OBJECTIVE: This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. METHODS: Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxillary premolar brackets with 0.022 inch [in] slots and a -7degrees torque. The orthodontic wires used included 0.018 round and 0.019 x 0.025 in rectangular stainless steel wires. The FR was measured at 0degrees, 5degrees, and 10degrees angulations as the wire was drawn through the bracket slots after attaching brackets from each group to the universal testing machine. Static and kinetic FRs were also measured. RESULTS: The passive self-ligating brackets generated a lower FR than all the other brackets. Static and kinetic FRs generally increased with an increase in the bracket-archwire angulation, and the rectangular wire caused significantly higher static and kinetic FRs than the round wire (p < 0.001). The metal passive self-ligating brackets exhibited the lowest static FR at the 0degrees angulation and a lower increase in static and kinetic FRs with an increase in bracket-archwire angulation than the other brackets, while the conventional twin brackets showed a greater increase than all three experimental brackets. CONCLUSIONS: The passive self-ligating brackets showed the lowest FR in this study. Self-ligating brackets can generate varying FRs in vitro according to the wire size, surface characteristics, and bracket-archwire angulation.
Bicuspid ; Ceramics ; Friction* ; Humans ; Orthodontic Wires ; Stainless Steel ; Torque

OBJECTIVE: We compared the skeletal and dental changes that resulted from the use of two methods of intermaxillary fixation (IMF)-miniscrews and surgical archwire-in 74 adult patients who had Class III malocclusion and were treated with the same orthognathic surgical procedure at a hospital in Korea. METHODS: All the patients underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy with rigid fixation. They were divided into two groups according to the type of IMF used-group 1 underwent surgical archwire fixation and group 2 underwent orthodontic miniscrew fixation. In a series of cephalograms for each patient, we compared vertical and horizontal tooth-position measurements: (a) immediately after surgery (T0), (b) 3 months after surgery (T1), and (c) 6 months after surgery (T2). Cephalometric changes within each group were examined using one-way analysis of variance (ANOVA) while the independent samples t-test procedure was used to compare the two groups. RESULTS: After surgery, the maxillary incisors tended to be proclined in both groups although there were no significant differences. Incisor overbite increased significantly in both groups from T0 to T1, and the miniscrew group (group 2) showed slightly greater overbite than the archwire group (group 1). CONCLUSIONS: This study suggest that the use of orthodontic miniscrews and orthodontic surgical archwire for IMF in adult patients results in similar skeletal and dental changes.
Adult* ; Humans ; Incisor ; Korea ; Malocclusion ; Orthognathic Surgery* ; Orthognathic Surgical Procedures ; Osteotomy ; Osteotomy, Sagittal Split Ramus ; Overbite

No abstract available.

In this report, we present the case of a girl with delayed odontogenesis of a lower second premolar for which she was followed up for 8.5 years. Congenital absence of permanent mandibular second premolars was observed at the initial radiographic examination at 8 years and 1 month. One year later, during the treatment period, an unexpected odontogenesis of a right second premolar was diagnosed on follow-up radiography. The original treatment plan was revised and a new plan was successfully implemented. Th is unusual case showed that the orthodontist's clinical philosophy must be flexible because unexpected situations can arise, especially when treating growing patients.
Bicuspid ; Follow-Up Studies ; Humans ; Odontogenesis ; Pediatric Dentistry ; Philosophy

OBJECTIVE: The purpose of this study was to investigate the antimicrobial effect of silverized elastomers on mutans streptococci in dental plaque. METHODS: Forty patients undergoing orthodontic treatment were randomly placed into 1 of 2 groups. We examined the maxillary right and left central incisors and premolars, and the mandibular right and left canines of all participants. We ligated the right maxillary and left mandibular teeth of the participants in group 1 with silverized elastomers and ligated their contralateral teeth with conventional elastomers. We ligated the left maxillary teeth and right mandibular teeth of group 2 participants with silverized elastomers. Each participant visited the clinic 4 times at 3-week intervals. We applied the elastomers to the teeth on one side of each patient's mouth during their first visit. During the second visit, the elastomers were removed for microbiological analysis and replaced with steel ligatures. During the third visit, we used silverized elastomers to ligate the teeth contralateral to those treated on the first visit. The elastomers were removed during the fourth visit, and microbiological analyses were performed. We compared the quantity of bacteria on silverized and conventional elastomers at the 0.05 level of significance. RESULTS: The percentage of mutans streptococci was not significantly different in cultures of dental plaque from the silverized and the conventional elastomers (p > 0.05). CONCLUSIONS: There was no significant difference between the antimicrobial effect of the silverized elastomers and that of the conventional elastomers.
Bacteria ; Bicuspid ; Dental Plaque ; Elastomers ; Humans ; Incisor ; Ligation ; Mouth ; Silver ; Steel ; Tooth

