• Imaging Science in Dentistry
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• 제47권4호
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• pp.261-267
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• 2017

Purpose: Analyzing different patterns of maxillary sinus septa in cone-beam computed tomography (CBCT) images and predicting maxillary sinus membrane perforations. Materials and Methods: In this cross-sectional study, CBCT images of 222 patients ranging from 20 to 81 years old were evaluated. One hundred fifty-two patients (93 females and 59 males) who had maxillary sinus septa in axial views were included in this study. Cross-sectional images were used to determine classifications of sinus septa and the risk of membrane perforation using a method modified from Al-Faraje et al. Variables of sex, age, and dental status were considered. Chi-squared and Kruskal-Wallis tests were used for data analysis(P<.05). Results: In this study, 265 maxillary sinus septal patterns were found. The mean age of the patients was $44.1{\pm}14.7$ years old. The Class I and VII-div II patterns had the greatest and least prevalence, respectively. Furthermore, there was a significant relationship between the location of septa and the frequency of membrane perforation risk (P<.05). In this study, the relationship of different patterns of septa with dental status did not differ significantly (P>0.05). Conclusion: A higher prevalence of moderate risk of membrane perforation in the molar region relative to the premolar region was observed. Furthermore, maxillary sinus septa occur most frequently in the molar region, demonstrating the importance of paying attention to this region during sinus lift surgery. This study did not show any relationship between tooth loss and the presence of septa.

• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.409-415
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• 2013

PURPOSE. The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS. A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS. A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION. Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.

• Imaging Science in Dentistry
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• 제47권3호
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• pp.157-164
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• 2017

Purpose: This study determined and compared the distances from the maxillary root apices of posterior teeth to the floor of the maxillary sinus, or maxillary sinus distances(MSDs), and the distances from the mandibular root apices of the posterior teeth to the mandibular canal, or mandibular canal distances(MCDs), in Thai subjects with skeletal open bite and skeletal normal bite. Materials and Methods: Pretreatment cone-beam computed tomography (CBCT) images were obtained from 30 Thai orthodontic patients (15 patients with skeletal normal bite and 15 with skeletal open bite) whose ages ranged from 14 to 28 years. The CBCT images of the patients were processed and measured using the Romexis Viewer program. The MSDs and MCDs from the root apices of the maxillary and mandibular second premolar, first molar, and second molar to the maxillary sinus floor or the mandibular canal were measured perpendicularly to the occlusal plane. The Student t test was used for comparisons between the 2 groups. Results: The greatest mean MSDs were from the root apex of the second premolars in both groups, whereas the least mean MSDs were from the mesiobuccal root apex of the second molars. The greatest mean MCDs were from the mesial root apex of the first molars, whereas the least mean MCDs were from the distal root apex of the second molars. Conclusion: There were no differences in the mean MSDs or the mean MCDs between the skeletal normal bite group and the skeletal open bite group.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제47권1호
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• pp.34-39
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• 2021

Objectives: The purpose of the study was to assess the occurrence, location, and dimensions of the intraosseous vascular canal in the lateral wall of the maxillary antrum using cone-beam computed tomography (CBCT). Materials and Methods: In this retrospective study, we examined 400 CBCT scans from our archive of patients who had earlier reported to a dental teaching hospital in the United Arab Emirates. The prevalence, location, and dimensions of the lateral antral intraosseous canal (LAIC) in the maxillary antrum were evaluated by 2 examiners using standardised methods. A third examiner was consulted in cases of disagreement. Results: The prevalence of LAIC was 62.3% (249 maxillary antra) among the study population. The mean distance between the most inferior point of the alveolar bone and the inferior border of the LAIC in the posterior maxillary region was 19.83±3.12 mm. There was a significant difference (P=0.05) between the maxillary molar and premolar regions in mean distance from the most inferior point of the alveolar bone and the inferior border of the LAIC. There was no statistically significant difference in mean distance between the most inferior point of the alveolar bone and the inferior border of the LAIC between dentulous and edentulous areas (P=0.1). The G3-intrasinusal type canal less than 1mm in diameter was the most common type of LAIC. Conclusion: This study established the approximate location of the LAIC in a United Arab Emirates cohort, which will assist the oral surgeon in selecting the appropriate site for sinus lift procedures with reduced risk of surgical hemorrhage.

