• 대한치과교정학회지
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• 제43권6호
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• pp.288-293
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• 2013

Objective: This study was aimed at comparing the mandibular arch forms of Korean and Vietnamese patients by using facial axis (FA) points on three-dimensional (3D) models. Methods: Mandibular casts of 68 Korean (Class I malocclusion, 30; Class II malocclusion, 38) and 78 Vietnamese (Class I malocclusion, 41; Class II malocclusion, 37) patients were scanned in their occluded positions and grouped according to arch form (tapered, ovoid, and square). The FA point of each tooth was digitized on the 3D mandibular models. The measurements and frequency distributions of the arch forms were compared between the ethnic groups. Results: The Vietnamese patients had significantly greater intercanine depth and intercanine and intermolar width-to-depth ratios than the Korean patients (p < 0.05). The frequency distributions of the arch forms were also significantly different (p = 0.038), but no sexual dimorphism was found. Conclusions: Vietnamese people tend to have deeper and wider arches than Korean people. The three arch forms are evenly distributed in Korean people, but Vietnamese people frequently have square arches. Clinicians should identify the correct arch form of an ethnic group before initiating orthodontic treatment.

• Journal of Dental Anesthesia and Pain Medicine
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• 제17권1호
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• pp.47-53
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• 2017

Background: Every patient who undergoes mandibular third molar surgery is concerned about post-operative pain. Indeed, previous researchers have used various methods to treat such pain. This study aimed to assess the effectiveness of sublingual injection of dexamethasone (8 mg) to treat post-operative pain after mandibular third molar surgery. Method: This was a randomized, double-blind, split-mouth, clinical trial, involving 48 healthy patients who required surgical removal of two mandibular third molars with similar bilateral positions. All operations were performed by the same experienced surgeon. The patients were randomized into a study group (8 mg dexamethasone injection) and a placebo group (normal saline injection). Both interventions were injected into the sublingual space immediately after local anesthesia, 30 min before the first incision. The study group received an 8 mg dexamethasone injection, while the placebo group received a normal saline injection. The wash period between the patients' two operations was 3 to 4 weeks. Pain was assessed by recording the number of analgesic tablets (rescue drug) consumed, as well as by noting the patients' responses to the visual analog scale (VAS) on the first, second, and third days after surgery. Results: The study group differed significantly from the placebo group in terms of VAS score and analgesic consumption. Conclusion: Dexamethasone (8 mg), injected sublingually, significantly eased post-operative pain after surgical removal of the mandibular third molar.

• Journal of Oral Medicine and Pain
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• 제48권4호
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• pp.152-158
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• 2023

Purpose: This pilot study aimed to evaluate changes in joint space (JS) using cone-beam computed tomography (CBCT) images of patients diagnosed with temporomandibular joint (TMJ) osteoarthritis (OA) and to determine the association between occlusal changes and JS. Methods: CBCT images were used to measure the anterior, superior, and posterior JSs of the sagittal plane. The differences in JS values over time and between groups were compared. The percentage change in the anteroposterior position of the mandibular condyle between groups was also analyzed. Results: Thirty-four subjects (mean age=43.91±20.13), comprising eight males (23.5%) and 26 females (76.5%), were divided into 18 patients with no change in occlusion (NCO) and 16 patients with a change in occlusion (CO) during TMJ OA. The JS measurements of the study subjects showed a decrease in anterior joint space (AJS) values over time. There was no difference in JS measurements between the groups at T1 and T2. AJS values measured at T1 were lower in the CO group than in the NCO group, but the difference was not statistically significant. In both groups, a posterior position of the mandibular condyle was initially observed with high frequency. However, there is a statistically significant difference in CBCT images taken after occlusal changes, with an increased frequency of condyles observed in the anterior or central positions. Conclusions: In conclusion, AJS decreased over time in TMJ OA, and the mandibular condyle became more anteriorly positioned with occlusal changes. Therefore, clinicians should diligently monitor mandibular condyle morphology and JS using CBCT, along with the patient's clinical symptoms, to treat and control TMJ OA effectively.

