• 구강회복응용과학지
• /
• 제25권2호
• /
• pp.109-123
• /
• 2009

임플란트 골유착의 성공과 임플란트 안정성에서 가장 중요한 것은 골의 양과 질이며 안정성을 평가하는 방법 중 하나인 주입회전력도 골질에 영향을 받는다. 임플란트를 식립할 때 모터에서 생긴 힘이 임플란트에 전달되면 임플란트는 회전력(moment)과 축력(axial force)을 갖게 되고 임플란트와 접촉한 골에서는 절삭과 압박 그리고 마찰이 일어나 응력이 생기는데 이 때 측정되는 주입회전력(insertion torque)은 골질에 따라 다양하게 나타난다. 본 연구에서는 임플란트를 하악 소구치 부위 골에 식립하는 것을 가정하여 골질을 치밀골의 두께와 망상골의 밀도 그리고 하방 치밀골 존재 시로 나누고, 골의 응력과 변위를 소탄성 범위의 유한요소법으로 분석하고 유효응력(von Mises stress)과 회전력 그리고 축력을 비교 연구하여 골질이 주입 회전력에 미치는 영향을 평가하였다. 임플란트($Br{\aa}nemark$ MKIII.RP, ${\phi}3.75{\times}10.0mm$, Nobel Biocare, $G{\ddot{o}}teborg$, Sweden) 와 원통형 골모형(${\phi}9.5{\times}12.0mm$)의 유한요소 모형을 설계하고 변수로 상부 치밀골의 두께(0.5 mm, 1.5 mm, 2.5 mm)와 치밀골 하부에 망상골의 밀도($0.85g/cm^3$, $1.11g/cm^3$, $1.25g/cm^3$) 그리고 골모형 하부에 1 mm 두께의 치밀골 유무에 따라 총 7개의 모형을 만들었으며, 임플란트가 식립될 때 발생하는 유효응력과 축력 그리고 회전력을 시간대 별로 비교하였다. 임플란트 플랜지 하연이 골의 상부를 파고드는 300 msec, 중간 정도 들어간 550 msec, 완전히 들어가 플랜지 상면이 골 표면과 일치한 800 msec로 나누어 관찰하였을 때 축력은 500 msec 전후에서, 회전력은 800 msec 전후에서 최대값를 보였으며 유효응력 분포는 서로 비슷하였다. 이 같은 실험 결과를 바탕으로 축력을 영역 별로 비교하여 다음과 같은 결과를 얻었다. 1. $Br{\aa}nemark$ MKIII 임플란트는 플랜지가 골을 파고들 때 축력이 치밀 골에서 가장 높았고, 회전력은 플랜지가 골상부에 걸리어 축력이 급격히 감소한 이후에 최대 회전력을 보였으며, 이 때 유효응력 분포는 플랜지와 접촉하는 골 상부에 집중되었다. 2. 임플란트 식립 시 치밀골의 두께가 두꺼울수록 축력과 회전력이 높게 나타났으며 치밀골의 두께가 축력과 회전력에 가장 큰 영향을 주었다. 3. 치밀골의 두께가 1.5 mm 이상인 경우 망상 골의 밀도가 축력에 미치는 영향은 작았고, 치밀골의 두께가 0.5 mm인 경우 망상골의 밀도가 축력과 회전력에 영향이 있을 것으로 사료되었다. 4. 양측 피질골 존재 시 축력의 합은 상부 피질골의 두께가 같은 다른 경우와 비슷하였으나 부위별 촉력은 골하부에서 양측 피질골 모형이 가장 높았고, 회전력은 하방 피질골과 접촉할 때는 피질골 두께가 같은 다른 모형보다 다소 높으나 최대 회전력은 비슷하였다. 위 결과를 토대로 하악 소구치 부위에 $Br{\aa}nemark$ MKIII 임플란트 식립 시 골질과 관련된 요소 중에 치밀골의 두께가 주입회전력에 가장 큰 영향을 주며 망상골의 밀도를 높이는 술식도 일차적 안정성 증가에 유용할 것으로 사료되는 바이다.

