• Imaging Science in Dentistry
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• 제36권3호
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• pp.145-149
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• 2006

Purpose : To assess the width of the labial alveolar bone of the incisive canal and the width of the incisive canal on spiral computed tomographic images of the anterior portion of the maxilla. Materials and Methods : Study materials included 38 CT scans taken for preoperative planning of implant placement. Axial cross-sectioned image entirely showing the incisive canal was selected and scanned with 600 DPI resolution. The width of the labial alveolar bone of the incisive canal at an orifice to the oral cavity, middle portion, and an orifice to the nasal cavity and the diameter of the incisive canal at the middle portion were determined by two specialist using Digora for Windows 2.1 The statistical analyses were carried out using SPSS 12.0.1. Results : When the maxillary central incisors remained, the mean labial alveolar bone width were $6.81{\pm}1.41mm,\;6.46{\pm}1.33mm$, and $7.91{\pm}1.33mm$. When the maxillary central incisors were missed the mean width were $5.42{\pm}2.20mm,\;6.23{\pm}2.29mm$, and $7.89{\pm}2.13mm$. Conclusions : The labial alveolar bone width at middle portion and an orifice to the nasal cavity were of no statistical significant difference according to presence of the maxillary central incisors (P>0.05). The width between oral cavity and nasal cavity, middle portion and to nasal cavity revealed statistically significant difference (P<0.05).

• Journal of Periodontal and Implant Science
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• 제40권3호
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• pp.132-138
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• 2010

Purpose: The purpose of this study was to compare the bone regeneration effects of cortical, cancellous, and cortico-cancellous human bone substitutes on calvarial defects of rabbits. Methods: Four 8-mm diameter calvarial defects were created in each of nine New Zealand white rabbits. Freeze-dried cortical bone, freeze-dried cortico-cancellous bone, and demineralized bone matrix with freeze-dried cancellous bone were inserted into the defects, while the non-grafted defect was regarded as the control. After 4, 8, and 12 weeks of healing, the experimental animals were euthanized for specimen preparation. Micro-computed tomography (micro-CT) was performed to calculate the percent bone volume. After histological evaluation, histomorphometric analysis was performed to quantify new bone formation. Results: In micro-CT evaluation, freeze-dried cortico-cancellous human bone showed the highest percent bone volume value among the experimental groups at week 4. At week 8 and week 12, freeze-dried cortical human bone showed the highest percent bone volume value among the experimental groups. In histologic evaluation, at week 4, freeze-dried cortico-cancellous human bone showed more prominent osteoid tissue than any other group. New bone formation was increased in all of the experimental groups at week 8 and 12. Histomorphometric data showed that freeze-dried cortico-cancellous human bone showed a significantly higher new bone formation percentile value than any other experimental group at week 4. At week 8, freeze-dried cortical human bone showed the highest value, of which a significant difference existed between freeze-dried cortical human bone and demineralized bone matrix with freeze-dried cancellous human bone. At week 12, there were no significant differences among the experimental groups. Conclusions: Freeze-dried cortico-cancellous human bone showed swift new bone formation at the 4-week healing phase, whereas there was less difference in new bone formation among the experimental groups in the following healing phases.

• 대한치과의사협회지
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• 제50권4호
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• pp.203-210
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• 2012

Objective: The aim of this study was to investigate the incidence of the C-shaped canal of permanent mandibular second molar (PMSM) in Korean sub-population using Cone-Beam CT (CBCT) data and analyze the types of C-shaped canal. Materials & Methods: The protocol for this study was approved by the Institutional Review Board at the Pusan National University Hospital (E-2011039). Among the CBCT images taken of patients who visited the St. Bennedict Dental Hospital (Busan, Korea) from May 2008 to April 2011 for implant surgery and surgical removal of impacted teeth, high-quality CBCTs from 705 patients (361 male and 342 female) were screened and 607 PMSMs of 383 patients were evaluated retrospectively. All PMSMs were anatomically analyzed in detail by using image viewer software (EasyDent; Vatech). PMSMs were evaluated in the axial plane to investigate the shape of root and canals. The C-shaped canals were classified into five types. The total incidence, gender ratio, bilateral and unilateral appearance. and the correlation between right-side and left-side occurrences of C-shaped PMSMs were computed and compared statistically using the chi-square test. Results: Among the 607 PMSMs of 383 CBCTs of 187 females and 196 males, 198 PMSMs(32.6%) had C-shaped root and 158 PMSMs(26.0%) had C-shaped canals. The shape of C-shaped root canals at the furcalion level did not have significant change at the level of mid root (P<0.0001). Female had more prevalence of C-shaped root canals than male (P<0.0001). The prevalence of bilateral occurrence of C-shaped root canals was higher than unilateral occurrence. Conclusions: The occurrence of C-shaped PMSMs among a Korean population was 32.6% and was higher than other countries and ethnicities. Understanding the prevalence of PMSMs with a C-shaped root and/or canal in a Korean population may be useful for successful endodontic treatments.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권2호
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• pp.136-142
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• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.41.1-41.6
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• 2016

