American Journal of Orthodontics and Dentofacial Orthopedics

Directory: AAO Officers and Organizations Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s):

August 2019 Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Allen H. Moffitt

Oops Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Laurance Jerrold

Effect of print layer height on the assessment of 3D-printed models Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Wyatt A. Loflin, Jeryl D. English, Catharine Borders, Lacey M. Harris, Audrey Moon, J. Nathaniel Holland, F. Kurtis Kasper Introduction Many variables can affect the accuracy of 3D-printed orthodontic models, and the effects of different printing parameters on the clinical utility of the printed models are just beginning to be understood. The objective of this study was to investigate the effect of print layer height on the assessment of 3D-printed orthodontic models with the use of the American Board of Orthodontics Cast-Radiograph Evaluation grading system. Methods Twelve cases were scanned using a desktop model scanner and 3D-printed using a stereolithography-based printer at three different layer heights (25, 50, and 100-μm; n = 12 per group). All models were scored by eleven graders using the Cast-Radiograph Evaluation grading system. All models were scored a second time, at least two weeks later. Results No statistically significant effects of print layer height were found on the scoring of the models for any of the grading metrics or total score. 3D-printed models of each layer height were highly positively correlated with stone models for the total score, with the strongest correlation found with models printed at 100-μm. Conclusions 100-μm layer height 3D-printed models are potentially clinically acceptable for the purposes of evaluation of treatment outcomes, diagnosis and treatment planning, and residency training.

Can forces be applied directly to the root for correction of a palatally displaced central incisor with a dilacerated root? Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Elsa Arango, Sonia P. Plaza, Angela M. Chaves, Birte Melsen This case report describes the interdisciplinary treatment of an ectopic horizontally placed maxillary right central incisor with severe root dilaceration. The root was distally angulated and entrapped by the root of the maxillary right lateral incisor. The initial force system was aimed at an occlusal displacement and applied to the crown. During the second phase, a button was cemented onto the apex of the impacted tooth. A force from the apex to a temporary anchorage device in the palate moved the root toward the midline. Finally, a root canal and an apectomy were performed and the central incisor could be moved to its ideal position. The treatment generated a normal height of the alveolar bone and an ideal occlusion with a healthy periodontium.

Corticotomy-assisted adult rapid maxillary arch expansion and ridge augmentation: An interdisciplinary case report with 7-year follow-up Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Juan Silva-Coll, Roberto Hernández-Orsini, Chin-Wei Wang Adult orthodontic treatment involving maxillary transverse deficiency is a challenge for an interdisciplinary team. Surgically assisted rapid palatal expansion to segment the maxilla was once the treatment of choice, but the invasiveness, bone deficiency, and gingival recession hindered its acceptance. Corticotomy-assisted rapid maxillary arch expansion with ridge augmentation has the advantage of augmenting alveolar bony housing to accommodate and facilitate tooth movement. This approach was used to correct a severely constricted maxilla with bilateral posterior crossbite and anterior crowding in a 46-year-old man. Treatment time was 14 months. The accelerated arch expansion overcame the crossbite in 7 months, increasing intercanine distance by 5.2 mm and intermolar distance by 9.8 mm. Subsequent implant prosthesis was able to be restored in a functional normal occlusion. Satisfactory and stable clinical outcome was followed for 7 years. Corticotomy-assisted rapid maxillary arch expansion with alveolar bone augmentation is a novel and effective interdisciplinary approach for correcting adult maxillary transverse deficiency. Well controlled prospective clinical trails are warranted for further investigation.

Upper airway in children with unilateral cleft lip and palate evaluated with computational fluid dynamics Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Tomonori Iwasaki, Hokuto Suga, Ayaka Minami-Yanagisawa, Makiko Hashiguchi-Sato, Hideo Sato, Yuushi Yamamoto, Yoshito Shirazawa, Toshiya Tsujii, Ryuzo Kanomi, Youichi Yamasaki Introduction Children with unilateral cleft lip and palate (UCLP) exhibit snoring and mouth breathing. They are also reported to show obstructive sleep apnea syndrome. However, their upper airway ventilation condition is not clearly understood. Therefore, this study was performed to evaluate upper airway ventilation condition in children with UCLP with the use of computational fluid dynamics. Methods Twenty-one children (12 boys, 9 girls; mean age 9.1 years) with UCLP and 25 children (13 boys, 12 girls; mean age 9.2 years) without UCLP who required orthodontic treatment underwent cone-beam computed tomography (CBCT). Nasal resistance and upper airway ventilation condition were evaluated with the use of computational fluid dynamics from CBCT data. The groups were compared with the use of Mann-Whitney U tests and Student t tests. Results Nasal resistance of the UCLP group (0.97 Pa/cm3/s) was significantly higher than that of the control group (0.26 Pa/cm3/s; P < 0.001). Maximal pressure of the upper airway (335.02 Pa) was significantly higher in the UCLP group than in the control group (67.57 Pa; P < 0.001). Pharyngeal airway (from choanae to base of epiglottis) pressure in the UCLP group (140.46 Pa) was significantly higher than in the control group (15.92 Pa; P < 0.02). Conclusions Upper airway obstruction in children with UCLP resulted from both nasal and pharyngeal airway effects.