• Journal of Periodontal and Implant Science
• /
• 제25권1호
• /
• pp.67-75
• /
• 1995

The progress of periodontal disease and the wound healing process after treatment result in alveolar bone bone change. So, detection of it is very important in the diagnosis and the radiograph of periodontal disease. Various effects have been made to assess the subtle alveolar bone change and digital subtraction radiography (DSR) has been reported to be the best method in evaluating it qualitatively and quantitatively. The present study was performed to estimate the detectable alveolar bone change qualitatively with digital subtraction radiography. For the in vitro study, 10 intraoral standard radiographs were taken from porcine dry mandible which a rectangular cortical bone chip of 0.1mm to 1.0mm thickness with 0.1mm increment was attached on the buccal surface. The radiographs without and with bone plates were reviewed at the same time by 10 observers and requested to detect the presence of cortical bone plates. Digital Subtraction radiograph was reviewed subsequently by using the DSR system(digital converter-256 grey-levels,DT 2851,Data Translation Co., U.S.A;IBM 386 ; CCD camera, FOTOVIX, Tamrom Co., Japan). The detectable thickness of cortical bone plate was O.4mm on the intraoral radiograph and 0.2mm on the subtaction images. For the human study, radiographs were taken from patients by using intraoral film holding device and aluminum reference wedge before and 3 month after bone graft and 1 week after osteoplasty. The grey level change was estimated in the subtraction images and calculated to aluminum equivalent thickness. The grey level of the grafted site was higher that that of healthy controls. Average grey levels of change on healthy controls were O.48mm aluminum equivalent. However, the amount of changes in grafted sites were 1.87mm aluminum thickness equivalent and in the site of osteoplasty were -1.49mm aluminum thickness equivalent. In conclusion, digital subtraction radiography was more effective in detecting as subtle change of alveolar bone than intraoral standard radiography. With the aid of quantitative analysis of digital subtraction radiography, alveolar bone resorption of apposition can be estimated during diagnosis and treatment of periodontally diseased patients.

• The Journal of Advanced Prosthodontics
• /
• 제5권4호
• /
• pp.494-501
• /
• 2013

PURPOSE. The purpose of this study was to provide an actual guideline in determining the shape, diameter, and position of the implant in immediate implantation by the measurement of the thickness of facial and palatal plate, the thickness of cortical bone on the facial and palatal plate, the diameter of the root, and the distance between the roots in the cadavers. MATERIALS AND METHODS. The horizontal sections of 20 maxillae were measured and analyzed to obtain the average values. Resin blocks were produced and cut serially at 1 mm intervals from the cervical line to the root apex. Images of each section were obtained and the following measurements were performed: The thickness of the facial and palatal residual bone at each root surface, the thickness of the facial and palatal cortical bone at the interdental region, the diameter of all roots of each section on the faciopalatal and mesiodistal diameter, and the interroot distance. Three specimens with measurements close to the average values were chosen and 3-dimensional images were reconstructed. RESULTS. The thickness of the facial and palatal cortical bone at the interdental region in the maxilla, the buccal cortical bone was thicker in the posterior region compared to the anterior region. The interroot distance of the alveolar bone thickness between the roots increased from anterior to posterior region and from coronal to apical in the maxilla. CONCLUSION. In this study, the limited results of the morphometric analysis of the alveolar ridge using the sections of maxilla in the cadavers may offer the useful information when planning and selecting optimal implant for immediate implantation in the maxilla.

• 한국음향학회지
• /
• 제32권2호
• /
• pp.181-189
• /
• 2013

본 연구의 목적은 생체 외 조건의 소 대퇴골에서 피질골이 해면질골의 음속(SOS) 및 광대역 초음파 감쇠(nBUA)와 같은 음향특성에 미치는 효과를 조사하는 것이다. 이를 위해 2개의 소 대퇴골을 이용하여 근위부로부터 12개의 해면질골 샘플 및 1.00, 1.47, 및 2.00 mm의 두께를 갖는 3개의 피질골 판을 제작하였다. 또한 해면질골 샘플에 피질골 판 부착 전후 측정된 음향특성과 해면질골 겉보기 골밀도 사이의 상관관계를 조사하였다. 해면질골 샘플의 초음파 입사면에 부착된 피질골 판의 두께가 증가함에 따라 SOS는 선형적으로 증가하는 반면에 nBUA는 피질골 판의 두께에 대해 비선형적인 의존성을 나타내는 것을 알 수 있었다. 또한 서로 다른 두께를 갖는 피질골 판이 부착되더라도 SOS(r = 0.95-0.97) 및 nBUA(r = 0.53-0.73)와 해면질골 겉보기 골밀도 사이의 높은 상관관계는 유지되는 것을 알 수 있었다. 이와 같은 결과는 생체 외 조건의 피질골이 제거되지 않은 대퇴골에서 측정된 음향특성이 해면질골의 골밀도를 예측하기에 충분한 지표라는 것을 의미한다.

