Treatment of class II malocclusion with Invisalign®: A pilot study using digital model-integrated maxillofacial cone beam computed tomography.

Background/purpose: The treatment effects of Invisalign® are still obscure due to methodological limitations of previous studies. We introduced a method to comprehensively evaluate the dental and skeletal changes of Class II malocclusion treated non-extraction with Invisalign® and compare with the virtual simulation of ClinCheck® using digital models integrated into maxillofacial cone-beam computed tomography (CBCT). Materials and methods: The pretreatment (T1) and posttreatment (T2) scanned digital images of actual dentitions were integrated into maxillofacial CBCT images. To evaluate three-dimensional movement of maxillary teeth and change of mandible position, T1 and T2 digital model-integrated maxillofacial CBCT images were superimposed using voxel-based registrations of stable cranial base structures. To evaluate movement of mandibular teeth, model-integrated mandibular CBCT superimposition was registered on mandibular basal bone. To compare achieved and predicted tooth movements, the actual dental images and the virtual digital models created by ClinCheck® were registered on the T1 dentitions. Results: For simulated upper first molar (U6) distalization of more than 1 mm, treatment accuracy ranged from 31.1% to 40.1%, which was significantly less than virtual planning and previous reports. In unilateral Class II subjects, the amount of U6 distalization on the Class II side was not significantly different from contralateral side, indicating efficacy of sequential distalization was questionable. Those with favorable overjet correction showed evidence of condylar distraction. Conclusion: Digital model-integrated CBCT superimpositions reflected the actual treatment changes in comparison with the virtual simulation, and showed that ideal occlusion was not achieved in mild to moderate Class II adult patients treated non-extraction with Invisalign®.

Current practice patterns and training project of orthodontic specialists in Taiwan in 2020.

BACKGROUND/PURPOSE: There were 661 board-certified orthodontic specialists in Taiwan in 2020. This study reported the current practice patterns and training project of orthodontic specialist in Taiwan. MATERIALS AND METHODS: This study exploited the secondary data analysis and interview to survey the current practice patterns and training project of orthodontic specialists in Taiwan. RESULTS: Of the 661 orthodontic specialists, there were 84 registered in the medical centers, 44 in the regional hospitals, 7 in the district hospitals, and 526 in the dental clinics, respectively. There were 20 orthodontic specialist training institutions (15 medical centers, 3 regional hospitals, one district hospital, and one dental clinic) that had 218 dentists in orthodontic departments of training institutions and a training capacity of 51 dentists. Of the 20 orthodontic specialist training institutions in Taiwan in 2020, 12 were located in the northern, 4 in the central, and 4 in the southern regions of Taiwan. Moreover, we found none of the training institutions in the eastern and offshore island regions of Taiwan and the number of the orthodontic specialists did increase along with the population and the number of the practicing dentists. CONCLUSION: There are three major orthodontic specialist occupation problems in Taiwan: a surplus of the orthodontic specialists in the near future, an uneven distribution of the orthodontic specialists, and a concentration of the orthodontic specialists in the metropolitan areas of the municipalities. Therefore, we suggest that the government and relevant professional groups should propose solutions for these problems as soon as possible.

Relationship between age at menarche and skeletal maturation stages in Taiwanese female orthodontic patients.

BACKGROUND/PURPOSE: The age at menarche reflects a pubertal girl's physiologic maturity. The aims of this study were to evaluate the relationship between the age at menarche and skeletal maturation in female orthodontic patients. METHODS: Hand-wrist radiographs and lateral cephalometric radiographs from 304 adolescent female subjects (age, 8-18.9 years) were selected from the files of the Department of Orthodontics, National Taiwan University Hospital (NTUH). Hand-wrist bone maturation stages were assessed using the NTUH Skeletal Maturation Index (NTUH-SMI). Cervical vertebral maturation stages (CVMS) were determined using the latest CVMS Index. Menarcheal ages were self-reported by the patients and verified by the patients' mothers. The relationships between the NTUH-SMI or CVM stages and menarcheal status were investigated. RESULTS: More than 90% of the 148 subjects who had already attained menstruation had skeletal maturation beyond the NTUH-SMI stage four or CVMS III. However, the subjects who had never experienced menarche mostly had skeletal maturation before NTUH-SMI stage five or CVMS IV. During the period of orthodontic treatment, 19 females experienced their menarche. The mean age at menarche for the 167 female patients in total was 11.97 years. In average, menarche occurred between NTUH-SMI stages four and five or between CVM stages III and IV. The percentage of girls with menses increased from 1.2% at age 9 to 6.6% at age 10, 39.5% at age 11, 81.4% at age 12, 97% at age 13, and 100% at age 14. Compared with the results obtained 20 years previously, we found a downward shift of 0.47 years per decade for the mean age at menarche in female orthodontic patients. CONCLUSION: The majority of female orthodontic patients have passed the pubertal growth spurt when they experience their menarche. Menarche usually follows the pubertal growth spurt by about 1 year and occurs after NTUH-SMI stage four or CVMS III.

Radiographic assessment of skeletal maturation stages for orthodontic patients: hand-wrist bones or cervical vertebrae?

BACKGROUND/PURPOSE: The skeletal maturation status of a growing patient can influence the selection of orthodontic treatment procedures. Either lateral cephalometric or hand-wrist radiography can be used to assess skeletal development. In this study, we examined the correlation between the maturation stages of cervical vertebrae and hand-wrist bones in Taiwanese individuals. METHODS: The study group consisted of 330 male and 379 female subjects ranging in age from 8 to 18 years. A total of 709 hand-wrist and 709 lateral cephalometric radiographs were analyzed. Hand-wrist maturation stages were assessed using National Taiwan University Hospital Skeletal Maturation Index (NTUH-SMI). Cervical vertebral maturation stages were determined by the latest Cervical Vertebral Maturation Stage (CVMS) Index. Spearman's rank correlation was used to correlate the respective maturation stages assessed from the hand-wrist bones and the cervical vertebrae. RESULTS: The values of Spearman's rank correlation were 0.910 for males and 0.937 for females, respectively. These data confirmed a strong and significant correlation between CVMS and NTUH-SMI systems (p less than 0.001). After comparison of the mean ages of subjects in different stages of CVMS and NTU-SMI systems, we found that CVMS I corresponded to NTUH-SMI stages 1 and 2, CVMS II to NTUH-SMI stage 3, CVMS III to NTUHSMI stage 4, CVMS IV to NTUH-SMI stage 5, CVMS V to NTUH-SMI stages 6, 7 and 8, and CVMS VI to NTUH-SMI stage 9. CONCLUSION: Our results indicate that cervical vertebral maturation stages can be used to replace hand-wrist bone maturation stages for evaluation of skeletal maturity in Taiwanese individuals.