• 대한치과교정학회지
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• 제53권1호
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• pp.26-34
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• 2023

Objective: The purpose of the present study was to compare the root positions in virtual tooth setups using only crowns in a simulated treatment with those achieved in the actual treatment. Methods: Pre- and post-treatment intraoral and corresponding cone beam computed tomography (CBCT) scans were obtained from 15 patients who underwent orthodontic treatment with premolar extraction. A conventional virtual tooth setup was used for the treatment simulation. Pre- and post-treatment three-dimensional digital tooth models were fabricated by integrating the patients' intraoral and CBCT scans. The simulated root positions in the virtual setup were obtained by merging the crown in the virtual setup and root in the pre-treatment tooth model. The root positions of the simulated and actual post-treatment tooth models were compared. Results: Differences in root positions between the simulated and actual models were > 1 mm in all teeth, and statistically significant differences were observed (p < 0.05), except for the maxillary lateral incisors. The differences in the inter-root angulation were > 1° in all teeth, and statistically significant differences were observed in the maxillary and mandibular canines. Conclusions: The virtual tooth setup using only crown data showed errors over the clinical limits. The clinical application of a virtual setup using crowns and roots is necessary for accurate and precise treatment simulation, particularly in extraction treatment.

• Imaging Science in Dentistry
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• 제38권4호
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• pp.203-208
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• 2008

Purpose : The purpose of this study was to develop a system for the measurement and simulation of the TMJ movement and to analyze the mandibular movement quantitatively. Materials and Methods : We devised patient-specific splints and a registration body for the TMJ movement tracking. The mandibular movements of the 12 subjects with facial deformity and 3 controls were obtained by using an optical tracking system and the patient-specific splints. The mandibular part was manually segmented from the CT volume data of a patient. Three-dimensional surface models of the maxilla and the mandible were constructed using the segmented data. The continuous movement of the mandible with respect to the maxilla could be simulated by applying the recorded positions sequentially. Trajectories of the selected reference points were calculated during simulation and analyzed. Results : The selected points were the most superior point of bilateral condyle, lower incisor point, and pogonion. There were significant differences (P<0.05) between control group and pre-surgical group in the maximum displacement of left superior condyle, lower incisor, and pogonion in vertical direction. Differences in the maximum lengths of the right and the left condyle were 0.59${\pm}$0.30 mm in pre-surgical group and 2.69${\pm}$2.63 mm in control group, which showed a significant difference (P<0.005). The maximum of differences between lengths of the right and the left calculated during one cycle also showed a significant difference between two groups (P<0.05). Conclusion : Significant differences in mandibular movements between the groups implies that facial deformity have an effect on the movement asymmetry of the mandible. (Korean J Oral Maxillofac Radiol 2008; 38 : 203-8)

• 대한치과보철학회지
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• 제30권3호
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• pp.338-360
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• 1992

This study was performed to investigate the phonetic alterations with upper anterior teeth were missing. To compare the changes of the phonations, before and after insertion of the temporary prosthesis, six subjects who lost their upper anterior teeth were selected (2-male, 4-female). Tested sounds (/ga(가), na(나), da(다), ra(라), sa(사), ja(자), cha(차), ta(타), pa(파), ha(하), gi(기), ni(니), di(디), ri(리), si(시), jl(지), chi(치), ti(티), pi(피), hi(히), seu(스), se(세), so(소), su(수)/were programmed into an IBM AT with and without temporary prosthesis. These experiments were analyzed by formants, consonants durations, and energy level changes with an LSI speech work station program. During the pronunciation of the tested sounds (with and without temporary prosthesis), mandibular movements were recorded to a Mandibular Kinesiogram and analyzed . The findings led to the following conclusions: 1. Objective differences could not be found. However, in every informant, subjective improvement could be noticed. 2. There were no persistant correlations of the formant's changes. And in every informant, phonetic changes were variable. 3. There were various changes of the consonant durations in every informant. By and large, those of /si(시), jl(지), chi(치), Pi(피), hi(히)/ were longer than other tested sounds. After insertion of the prosthesis, durations were shorter. Consonants with /i(ㅣ)/ were longer than with /a(ㅏ)/, with or without prosthesis. 4. With and without temporary prosthesis, mandibular movements were various in the frontal view. Mandibular movements showed lateral deviations, and mandibular positions with /si(시), ji(지), ti(티), seu(스), hi(히)/ were nearer to the mandibular rest position. 5. The kinds of temporary prosthesis and conditions of the missing teeth influenced every informant variously, so there were no correlation between informants. 6. Energy levels increased in all tested sounds with a fixed temporary prosthesis. And, there were no differences between before and after insertion of a removable temporary prosthesis. However, sibilant sounds, and consonants with /i(ㅣ)/ showed a little increased energy level.

