Characterization of facial asymmetry phenotypes in adult patients with skeletal Class III malocclusion using three-dimensional computed tomography and cluster analysis / 대한치과교정학회지

Objective@#To classify facial asymmetry (FA) phenotypes in adult patients with skeletal Class III (C-III) malocclusion. @*Methods@#A total of 120 C-III patients who underwent orthognathic surgery (OGS) and whose three-dimensional computed tomography images were taken one month prior to OGS were evaluated. Thirty hard tissue landmarks were identified. After measurement of 22 variables, including cant (°, mm), shift (mm), and yaw (°) of the maxilla, maxillary dentition (Max-dent), mandibular dentition, mandible, and mandibular border (Man-border) and differences in the frontal ramus angle (FRA, °) and ramus height (RH, mm), K-means cluster analysis was conducted using three variables (cant in the Max-dent [mm] and shift [mm] and yaw [°] in the Manborder). Statistical analyses were conducted to characterize the differences in the FA variables among the clusters. @*Results@#The FA phenotypes were classified into five types: 1) non-asymmetry type (35.8%); 2) maxillary-cant type (14.2%; severe cant of the Max-dent, mild shift of the Man-border); 3) mandibularshift and yaw type (16.7%; moderate shift and yaw of the Man-border, mild RH-difference); 4) complex type (9.2%; severe cant of the Max-dent, moderate cant, severe shift, and severe yaw of the Man-border, moderate differences in FRA and RH); and 5) maxillary reverse-cant type (24.2%; reverse-cant of the Max-dent). Strategic decompensation by pre-surgical orthodontic treatment and considerations for OGS planning were proposed according to the FA phenotypes. @*Conclusions@#This FA phenotype classification may be an effective tool for differential diagnosis and surgical planning for Class III patients with FA.

In-vitro investigation of the mechanical friction properties of a computer-aided design and computer-aided manufacturing lingual bracket system under diverse tooth displacement condition / 대한치과교정학회지

OBJECTIVE@#The purpose of this study was to compare the static (SFF) and kinetic frictional forces (KFF) of a computer-aided design and computer-aided manufacturing lingual bracket (CAD/CAM-LB) with those of conventional LB (Con-LB) and Con-LB with narrow bracket width (Con-LB-NBW) under 3 tooth displacement conditions.@*METHODS@#The samples were divided into 9 groups according to combinations of 3 LB types (CAD/CAM-LB [Incognito], Con-LB [7th Generation, 7G], and Con-LB-NBW [STb]) with 3 displacement conditions (no displacement [control], maxillary right lateral incisor with 1-mm palatal displacement [MXLI-PD], and maxillary right canine with 1-mm gingival displacement [MXC-GD]; n = 6/group). While drawing a 0.016-inch copper or super-elastic nickel-titanium archwire with 0.5 mm/min for 5 minutes in a chamber maintained at 36.5℃, SFF and KFF were measured. The Kruskal-Wallis method with Bonferroni correction was performed.@*RESULTS@#The Incognito group demonstrated the highest SFF, followed by the 7G and STb groups ([STb-control, STb-MXLI-PD, Stb-MXC-GD] < [7G-MXC-GD, 7G-MXLI-PD, 7G-control] < [Incognito-MXLI-PD, Incognito-control, Incognito-MXC-GD]; p < 0.001). However, there were no significant differences in SFF among the 3 displacement conditions within each bracket group. Within each displacement condition, the Incognito group demonstrated the highest KFF, followed by the 7G and STb groups ([STb-control, STb-MXLI-PD] < Stb-MXC-GD < 7G-MXLI-PD < [7G-control, 7G-MXC-GD] < [7G-MXC-GD, Incognito-MXLI-PD, Incognito-control] < [Incognito-control, Incognito-MXC-GD]; p < 0.001). MXC-GD exhibited higher KFFs than MXLI-PD in the same bracket group.@*CONCLUSIONS@#The slot design and ligation method of the CAD/CAM-LB system should be modified to reduce SFF and KFF during the leveling/alignment stage.

Emergency response team activation in the outpatient clinic of a single dental teaching hospital in Korea: a retrospective study of 10 years' records

BACKGROUND: To prepare for possible emergency situations during dental treatment, it is helpful to know how often and what kinds of emergencies may arise. This study set out to evaluate the incidences, causes, treatments, and outcomes of emergency situations in the outpatient clinic of a dental teaching hospital in Korea. METHODS: We retrospectively reviewed the records of patients who had experienced an emergency situation and emergency response team activated in a selected outpatient clinic between November 2004 and November 2013. Specific information about the emergency cases was collected, including the patient characteristics and the frequency, types, treatments, and outcomes of the emergency situations. RESULTS: We identified 35 instances of emergency situations in 2,890,424 patients (incidence = 0.012 per 10,000 outpatients). The number of cases was as follows: 10 (28.6%) in the Department of Periodontics, 10 (28.6%) in the Department of Oral and Maxillofacial Surgery, 6 (17.1%) in the Department of Oral and Maxillofacial Radiology, 4 (11.4%) in the Department of Prosthodontics, 2 (5.7%) in the Department of Conservative Dentistry, 2 (5.7%) in the Department of Pediatric Dentistry, and 1 (2.9%) in the Department of Orthodontics. Three (8.6%) of the emergency situations arose before treatment, 22 (62.9%) during treatment, 7 (20.0%) after treatment, and 2 (5.7%) in a patient's guardian. CONCLUSIONS: In accordance with the growing elderly population and more aggressive dental procedures, the number of emergency situations may increase in the future. We recommend that clinicians keep in mind airway management and the active control of emergency situations.