Mixed dentition analysis using a multivariate approach / 대한치과교정학회지

OBJECTIVE: To develop a mixed dentition analysis method in consideration of the normal variation of tooth sizes. METHODS: According to the tooth-size of the maxillary central incisor, maxillary 1st molar, mandibular central incisor, mandibular lateral incisor, and mandibular 1st molar, 307 normal occlusion subjects were clustered into the smaller and larger tooth-size groups. Multiple regression analyses were then performed to predict the sizes of the canine and premolars for the 2 groups and both genders separately. For a cross validation dataset, 504 malocclusion patients were assigned into the 2 groups. Then multiple regression equations were applied. RESULTS: Our results show that the maximum errors of the predicted space for the canine, 1st and 2nd premolars were 0.71 and 0.82 mm residual standard deviation for the normal occlusion and malocclusion groups, respectively. For malocclusion patients, the prediction errors did not imply a statistically significant difference depending on the types of malocclusion nor the types of tooth-size groups. The frequency of prediction error more than 1 mm and 2 mm were 17.3% and 1.8%, respectively. The overall prediction accuracy was dramatically improved in this study compared to that of previous studies. CONCLUSIONS: The computer aided calculation method used in this study appeared to be more efficient.

Class III nonsurgical treatment using indirect skeletal anchorage: A case report / 대한치과교정학회지

Treatment of adult patients with Class III malocclusion frequently requires a combined orthodontic and surgical approach. However, if for various reasons, nonsurgical orthodontic treatment is chosen, a stable outcome requires careful consideration of the patient's biologic limitation. This case presents the orthodontic treatment of an adult with a Class III malocclusion, which was treated nonsurgically using indirect skeletal anchorage.

Cortical bone thickness and root proximity at mandibular interradicular sites: implications for orthodontic mini-implant placement / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to provide clinical guidelines to indicate the best location for mini-implants as it relates to the cortical bone thickness and root proximity. METHODS: CT images from 14 men and 14 women were used to evaluate the buccal interradicular cortical bone thickness and root proximity from mesial to the central incisor to the 2nd molar. Cortical bone thickness was measured at 4 different angles including 0degrees, 15degrees, 30degrees, and 45degrees. RESULTS: There was a statistically significant difference in cortical bone thickness between the second premolar/ first permanent molar site, central incisor/central incisor site, between the first/second permanent molar site and in the anterior region. A statistically significant difference in cortical bone thickness was also found when the angulation of placement was increased except for the 2 mm level from the alveolar crest. Interradicular spaces at the 1st/2nd premolar, 2nd premolar/1st permanent molar and 1st/2nd permanent molar sites are considered to be wide enough for mini-implant placement without root damage. CONCLUSIONS: Given the limits of this study, mini-implants for orthodontic anchorage may be well placed at the 4 and 6 mm level from the alveolar crest in the posterior region with a 30degrees and 45degrees angulation upon placement.

Orthodontic treatment of an impacted maxillary central incisor with dilacerations / 대한치과교정학회지

Impaction with a severely dilacerated root is seldom reported, especially in the maxillary incisor. It is probably because of the high clinical difficulty associated with bringing the dilacerated tooth into proper position, and the high chance of failure due to ankylosis, external root resorption, and root exposure after orthodontic traction. Even the successful cases may need periodontal surgery to improve the unesthetic gingival shape. However, it has previously been reported that an impacted maxillary central incisor was successfully treated by proper crown exposure and orthodontic traction. This article presents a case of an invertedly impacted maxillary right central incisor with a developing dilacerated root, which was aligned into proper position after orthodontic traction composed of two stages of a closed eruption technique.

Quantitative evaluation of cortical bone and soft tissue thickness in the mandible / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to provide an anatomical reference for cortical bone and soft tissue thickness, and the attached gingiva width in the mandible. METHODS: Fifteen males and fifteen females participated in this study. An acrylic template was fabricated and the radiopaque markers were bonded on the estimated alveolar crest to take measurements of the hard and soft tissue thickness at the same locations. CT images were taken in samples wearing an acrylic template. Cortical bone and soft tissue thickness were measured at 2, 4, 6 and 8 mm from the alveolar crest in interradicular spaces from central incisor to first permanent molar. The attached gingival width was calibrated. RESULTS: Cortical bone thickness was 1.33 +/- 0.38 mm and soft tissue thickness was 1.49 +/- 0.54 mm. Cortical bone thickness was increased in the posterior area, while it was not the case for the soft tissue thickness. In addition, the total thickness was 2.82 +/- 0.70. The attached gingival width was wider in the anterior area compared to that in posterior area. CONCLUSION: These results suggest that the attached gingiva width should be considered upon placement of mini-implants in the mandibular posterior area for orthodontic anchorage.

Maxillary protraction effects of TTBA (Tandem Traction Bow Appliance) therapy in Korean Class III children / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to investigate the maxillary protraction effects of the Tandem Traction Bow Appliance (TTBA), a new appliance devised several years ago for the treatment of growing skeletal Class III patients. METHODS: Participants were 88 Korean children (42 boys, 46 girls) with skeletal Class III malocclusion treated with TTBA at the orthodontic clinic of Ewha Womans University Mokdong Hospital. Mean age at the start of treatment was 7.5 years +/- 1.5 years. Mean treatment periods were 13 +/- 3 months. Pretreatment and posttreatment lateral cephalograms were traced and superimposed by the same investigator and analyzed by modified McNamara analysis and pitchfork analysis. Changes were evaluated with paired t-tests at a significance level of p < 0.05. RESULTS: The maxilla and maxillary dentition moved forward. The mandible moved backward, although not significantly; and the mandibular dentition moved forward. The net dental changes combined with the apical base change resulted in a favorable total molar relationship correction. Net dental movement was 26% and the apical base change 74% of the total molar relationship correction. CONCLUSION: These results suggest that TTBA has a maxillary protraction effect that can be useful in the treatment of growing skeletal Class III malocclusion with maxillary deficiency.