• 대한치과교정학회지
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• 제17권1호
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• pp.23-32
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• 1987

There are variations in regional cranial and facial balance as a normal developmental process and regional imbalances often tend to compensate each other to provide functional equilibrium. This study was designed to analyse the patterns of morphologic harmony and inharmony inherent in normal occlusion and malocclusion. The subjects consisted of 92 individuals with normal occlusion and 60 Class III malocclusion patients. Their lateral cephalograms were traced and analysed using the counterpart analysis described by Enlow. The normal occlusion group was divided into Normal Types A and B according to the relative positions of Points A and B. The following conclusions were reached: 1 The normal occlusion consisted of $28.3\%$ of Normal Type A and $69.6\%$ of Normal Type B. 2. The Normal Type A and B differed from each other in the morphology of the cranial base, the mandibular ramus and corpus, and the functional occlusal plane. The Normal Type B showed considerable mandibular protrusion effect in the effective dimension and alignment of the above factors. 3. Most normal individuals showed some degree of disharmony among morphologic factors but the deviations were relatively small. 4. The Normal Type B was less balanced than the Normal Type A. 5. More regional imbalances were involved in Class III malocclusion and the imbalances were more severe.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권5호
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• pp.324-328
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• 2009

Submentovertex(SMV) projection shows the base of skull, positions of mandibular condyle and zygomatic arches. We would like to investigate how to use SMV and evaluate its availability for the construction of the plan for orthognathic surgery of mandible prognathism and asymmetry. Preoperative Surgical Treatment Objective(STO) using SMV was performed to 12 patients, who visited to Seoul National University Bundang Hospital with chief complaints like mandible prognathism or asymmetry from Dec 2007 to Feb 2009. Surgical splint was made of stone model repositioned according to STO using SMV. We estimate the change in skeletal midline and the stability of occlusion through superposition between preoperative and postoperative SMV. It was effective on the amount of mandible movement and the correction of mandibular asymmetry, while the facial asymmetry involved with maxilla was excluded. It was concluded that STO using SMV is available and predictable method for not only the setback of prognathic mandible but also the correction of mandible asymmetry accurately.

• Journal of Periodontal and Implant Science
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• 제30권2호
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• pp.483-490
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• 2000

The aim of this study was to analyze the reliability of an ultrasonic device(SDM) measuring soft tissue thickness in relation to tooth position, and to find factors which can influence the reliability. The results showed that 1. measurement error was the largest in the maxillary second molar position and the smallest in the mandibular central incisor position. 2. in a box whisker plot, the difference between two measurements was most widely distributed in molar positions. 3. in Pearson correlation analysis, the relationship between two measurements was the highest in the maxillary lateral incisor position and, the lowest in the maxillary second molar, mandibular first and second premolar position. 4. a stepwise multiple regression analysis could explain the difference of two measurements with various independent variables in 29.7% (P<0.0001). Gingival thickness was the only variable influencing the measurement difference in a statistically significant level(P<0.0001). It can be concluded that its high reliability, ease to use and patient comfort justified the application of the SDM in measurement of soft tissue thickness.

• 구강회복응용과학지
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• 제16권1호
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• pp.37-49
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• 2000

It was clinically important to substitute the physiologic centric relation to the therapeutic position of the patients who needed the oral rehabilitation or occlusal treatment. There were several methods for recording the centric relation. One of the known methods was to use the gothic arch tracer. However the existing intraoral device was difficult to adjust the three dimensional angulation of the recording plate and recording stylus depending on the hinge movement arch of the individual. The purpose of this study was to develop new intraoral tracer which had adjustable stylus within hinge movement arch for the record of centric relation and to evaluate the clinical application of this device. The results were as follow; 1. A stylus of new developed intraoral tracer was so adjustable that the recording of mandibular positions could be reproducible within the hinge movement arc. 2. A record plate of new developed intraoral tracer was so adjustable to parallel with the occlusal plane that lateral recording of mandibular position was able to obtain stably. This study showed that new developed intraoral tracer allowed the determination of the treatment position which can be used in the full mouth rehabilitation and occlusal treatments.