Background: The goal of this study was to retrospectively evaluate the prognosis of minimal invasive horizontal ridge augmentation (MIHRA) technique using small incision and subperiosteal tunneling technique. Methods: This study targeted 25 partially edentulous patients (10 males and 15 females, mean age $48.8{\pm19.7years$) who needed bone graft for installation of the implants due to alveolar bone deficiency. The patients took the radiographic exam, panoramic and periapical view at first visit, and had implant fixture installation surgery. All patients received immediate or delayed implant surgery with bone graft using U-shaped incision and tunneling technique. After an average of 2.8 months, the prosthesis was connected and functioned. The clinical prognosis was recorded by observation of the peri-implant tissue at every visit. A year after restoration, the crestal bone loss around the implant was measured by taking the follow-up radiographs. One patient took 3D-CT before bone graft, after bone graft, and 2 years after restoration to compare and analyze change of alveolar bone width. Results: This study included 25 patients and 39 implants. Thirty eight implants (97.4 %) survived. As for postoperative complications, five patients showed minor infection symptoms, like swelling and tenderness after bone graft. The other one had buccal fenestration, and secondary bone graft was done by the same technique. No complications related with bone graft were found except in these patients. The mean crestal bone loss around the implants was 0.03 mm 1 year after restoration, and this was an adequate clinical prognosis. A patient took 3D-CT after bone graft, and the width of alveolar bone increased 4.32 mm added to 4.6 mm of former alveolar bone width. Two years after bone graft, the width of alveolar bone was 8.13 mm, and this suggested that the resorption rate of bone graft material was 18.29 % during 2 years. Conclusions: The bone graft material retained within a pouch formed using U-shaped incision and tunneling technique resulted with a few complications, and the prognosis of the implants placed above the alveolar bone was adequate.

• Journal of Periodontal and Implant Science
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• 제40권2호
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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.

• 치과방사선
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• 제28권1호
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• pp.225-234
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• 1998

We used five adult dog mandibles embedded in resin block and six different cross-sectional planes for each mandible were choosen. According to the angle of mandibular occulsal plane to vertical plane(mandibular angle) and gantry angle of CT machine, we classified 4 experimental groups and 1 control group. The control group images were taken at the mandibular angel 0° and gantry angle 0°. The experimental images were taken at the mandibular angle 15° and gantry angle 0°(group 1); 30° and 0°(group 2); 15° and 15°(group 3) ;30° and 30°(group 4), respectively. Using the reformatted cross-sectional images, the distance from the mandibular canal to the alveolar crest and the distance from the mandibular canal to the buccal cortex and to the lingual cortex was measured and compared. The obtained results were as follows: 1. The distance from the mandibular canal to the alveolar crest of group 1 and 2 was larger than control group, but the distance of group 3 and 4 was smaller. The distance from the mandibular canal to the buccal cortex and to the lingual cortex of all experimental groups was smaller than control group. 2. The distance from the mandibular canal to the alveolar crest showed the largest difference from control group in all experimental groups, especially in group 2 and 4(p<0.05). 3. In the distance from the mandibular canal to the alveolar crest, the number of deviation value under 1 mm was 20 in group 3 and was 11 in group 2 and 4, respectively. 4. The deviation value of the distance from the mandibular canal to the buccal cortex and to the lingual cortex was under 1 mm in most cases.