• 구강회복응용과학지
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• 제25권2호
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• pp.171-181
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• 2009

훼이스 마스크(Face mask)를 사용하여 상악을 견인하였을 때, 두개안면 복합체의 생역학적 반응을 이해하는 것은 임상적으로 매우 중요하다. 이 연구의 목적은 face mask를 사용하여 상악 제 1 소구치와 제 1 대구치에서 상악을 전방으로 견인하였을 때 두개봉합구조에 발생하는 응력 분포를 분석하는 것이다. 13세 6개월 된 남자 환자의 유한요소분석을 위하여 전산화단층사진 촬영으로 얻은 DICOM 영상정보를 개인용 컴퓨터로 옮긴 후 3차원 영상프로그램인 $Mimics^{(R)}$(Materialise, Germany)를 사용하여 얻은 24개의 물성으로 이루어진 상악모델과, 제1소구치와 제1대구치, RME의 협측부, RME의 설측부의 4가지 구성요소를 각기 Nastran 파일형식인 "out"으로 저장하고 Patran에서 합체한 두개안면 복합체의 3차원적 유한요소모델을 생성하였다. 생성된 모델은 제1소구치에서 FH 평면의 45도 하방으로, 제 1 대구치에서 FH 평면의 20도 하방으로 500g의 전방견인력을 주었다. 상악 제1소구치에서 45도 하방으로 견인하였을 때 x축에서는 대구치부위의 확장과 소구치부에서의 협착을 보였고 최대변위량은 0.00011mm였다. y축에서는 전반적으로 전방이동을 보였으며 최대 0.00030mm의 변위와 소구치부위의 변형이 컸다. z축에는 소구치부위에서 하방으로 최 0.00036mm 이동했고, 상악복합체가 전하방으로 이동하였다. 제 1 대구치에서의 20도 하방견인 하였을 때, x축에서는 대구치부위의 협착과 lateral nasal wall의 확장을 보이며 최대 변위는 0.001mm였다. y축에서는 전체적인 전방이동을 보이며, 최대변위는 0.004mm였다. z축에서는 소구치와 대구치 중간부위를 중심으로 ANS는 상방으로 pterygoid plate는 하방으로 반시계방향의 회전양상을 보였으며 최대변위는 0.002mm였다.

• Restorative Dentistry and Endodontics
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• 제31권6호
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• pp.427-436
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• 2006

본 연구의 목적은 3차원유한요소분석법을 이용하여 정상 상악 제2소구치의 협측부의 응력분포에 다양한 교합응력이 미치는 영향을 평가하고자 하였다. 상악 제2소구치의 3차원유한요소모델을 형성한 후 형성된 모델에 3종류의 정적인 500N 점하중의 응력조건을 부여하였다. ANSYS 프로그램 (Swanson Analysis Systems, Inc., Houston, USA)으로 최대주응력과 최소주응력을 4개의 수평면 상(CEJ 상방 1 mm, CEJ 상방 0.5 mm, CEJ, CEJ 하방 0.5 mm)에서 분석하여 다음 결과를 얻었다. 1. peak stress가 협측 백악법랑경계를 따라 비대칭적인 모습으로 나타났다. 2. 압축응력 값은 법랑질의 압축파괴응력 범위 내에 있었지만 인장응력은 법랑질의 인장파괴응력 범위를 넘어섰다. 3. 비우식성치경부병소를 발생시키는 주요인은 설측교두의 협측경사면에 가해지는 교합압에 의한 인장응력이라고 보여진다.

• 대한치과의사협회지
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• 제56권3호
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• pp.142-150
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• 2018

In the posterior maxillary area, due to resorption of the ridge after extraction and pneumatization of the maxillary sinus, the height of the alveolar ridge may not be sufficient for placement of implants. To solve this problem, sinus augmentation using both crestal and lateral approaches have been widely used. Jung et al. (2010) introduced the modified lateral approach technique, which is a simplified technique that combines the advantages of crestal and lateral approaches. The purpose of this case report is to report two cases in the posterior maxilla in which simultaneous implant placement with maxillary sinus augmentation has been performed using the modified lateral approach technique. In two female patients, 67 and 74 years old, respectively, simultaneous implant placement was performed using the modified lateral approach technique on the left maxillary second premolar and the first molar. In both patients, the residual bone height on the distal side of the maxillary second premolar was measured to be approximately 5 mm, and the residual bone height of the first molar was measured to be 2-3 mm. After flap elevation, osteotomy of the lateral window was performed in the form of a mesiodistally extended slot above the sinus floor and the Schneiderian membrane was elevated. Sequenced drilling was performed while protecting the membrane with a periosteal elevator. Bone graft and implant placement was performed after preparation of the implant site. Sufficient primary stability was achieved for each implant and sinus membrane was not perforated. After four and five months respectively, implant second surgery was performed. Clinically, the implants were observed to be stable. Implants and surrounding peri-implant mucosa were well maintained after prosthodontic treatment. In conclusion, the modified lateral approach could be a predictable and efficient technique for implant placement in the atrophied posterior maxilla.

