• 대한소아치과학회지
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• 제40권4호
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• pp.260-267
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• 2013

본 연구는 Cone-beam computed tomography(CBCT)를 이용하여 상악 정중치의 크기, 형태, 위치 등의 3차원적 특성을 분석하고 이들이 영구치열에 미치는 영향에 대해 알아보고자 시행되었다. 2006년 6월부터 2012년 12월까지 내원하여 CBCT를 촬영한 환자 중 15세 이하의 환자, 191명을 대상으로 하였으며 이 중 정중이개를 보이는 43명을 대상으로 정중치의 크기, 위치와 정중이개량과의 상관관계를 분석하였다. 연구 결과, 정중치는 남성에서 약 3.9배 많이 발견되었고 7세에서 가장 많이 나타났다. 평균 길이는 13.0 mm, 폭경은 6.8 mm이였으며, 원추형이 59.2%로 가장 많았다. 정중치는 순측보다 구개측에 다수 존재하였고 수직적으로는 영구치의 치관부위에 근접해 있는 경우가 많았다. 정중치의 63.0%가 역위 형태였으며 정중치에 의해 유발된 병발증은 맹출지연이 39.0%, 정중이개 23.6%, 치아회전이 15.9%를 차지하였다. 이 중 정중이개량은 정중치의 크기와 중등도의 상관관계를 보였으며 정중치의 근원심 위치도 정중이개량과 통계적 상관관계를 보였다. 본 연구에서 시행한 정중치의 3차원 분석을 통해 정중치의 크기, 위치, 병발증의 발생분포를 파악할 수 있으며, 이 중 정중이개량은 정중치의 크기, 근원심 위치와 상관성이 있다는 것을 알 수 있었다.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.99-104
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• 2020

Purpose: The purpose of this study was to use cone-beam computed tomography (CBCT) images to determine the prevalence of calcifications in the temporomandibular joint (TMJ) and to evaluate any associations between the presence of such calcifications and degenerative bone alterations of the TMJ, sex, or age. Materials and Methods: In this retrospective study, 1,058 CBCT exams were analyzed, and data regarding the presence and quantity of calcifications, the affected side, any degenerative alterations of the condyle, sex, and age were collected. To evaluate associations between the presence of calcifications and sex or age, the Fisher exact test or the Spearman correlation coefficient, respectively, was used. To assess the association between the presence of calcifications and joint bone alterations, the chi-square and Fisher exact tests were used. The significance level adopted was 5% (P<0.05). Results: Twenty-eight patients (2.7%) presented with TMJ calcifications, including 23 women (82.1%) and 5 men (17.9%). Significant correlations were found between the presence of calcifications and age (P<0.05) and between the presence of calcifications and the presence of condylar alterations (P<0.05), with 73.2% of patients with bone alterations having TMJ calcifications. Conclusion: It may be concluded that, although rare (with a prevalence of only 2.7%), intra-articular calcifications are associated with both degenerative bone alterations and age.

• Journal of Oral Medicine and Pain
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• 제39권1호
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• pp.2-9
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• 2014

Purpose: The purpose of this study was to compare the clinical and radiographic features of temporomandibular joint (TMJ) osteoarthritis (OA) between adolescents and middle-old aged patients. Methods: The subjects were chosen among the patients who presented to the Department of Oral Medicine of Pusan National University Hospital and were diagnosed with TMJ OA by clinical exam, X-ray and cone-beam computed tomography (CBCT) from 2010 to 2011. We investigated 93 adolescent patients (12-19 years) and 53 middle-old aged (>45 years) patients who observed the erosive bony changes in TMJ. CBCT scans were retaken at intervals at an average of 8 months. Results: The adolescent patients showed unilateral degenerative changes more often, and the middle-old aged patients showed degenerative changes more frequently on both sides. The transition of bone changes to the improved group occurred most commonly in both the adolescent and middle-old aged patients. The adolescent patients were more likely to improve than middle-old aged patients. In the adolescent patients, loss of erosion and subjective symptoms occurred in shorter periods than in the middle-old aged patients. In the adolescent patients, the transition of erosion was distributed into proliferative, normal, and shortening in order. In the middle-old aged patients, the transition of erosion was distributed into shortening, proliferative, and normal in order. Conclusions: The clinical and radiographic features of TMJ OA are a significantly different between the adolescent and middle-old aged patients. Moreover, the difference by age of the adaptive and regenerative capacity of TMJ affects the prognosis of TMJ OA and adolescent patients have a better prognosis after treatment.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제40권3호
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• pp.103-110
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• 2014