OBJECTIVE: This study aimed to investigate the current data regarding age, sex, and Angle Classification of Korean orthodontic patients and influence of these factors on the tendency to undergo extraction and orthognathic surgery. METHODS: The recent trends of Korean orthodontic patients were assessed using questionnaire survey. The questionnaires were e-mailed to orthodontists who met the study criteria; 58% of the orthodontists opened the e-mails, and 27.7% replied to the e-mails. In all, the medical records of 11,340 patients who underwent orthodontic treatment at private clinics and small dental hospitals in Korea were analyzed. RESULTS: The percentage of female patients in the study sample was 69.6%, and the average age of the patients was 19.87 years. The percentage of patients who were older than 19 years was 50.2%. Class II and Class III malocclusions were noted in 33.6% and 23.6% of patients, respectively. Extraction and orthognathic surgery were performed in 60.4% and 6.9% of patients, respectively. CONCLUSIONS: The results showed that there were a high percentage of adult, Class II malocclusion and extraction patients in private practices and small dental hospitals during the study period. Further, a relatively high proportion of adult patients opted to undergo orthognathic surgery.
Adult ; Electronic Mail ; Female ; Humans ; Jaw ; Korea ; Malocclusion ; Medical Records ; Orthognathic Surgery ; Private Practice ; Surveys and Questionnaires

OBJECTIVE: The purpose of this study was to investigate the effects of a newly developed rapid maxillary expansion screw-the memory screw-over 6 months. METHODS: Five subjects, aged between 11.7 and 13.75 years, were enrolled in this study. All subjects underwent placement of a maxillary expansion appliance containing superelastic nickel-titanium open-coil springs in its screw bed. The parents of the patients and/or the patients themselves were instructed to activate the expansion screw by 2 quarter-turns 3 times a day (morning, midday, and evening; 6 quarter-turns a day). The mean expansion period was 7.52 +/- 1.04 days. Dentoskeletal effects of the procedure, including dentoalveolar inclination, were evaluated. Measurements of all the parameters were repeated after 6 months of retention in order to check for relapse. RESULTS: Sella-Nasion-A point (SNA) and Sella-Nasion/Gonion-Menton angles increased, and Sella-Nasion-B point (SNB) angle decreased in all the subjects during the expansion phase. However, they approximated to the initial values at the end of 6 months. On the other hand, the increments in maxillary apical base (Mxr-Mxl) and intermolar widths was quite stable. As expected, some amount of dentoalveolar tipping was observed. CONCLUSIONS: The newly developed memory expansion screw offers advantages of both rapid and slow expansion procedures. It widens the midpalatal suture and expands the maxilla with relatively lighter forces and within a short time. In addition, the resultant increments in the maxillary apical base and intermolar width remained quite stable even after 6 months of retention.
Aged ; Hand ; Humans ; Maxilla ; Memory ; Palatal Expansion Technique ; Parents ; Retention (Psychology) ; Sutures

OBJECTIVE: The aims of this study were to examine whether a passive stretch stimulus by means of a functional appliance induces changes in the fiber composition of masticatory muscles and whether these changes are similar to the changes in stretched limb muscle fibers by using RT-PCR, western blot, and immunohistochemical assays. METHODS: Five male New Zealand White rabbits were fitted with a prefabricated inclined plane on the maxillary central incisors to force the mandible forward (- 2 mm) and downward (- 4 mm). Further, 1 hind limb was extended and constrained with a cast so that the extensor digitorum longus (EDL) was stretched when the animal used the limb. The animals were sacrificed after 1 week and the masseter, lateral pterygoid, and EDL were processed and compared with those from control animals (n = 3). RESULTS: The stretched EDL had a significantly higher percentage of slow fibers, whereas the stretched masticatory muscles did not show changes in the composition of the major contractile proteins after 7 days. CONCLUSIONS: The transition of fiber phenotypes in response to a stretch stimulus may take longer in the masticatory muscles than in the limb muscles.
Animals ; Blotting, Western ; Contractile Proteins ; Extremities ; Humans ; Incisor ; Male ; Mandible ; Masticatory Muscles ; Muscles ; Myosin Heavy Chains ; Phenotype ; Rabbits

OBJECTIVE: To identify the right and left difference of the facial soft tissue landmarks three-dimensionally from the subjects of normal occlusion individuals. MATERIALS AND METHODS: Cone-beam computed tomography (CT) scans were obtained in 48 normal occlusion adults (24 men, 24 women), and reconstructed into 3-dimensional (3D) models by using a 3D image soft ware. 3D position of 27 soft tissue landmarks, 9 midline and 9 pairs of bilateral landmarks, were identified in 3D coordination system, and their right and left differences were calculated and analyzed. RESULTS: The right and left difference values derived from the study ranged from 0.6 to 4.6 mm indicating a high variability according to the landmarks. In general, the values showed a tendency to increase according to the lower and lateral positioning of the landmarks in the face. Overall differences were determined not only by transverse differences but also by sagittal and vertical differences, indicating that 3D evaluation would be essential in the facial soft tissue analysis. CONCLUSIONS: Means and standard deviations of the right and left difference of facial soft tissue landmarks derived from this study can be used as the diagnostic standard values for the evaluation of facial asymmetry.
Adult ; Cone-Beam Computed Tomography ; Facial Asymmetry ; Humans ; Male

No abstract available.