• Journal of Periodontal and Implant Science
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• 제53권2호
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• pp.120-134
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• 2023

Purpose: We investigated whether repeated irradiation with light-emitting diodes (LEDs) at a combination of 470 nm and 525 nm could suppress the progression of experimental periodontitis. Methods: A experimental periodontitis model was established in the second, third, and fourth premolars of the mandible in beagle dogs for 2 months. The spontaneous progression of periodontitis was monitored under the specified treatment regimen for 3 months. During this period, the animals were subjected to treatments of either plaque control only (control) or plaque control with LED application (test) at 2-week intervals. The clinical parameters included the probing pocket depth (PPD), gingival recession (GR), and the clinical attachment level (CAL). Histomorphometric analysis was performed using measurements of the length of the junctional epithelium, connective tissue (CT) zone, and total soft tissue (ST). Results: There were significant differences in PPD between the control and test groups at baseline and 12 weeks. When the change in PPD was stratified based on time intervals, it was shown that greater differences occurred in the test group, with statistical significance for baseline to 12 weeks, 6 to 12 weeks, and baseline to 6 weeks. There was no significant difference in GR between the control and test groups at any time points. Likewise, no statistically significant differences were found in GR at any time intervals. CAL showed a statistically significant difference between the control and test groups at baseline only, although significant differences in CAL were observed between baseline and 12 weeks and between 6 and 12 weeks. The proportion of CT to ST was smaller for both buccal and lingual areas in the control group than in the test group. Conclusions: Repeated LED irradiation with a combination of 470-nm and 525-nm wavelengths may help suppress the progression of periodontal disease.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권4호
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• pp.249-255
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• 2002

Recently, Skeletal Anchorage System (SAS) has been focused clinically with the view point that it could provide the absolute intraoral anchorage. First, it began to be used for the patient of orthognathic surgery who had difficulty in taking intermaxillary fixation due to multiple loss of teeth. And then, its uses have been extended to many cases, the control of bone segments after orthognathic surgery, stable anchorage in orthodontic treatment, and anchorage for temporary prosthesis and so on. SAS has been developed as dental implants technique has been developed and also called in several names; mini-screw anchorage, micro-screw anchorage, mini-implant anchorage, micro-implant anchorage (MIA), and orthosystem implant etc. Now many clinicians use SAS, but the anatomical knowledges for the installed depth of intraosseous screws are totally dependent on general experiences. So we try to study for the cortical thickness of maxilla and mandible in Korean adults without any pathologic conditions with the use of Computed Tomography at the representative sites for the screw installation.

• 구강회복응용과학지
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• 제28권4호
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• pp.423-439
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• 2012

NobelGuide$^{TM}$ 임플란트 시스템은 골량과 골질을 수술 전에 판단하여 점막을 젖히지 않고 미리 계획된 스텐트와 보철물을 이용하여 즉시하중을 부여하는 CAD/CAM 기반의 임플란트 보철 치료방법이다. 환자의 불편감을 최소화하여 미리 예측 가능한 위치에 임플란트를 식립함으로써 술 후 합병증 및 보철과정을 간소화 할 수 있는 장점이 있다. 본 증례의 환자는 56세 남성으로 상,하악 부분 무치악 상태였으며, 상악전치부 보철물 탈락과 하악 전치가 흔들린다는 주소로 내원하였다. 이에 상악 잔존치 모두와 하악 4전치 발거 및 치주치료를 실시한 뒤 임시 의치를 6개월간 사용하여 발치와 치유 및 의치 적응여부를 평가하였다. 골량은 충분하다고 판단되었고 환자의 협조도와 경제적인 여건, 전신건강 등 여러 사항이 양호하여 CAD/CAM 기반의 수술템플렛을 이용한 무판막 수술을 통해, 미리 제작된 임시 고정성 보철물로 즉시하중을 부여하는 상악 NobelGuide$^{TM}$ 임플란트 시스템을 계획하였다. 사용중인 임시의치를 이용하여 제작한 방사선 스텐트로 CT를 촬영하고, computer based planning (Procera$^{(R)}$ software)을 통해 3차원적인 골형상과 각 부위별 단면상을 참고하여 상악에 8개의 임플란트 식립체를 생역학적 관점 및 골조건을 고려하여 분산 배치하였다. 미리 제작된 임시 고정성 보철물을 임플란트 수술 후 즉시 장착 및 하중을 부여하여 기능하도록 하였으며 6개월 후 골유착 정도를 평가한 뒤 금속구조물을 이용한 최종 보철물을 제작하였다. 하악의 경우 전치부 도재전장주조금속관과 우측 구치부 임플란트 보철물 제작을 통해 상, 하악 치료를 마무리하였다.