Objectives: In this study, we assessed soft tissue asymmetry that occurred after open reduction of unilateral zygomaticomaxillary complex (ZMC) fractures. We proposed a simple method to assess soft tissue asymmetry after reduction surgery by evaluating the symmetry between the affected and the unaffected sides. The factors affecting soft tissue contour after surgery were also analyzed. Materials and Methods: Subjects included patients admitted to Wonkwang University Dental Hospital from 2008 to 2013. Cone-beam computed tomography (CBCT) images of asymmetric patients who underwent open reduction at least 3 months prior were compared with healthy patients. Results: The degree of asymmetry was measured in both the open reduction and control groups. Landmarks that showed a statistically significant difference between the two groups were zygion ($1.73{\pm}0.24mm$), bucclae ($1.08{\pm}0.26mm$), point of cheek ($2.05{\pm}0.33mm$) and frontozygomatic point ($1.30{\pm}0.31mm$). Conclusion: When compared with the normal group, asymmetry can occur in the affected side, which usually shows depression of overlying soft tissue and is statistically significantly different. Evaluation of soft tissue asymmetry with CBCT images after open reduction of ZMC fracture is useful.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제39권4호
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• pp.168-174
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• 2013

Objectives: The aim of this study is to investigate the correlation between 2-dimensional (2D) cephalometric measurement and 3-dimensional (3D) cone beam computed tomography (CBCT) measurement, and to evaluate the availability of 3D analysis for asymmetry patients. Materials and Methods: A total of Twenty-seven patients were evaluated for facial asymmetry by photograph and cephalometric radiograph, and CBCT. The 14 measurements values were evaluated and those for 2D and 3D were compared. The patients were classified into two groups. Patients in group 1 were evaluated for symmetry in the middle 1/3 of the face and asymmetry in the lower 1/3 of the face, and those in group 2 for asymmetry of both the middle and lower 1/3 of the face. Results: In group 1, significant differences were observed in nine values out of 14 values. Values included three from anteroposterior cephalometric radiograph measurement values (cant and both body height) and six from lateral cephalometric radiographs (both ramus length, both lateral ramal inclination, and both gonial angles). In group 2, comparison between 2D and 3D showed significant difference in 10 factors. Values included four from anteroposterior cephalometric radiograph measurement values (both maxillary height, both body height) and six from lateral cephalometric radiographs (both ramus length, both lateral ramal inclination, and both gonial angles). Conclusion: Information from 2D analysis was inaccurate in several measurements. Therefore, in asymmetry patients, 3D analysis is useful in diagnosis of asymmetry.

• 대한치과교정학회지
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• 제48권1호
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• pp.63-70
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• 2018

Objective: The aim of this study is to quantitatively evaluate the stability of the skeletal and dental widths using cone-beam computed tomography (CBCT) after segmental Le Fort I osteotomy in adult patients with skeletal Class III malocclusion requiring maxillary expansion. Methods: In total, 25 and 36 patients with skeletal Class III malocclusion underwent Le Fort I osteotomy (control group) and segmental Le Fort I osteotomy (experimental group), respectively. Coronal CBCT images were used to measure the dental and skeletal widths before (T1) and after (T2) surgery and at the end of treatment (T3). The correlation between the extent of surgery and the amount of relapse in the experimental group was also determined. Results: In the control group, the dental width exhibited a significant decrease of $0.70{\pm}1.28mm$ between T3 and T2. In the experimental group, dental and skeletal expansion of $1.83{\pm}1.66$ and $2.55{\pm}1.94mm$, respectively, was observed between T2 and T1. The mean changes in the dental and skeletal widths between T3 and T2 were $-1.41{\pm}1.98$ and $-0.67{\pm}0.72mm$, respectively. There was a weak correlation between the amount of skeletal expansion during segmental Le Fort I osteotomy and the amount of postoperative skeletal relapse in the experimental group. Conclusions: Maxillary expansion via segmental Le Fort I osteotomy showed good stability, with a skeletal relapse rate of 26.3% over approximately 12 months. Our results suggest that a greater amount of expansion requires greater efforts for the prevention of relapse.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제41권5호
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• pp.232-239
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• 2015

Objectives: The purpose of this study was to estimate the volumetric change of augmented autobone harvested from mandibular body cortical bone, using cone-beam computed tomography (CBCT) and three-dimensional reconstruction. In addition, the clinical success of dental implants placed 4 to 6 months after bone grafting was also evaluated. Materials and Methods: Ninety-five patients (48 men and 47 women) aged 19 to 72 years were included in this study. A total of 128 graft sites were evaluated. The graft sites were divided into three parts: anterior and both posterior regions of one jaw. All patients included in the study were scheduled for an onlay graft and implantation using a two-stage procedure. The dental implants were inserted 4 to 6 months after the bone graft. Volumetric stability was evaluated by serial CBCT images. Results: No major complications were observed for the donor sites. A total of 128 block bones were used to augment severely resorbed alveolar bone. Only 1 of the 128 bone grafts was resorbed by more than half, and that was due to infection. In total, the average amount of residual grafted bone after resorption at the recipient sites was $74.6%{\pm}8.4%$. Conclusion: Volumetric stability of mandibular body autogenous block grafts is predictable. The procedure is satisfactory for patients who want dental implants regardless of atrophic alveolar bone.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제40권1호
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• pp.11-16
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• 2014

