Mechanical and geometric properties of thermoformed and 3D printed clear dental aligners Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Prashant Jindal, Mamta Juneja, Francesco Luke Siena, Divya Bajaj, Philip Breedon Introduction The aim of this research was to compare compressive mechanical properties and geometric inaccuracies between conventionally manufactured thermoformed Duran clear dental aligners and 3D printed Dental Long Term (LT) resin-based clear aligners using 3D modeling and printing techniques. Methods Impressions of the patient's dentition were scanned and using 3D modeling software, dental models were designed and 3D printed. These printed models then underwent vacuum thermoforming to thermoform a clear Duran thermoplastic sheet of 0.75-mm thickness into clear dental aligners of the same thickness of 0.75 mm. For the same dental model, aligners were also designed and 3D printed to 0.75-mm thickness creating biocompatible clear dental aligners using Dental LT resin utilizing a Formlabs 3D printing machine for direct usage by the patients. Five observers calculated teeth height for both types of aligners for evaluation of geometric deviations. Both types of aligners were subjected to compression loading of 1000 N to evaluate their load vs displacement behavior. Results 3D printed cured clear dental aligners were found to be geometrically more accurate with an average relative difference in tooth height of 2.55% in comparison with thermoformed aligners (4.41%). Low standard deviations (0.03-0.09 mm) were observed for tooth height measurements taken by all the observers for both types of aligners. 3D printed aligners could resist a maximum load of nearly 662 N for a low displacement of 2.93 mm; whereas, thermoformed aligners could resist a load on only 105 N for 2.93-mm displacement. Thermoformed aligners deformed plastically and irreversibly for large displacements; whereas, 3D printed aligners deformed elastically with reversibility for lower displacements. Conclusions 3D printed and suitably cured Dental LT resin-based clear dental aligners are suggested to be more suitable for patient use as they are geometrically more accurate; this presents an opportunity to make processing time savings while ensuring an aligner is mechanically stronger and elastic in comparison with the conventionally produced thermoplastic-based thermoformed clear dental aligners.

Virtual surgical planning: Balancing esthetics, practicality, and anticipated stability in a complex Class III patient Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Éva Veiszenbacher, Jue Wang, Matthew Davis, Peter D. Waite, Peter Borbély, Chung H. Kau The treatment of skeletal Class III malocclusion with anterior open bite is a complex and challenging aspect of orthodontics. Facial esthetic factors, practicality and the anticipated stability of a provisional surgical plan must all be factored into the final decision of the actual orthodontic-orthognathic treatment. This case report presents the multidisciplinary treatment of a 39-year-old female patient with skeletal Class III, severe open bite with first dental contact being on the second molars, lateral crossbite, and crowding in both arches. The nonextraction treatment started with aligning and leveling of the teeth in both arches followed by an initial surgical plan based on the clinical evaluation of the smile esthetics. Precise surgical planning information was imported into the Virtual Surgica (VSP Orthognathics) workflow to visualize the direction and amount of movement necessary. The final plan was adjusted because of anticipated practical limitations of the surgery as well as to insure the stability. LeFort I, bilateral sagittal split osteotomies, and setback genioplasty were thus performed. After the surgery, the treatment concluded with the fine adjustment of the occlusion. In the end, good esthetic and functional outcomes with long-term stability were achieved as a result of this delicate multidisciplinary approach.

Retreatment of a patient: Orthognathic surgery-first approach with customized lingual appliances combined with miniplate anchorage Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Graziane Olímpio Pereira, Wilana Moura, Guilherme Janson, José Fernando Castanha Henriques, Carlos Henrique Guimarães Jr, Ravindra Nanda Orthognathic surgery is necessary when a patient's major complaints include skeletal discrepancies that cannot be corrected with orthodontic treatment alone. Currently, orthognathic surgery can be performed through conventional and surgery-first approaches. Some advantages are attributed to the surgery-first approach, such as shortened treatment time and immediate esthetic improvement. The aim of this case report is to present the retreatment of a patient presenting with a skeletal Class III malocclusion, with maxillary retrusion and mandibular protrusion, who was successfully treated with the surgery-first approach and customized lingual appliances, combined with miniplate anchorage in the postoperative orthodontic treatment. The total orthodontic treatment time was 8 months.

Current trends in orthodontic journals listed in Journal Citation Reports. A bibliometric study Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Juan Ignacio Aura-Tormos, Verónica García-Sanz, Filomena Estrela, Carlos Bellot-Arcís, Vanessa Paredes-Gallardo Introduction The aim of this study is to analyze articles published in orthodontic journals included in Journal Citation Reports (JCR) to determine current trends in orthodontic publishing. Methods Articles included in orthodontic journals in 2016 JCR and published during 2007-2017 were selected. After applying inclusion criteria, author-based parameters (article title, first author's name, institution and sex, number of authors, number of affiliations, first author's origin, and geographic origin), article-based parameters (article type, main topic, and research design), and the number of cites and self-cites were registered for each article. Results A total of 7119 articles were analyzed, and 842 different centers and 4483 different authors were identified. The percentage of female authors showed a tendency to increase over the decade; the most productive country was the United States (17.4%). Bone anchorage was the most recurrent topic (7.2%). More than three-fourths of articles (80.8%) proceeded from orthodontic departments belonging to public institutions, with a decreasing trend in nonacademic or private affiliations. Positive and negative correlations were found to exist between citation counts and other variables. Conclusions American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, and European Journal of Orthodontics were the 3 main journals with regard to production volume, with the United States being the most productive country. The most recurrent topic was bone anchorage, and most of the studies were research articles with observational cross-sectional design. Study design, geographic origin of the articles, article type, and the main subject of the article may be predictive of citation numbers.

