• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.28-37
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• 2020

Purpose: The aim of our study was to determine the prevalence and degree of lingual concavities in the first molar region of the mandible to reduce the risk of perforating the lingual cortical bone during dental implant insertion. Methods: A total of 163 suitable cross-sectional cone-beam computed tomography images of edentulous mandibular first molar regions were evaluated. The mandibular morphology was classified as a U-configuration (undercut), a P-configuration (parallel), or a C-configuration (convex), depending on the shape of the alveolar ridge. The characteristics of lingual concavities, including their depth, angle, vertical location, and additional parameters, were measured. Results: Lingual undercuts had a prevalence of 32.5% in the first molar region. The mean concavity angle was 63.34°±8.26°, and the mean linear concavity depth (LCD) was 3.03±0.99 mm. The mean vertical distances of point P from the alveolar crest (Vc) and from the inferior mandibular border were 9.39±3.39 and 16.25±2.44, respectively. Men displayed a larger vertical height from the alveolar crest to 2 mm coronal to the inferior alveolar nerve (Vcb) and a wider LCD than women (P<0.05). Negative correlations were found between age and buccolingual width at 2 mm apical to the alveolar crest, between age and Vcb, between age and Vc, and between age and LCD (P<0.05). Conclusions: The prevalence of lingual concavities was 32.5% in this study. Age and gender had statistically significant effects on the lingual morphology. The risk of lingual perforation was higher in young men than in the other groups analyzed.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.27 no.2
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• pp.97-104
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• 2018

Mandibular anterior region has high implant survival rates and better accessibility compared with any other region. Even if there are possibilities for perforation on lingual cortical bone due to improper drilling and bleeding caused by lingual artery damage, mandibular anterior region is a safe region because less amount of major anatomical structures exist compared with other regions. However, because of narrow bucco-lingual width of alveolar ridge, it is challengeable to obtain esthetic implant prosthesis. Although patients are less sensitive subjectively, mandibular anterior region is as difficult as maxillary anterior region in that implant placement location plays a critical role on the prognosis of implant prosthesis. One-piece implant is a very useful option for mandibular anterior region. Considering the narrow roots and thin alveolar bone of mandible, it is clinically difficult for implant diameter to be greater than 3mm In this case, we could approach the esthetic restoration in mandibular anterior region with one-piece implant and immediate loading.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.281-290
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• 2020

Purpose: The objective of the present study was to evaluate the prevalence of dental implants positioning errors and their associations with adjacent structures and anatomical variations by means of cone-beam computed tomography (CBCT). Materials and Methods: CBCT images of 207 patients (584 dental implants) were evaluated by 2 oral radiologists. The distance between the implant and the adjacent teeth/implants was measured and classified as adequate (≥1.5 mm and ≥3 mm, respectively) or inadequate. The presence of thread exposure, cortical perforation, implant dehiscence, implant penetration into adjacent structures, and anatomical variations was also recorded. The incisor canal diameter and the depth of the concavity of the submandibular fossa were measured in order to evaluate their correlations with the frequency of implant penetration in these structures. Descriptive analyses, the Fisher exact test, and Spearman correlation analysis were performed (α=0.05). Results: The overall prevalence of positioning errors was 82.9%. The most common error was the inadequate distance between the implant and the adjacent teeth/implants. The presence of anatomical variations did not significantly influence the overall prevalence of errors (P>0.05). There was a positive correlation between the diameter of the incisor canal and the frequency of implant penetration in this structure (r=0.232, P<0.05). Conclusion: There was a high prevalence of dental implant positioning errors, and positioning errors were not associated with the presence of anatomical variations. Professionals should be aware of the space available for implant placement during the preoperative planning stage.

• Imaging Science in Dentistry
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• v.51 no.1
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• pp.73-80
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• 2021

Purpose: The purpose of this study was to evaluate the cone-beam computed tomographic (CBCT) imaging and histopathological characteristics of osteoradionecrosis(ORN) and medication-related osteonecrosis of the jaw(MRONJ). Materials and Methods: Ten surgical specimens from segmental mandibulectomy (3 ORN and 7 MRONJ) were analyzed using CBCT. The CBCT parameters were as follows: high-resolution mode (tube voltage, 90.0 kV; tube current, 4.00 mA; rotation time, 16.8 s; field of view, 56 mm×56 mm; thickness, 0.099 mm). Histopathological characteristics were evaluated using histological slides of the surgical specimens. The Pearson chi-square test was used to compare ORN and MRONJ in terms of CBCT findings(internal texture, sequestrum, periosteal reaction and cortical perforation) and histopathological characteristics(necrotic bone, inflammatory cells, reactive bone formation, bacteria, Actinomyces, and osteoclasts). A P value less than 0.05 was considered to indicate statistical significance. Results: MRONJ showed periosteal reaction on CBCT more frequently than ORN (7 of 7 [100%] vs. 0 of 3 [0%], P<0.05). Regarding histopathological characteristics, MRONJ showed osteoclasts more frequently than ORN (6 of 7 [85.7%] vs. 0 of 3 [0%], P<0.05). Conclusion: This study evaluated the CBCT imaging and histopathological characteristics of ORN and MRONJ, and the findings suggest that CBCT could be useful for the evaluation of ORN and MRONJ.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.63-70
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• 2004