Objectives: The aim of this study was to evaluate the pattern of lingual split line when performing a bilateral sagittal split osteotomy (BSSO) for asymmetric prognathism. This was accomplished with the use of cone-beam computed tomography (CBCT) and three-dimensional (3D) software program. Materials and Methods: The study group was comprised of 40 patients (20 males and 20 females) with asymmetric prognathism, who underwent BSSO (80 splits; n=80) from January 2012 through June 2013. We observed the pattern of lingual split line using CBCT data and image analysis program. The deviated side was compared to the contralateral side in each patient. To analyze the contributing factors to the split pattern, we observed the position of the lateral cortical bone cut end and measured the thickness of the ramus that surrounds the mandibular lingula. Results: The lingual split patterns were classified into five types. The true "Hunsuck" line was 60.00% (n=48), and the bad split was 7.50% (n=6). Ramal thickness surrounding the lingual was $5.55{\pm}1.07$ mm (deviated) and $5.66{\pm}1.34$ mm (contralateral) (P =0.409). The position of the lateral cortical bone cut end was classified into three types: A, lingual; B, inferior; C, buccal. Type A comprised 66.25% (n=53), Type B comprised 22.50% (n=18), and Type C comprised 11.25% (n=9). Conclusion: In asymmetric prognathism patients, there were no differences in the ramal thickness between the deviated side and the contralateral side. Furthermore, no differences were found in the lingual split pattern. The lingual split pattern correlated with the position of the lateral cortical bone cut end. In addition, the 3D-CT reformation was a useful tool for evaluating the surgical results of BSSO of the mandible.

• 대한치과교정학회지
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• 제50권1호
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• pp.3-12
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• 2020

Objective: This study compared three prominent midsagittal planes (MSPs) to identify the MSP that best approximates the true symmetrical MSP. Methods: Forty-three patients (mean age, 23.0 ± 8.20 years) were grouped as follows: group 1 consisted of 10 patients with skeletal Class I and a menton (Me) deviation of < 2 mm; group 2, 11 patients with skeletal Class III and a Me deviation < 2 mm; group 3, nine patients with skeletal Class III and a Me deviation of 2 to less than 4 mm; and group 4, 13 patients with skeletal Class III and an Me deviation ≥ 4 mm. The candidate MSPs were established by three-dimensional (3D) cone beam computed tomography (CBCT) reorientation methods (RMs): (1) the MSP perpendicular to the Frankfort horizontal (FH) plane while passing through the crista galli and basion; (2) the MSP including the nasion, incisive foramen, and basion; (3) the MSP including the nasion, anterior nasal spine, and posterior nasal spine. The mean absolute distances (MADs) to the MSPs were calculated from the coordinates of 1,548 points on 129 CBCT images. The differences in the values of the 3D coordinates among RMs were compared. Results: The MADs of the three RMs showed significant differences (p < 0.05). Most of the differences in values of the coordinates were not significant among RMs. Conclusions: Although the differences in distance among the three MSPs were minor, the MSP perpendicular to the FH plane while passing through the crista galli and basion best approximated the true symmetrical MSP.

• Imaging Science in Dentistry
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• 제39권3호
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• pp.115-120
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• 2009

Purpose : The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density ($g\;cm^{-3}$) obtained from cone-beam computed tomography ($CBMercuRay^{TM}$) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. Materials and Methods : CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the $CBMercuRay^{TM}$ (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using $CBWorks^{TM}$. Linear regression analysis and Student t-test were performed statistically. Results : There was no significant difference (P > 0.54) between real densities and measured densities. A linear regression was performed using the density, $\rho$($g\;cm^{-3}$), as the dependent variable in terms of the HU (H). The regression equation obtained was $\rho=0.00072H-0.01588$ with an $R^2$ value of 0.9968. Density values based on the Hounsfield scale was $1697.1{\pm}24.9\;HU$ in cortical bone, $526.5{\pm}44.4\;HU$ in trabecular bone, $2639.1{\pm}48.7\;HU$ in enamel, $1246.1{\pm}39.4\;HU$ in dentin of dental head phantom. Conclusion : CBCT provides an effective option for determination of material density expressed as Hounsfield Units.