• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.111-119
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• 2015

Purpose: The objective of this study was to evaluate the accuracy of a stereolithographic surgical guide that was made with information from intraoral digital impressions and cone beam CT (CBCT). Materials and methods: Six sets of resin maxilla and mandible models with missing teeth were used in this study. Intraoral digital impressions were made. The virtual models provided by these intraoral digital impressions and by the CBCT scan images of the resin models were used to create a surgical guide. Implant surgery was performed on the resin models using the surgical guide. After implant placement, the models were subjected to another CBCT scan to compare the planned and actual implant positions. Deviations in position, depth and axis between the planned and actual positions were measured for each implant. Results: The mean deviation of the insertion point and angulation were 0.28 mm and $0.26^{\circ}$, apex point were 0.11 mm and 0.14 mm respectively. The implants were situated at a mean of 0.44 mm coronal to the planned vertical position. Conclusion: This study demonstrates that stereolithographic surgical guides created without the use of impressions and stone models show promising accuracy in implant placement.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.61-70
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• 2017

In this case, the impression surface of the existing denture was scanned and was inverted three-dimensionally to express the residual ridge form. Implant planning was performed on the superimposed data of the CT with the scanned image of the denture with radiopaque markers attached. At the day of surgery, customized abutments fabricated in accordance with the form of the gingival margin were linked with fixtures and temporary restorations were set. In the process of fabricating the final prosthesis after the osseointegration of implant fixture, the intraoral scan images at abutment level were merged with images of the abutments scanned and stored before implant surgery. By fabricating the final prosthesis with the abutments obtained by merging can increase the marginal fitness of the final prosthesis and simplify the clinical process.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.55-59
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• 2010

Purpose: Renal excretion is the main route of FDG clearance in FDG PET/CT scan. Applying optimal method of renal excretion is very important for enhancing image quality and diagnostic accuracy. We evaluated several methods of renal excretion in FDG PET/CT scan. Materials and Methods: Thirty patients with normal renal function were prospectively included. Patients were divided into three group and undergone early and delayed FDG PET/CT scans. (1) Delay group; at 1 hour later of early scan, delayed scan was performed without additional hydration, (2) Hydration group; at 1 hour later of early scan, delayed scan was performed with additional oral hydration (700 mL of water), (3) Lasix group; lasix was administered at the end of early scan and dealyed scan was performed 30 min later. Early and delayed scans were compared to evaluate efficiency of renal excretion. Visual and quantitative analyses were performed by experienced physician and technologist of nuclear medicine. Results: On the visual analysis, renal excretion was the most evident in Lasix group followed by Hydration group. Delay group showed poor renal excretion. On the quantitative analysis, washout rates were $9.2{\pm}20.7%$, $28.1{\pm}22.8%$ and $29.5{\pm}23.1%$ for Delay, Hydration and Lasix groups, respectively. Conclusion: Administration of lasix was the best method for enhancing renal excretion. Delayed scan with hydration was also efficient method, but delayed scan without hydration was not adequate method.

• Journal of Oral Medicine and Pain
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• v.23 no.4
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• pp.457-473
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• 1998

This study was performed to investigate the morophological and positional correlation between the upper cervical vertebra, the oral structures and the pharyngeal tissues, and the correlation of these anatomical structures with dental features, such as teeth wear area nad tooth contact status, etc. Seventy patients with temporamandibular disorders and sixty three dental students without any signs and symptoms in head and neck region were selected for this study. All they had natural dentition without any fixed and removable protheses. Teeth wear area and arch width wre measured from the upper dental cast, tooth contact status were observed by T-Scan system$^\textregistered$ and four cephaloradiograpohs were taken from four head postures, namely, natural(NHP), forward(FHP), upward(UHP), and downward head postiure(DHP). 22 cephalometric items were measured on the films and the data were processed with SAS statistical program. The result of this study were as follows : 1. In normal group, angle of cervical vertebra tangent and of between hard and soft palate were broader in female subjects than those in male subjacets, but distance from subocciput to axis, size of soft palate, and pharyngeal space width were larger in male subjects. 2. In normal group with natural head posture, the items correlated each others from the three anatomical regions were distance between first nad second vertebra in posterior part, distance from the lingual surface of lower anterior teeth to anterior surface of soft palate, and distance from the hyoid bone to third vertebra. 3. Three set of items showed significant correlation each other in the four head postures in normal group. First set was the angle between hard and soft palate and the idstance from subocciput to posterior arch of first vertebra, second set was the distance between first and second vertebra in posterior part and the teeth wear area, third set was number and force of tooth contact and length of soft palate and distance from anterior tip of hyoid bone to mandibular plane.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.23.1-23.7
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• 2016