The midpalatal suture area has some advantages for supporting miniscrews : it has no specific anatomical structure, it is composed of thick cortical bone, and covered with attached gingiva. So it is suitable area for inserting miniscrews. However, the midpalatal suture area appears thinner when seen in ceph. As a result, Clinicians can misunderstand that inserting miniscrews cause the problem, both the risk of perforation and the decrease of stability. The purpose of this article is measuring the vertical bone thickness of the midpalatal suture area for inserting miniscrews. The total of 25patient (male : 13, female : 12), who are in their twenties, were taken CT. The vertical bone thickness of the midpalatal suture area was measures from the transverse section of CT. As a result, We reached a conclusion from the differences of each area. It is as follows: 1. There is no significant difference between the thickness of male group and that of female group. 2. In coronal section, Bone thickness becomes thinner from the midpalatal suture to Left & Right side, in sagittal section, Bone thickness becomes thinner from incisive foramen to PNS. 3. The area that is within 3mm of left and right from the midpalatal suture area transversely and within 25mm backward from the incisive foramen sagittaly is enough for inserting miniscrews.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.2
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• pp.122-126
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• 2011

Introduction: In the lateral window approach for a maxillary sinus bone graft, there has been considerable controversy regarding the placement of a barrier membrane over the osteotomy site. In particular, when there is no damage to the Schneiderian membrane, clinicians should decide whether to use a barrier membrane or not, considering the benefits and costs. This study presents the clinical cases to demonstrate that only repositioning the detached window can lead to satisfactory bony healing of the grafted material without using a barrier membrane in the lateral approach for a maxillary sinus bone graft. Materials and Methods: Five consecutive patients were treated with the same surgical procedures. After performing the antrostomy on the lateral maxillary wall using a round carbide bur and diamond bur, the bony window was detached by a gentle levering action. After confirming no perforation of the Schneiderian membrane, the grafting procedure was carried out the detached window of the lateral maxillary wall was repositioned over the grafted material without using a barrier membrane. A gross examination was carried out at the postoperative 6 month re-entry, and the the preoperative and postoperative dental computed tomography (CT) at re-entry were compared. Results: All the procedures in the 5 patients went on to uneventful healing with no complications associated with the bone graft. Satisfactory bone regeneration without the interference of fibrous tissue on the gap between the repositioned window and lateral wall of the maxillary sinus was observed in the postoperative 6 month re-entry. The CT findings at re-entry revealed the, reconstruction of the external cortical plate including repositioned bony window. In addition, the loss of the discontinuity of the lateral maxillary wall was confirmed. Conclusion: This preliminary report showed that the detached window, which was just repositioned on the grafted material, could function as a barrier membrane in the lateral approach for a maxillary sinus bone graft. Therefore additional morphometric and histologic studies will be needed.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.1
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• pp.52-60
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• 2003

Purpose: To analyse their end results and also to differentiate the single or multiple giant cell tumor(GCT) of tendon sheath in hand. Materials & Methods: Total 21 cases with GCT of tendon sheath in hand were treated surgically and analyzed their end results with clinically, radiologically and pathologically to allowed for average 16 months after surgical excision. Results: The finger flexor tendons, especially on index and ring finger, involving distal interphalangeal joint and mid-phalanges in fourth decades (average age of 47 years old) were frequently involved, and the mass was not exceed than 2 cm in size, fixed on tendon sheath with rubbery hard tenderness but rare bony involvements except 4 cases of bony erosion and cortical perforation. The three cases with multiple GCT of hand was also combined with familial hypercholesterolemia, and are commonly involved the extensor tendons as well as achilles tendons bilaterally, treated with partial excision because of multiplicity. Average 16 months after surgical excision for single GCT cases was followed and showed the recurrence in 3 cases(3/18,16.7%), treated with wide excision. The single and multifocal GCT are similar in pathologic changes but different soft tissue tumors in their pathogenesis, treatment and prognosis. Conclusion: Incomplete excision of GCT of tendon sheath in hand are thought to be the cause of recurrence, especially in cases with incomplete lesional excision, in multilobular and bony involvement etc. So careful wide excision is necessary to prevent the recurrence.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.1
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• pp.124-129
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• 2003

Purpose: To analyze the clinical outcome and radiological features after surgical treatment of stage III giant cell tumor around the knee. Materials and Methods: 21 patients with stage III giant cell tumor around the knee joint, who were operated at our institutes between March 1991 and February 2000, were selected for this study. The average follow-up was 5.7 years (range, 1~9 years). After thorough curettage using high speed burr, cryosurgery and cementing with polymethymethacrylate (PMMA) were performed in 11 patients. 7 patients were treated with PMMA cementing (4 patients) or bone grafting (3 patients) after curettage without cryosurgery. Reconstruction with prosthesis composite allograft and knee fusion with Huckstep nail were performed in 3 patients with huge defect and joint perforation. Results: Local recurrence developed in 1 out of 11 patients who was treated with curettage and cementing with cryosurgery (9.1%) and 3 out of 7 patients who underwent curettage and cementing without cryosurgery (28.6%). Joint space narrowing more than 3mm was noted in 1 patient (9.1%), who treated with cryosurgery and anther patient (14.5%) who treated without cryosurgery. There was no local recurrence in case of wide resection and reconstruction. Conclusion: Thorough curettage and PMMA cementing with cryosurgery as an adjuvant is thought to be effective modalities in the treatment of stage 3 giant cell tumors around the knee. Wide resection and reconstruction can be reserved mainly for the cases of stage 3 giant cell tumor with significant cortical destruction and marked joint destruction, and the cases of local recurrence with poor bone stock.