• 대한치과보철학회지
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• 제30권2호
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• pp.259-271
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• 1992

This study was designed to investigate the criteria of the perfect smile that was necessary to improve the esthetic problem in oral and maxillo-facial region and treating the anterior tooth region. The author took the facial straight photograph of 240 university students(male : 129, female : 111) in a resting and a smiling position, measured and analized the lip pattern and the relation between the lip and the teeth when they were smiling. Besides, 10 members of committee for appraisal (dentist : 5 persons, professor of the college of fine arts : 5 persons) estimated the smiling pattern. After that the author have compared and analyzed the obtained results. The results obtained were as follows : 1. In the shape of the upper lip, when the upper lip curved downward, it was 42.92% , straight was 45.00% and curved upward was 12.08%. The group in which the upper lip curved upward was the most esthetic. 2. In the relation between the upper lip and the teeth, high smile was 29.17%, average smile was 55.83% and low smile was 15.00%. The group of average smile was the most esthetic. 3. In the parallel relation between the lower lip and maxillary anterior incisal curvature, the group of paralled was 60.42%, the group of straight was 34.17% and the group of reverse was 5.41%. The group of parallel was the most esthetic. 4. In the relationship between maxillary anterior incisor and lower lip, the group of the maxillary anterior incisor were slightly covered by the lower lip was 10.42%, the group of the maxillary anterior teeth touched to the lower lip was 35.83%, and the no-touching was 53.75%. The group of the maxillary anterior teeth touched to the lower lip was the most esthetic. 5. In the teeth displayed in a smile, displayed to the canine was 0.84%, displayed to the first premolar was 19.17%, displayed to the second premolar was 57.92%, displayed to the first molar was 20.00% and displayed to the second molar was 2.08%. The group of displayed to the first molar was the most esthetic. 6. At smiles, the width of the mouth corner was 0.46 times of the full face width, 0.95 times of the interpupillary distance, and 1.23 times of the resting position. 7. At smiles, the lengh of the upper lip was 0.71 times and lower lip was 0.93 times of the length in the resting position.

• 대한치과보철학회지
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• 제46권2호
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• pp.193-200
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• 2008

임플랜트 고정체의 표면처리 기술의 발달에 기인하여 골유착의 성공률이 좋아지고 있으며 임플랜트를 이용하는 보철물의 형태와 임상 술 식도 다양하게 발전되고 있다. 상악의 임플랜트 피개의치는 아직 표준화된 치료법에 대한 의견이 분분하다. 본 연구는 상악 무치악의 치료를 위하여 해부학적인 요소와 생역학적인 요소를 고려하여 양측 견치부 또는 소구치부위에 2개의 임플랜트를 식립할 때의 응력분포를 삼차원 유한요소분석을 이용하여 관찰하고자 하여 다음과 같은 결론을 얻었다. 1. 임플랜트를 양측 견치 부위에 식립한 모형에서 부하가 가해지는 우측의 임플랜트의 원심면에 최대 응력이 집중되었다. 2. 임플랜트를 양측 제2소구치 부위에 식립한 모형에서 임플랜트 주위의 응력 분포는 부하지점의 거리와 상관없이 고르게 나타났다. 3. 치조골에 발생하는 응력 분포의 관찰 결과, 임플랜트가 양측 제2소구치 부위에 식립된 모형이 양측 견치부위에 식립된 모형보다 고르게 나타났다. 이상의 결과로 볼 때, 상악 피개의치를 위한 임플랜트 식립 위치는 견치 부위에서보다 제2소구치 부위가 구강점막, 주위 골과 임플랜트에 전달되는 응력의 분포에 유리한 것으로 사료된다.

• 대한치과교정학회지
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• 제37권2호
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• pp.98-113
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• 2007

상악 전치부 후방 견인 시의 이동 양상 및 응력 분포를 건조 두개골을 전산화 단층 촬영에 의해 3차원 영상화한 유한 요소 모델 상에서 알아보고자 하였다. 피질골 절단술의 시행 여부와 고정원, 힘의 작용점을 각기 달리 설정하여 8개의 실험군을 구성하여 비교하였다. 통상적인 T-loop을 이용하여 공간폐쇄를 하는 경우 전치부는 후하방으로 경사이동 하였으며, 구치부에서도 약간 전방 이동하였다. 피질골 절단술을 동반하여 전치부를 견인한 경우, 전치부 골편에서의 응력 분포가 전반적으로 넓게 분포되었으며, 전치부 경사의 정도가 적은 반면에 변위량은 훨씬 더 많았다. 협측에서의 견인 시 상악 협측에 식립된 미니 임플랜트와 견치 Power arm간에 견인력을 가한 경우가 미니 임플랜트로 고정원이 강화된 제2소구치와 견치 브라켓 간에 견인력을 가한 경우보다 전치부의 후하방 경사 정도가 적었다. 구개측에서 Powerarm에 대한 견인 시 정중구개봉합 부위에 식립한 미니 임플랜트로부터 견인력을 가한 경우가 상악 제1, 2대구치 간 구개면에 식립된 미니 임플랜트로부터 견인력을 가한 경우보다 전치부의 후하방 경사 정도가 컸다. 이러한 결과로써 치아이동 시 피질골 절단술의 효과와 저항중심에 대한 교정력 벡터 조정의 의미를 확인할 수 있었다.