Quantitative cervical vertebral maturation assessment in adolescents with normal occlusion: a mixed longitudinal study.

INTRODUCTION: The purpose of this study was to establish a quantitative cervical vertebral maturation (CVM) system for adolescents with normal occlusion. METHODS: Mixed longitudinal data were used. The subjects included 87 children and adolescents from 8 to 18 years old with normal occlusion (32 boys, 55 girls) selected from 901 candidates. Sequential lateral cephalograms and hand-wrist films were taken once a year for 6 years. The lateral cephalograms of all subjects were divided into 11 maturation groups according to the Fishman skeletal maturity indicators. The morphologic characteristics of the second, third, and fourth cervical vertebrae at 11 developmental stages were measured and analyzed. RESULTS: Three characteristic parameters (H4/W4, AH3/PH3, @2) were selected to determine the classification of CVM. With 3 morphologic variables, the quantitative CVM system including 4 maturational stages was established. An equation that can accurately estimate the maturation of the cervical vertebrae was established: CVM stage=-4.13+3.57xH4/W4+4.07xAH3/PH3+0.03x@2. CONCLUSIONS: The quantitative CVM method is an efficient, objective, and relatively simple approach to assess the level of skeletal maturation during adolescence.

[Assessment of facial skeletal growth and response to implanted functional appliance therapy with three-dimensional images].

PURPOSE: To evaluate the facial skeletal growth and response to implanted functional appliance therapy with three-dimensional images. METHODS: Eleven male Beagle dogs (7 months old and in late mixed dentition) were randomly divided into four groups: implanted functional appliance group, semi-implanted functional appliance group, modified Forsus(TM) group and the control group. After the appliances were inserted in the experimental groups for 4, 8, 12 weeks and 4 weeks after the appliances were removed, the facial skeleton and teeth of the Beagle dogs digital information was obtained by using spiral computed tomography, then Mimics 8.1 software and a kind of retro-engineering software called qualify V8.0 were used to establish three-dimensional facial skeletal and dental images of the Beagle dogs. Three-dimensional structure changes of the facial skeleton and teeth in each group at different stages were assessed by the Bjork method, i.e. the superimposition technique based on the "best fit" of anterior cranial base structure and mandible metallic implants. RESULTS: Mandibles in the groups with implanted functional appliance, semi-implanted functional appliance, and modified ForsusTM were obviously displaced forward, while the growth of the maxilla was inhibited in some degree. The displacement of upper teeth in the group with implanted functional appliance was not obvious, while the distal movement of upper teeth in the group with semi-implanted functional appliance and modified ForsusTM was significant compared with that in the control group. CONCLUSIONS: The implanted functional appliance can significantly stimulate the growth of the mandible and avoid the unwanted movement of teeth which is frequently found in other functional appliances. Supported by Wenzhou International Cooperative Research Project (Grant No. B00260027).