Background: The purpose of this retrospective study was to develop a two- and three-dimensional analysis of the airway using cone-beam computed tomography (CBCT) and to determine whether the airway space would be changed in mandibular prognathism after bimaxillary surgery involving maxillary posterior impaction. Methods: Patients requiring orthognathic surgery from 2012 to 2014 were recruited for this study. CBCT scans were obtained at three points: preoperatively (T0), immediate postoperatively (T1), and after 6 months postoperatively (T2). The nasopharynx, oropharynx, and hypopharynx were measured on the CBCT scan for each patient in a repeatable manner. With the midsagittal plane, linear measurements in the middle of each were obtained. For the CBCT, volumetric measurements of each and total airway were obtained. Results: A total of 22 consecutive patients (11 men and 11 women) were included in the present study. The total volume was significantly reduced (p < .001). However, the change of the diameter and volume of the nasopharynx was not statistically significant (p = .160, p = .137, respectively). In the oropharynx, the change of both the diameter and volume showed statistical significance between preoperatively and immediate postoperatively (p < .001, p = .001, respectively) and also preoperatively and after 6 months postoperatively (p = .001, p = .010, respectively). In the hypopharynx, the change of both the diameter and volume showed statistical significance between preoperatively and immediate postoperatively (p = .001, p < .001, respectively) and also preoperatively and after 6 months postoperatively (p = .001, p < .001, respectively). Conclusions: The bimaxillary surgery involving maxillary posterior impaction can reduce the volume of airway in the patients of mandibular prognathism. Although total airway volume was reduced significantly, the changes in the volume and diameter of the nasopharynx were not statistically significant. The maxillary posterior impaction affects on the nasopharyngeal airway minimally.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.381-386
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• 2017

PURPOSE. To integrate extra-oral facial scanning information with CAD/CAM complete dentures to immediately rehabilitate terminal dentition. MATERIALS AND METHODS. Ten patients with terminal dentition scheduled for total extraction and immediate denture placement were recruited for this study. The patients were submitted to a facial scanning procedure using the in-office PritiMirror scanner with bite registration records in-situ. Definitive stone cast models and bite records were subsequently submitted to a lab scanning procedure using the lab scanner (iSeries DWOS; Dental Wings). The scanned models were used to create a virtual teeth setup of a complete denture. Using the intra-oral bite records as a reference, the virtual setup was incorporated in the facial scan thereby facilitating a virtual clinical evaluation (teeth try-in) phase. After applying necessary adjustments, the virtual setup was submitted to a CAM procedure where a 5-axis industrial milling machine (M7 CNC; Darton AG General) was used to fabricate a full-milled PMMA immediate provisional prosthesis. RESULTS. Total extractions were performed, the dentures were immediately inserted, and subjective clinical fit was evaluated. The immediate provisional prostheses were inserted and clinical fit, occlusion/articulation, and esthetics were subjectively assessed; the results were deemed satisfactory. All provisional prostheses remained three months in function with no notable technical complications. CONCLUSION. Ten patients with terminal dentition were treated using a complete digital approach to fabricate complete dentures using CAD/CAM technology. The proposed technique has the potential to accelerate the rehabilitation procedure starting from immediate denture to final implant-supported prosthesis leading to more predictable functional and aesthetics outcomes.

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.73-87
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• 1992

저자는 28명의 측두하악장애 환자와 31명의 정상인을 대상으로 최적기능교합의 개념에 입각하여 교합시의 치아접촉점을 동적이며 정량적인 방법으로 평가하여 교합안정장치의 사용으로 인한 교합안정성의 개선여부를 알아보고자 하였다. 이와 동시에 교근과 전측두근의 활성도를 측정하여 치료의 경과에 따른 근활성의 변화를 알아보기 위해 본 연구를 시행하였다. 측정항목은 개구범위, 두개하악장애지수, 치아접촉점 좌우균형치, 치아접촉점 전후균형치, 치아접촉점 평균시간간격, 치아접촉점의 개수, 접촉시간, 좌우측 교근과 좌우측 전측두근의 근활성, 근활성 비대칭 지수 등이었다. 이의 측정을 위해 T-Scan System, K-6 Diagnostic System 그리고 EM 2등을 사용하였으며 얻어진 자료에 대해 검정한 후 다음과 같은 결론을 얻었다. 1. 교합안정장치를 이용하여 측두하악장애 환자들을 4주간 치료한 결과 전반적인 임상증상이 호전되어 개구범위와 두개하악장애지수에 있어서 뚜렷한 개선이 있었다. 2. 측두하악장애 환자에서 최대 악물기시의 치아접촉점 좌우균형치및 평균시간 간격이 큰 것으로 나타나 치아접촉이 일어나는 순간의 교합안정성이 좋지 않은 것으로 평가되었다. 3. 치료 4주후 교하안정장치를 장착한 상태에서 측정한 치아접촉점 좌우균형치및 치아접촉점 평균시간간격은 치료전에 비해 개선된 것으로 나타났다. 4. 치료 4주후 치아접촉점의 전후방 분포가 구치부위로 이동되는 양상을 보였다. 5. 측두하악장애 환자에서 최대 악물기시의 좌우측 교근 및 전측두슨의 근활성은 정상인에 비해 낮에 나타났으며, 이는 치료기간 동안 감소되는 경향을 나타내었다. 6. 측두하악장애 환자에서 전측두근의 근활성 비대칭지수는 정상인에 비해 상당히 높게 나타났으며 이는 치료기간 동안 감소되는 경향을 나타내었다.

