• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.1
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• pp.43-48
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• 2011

Introduction: This study examined the anatomical morphology of the medial surface of the posterior mandible using 3-dimensional cone-beam computed tomography (CT) images to reduce the number of complications related to dental implant placement. Materials and Methods: Fifty patients were enrolled in this study with an average age (${\pm}$standard deviation) of 44.28 (${\pm}13.05$). On the coronal views cone-beam CT of the first molars, the distance between the top of the canal and alveolar crest vertical distance (VD), the distance between the upper-most point of the canal and the point perpendicular to the lingual cortical margin of the mandible lingual distance (LD), the location of the starting point of VD for reducing from the vertical reference line (VD point), and the inclination of the mandibular medial surface (lingual inclination) were measured, and a statistical evaluation was performed using SPSS for Windows version 15.0. Results: The mean VD0 was $16.91{\pm}2.47\;mm$ and VDx decreased with increasing x value. The mean LD was $5.27{\pm}1.36\;mm$. The VD began to decrease at the mean location of $6.12{\pm}0.96\;mm$ from the vertical reference line. The mean lingual inclination was $1.52{\pm}0.72^{\circ}$. Conclusion: These results will assist in the accurate placement of dental implants and the reduction of complications, particularly in the case of preoperative implant planning using only 2-dimensional imaging methods. (ex. panoramic radiography)

• The Journal of the Korean dental association
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• v.54 no.10
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• pp.811-819
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• 2016

Panfacial fracture is extremely difficult to manage facial injuries but concomitant injuries and severe complications including facial esthetic and functional problems can make it harder. Thorough evaluation and closed co-work with other specialists is needed when reduction and fixation cannot be achieved quickly. Emergency bony support and soft tissue key suture provide the patients with airway integrity, hard and soft tissue vitality. A systemic treatment plan must be made by 3D CT image. This plan include airway management for surgery, sequence of reduction and fixation, approach method, soft tissue resuspension and reconstruction of lost tissue like inferior orbital wall, zygomaic buttress and soft tissue. From known to unknown structures, accurate reduction and fixation will provide proper occlusion, facial projection, width, hight and function. Consideration about facial retaining ligaments must be given to prevent soft tissue sagging.

• Journal of Periodontal and Implant Science
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• v.40 no.2
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• pp.56-60
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• 2010

Purpose: The sinus lift procedure requires detailed knowledge of maxillary sinus anatomy and the possible anatomical variations. This study evaluated the location and prevalence of maxillary sinus septa using computed tomography (CT). Methods: This study was based on the analysis of CT images for posterior maxilla which were obtained from patients who visited Chonbuk National University Dental Hospital during the period of June 2007 to December 2008. With the exclusion of cases presenting any pathological changes, 236 maxillary sinuses in 204 patients were retrospectively analyzed. The average age of the patients was 50.9. The cases were divided into two groups, an atrophy/edentulous segment and a non-atrophy/dentate segment, and maxillary sinus septa of less than 2.5 mm were not taken in-to consideration. The location of septa was also divided for analysis into 3 regions: the anterior (1st and 2nd premolar), middle (1st and 2nd molar) and posterior (behind 2ndmolar) regions. Results: In 54 (20.9%) of the 204 patients there were pathologic findings, and those patients were excluded from the analysis. Sinus septa were present in 58 (24.6%) of the 236 maxillary sinuses and in 55 (27%) of the 204 total patients. In the atrophy/ edentulous ridge group (148 maxillary sinuses), 41 cases (27.7%) were found, and 17 cases (19.3%) were found in the non-atrophy/ dentulous ridge group (88 maxillary sinuses). In terms of location, septa were found in 18 cases (27.3%) in the anterior, in 33 cases (50%) in the middle and in 15 cases (22.7%) in the posterior regions. Conclusions: In the posterior maxilla, regardless of type of ridge (atrophy/edentulous or non-atrophy/dentate), the anatomical variation of sinus septa is diverse in its prevalence and location. Thus, accurate information on the maxillary sinus of thepatient is essential and should be clearly understood by the surgeon to prevent possible complications during sinus lifting.

