Soegiharto, B.M.; (2007) Skeletal maturation assessment in orthodontics. Doctoral thesis , University of London.

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Abstract

Aims: (1) To assess skeletal maturation in orthodontics using hand-wrist and cervical vertebrae methods and (2) To characterise the morphological differences of the craniofacial and cervical vertebrae morphologies at different growth stages in two different populations.;Subjects and Methods for the main study: The study included 2,167 subjects with hand-wrist and lateral cephalometric radiographs. Of these, there were 648 Indonesian males, 303 Caucasian males (age range 10-17 years), 774 Indonesian females and 442 Caucasian females (age range 8-15 years). Each hand-wrist radiograph was observed and classified according to the Skeletal Maturation Index (SMI) (Fishman, 1982). Similarly, cervical vertebrae maturation was assessed using lateral cephalometric radiographs. The outlines of the cervical vertebrae were traced and classified according to the Cervical Vertebrae Maturation (CVM) Index (Baccetti et al., 2002). Craniofacial and cervical vertebrae morphologies were evaluated from the lateral cephalograms. Each radiograph was initially traced and then digitised using a customised computer program.;Results: 1. Repeatability study (Chapter 2) Kappa values showed substantial to good intra-operator repeatability for the Skeletal Maturation Index (SMI) and Cervical Vertebrae Maturation (CVM Index) for both ethnic groups and these two methods were used in the main study. For the cephalometric data, the Bland and Altaian method and the Lin's Concordance Correlations showed acceptable agreement and the methods were considered appropriate for use in the main study. 2. Main study: Chapter 3: Skeletal maturation stages were described using the SMI and CVM Index. On average, the Caucasian children attained each maturational stage at an earlier age than their Indonesian peers although the differences were less obvious in females than in males. Multiple regression analysis showed that, on average at any given age, the Caucasian males were 1 SMI stage ahead of the Indonesians, whilst the Caucasian females were around 0.5 SMI stage ahead of their Indonesian peers. Chapter 4: Ages of attainment of peak pubertal growth for the selected craniofacial parameters were determined. Growth curves and growth velocity curves were constructed for each of these parameters. The results for the craniofacial parameters showed that the Caucasian males attained peak pubertal growth slightly earlier than their Indonesian peers for the majority of parameters. However, in contrast to the SMI and CVM Index results, the Indonesian female, on average, reached peak pubertal growth earlier than the Caucasians for the majority of parameters. In both Indonesians and Caucasians, on average, the females reached peak pubertal growth of the craniofacial parameters earlier than the males. Chapter 5: Receiver Operating Characteristic (ROC) analysis was performed to assess, and compare, the ability of the SMI and CVM Index to discriminate between subjects who had yet to attain peak pubertal growth and those who had reached, or passed it. This analysis was based on the velocity growth curves produced for Chapter 4. Areas Under the ROC Curve analysis (AUC) for the SMI (AUC > 0.9) were greater than those for the CVM Index (AUC > 0.8) and the differences between the two methods were statistically significant (P<0.05 for all parameters investigated). Nevertheless, the curves for both SMI and CVM approached the top left comer of the ROC graphs, indicating that both tests have good discriminatory ability. The differences between the two methods ranged between only 1 and 7%. Chapter 6: Differences in the craniofacial and cervical vertebrae structures at different growth stages in both ethnic and gender groups were investigated.;Conclusions: Differences in the age of attainment of each skeletal maturation stage, as well as the age of attainment of the peak pubertal growth of selected craniofacial parameters, exist between the two ethnic and gender groups. These differences need to be taken into account in orthodontic diagnosis and treatment planning. This study also confirmed the validity of both the SMI and CVM Index to discriminate individuals into those who have yet to attain peak pubertal growth and those who have reached/passed peak pubertal growth. However, as the differences in the discriminatory ability were low, this study questions the benefit of taking additional hand-wrist radiographs when the use of lateral cephalograms can be optimised. There were differences in craniofacial and cervical vertebrae morphologies between the two ethnic and gender groups, although they were usually not statistically significant. A small number of parameters showed statistically significant differences, however, these differences were small and unlikely to be clinically relevant. Therefore this study suggests that orthodontic modalities commonly used in Caucasians, may also be applied in Indonesian subjects and that the use of the CVM Index is justified in Indonesians. (Abstract shortened by UMI.).

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