A geometric morphometric evaluation of facial hard tissue patterns
Tamana Sazgar1, Nagham M Al-Jaf2, Noraina Hafizan Norman3, Aspalilah Alias4
1 Centre of Pediatric Dentistry and Orthodontic Studies, Faculty of Dentistry, Universiti Teknologi MARA, Selangor, Malaysia; Department of Orthodontics, Faculty of Dentistry, Kabul University of Medical Sciences, Kabul, Afghanistan
2 Centre of Comprehensive Care Studies, Faculty of Dentistry, Universiti Teknologi MARA, Selangor, Malaysia
3 Centre of Pediatric Dentistry and Orthodontic Studies, Faculty of Dentistry, Universiti Teknologi MARA, Selangor, Malaysia
4 Department of Basic Sciences and Oral Biology, Faculty of Dentistry, Universiti Sains Islam Malaysia, Kuala Lumpur, Malaysia; Forensic Odontology Unit, Department of Imaging & Pathology, KU Leuven, Belgium; Department of Forensic Odontology, Faculty of Dental Medicine, Universitas Airlangga, Indonesia
Nagham M Al-Jaf
Center of Comprehensive Care Studies, Faculty of Dentistry, Universiti Teknologi MARA, Jalan Hospital, 47000 Sungai Buloh, Selangor
Source of Support: None, Conflict of Interest: None
OBJECTIVE: The purpose of this study was to investigate the size and shape variations of hard tissue patterns in different skeletal relations in Malaysian Malay subjects using the two-dimensional geometric morphometrics method.
MATERIALS AND METHODS: A total of 188 lateral cephalograms of adult Malay subjects (aged between 18 and 40 years) with Class I, II, and III skeletal relations were collected. Ten two-dimensional hard tissue landmarks were applied on lateral cephalograms which underwent landmark application and shape analyses as Procrustes ANOVA analysis, principal component analysis, canonical variate analysis, and discriminant function analysis. Statistical analyses were performed to find the mean and variance of each landmark using one-way ANOVA. The raw data from shape analysis were used to calculate the link between landmarks.
RESULTS: Skeletal relations showed 16 Principal Components which indicated that variances existed in 16 different dimensions. In Procrustes ANOVA, the Centroid size was significantly different in genders and skeletal relations (P < 0.01). Canonical variate analysis showed the highest Mahalanobis distances and Procrustes distances between Class II and III among skeletal relations and between gender groups (P < 0.0001). Discriminant function analysis showed the classification was mostly accurate, especially for Class II and Class III with success rates of 90.6% and 83.3%, respectively, after cross-validation. The statistical analysis showed significant differences (P < 0.05) in hard tissue landmarks.
CONCLUSION: There were different ANB angles in different skeletal relations. The GMM could be used as an alternative tool for diagnosis and treatment planning for craniofacial shape evaluations for future orthodontists and maxillofacial surgeons.