• The korean journal of orthodontics
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• v.49 no.5
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• pp.279-285
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• 2019

Objective: This study evaluated the efficiency of anchorage provided by temporary anchorage devices (TADs) in maxillary bicuspid extraction cases during retraction of the anterior teeth using a fixed appliance. Methods: Patients aged 12 to 50 years with malocclusion for which bilateral first or second maxillary bicuspid extractions were indicated were included in the study and randomly allocated to the TAD or control groups. Retraction of the anterior teeth was achieved using skeletal anchorage in the TAD group and conventional dental anchorage in the control group. A computed tomography (CT) scan was performed after alignment of teeth, and a second CT scan was performed at the end of extraction space closure in both groups. A three-dimensional superimposition was performed to visualize and quantify the maxillary first molar movement during the retraction phase, which was the primary outcome, and the stability of TAD movement, which served as the secondary outcome. Results: Thirty-four patients (17 in each group) underwent the final analysis. The two groups showed a significant difference in the movement of the first maxillary molars, with less significant anchorage loss in the TAD group than that in the control group. In addition, TAD movement showed only a slight mesial movement on the labial side. On the palatal side, the mesial TAD movement was greater. Conclusions: In comparison with conventional dental anchorage, TADs can be considered an efficient source of anchorage during retraction of maxillary anterior teeth. TADs remain stable when correctly placed in the bone during the anterior tooth retraction phase.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.6
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• pp.479-506
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• 2021

Background: Chronic neuropathic pain (NP) presents therapeutic challenges. Interest in the use of cannabis-based medications has outpaced the knowledge of its efficacy and safety in treating NP. The objective of this review was to evaluate the effectiveness of cannabis-based medications in individuals with chronic NP. Methods: Randomized placebo-controlled trials using tetrahydrocannabinol (THC), cannabidiol (CBD), cannabidivarin (CBDV), or synthetic cannabinoids for NP treatment were included. The MEDLINE, Cochrane Library, EMBASE, and Web of Science databases were examined. The primary outcome was the NP intensity. The risk of bias analysis was based on the Cochrane handbook. Results: The search of databases up to 2/1/2021 yielded 379 records with 17 RCTs included (861 patients with NP). Meta-analysis showed that there was a significant reduction in pain intensity for THC/CBD by -6.624 units (P < .001), THC by -8.681 units (P < .001), and dronabinol by -6.0 units (P = .008) compared to placebo on a 0-100 scale. CBD, CBDV, and CT-3 showed no significant differences. Patients taking THC/CBD were 1.756 times more likely to achieve a 30% reduction in pain (P = .008) and 1.422 times more likely to achieve a 50% reduction (P = .37) than placebo. Patients receiving THC had a 21% higher improvement in pain intensity (P = .005) and were 1.855 times more likely to achieve a 30% reduction in pain than placebo (P < .001). Conclusion: Although THC and THC/CBD interventions provided a significant improvement in pain intensity and were more likely to provide a 30% reduction in pain, the evidence was of moderate-to-low quality. Further research is needed for CBD, dronabinol, CT-3, and CBDV.

• Imaging Science in Dentistry
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• v.53 no.4
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• pp.325-333
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• 2023

Purpose: The objective of this study was to evaluate and compare the accuracy and image quality of root surface area (RSA) measurements obtained with various cone-beam computed tomography (CBCT) protocols, relative to the gold standard of micro-computed tomography (CT), in an in vitro setting. Materials and Methods: Four dry human skulls were scanned using 8 different protocols, with voxel sizes of 0.15 mm, 0.3 mm, and 0.4 mm. Three-dimensional models of the selected teeth were constructed using CBCT and microCT protocols, and the RSA was automatically measured by the image-processing software. The absolute difference in the percentage of the RSA(%ΔRSA) was calculated and compared across the 8 CBCT protocols using repeatedmeasures analysis of variance. Finally, image quality scores of the RSA measurements were computed and reported in terms of percent distribution. Results: No significant differences were observed in the %ΔRSA across the 8 protocols (P>0.05). The deviation in %ΔRSA ranged from 1.51% to 4.30%, with an increase corresponding to voxel size. As the voxel size increased, the image quality deteriorated. This decline in quality was particularly noticeable at the apical level of the root, where the distribution of poorer scores was most concentrated. Conclusion: Relative to CBCT protocols with voxel sizes of 0.15mm and 0.3mm, the protocols with a voxel size of 0.4 mm demonstrated inferior image quality at the apical levels. In spite of this, no significant discrepancies were observed in RSA measurements across the different CBCT protocols.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.169-174
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• 2016