Dentoskeletal morphology in adults with Class I, Class II Division 1, or Class II Division 2 malocclusion with increased overbite Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Fatma Deniz Uzuner, Belma Işık Aslan, Müfide Dinçer Introduction The treatment options for adults with increased overbite are limited to dentoalveolar changes that camouflage the condition. Because of high relapse tendency, defining the problem area is important when creating a treatment plan. This study aimed to evaluate dentoskeletal morphology in skeletal Class I and II anomalies associated with Angle Class I, Class II Division 1 (Class II/1), and Class II Division 2 (Class II/2) malocclusions with increased overbite compared with normal occlusion. Methods Pretreatment cephalograms of 306 patients (131 men, 175 women; overall ages 18-45 years) were evaluated. Four groups were constructed. Three groups had increased overbite (>4.5 mm): group 1 (n = 96) skeletal Class I (ANB = 0.5°-4°), group 2 (n = 85) skeletal Class II (ANB >4.5°) with Class II/1; and group 3 (n = 79) skeletal Class II with Class II/2 malocclusion. Group 4 as a control (n = 46) skeletal Class I normal overbite. Dental and skeletal characteristics of the groups were compared by sex. For statistical evaluations, analysis of variance followed by Tukey post hoc, Mann-Whitney U, and Kruskall-Wallis tests were used. Additionally correlation coefficients between overbite and skeletal/dental parameters were calculated. Results Between sexes, with regard to skeletal parameters, the men had greater values in millimetric measurements, and the women had higher SN/GoGn values. Maxillary/mandibular molar heights and the mandibular incisor heights were higher in men. In group 1, decreased lower anterior facial height (LAFH), retrusive mandibular incisors, and increased interincisal degree were determined. The maxillary molars were intrusive, whereas the vertical position of the mandibular molars and incisors in both jaws were normal. In group 2, retrognathic mandible, increased LAFH and mandibular plane angle, extrusive maxillary/mandibular incisors, protrusive mandibular incisors, and decreased interincisal degree were found. In group 3, decreased LAFH, increased interincisal degree, and retrusive incisors in both jaws were determined. There were significant negative correlations between SN/GoGN, palatal plane, and overbite in group 2 and between ANS-SN and overbite in group 3, and positive correlation between interinsical angle and overbite in all increased overbite groups. Conclusions Dental morphology seems to be the main factor of increased overbite. Differences between groups were related primarily to inclinations and vertical positions of the incisors, rather than molar positions.

Tooth agenesis patterns in Japanese orthodontic patients with nonsyndromic oligodontia Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Kazuhito Arai Introduction Tooth agenesis is the most common dental anomaly in humans and is often found in orthodontic patients. However, severe tooth agenesis (oligodontia) is rare and its characteristics are poorly understood. This study aimed to investigate tooth agenesis patterns of Japanese orthodontic patients with nonsyndromic oligodontia. Methods Panoramic radiographs of 228 orthodontic patients (141 females, 87 males) with nonsyndromic oligodontia were selected and permanent tooth agenesis excluding third molars was evaluated. Influence of cutoff age was tested, tooth agenesis patterns for each quadrant were calculated, and antagonistic maxillary and mandibular quadrants were merged as the occluding tooth agenesis pattern. Full-mouth tooth agenesis patterns were also evaluated. Results The highest prevalence of tooth agenesis was observed in maxillary and mandibular second premolars, followed by maxillary first premolars. Prevalence of a symmetric pattern between right and left quadrants was significantly higher than matched patterns between maxillary and mandibular antagonistic quadrants. Among 456 possible tooth agenesis patterns, 51 and 49 patterns were observed for the maxillary and mandibular quadrants, respectively, but 215 patterns for the occluding patterns were observed. In addition, 180 full-mouth tooth agenesis patterns were observed in the 228 patients. Conclusions Distinct characteristics in highly ranked patterns were observed compared with studies from other geographic areas, especially in the maxillary arch. Occluding and full-mouth tooth agenesis patterns showed wide variation, suggesting difficulty in orthodontic diagnosis.

Dental development and craniofacial morphology in school-age children Publication date: August 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 2 Author(s): Strahinja Vucic, Brunilda Dhamo, Vincent W.V. Jaddoe, Eppo B. Wolvius, Edwin M. Ongkosuwito Introduction The growth of the craniofacial complex is important for establishing a balanced relationship among the teeth, jaws, and other facial structures. However, there is still a lack of information about craniofacial parameters that are affected by the rate of dental development. The aim of this study was to investigate the association between dental development and craniofacial morphology in school-age children. Methods This study was embedded in the Generation R Study, Rotterdam, The Netherlands. In 3,896 children aged 8 to 11 years, dental development was assessed from panoramic radiographs and craniofacial morphology was assessed by combining cephalometric parameters into 9 uncorrelated principal components, each representing a distinct skeletal or dental craniofacial pattern. The statistical analysis was performed using linear and nonlinear regression model. Results Dental development was positively associated with the bimaxillary growth (β = 0.04; 95% CI 0.01 to 0.08). Children with above-average dental development had a tendency toward Class II jaw relationship (β = −0.08; 95% CI −0.13 to −0.04). Regarding dental parameters, the proclination increased for incisors and lips with advanced dental development (β = 0.15 [95% CI 0.10 to 0.19] and β = 0.13 [95% CI 0.09 to 0.17], respectively), but the incisor proclination remained more pronounced in children that had above-average dental development. Conclusions The findings of this large population-based study show that dental development is associated with specific dental and skeletal cephalometric characteristics in school-age children. Further longitudinal studies are necessary to confirm the observed effects over time.