• Journal of Oral Medicine and Pain
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• v.19 no.1
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• pp.137-149
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• 1994

This study was performed to investigate the relationship between Forward Head Posture(FHP) and Craniomandlbular Disorders(CMDs). Many studies reported that there was some relationship between them, however, there is still controversy. So It Is necessary to observe and compare many more patients with CMDs wirh normal controls. For the study 85 patients with CMDs and 37 dental students were selected as experimentals and controls, respectively. And the experimentals were classified Into two groups, that is, TMJ internal derangement group and muscle disorders group according to clinical diagnosis. For measuring the FHP, CROM(Cervical-Range-of-Notion)was used. This goniometer is composed of three part. First, gravity goniometer for flexion and extension. Second, magnetic compass and yoke for rotational movement. And last, forward head arm and vertebra locator for forward head posture. Next T-Scan, electronic occlusal analyzer, was used for recording of occlusal contact state. Other items such as maximum opening, lateral excursion, Helkimo's anamnestic index, and muscle palpation point from Friction's craniomandibular index were checked clinically by one examiner. The result of this study were as follows : 1. In male, control group showed much more measurement in resting forward head posture than did experimental group. But there were not significant differences between groups in female subject. From this results, the author contended that CROM is new measuring system and differ from other goniometers in some aspect, so that results should be re-evaluated 2. Mean value of maximum mouth opening in nearly all groups were greater than 40mm. and mouth opening had a significant correlation with occlusal force and with anamnestic index both sex. 3. Mean value of palpation point had not any correlationship with forward head posture in both sex, but there was significant difference between upper and lower group by rounded shouldes. 4. In summary, there was no significant relationship between forward head posture and sign and symptom of Craniomandibular Disorders.

• Imaging Science in Dentistry
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• v.40 no.2
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• pp.63-68
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• 2010

Purpose : To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Materials and Methods : Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, $\rho$ ($g/cm^3$), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. Results : CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were $\rho$=0.001H+1.07 with $R^2$ value of 0.999 for Somatom Emotion, $\rho$=0.002H+1.09 with $R^2$ value of 0.991 for Alphard VEGA, $\rho$=0.001H+1.43 with $R^2$ value of 0.980 for i-CAT and $\rho$=0.001H+1.30 with $R^2$ value of 0.975 for Implagraphy. Conclusion: CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.323-330
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• 2020

Purpose: The mastoid region is ideal for studying sexual dimorphism due to its anatomical position at the base of the skull. This study aimed to determine sex in the Iranian population based on measurements of the mastoid process using different data mining algorithms. Materials and Methods: This retrospective study was conducted on 190 3-dimensional cone-beam computed tomographic (CBCT) images of 105 women and 85 men between the ages of 18 and 70 years. On each CBCT scan, the following 9 landmarks were measured: the distance between the porion and the mastoidale; the mastoid length, height, and width; the distance between the mastoidale and the mastoid incision; the intermastoid distance (IMD); the distance between the lowest point of the mastoid triangle and the most prominent convex surface of the mastoid (MF); the distance between the most prominent convex mastoid point (IMSLD); and the intersecting angle drawn from the most prominent right and left mastoid point (MMCA). Several predictive models were constructed and their accuracy was compared using cross-validation. Results: The results of the t-test revealed a statistically significant difference between the sexes in all variables except MF and MMCA. The random forest model, with an accuracy of 97.0%, had the best performance in predicting sex. The IMSLD and IMD made the largest contributions to predicting sex, while the MMCA variable had the least significant role. Conclusion: These results show the possibility of developing an accurate tool using data mining algorithms for sex determination in the forensic framework.