In this study, we evaluated the virtual reality model for dental implant surgery and discussed about the method to make the surgical environment for virtual reality with practical patient data. The anatomical model for patient face was fabricated by facial and oral scan data based on CT data. The simulation scenario was composed step by step fashion with Unity3D. From incision and sinus bone graft procedure which is needed to this patient model to implant installation and bone graft was included in this scenario. We used the HMD and leap motion for immersiveness and feeling of real operation. Twenty training doctor was attended this simulation study, and surveyed their satisfactory results by questionnaire. Implant surgery education program was showed the possibilities of educational tool for dental students and training doctors. Virtual reality for surgical education with HMD and leap motion had advantages, in terms of cheap prcie, easy access.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.289-299
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• 2009

Objective: The purpose of the present study was to evaluate the effectiveness of the use of Head Posture Aligner (HPA) during cone-beam computed tomography (CBCT) scan in generation of frontal cephalograms using 3D CBCT images. Methods: CBCT scans and frontal cephalograms were made in 30 adult individuals. While a couple of CBCT scan was made for one subject, one was made with conventional method, without use of HPA, the other was acquired with the use of HPA. After creation of virtual frontal cephalogram from each 3D CBCT image, it was traced and compared with the tracing of real frontal cephalogram. Results: In the comparison of the measurements, the virtual cephalograms with the use of HPA did not show statistically significant differences with the real cephalograms whereas the virtual cephalograms without the use of HPA presented significant differences with real cephalograms in many measurements. In the correlation analysis with the measurements of the real cephalograms, the virtual cephalograms with the use of HPA showed higher correlations in all measurements than the virtual cephalograms without the use of HPA. Conclusions: Measurements from CBCT-generated cephalograms become similar to those from real cephalograms with the use of HPA during CBCT scan. Thus, the use of HPA is suggested during the CBCT scan in order to construct accurate virtual frontal cephalograms using 3D CBCT images.

• The Korean Society of Law and Medicine
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• v.17 no.1
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• pp.281-297
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• 2016

In order to make a treatment plan and outcome prediction, it is important to evaluate accurately and objectively osseous tissues of the implant area. The evaluation of osseous tissues is the most objective method for the decision of production time of upper structure of alveolar bone. However, the evaluation of osseous tissues contains contradiction because it is made by subjective opinions of dental surgeons. Many dentists also point out the problem of subjective evaluation of osseous tissues. Therefore, it is necessary to create accurate and objective standards. Previously, the evaluation of bone density depends on dentist's subjective sensation during drilling procedure of implant. However, the HU(Hounsfield unit) figure of CT(computed tomography) scan allows of objective and precise categorization of bone density now. Misch and Kircos divided the bone density levels from D1 to D5 with subjective separation of bone density. Their method also depended on not objective and quantification data but subjective separation by sensation. Thus, we need the evaluation of implant area through comparative analysis of more objective and quantification data. Implant treatment comprises the highest frequency of medical disputes of dental clinic. If we bring objective checkup and reasonable treatment method in the implant treatment, we can deduce more reasonable results, and the failure late of implant treatment also can decrease. The ultimate objective of this study is the minimization of dental disputes between dental patients and dentists by creating new legal standards on the basis of objective and quantification data.

• Imaging Science in Dentistry
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• v.30 no.1
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• pp.63-70
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• 2000

Purpose: To propose a standard value for the maxillary sinus volume of a normal Korean adult by measuring the width and height of the sinus and analyzing their correlation and the difference of the sinus size respectively between sexes, and on the right and left sides. Materials and Methods: Fifty-two (95 maxillary sinuses) out of 20 years or over aged patients who had taken CT in the Department of Dental Radiology, Yonsei University, Dental Hospital, between February 1997 and July 1999 who were no specific symptom, prominent bony septa, pathosis, clinical asymmetry and history of surgery in the maxillary sinus were retrospectively analyzed. Results: The mean transverse width, antero-posterior width, height and volume of the normal Korean adult's maxillary sinuses were 28.33 mm, 39.69 mm, 46.60 mm and 21.90 cm³, respectively. There was a significant sex difference in the sinus volume (p>0.05). In the mean antero-posterior width, height and volume of the sinus, no significant difference was observed between both sides. All four measurements showed a significant correlation between both sides (p>0.0001). The widths and height of the sinus all showed a significant correlation with the sinus volume (p>0.0001). Conclusion : In the Korean normal adult's maxillary sinus, males tended to be larger than females. Except for the transverse width, all of the measurements showed no significant difference between the right and left side, but significant correlations in the four measurements between both sides were observed. Thus, the overgrowth or undergrowth in the unilateral maxillary sinus may suggest a certain pathosis or developmental abnormalities in the maxillary sinus.