Objectives: The purpose of this retrospective study was to evaluate the accuracy of intraoral scan (IOS) images in the maxillary and mandibular arches with orthodontic brackets. Material and methods: From digital impressions of 140 patients who underwent orthodontic treatment, consecutive IOS images were selected based on standardized inclusion criteria: Two pre-orthodontic IOS images (IOS1 and IOS2) of permanent dentition with fully erupted second molars and IOS images obtained immediately after orthodontic bracket bonding (IOSb). Superimpositions were performed to evaluate the reproducibility of repeated IOS images. Accuracy of IOSb images was analyzed by comparing the average surface errors between IOS1c and IOS2c images, which were IOS images cut based on the same region of the interest as between IOS1 and IOSb images. Results: A total of 84 IOS images was analyzed. The average surface errors between IOS1 and IOS2 images were 57 ± 8 μm and 59 ± 14 μm in the maxillary and mandibular arch, respectively, and their reliability was almost perfect. The average errors between IOSb and IOS1c images exhibited an increase, which measured 97 ± 28 μm in the maxillary arch and 95 ± 29 μm in the mandibular arch. These surface deviations between IOSb and IOS1c images were significantly larger in each region as well as entire dentition (P < 0.001) compared to those between IOS1c and IOS2c images. Conclusions: The average surface errors of the scans with brackets showed increased values compared with those without brackets. This suggests that orthodontic brackets could affect the trueness of intraoral scan images. Clinical relevance: It is necessary for clinicians to consider the effect of brackets on digital impression when using IOS images in orthodontic patients.

Objective: : To evaluate the changes in soft tissue around the lips after orthodontic bracket debonding using three-dimensional (3-D) stereophotogrammetry. Materials and Methods: : 3-D facial images of 20 subjects (10 men and 10 women; mean age, 26.81 ± 7.23 years) were taken with a white light scanner before and after debonding the labial brackets. Two images acquired from each subject were superimposed, and 15 soft tissue landmarks around the lips were plotted and analyzed. Statistical analysis was performed using both paired and independent t -tests ( P < .05). Results: : There were no significant changes in position of any landmark on the x (left-right)- or y (vertical)-axes after removal of the brackets. However, the landmarks in the oral commissures and lower lip (LLP, −0.55 mm; Li, −0.44 mm; Ch-L, −0.56 mm, all P < .05) on the z (anteroposterior)-axis showed statistically significant differences. There were no significant positional changes of most landmarks on the x-, y-, or z- axes after bracket removal among the various genders and lip thicknesses. Conclusions: : There was a slight retrusion in the oral commissure and lower lip areas after debonding, but no changes were found in the upper lip area. This study showed that 3-D stereophotogrammetry can be useful in evaluating facial soft tissue changes in orthodontic patients.

This study was performed to evaluate patterns of failure time after insertion, failure rate according to loading time after insertion, and the patterns of failure after loading. A total of 331 mini-implants were classified into the non-failure group (NFG) and failure group (FG), which was divided into failed group before loading (FGB) and failed group after loading (FGA). Orthodontic force was applied to both the NFG and FGA. Failed mini-implants after insertion, ratio of FGA to NFG according to loading time after insertion, and failed mini-implants according to failed time after loading were analyzed. Percentages of failed mini-implants after insertion were 15.79%, 36.84%, 12.28%, and 10.53% at 4, 8, 12, and 16 weeks, respectively. Mini-implant failure demonstrated a peak from 4 to 5 weeks after insertion. The failure rates according to loading time after insertion were 13.56%, 8.97%, 11.32%, and 5.00% at 4, 8, 12, and 16 weeks, respectively. Percentages of failed mini-implants after loading were 13.79%, 24.14%, 20.69%, and 6.9% at 4, 8, 12, and 16 weeks, respectively. Mini-implant stability is typically acquired 12 to 16 weeks after insertion, and immediate loading can cause failure of the mini-implant. Failure after loading was observed during the first 12 weeks.