Among the different indexes for assessing skeletal maturation in patients, the cervical vertebral maturation (CVM) method has been gaining attention in recent years. It has been used in a number of studies concerning the treatment effects and timing for various orthodontic and orthopedic appliances.1, 2, 3 In the “Ask Us” section of the Reader's Forum in the July 2002 issue of the AJO-DO, Dr Leonard Fishman replied to the question about the accuracy of the CVM method to evaluate skeletal maturity. Because of its many clinical implications and the limited information that can be gained from Dr Fishman's response (which focused mostly on the hand and wrist method), we believe that further clarification is needed to highlight the characteristics and the potential of the CVM method.
The method is based on the morphological characteristics of the cervical vertebrae at different developmental stages that correlate with different growth rates in facial and somatic structures. The original CVM method4, 5 comprised 6 stages of development that involved changes in the morphology of the second through sixth vertebrae, as seen in lateral cephalograms. A newly improved CVM method6 consists of 5 stages of development in the second through fourth vertebrae. Thus, analysis is possible with the patient wearing a high protective collar.
The reliability and efficiency of a biologic indicator of individual mandibularskeletal maturity can be evaluated with respect to several fundamental requirements.7
•Efficacy in detecting the peak in mandibular growth. The method should have a definite stage or phase that coincides with the peak in mandibular growth in most subjects. The efficacy of several biologic indicators has been evaluated with regard to the growth spurt in body height. An evaluation of the direct correlation between changes in the biologic indicator and changes in mandibular growth at puberty (which is of the greatest clinical interest for orthodontists) is available for only a few methods (CVM, hand and wrist, changes in body height).
•No need for additional x-ray exposure.
•Ease in recording.
•Consistency in the interpretation of the data. The interexaminer error in the appraisal of the definite stages or phases should be as low as possible.
•Usefulness for anticipating the growth peak. The method should have a definite stage or phase that occurs before the peak in mandibular growth in most subjects.
With respect to these 5 “ideal” features of a biologic indicator, the CVM method has the following characteristics:
•In over 90% of North American subjects, the growth interval between stages 3 and 4 in the original CVM5 coincides with the pubertal peak in both mandibular growth and body height. The peak in mandibular growth occurs during the interval between stages 2 and 3 in the newly improved CVM method.6
•The appraisal of CVM is performed on the lateral cephalogram that is used routinely for orthodontic diagnosis. Therefore, no additional x-ray exposure is required.
•The ease of recording the various CVM stages has been improved.6, 7
•Reproducibility of recorded data (identification of CVM stages) is very high: 91.2% according to Pancherz and Szyska8 and 98.6% according to Baccetti et al.6
•The method is useful for anticipating the pubertal peak in mandibular growth. The peak has not been reached if the initial stages in CVM are recorded in a patient. Active growth is completed when the last stage in CVM is recorded.
Our investigations during the past few years were based on longitudinal observations in both boys and girls who were analyzed throughout the circumpubertal period. The findings of these studies indicate clearly that the CVM method is a highly reliable way to assess skeletal maturity in a patient, with special regard to the growth rate of the mandible. Therefore, the method is suitable for orthodontic diagnosis and for classifying groups of patients according to skeletal maturation. The use of the CVM method is recommended in investigations that deal with treatment outcomes of various protocols of orthodontic therapy, especially when lateral cephalograms are the only radiographic material available.
No differences in the assessment of individual maturity between the CVM and the hand-wrist method have been reported in previous studies,8, 9 and the CVM method has the advantage of not requiring additional x-ray exposure. Finally, the CVM method describes the entire circumpubertal period by covering all significant phases in craniofacial growth during adolescence and young adulthood, and it is valid for both sexes.
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