Dento-facial relationships in individuals with normal occlusion.

The aim of this study was to evaluate the relationships of selected facial measurements with mesio-distal crown widths and dental arch dimensions in individuals with normal occlusions. A cross-sectional study was conducted on 276 subjects with Angle's Class I normal occlusions. Three-dimensional images of the face and dental casts were captured and analyzed using stereophotogrammetric systems. Significant correlations were found between the sagittal facial variables and both upper and lower dental arch dimensions and to lesser degree with the horizontal and vertical variables. The values of correlation coefficients calculated between facial and dental crown measurements ranged from .01 to .50 for upper teeth and .01 to .49 for lower teeth. The values of correlation coefficients between facial and upper dental arch dimensions ranged from .01 to .55 and those between facial and lower dental arch dimensions ranged from .01 to .60. A principal components analysis showed that the sagittal dimensions, face height, nose, labial fissure, binocular widths were positively associated with dental arch dimensions and mesio-distal crown diameters in males. On the other hand, only the sagittal variables were associated with dental dimensions in females. The results of this study confirm that positive associations exist between facial and dental arch dimensions. These relationships should be taken into consideration when attempts are made to modify dental arch size as part of orthodontic treatment. Moreover, these relationships are also relevant to prosthodontists involved with selecting tooth sizes that display optimal functional balance with the craniofacial structures.

Validity and reliability of tooth size and dental arch measurements: a stereo photogrammetric study.

BACKGROUND: The development of three-dimensional computer imaging has many applications in dentistry, including the analysis of dental casts. AIMS: To assess the validity and reliability of a dental stereophotogrammetric imaging system. METHODS: The sample consisted of 35 sets of dental costs. Maxillary and mandibular dental crown widths and selected dental arch dimensions were measured directly using digital calipers. Cast images were also captured by a stereophotogrammetric system and analysed using Australis software. Dahlberg's formula, paired t-tests and intra-class correlations were used to assess the random error, validity and reliability of the measurements, respectively. RESULTS: Most values demonstrated no significant difference between the direct and three-dimensional measurements with mean differences ranging from 0.05-0.21 mm. Moreover, values of intra-class correlation coefficients ranged between 0.80-0.99 for intra-examiner reliability. CONCLUSIONS: Mesiodistal crown widths and dental arch dimensions may be measured accurately with relatively small error by the specially-designed 3D system and confirms its suitability for clinical and research purposes.

Stereophotogrammetric analysis of nasolabial morphology among Asian Malays: influence of age and sex.

OBJECTIVE: It is clear that population-specific norms should be used when planning plastic and reconstructive surgery for selected patients. In this study, we aimed to generate nasal and labial reference values by applying a stereophotogrammetric technique. A further aim was to investigate the effect of sexual dimorphism, age-related changes, and the interrelation between nasal and labial morphology. DESIGN: Cross-sectional study. SETTING: The data were collected from different locations on the Malaysian peninsula. PARTICIPANTS: A total of 276 Asian Malays (138 males and 138 females) were included in this study, and a three-dimensional system was used for capturing data. The sample was divided into three age groups: 13 to 14, 15 to 17, and 18 to 36 years. MAIN OUTCOME MEASURE(S): Twenty-five dimensions of the nose and lips were measured and analyzed separately in males and females. RESULTS: Significant differences between males and females were identified in 11 distances, and significant effects of age were found in most of the dimensions (p < .05). Significant correlations between the nasal and labial dimensions were recorded, particularly between lateral lip height and width of the ala insertion. A principal component analysis showed interrelationships between the nasal width distances and upper lip height. CONCLUSION: This study has provided a new three-dimensional database for nose and lip morphology in Malays and demonstrated patterns of variation that can be used by surgeons to make comparisons within and between different human populations and also to develop treatment plans for their patients.