• 대한치과교정학회지
• /
• 제38권6호
• /
• pp.397-406
• /
• 2008

교정용 미니 임플랜트의 식립 부위에 대한 연구는 주로 구치부 치근사이 공간에 집중되어 왔다. 본 연구의 목적은 전치에서 구치에 이르는 치아간의 피질골 두께와 치근간 거리를 측정함으로써 교정용 미니 임플랜트 식립 시에 참고 할 수 있는 임상적 지침을 제공하는 것이다 연구를 위해 성인 28명(남자 14명, 여자 14명)의 CT를 V-works $4.0^{TM}$을 이용하여 3차원 영상으로 전환하였다. 중절치에서 제2대구치에 이르는 모든 치아 사이를 치간 접촉점을 지나면서 교합 평면에 수직이 되도록 잘라 $90^{\circ}$ 단면을 형성한 후 치조정으로부터 높이를 달리하여 0, 15, 30, $45^{\circ}$의 각도를 주어 피질골의 두께를 측정하였다. 또한 치조정으로부터 2, 4, 6 mm 높이에서 교합 평면에 평행하게 잘라 $90^{\circ}$ 단면을 만든 후 치근간 거리를 측정하였다. 피질골의 두께는 전 치부에서 구치부로 갈수록 두꺼워지는 경향을 보였으며, 5-6과 1-1 사이, 6-7과 1-1, 1-2, 2-3 사이에서는 유의한 차이를 보였다 (p < 0.05). 치조정으로부터 2 mm 높이를 제외한 대부분의 위치에서 각도가 증가함에 따라 피질골의 두께가 급격히 증가하는 경향을 보였고, 4 - 6 mm 높이에 식립시 $30-45^{\circ}$ 이상의 각도를 부여해야 피질골 보유량(engage 양)에 유의한 차이를 보였다. 치근간 거리 측정 결과 4-5, 5-6, 6-7 사이가 치근 손상 없이 미니 임플랜트를 식립하기에 적절한 위치라고 볼 수 있었고, 1-1과 1-2 사이는 미니 임플랜트 식립을 위한 충분한 치근간 거리를 제공하지 못하는 것으로 나타났다. 본 실험의 결과로 볼 때 피질골과 미니임플랜트의 접촉면을 증가시키기 위해서는 치조정에서 치근단부로 4와 6 mm 되는 부위에서 $30^{\circ}$ 또는 $45^{\circ}$로 식립하는 것이 유리할 것으로 보인다.

• Restorative Dentistry and Endodontics
• /
• 제47권3호
• /
• pp.33.1-33.10
• /
• 2022

Objectives: This study aimed to analyze the proximity of maxillary molar roots to their overlying cortical bone surfaces and the maxillary sinus. Materials and Methods: Cone-beam computed tomographic images of 151 patients with completely erupted upper molars that had 3 separate roots were studied. The following distances were measured: from the root apex to the cortical plate and maxillary sinus floor, and from the apical 3-mm level of the root to the cortical plate. Differences between groups were analyzed with 1-way analysis of variance and the Scheffé post hoc test, the significance of differences between cone-beam computed tomography views with the paired t-test, and the significance of differences among age groups with linear regression analysis. The significance level was set at p < 0.05. Results: The mesiobuccal and distobuccal root apexes of maxillary second molars were more distant from the buccal cortical plate than the maxillary first molars (p < 0.05). The apical 3-mm level of the mesiobuccal root of the first molar was closer to the buccal cortical bone than the second molar (p < 0.05). In the maxillary first molars, the thickness of the buccal cortical bone decreased in all roots with age (p < 0.05). In all root apexes of both molars, the difference in the vertical level between the maxillary sinus floor and the root apex increased with age (p < 0.05). Conclusions: Awareness of the anatomical profile of maxillary molar apices in relation to the cortical bones and maxillary sinus will be beneficial for apical surgery.