Three-dimensional changes of the zygomaticomaxillary complex after mini-implant assisted rapid maxillary expansion Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Kyeong-Tae Song, Jae Hyun Park, Won Moon, Jong-Moon Chae, Kyung-Hwa Kang Introduction The aim of this study was to investigate 3-dimensional changes of the zygomaticomaxillary complex (ZMC) after mini-implant assisted rapid maxillary expansion (MARME). Methods A total of 15 pairs of cone-beam computed tomography 3-dimensional images taken before expansion (T0) and after expansion (T1) were analyzed by measuring changes in the coordinates of the landmarks of the ZMC. Results Changes in the x coordinates of the landmarks showed significant expansion (P <0.01) and greater expansion at the lower than upper portion of the ZMC (P <0.05) in the transverse dimension. All y coordinates of the landmarks except the jugal point (J) showed forward displacement (P <0.05), and the z coordinates of ANS, PNS, Alare, A, and ectocanine showed downward displacement (P <0.01) in the sagittal and vertical dimensions. Also, z coordinates of the landmarks that were closer to the midsagittal plane and in a more posterior portion of the ZMC displaced further downward (P <0.05). SNA and ANB angles increased (P <0.05 and P <0.001, respectively) and the SNB angle decreased (P <0.01). There was a significant correlation between changes in the x coordinates of the ectomolare and ectocanine and the amount of expansion measured from the center of resistance of the maxillary first molars (CR6; P <0.05). There was no significant correlation between the amount of CR6 expansion and changes in y and z coordinates of the landmarks. Conclusions 3-Dimensional changes of the ZMC after MARME showed expansion in a pyramidal shape from the coronal view, downward and forward displacement from the sagittal view, and parallel palatal expansion from the axial view. These findings might be useful for understanding skeletal expansion patterns using MARME.

Contribution of the mandible position to the facial profile perception of a female facial profile: An eye-tracking study Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Peishan Huang, Bin Cai, Chen Zhou, Weicai Wang, Xi Wang, Dingguo Gao, Baicheng Bao Introduction Studies concerning the visual attention of laypersons viewing the soft tissue facial profile of men and women with malocclusion are lacking. This study aimed to determine the visual attention to the facial profile of patients with different levels of mandibular protrusion and facial background attractiveness using an eye-tracking device. Methods The scanning paths of 54 Chinese laypersons (50% female, 50% male, aged 18-23 years) were recorded by an eye-tracking device when they observed composite female facial profile images (n = 24), which were combinations of different degrees of mandibular protrusion (normal, slight, moderate, and severe) and different levels of facial background attractiveness (attractive, average, and unattractive). Dependent variables (fixation duration and first fixation time) were analyzed using repeated-measures factorial analysis of variance. Results For normal mandibular profiles, the fixation duration of the eyes was significantly higher than that of other facial features (P <0.001). The lower face and nose received the least attention. As the degree of protrusion increased from slight to moderate, more attention was drawn to the lower face accompanied by less attention to eyes in the unattractive group (P <0.05). When protrusion degree increased from moderate to severe, attention shifted from nose to lower face significantly in the attractive group (P <0.05). Attention shift from eyes to lower face was also found in the average group when protrusion degree rose to moderate protrusion from normal profile (P <0.05). A significant interaction between facial attractiveness and mandibular protrusion was found in the lower face duration (P = 0.020). The threshold point (the point of mandibular protrusion degree that evoked attention to the lower face) of the attractive facial background was higher than that of the unattractive background. Once evoked, the effect of mandibular protrusion of the attractive group tended to be stronger than that of the unattractive group, though without statistical difference. Conclusions Eyes are the most salient area. The increasing degree of mandibular protrusion tends to draw attention to the lower face from other facial features. Background attractiveness can modify this behavior.

Alterations of the oral microbiome in patients treated with the Invisalign system or with fixed appliances Publication date: November 2019 Source: American Journal of Orthodontics and Dentofacial Orthopedics, Volume 156, Issue 5 Author(s): Qian Wang, Jin-bao Ma, Bo Wang, Xue Zhang, Yu-ling Yin, Hua Bai Introduction Although the Invisalign system has been used widely in recent years, the influences of this treatment on the oral microbiome and whether or not this influence is different from that of fixed appliances is still unknown. In this study, we investigated the changes in the oral microbiome in patients treated with the Invisalign system or with fixed appliances. Methods Fifteen subjects were enrolled, comprising 5 fixed appliance patients, 5 Invisalign patient, and 5 healthy controls. Saliva samples were collected, and high-throughput pyrosequencing was performed based on the 16S rRNA gene. Results Both fixed and Invisalign orthodontic treatments resulted in dysbiosis of the oral microbiome. Firmicutes and TM7 at the phyla level and Neisseria at the genus level displayed statistically significant differences between the 2 orthodontic groups. The effect of these changes with microbiome on oral health was inconsistent. The inferred microbial function of the Invisalign group suggested this group was more predisposed to periodontal diseases. Conclusion The influence of the Invisalign system on the oral microbiome was no better for oral health compared with fixed appliances. The convenience of maintaining oral hygiene rather than changes in the oral microbiome may be the underlying reason for the performance of the Invisalign system on oral health.