Facial form in hypodontia using novel 3D life-like average images

Background: The clinical experience of the Newcastle hypodontia team, UK supported by cephalometric evidence indicates that there is an altered facial form in hypodontia patients. Cephalometric radiographs can provide useful information about craniofacial morphology.  However, they are invasive, two-dimensional and offer little information about facial shape.  New 3D imaging system may offer more useful information and allow the study of the complete facial shape.

Objectives: To compare the facial form of hypodontia and control children using novel constructed 3D life-like average faces.

Methods: Cross-sectional prospective case-controlled study was undertaken at Newcastle Dental Hospital during 2004-2008. 65 hypodontia and 54 Class I controls, male and female children between the ages of 10 and 17 years participated. 3D facial stereophotogrammetric images obtained using 3dMD imager (3dMD & 3Q company, Atlanta/USA). Images were analysed using MorphoAnalyser (Tiddeman B.P., St Andrews University, UK). For each image, 28 landmarks were digitized and the images merged to construct life-like average faces for males and females in each group. Superimposition of the averages of the two groups was undertaken using Procrustes analysis and the differences were analysed using independent t-tests.

Results: There was a significant variation in the facial ‎form of hypodontia and control children. Hypodontia patients are characterised by a decreased anterior facial height (4.79mm/P=0.005) and width (3.25mm/P=0.032), retruded and shorter lips (1.69mm/P=0.028), protruded chin (1.67mm/P=0.019), increased nasolabial (5.39^O/P=0.007) and interlabial angles (4.62^O/P=0.021). Male hypodontia patients had a more feminine appearance. ‎

Conclusions: 3D life-like face averages of the control and hypodontia children provide valuable information about facial morphology that can be compared with face averages of children with craniofacial anomalies. There was a significant difference in the facial soft-tissue form of hypodontia patients. These results will hopefully lead to improved ‎understanding of the effects of hypodontia on facial form.