• 대한치과교정학회지
• /
• 제43권2호
• /
• pp.83-95
• /
• 2013

Objective: To evaluate the changes in cortical bone thickness, alveolar bone height, and the incidence of dehiscence and fenestration in the surrounding alveolar bone of posterior teeth after rapid maxillary expansion (RME) treatment using cone-beam computed tomography (CBCT). Methods: The CBCT records of 20 subjects (9 boys, mean age: $13.97{\pm}1.17$ years; 11 girls, mean age: $13.53{\pm}2.12$ year) that underwent RME were selected from the archives. CBCT scans had been taken before (T1) and after (T2) the RME. Moreover, 10 of the subjects had 6-month retention (T3) records. We used the CBCT data to evaluate the buccal and palatal aspects of the canines, first and second premolars, and the first molars at 3 vertical levels. The cortical bone thickness and alveolar bone height at T1 and T2 were evaluated with the paired-samples t-test or the Wilcoxon signed-rank test. Repeated measure ANOVA or the Friedman test was used to evaluate the statistical significance at T1, T2, and T3. Statistical significance was set at p < 0.05. Results: The buccal cortical bone thickness decreased gradually from baseline to the end of the retention period. After expansion, the buccal alveolar bone height was reduced significantly; however, this change was not statistically significant after the 6-month retention period. During the course of the treatment, the incidence of dehiscence and fenestration increased and decreased, respectively. Conclusions: RME may have detrimental effects on the supporting alveolar bone, since the thickness and height of the buccal alveolar bone decreased during the retention period.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제48권4호
• /
• pp.219-224
• /
• 2022

Objectives: There have been few studies to date on the residual effect of bisphosphonate. This study investigated the radiographic changes of mandibular cortical thickness upon bisphosphonate drug holiday. Materials and Methods: This retrospective study includes 36 patients diagnosed with MRONJ (medication-related osteonecrosis of the jaw) at Ajou University Dental Hospital in 2010-2021. All patients stopped taking bisphosphonate under consultation with the prescribing physicians. Panoramic radiographs were taken at the start of discontinuation (T₀), 12 months after (T₁), and 18 months after (T₂) discontinuation of bisphosphonate, respectively. Mental index and panoramic mandibular index were calculated using Ledgerton's method. Paired t-tests were used to analyze differences over time. Results: The difference in indices (mental index and panoramic mandibular index) between T₀ and T₁ was not statistically significant (paired t-test, P>0.05). However, the difference in these indices between T₁ and T₂ was statistically significant (paired t-test, P<0.05). Conclusion: The cortical thickness of the mandible decreased in the late stage (after 18 months) as observed by panoramic radiograph.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제20권4호
• /
• pp.275-278
• /
• 1998

Recently, the clinical applications of the autogenous cancellous bone from the proximal tibial metaphysis show satisfactory results in the repair of maxillofacial bony defect or deformity. The proximal tibia has the potential to yield viable cancellous bone with a minimum of morbidity. The purpose of this study was to investigate the regeneration of a full thickness proximal tibial bone defect with covering or uncovering of cortical bone. The follow-up periods were 4, 8, and 12 weeks. Bone defect of right side was uncovered and left side was covered with cortical bone. In the experimental group (uncovered cortical bone) at 12 weeks, the inside of defect was filled to normal marrow tissue. The cortical bone defect was united of inner, outer callus at 4, 8 weeks in both study group. At 12 weeks, the cortical bone defect was remodeled and invaded by osteoclast (giant cell) in experimental group. In the experimental specimen at 12 weeks, the regenerating tissue of bone defect was not differ from the control group.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제49권2호
• /
• pp.100-104
• /
• 2023

Autogenous bone grafts from the mandibular ramus are a known source of inadequate bone volume scenarios of the residual alveolar ridge. However, the conventional block-type harvesting technique cannot prevent bone marrow invasion, which can cause postoperative complications such as pain, swelling, and inferior alveolar nerve injury. This study aims to suggest a complication-free harvesting technique and present the results of bone grafting and donor sites. One patient received two dental implants with a complication-free harvesting technique that involves creation of ditching holes with a 1 mm round bur. Sagittal, coronal, and axial osteotomies produced grid-type cortical squares using a micro-saw and a round bur to confirm the cortical thickness. The grid-type cortical bone was harvested from the occlusal aspect, and the harvesting was extended through an additional osteotomy on the exposed and remaining cortical bone to prevent bone marrow invasion. The patient did not suffer postoperative severe pain, swelling, or numbness. After 15 months, the harvested site exhibited new cortical bone lining, and the grafted area had healed to a cortico-cancellous complex with functional loading of the implants. Our technique, grid-type cortical bone harvesting without bone marrow invasion, allowed application of autogenous bone without bone marrow invasion to achieve acceptable bone healing of the dental implants and to regenerate the harvested cortical bone.