canon of upper face height as one-third (33·3%), midface height as one-third (33·3%) and LAFH as one-third (33·3%) of total anterior face height may be used as an 'ideal' proportional ratio. Mild LAFH variations were largely acceptable. In terms of the percentage LAFH to total anterior face height (TAFH) and anterior face height (AFH), observers did not desire surgery for LAFH variations of 25-42% of TAFH (40-66% of AFH) for male faces, and 28-42% of TAFH (45-66% of AFH) for female faces.

The influence of combined orthodontic-orthognathic surgical treatment on perceptions of attractiveness: a longitudinal study.

The purpose of this investigation was to quantitatively evaluate the influence of completing the orthognathic treatment process on patients' perceptions of attractiveness and their desire for surgical correction. The mandibular prominence of an idealized profile image was altered in 2 mm increments from -16 to 12 mm, in order to represent retrusion and protrusion of the mandible, respectively. These images were rated on a seven-point Likert scale by 50 patients at T1 (pre-treatment) and T2 (6 months following orthodontic appliance removal). At T1, mandibular retrusion became noticeable at -4 mm and protrusion at 2 mm. The results remained unchanged at T2. Surgery was desired from -9 mm at T1 and -10 mm at T2. For mandibular protrusion, surgery was desired from 3 mm at T1 and 4 mm at T2. The odds of desire for surgery were reduced by 85 per cent for those patients who had undergone bimaxillary surgery in relation to those with single jaw surgery. The lowest rated images demonstrated severe degrees of mandibular protrusion and retrusion. The highest rated images represented the idealized facial profile and minor variations thereof; there was little change in perception between T1 and T2. Going through the process of orthognathic treatment does not appear to have any significant effect on patients' perceptions of facial profile attractiveness or the limits of mandibular sagittal deviation at which they would desire surgery. The clinician's information provision during treatment does not seem to unduly influence orthognathic patients and does not make them more critical of jaw deformities.

Assessing the influence of lower facial profile convexity on perceived attractiveness in the orthognathic patient, clinician, and layperson.

OBJECTIVE: The aim was a quantitative evaluation of how the severity of lower facial profile convexity influences perceived attractiveness. STUDY DESIGN: The lower facial profile of an idealized image was altered incrementally between 14° to -16°. Images were rated on a Likert scale by orthognathic patients, laypeople, and clinicians. RESULTS: Attractiveness ratings were greater for straight profiles in relation to convex/concave, with no significant difference between convex and concave profiles. Ratings decreased by 0.23 of a level for every degree increase in the convexity angle. Class II/III patients gave significantly reduced ratings of attractiveness and had greater desire for surgery than class I. CONCLUSIONS: A straight profile is perceived as most attractive and greater degrees of convexity or concavity deemed progressively less attractive, but a range of 10° to -12° may be deemed acceptable; beyond these values surgical correction is desired. Patients are most critical, and clinicians are more critical than laypeople.

Assessing the influence of asymmeftry affecting the mandible and chin point on perceived attractiveness in the orthognathic patient, clinician, and layperson.

PURPOSE: The purpose of this investigation was to undertake an objective and quantitative evaluation of how severity of asymmetries affecting the mandible and chin point influence perceived attractiveness. MATERIALS AND METHODS: The mandible and chin point of idealized male and female frontal facial images were altered in 5-mm increments from 0 to 25 mm and to the left and right, to represent horizontal, vertical, and combined asymmetry affecting these regions. These images were rated on a 7-point Likert scale by a preselected group of orthognathic patients before treatment, clinicians, and laypeople. RESULTS: In relation to a 5-mm asymmetry, observers progressively decreased attractiveness ratings and increased the desire for surgery for greater asymmetries. Clinicians and patients were found to be more critical than laypeople. The desire for surgery decreased by 3% for each year increase in age, was 53% less for men, and 45% greater for white observers. CONCLUSIONS: Asymmetry of 10 mm is perceived as being significant; at 5 mm and below, it is largely unnoticed. The greater the degree of asymmetry greater than 10 mm, the more noticeable and the greater the desire was for correction. Clinician and patient ratings were similar and more critical than ratings of laypeople. A desire for surgery was negligible for 5 mm of asymmetry but increased considerably at 10 mm and continued to increase with greater degrees of asymmetry. The highest-rated images showed perfect bilateral symmetry, whereas the lowest-rated images showed significant degrees of mandibular and chin asymmetry.

