The purpose of the current report was to investigate cephalometrically possible orthopaedic effects of a modified maxillary protraction headgear (MPH) on dentofacial morphology in skeletal Class III female patients before and during the pubertal growth spurt period. Sixty-one patients were divided into three groups, the prepubertal (7-10 years, n = 20), the mid-pubertal (10-12 years, n = 22), and the late pubertal (12-15 years, n = 19) groups. Longitudinal record sets of subjects with acceptable good occlusion were used as the control. Patients were treated by protracting from the upper canine area. The mean ages at completion of the MPH treatment were 8.9, 11.3, and 13.3 years for the three test groups, respectively. The average treatment time was 1.1, 1.0, and 1.4 years for each of these groups. Lateral cephalograms at the start and completion of use of the MPH were collected. Annual differences were calculated from these paired records for each of 21 dentoskeletal variables in the test groups and compared to those of the control group. The pre- and mid-pubertal groups revealed significant increases in both the SNA (P < 0.01 and P < 0.001) and the maxillary length (Ptm-A/PP, P < 0.01), while the late pubertal group showed a less significant increase in the SNA (P < 0.05) alone. The decreased SNB, increased ANB and SNMP of the pre- and mid-pubertal groups was accounted for by the backward and downward rotation of the mandible. The results suggest possible orthopaedic effects of the MPH on dentofacial morphology in young females when it is applied before or during acceleration of the pubertal growth spurt.

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Objectives To elucidate the relationships and factors affecting the proximity between the incisive canal (IC) and maxillary central incisors and to predict the probable outcomes after anterior tooth retraction using cone beam computed tomography (CBCT). Materials and Methods Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction. Results All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC. Conclusions Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.

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