Influence of chin height on perceived attractiveness in the orthognathic patient, layperson, and clinician.

OBJECTIVE: To determine an objective and quantitative evaluation of how severity of chin height variations influence perceived attractiveness. MATERIALS AND METHODS: The chin height of an idealized male and female frontal facial image was altered in 2.5-mm increments from -12.5 to 22.5 mm (male images) and from -10 to 20 mm (female images). These images were rated on a seven-point Likert scale by a preselected group of pretreatment orthognathic patients, clinicians, and laypeople. RESULTS: The classical lower facial proportional canon of upper lip height as one third (33.3%), lower lip height as one third (33.3%) and chin height as one third (33.3%) of lower anterior face height (LAFH) may be used as an "ideal" proportional ratio. However, chin height variations within a given proportional range are largely unnoticed, ie, from approximately 30% chin height in relation to LAFH (male and female) up to approximately 40% (males) and 50% (females) chin height in relation to LAFH. Additionally, surgery is only desired with greater variations in chin height: greater than 50% and less than 20%-23% of LAFH in males, and greater than 58% and less than 20%-22% of LAFH in females. Patients and clinicians are more critical than laypeople, but no significant differences were found between clinicians and patients. CONCLUSIONS: In relation to the classical canon, surgical correction of chin height deformities are desired with chin height greater than 50% and less than 20%-23% of LAFH in males, and greater than 58% and less than 20%-22% of LAFH in females.

Reliability and cross-cultural validity of a Japanese version of the Dental Fear Survey.

BACKGROUND: This study established the reliability and cross-cultural validity of a Japanese version of the Dental Fear Survey (DFS). METHODS: Two studies were carried out in separate populations. The first involved 166 Japanese dental and nursing students and assessed internal consistency and test-retest reliability. The second involved 2,095 Japanese parents or guardians of school children and tested the hypothesis that the conceptual structure of the Japanese translation was consistent with the U.S. version using Structural Equation Modeling (SEM). RESULTS: In the first study Cronbach alpha ranged from .94 to .96 and test-retest reliability (Spearman correlation) ranged from .89 to .92. The intra-class correlation coefficients (ICC) was 0.919 (95%CI: 0.892 - 0.940). In the second study SEM was used on the covariance matrix of the 20 questions in a random sample of 600 questionnaires to evaluate the goodness of fit of the theoretical model; and then, in an exploratory manner corrected for specification errors until a model that fit the data well was achieved. CONCLUSION: The Japanese version of the DFS appears reliable and demonstrates cross-cultural validity. The modeling confirms the three factors on which the English language version was based.

Dental age assessment (DAA): reference data for British caucasians at the 16 year threshold.

UNLABELLED: The purpose of this study was to determine reference data for dental age assessment (DAA) for the 16 year threshold in British caucasians. PATIENTS, MATERIALS AND METHODS: One thousand seven hundred and twenty-two Dental Panoramic Radiographs of individuals aged between 4 and 24 years were re-used to establish reference intervals using the tooth development stages (TDSs) previously described [A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age, assessment, Human Biology 45 (1973) 221-227]. All teeth present in the left maxilla and mandible, and the third permanent molars were assessed. In addition, to test the accuracy of DAA, the radiographs of a study sample of 50 children of known chronological age (CA) were assessed in the same manner as the reference population. These were aged between 15 and 17 years and separate from the database. For each subject in the study sample a new method of mathematical manipulation based on meta-analysis was applied to all teeth that were still developing [G.J. Roberts, S. Parekh, A. Petrie, V.S. Lucas, Dental age assessment (DAA): a simple method for children and emerging adults, British Dental Journal 204(4) (2008) 192-193]. The estimated calculated average of all the teeth present on the radiograph of each individual generated by the meta-analysis was assigned to each individual as the dental age. For each test subject this was then compared to the gold standard of chronological age. RESULTS: The average difference between dental age and chronological age for individuals in the test sample was 0.27 years (3.24 months) in females and 0.23 years (2.76 months) in males. CONCLUSION: Dental age assessment obtained by calculation of tooth development stages using meta-analysis provides estimates of age around the 16 year threshold.