• Imaging Science in Dentistry
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• 제38권2호
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• pp.95-101
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• 2008

Purpose: To assess the positional relationship between the maxillary sinus floor and the apex of the maxillary first molar using cone beam computed tomograph (CBCT). Materials and Methods: CBCTs from 127 subjects were analysed. A total of 134 maxillary first molars were classified according to their vertical and horizontal positional relationship to the maxillary sinus floor and measured according to the distance between the maxillary sinus floor and the maxillary first molar. Results: Type III (The root projected laterally on the sinus cavity but its apex is outside the sinus boundaries) was dominated between 10 and 19 years and type I (The root apex was not in contact with the cortical borders of the sinus) was dominated (P<0.05) between 20 and 72 years on the vertical relationship between the maxillary sinus floor and the apex of the maxillary first molar. The maxillary sinus floor was located more at the apex (78.2%) than at the furcation (21.3%) for the palatal root. The distance from the root apex to the maxillary sinus floor confined to type I was increased according to the ages (P<0.05). Type M (The maxillary sinus floor was located between the buccal and the palatal root) was most common (72.4%) on the horizontal relationship between the maxillary sinus floor and the apex of the maxillary first molar. Conclusion: CBCT can provide highly qualified images for the maxillary sinus floor and the root apex of the maxillary first molar.

• 대한소아치과학회지
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• 제32권4호
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• pp.628-633
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• 2005

유구치의 깊은 우식은 치수병소을 유발하고 이를 조기에 치료하지 않을 경우에는 치수강저의 수많은 부근관을 통하여 치근분지부 병소로 이어진다. 지금까지 대부분의 교과서나 문헌에서는 이와 같은 경우를 발치의 적응증으로 기술하여 왔고 임상에서도 상례적으로 발치를 흔히 시행하였다. 그러나 유구치의 조기 상실은 수많은 부작용을 낳는 것이 필연적이다. 어린이의 골재생 능력 이 우수하며, 치수강저와 치근분지부를 잇는 많은 부근관이 있음을 생각해 볼 때 유구치 치수 내의 감염원을 치수절제술로 제거하고, 이미 발생한 치근분지부 병소에 대해서는 소파술을 시행한다면 치근분지부 골조직의 신속한 재생이 가능하지 않을까 하는 의문이 제기되었다. 본 증례는 $3{\sim}6$세 어린이에서 유구치 치근분지부 방사선 투과상이 $2{\sim}4mm$ 정도의 깊이를 보이는 비교적 경미한 수준이면서, 연조직 누공을 보이는 10개 증례를 선별하여 치수절제술과 치근분지부 소파술을 시행한 결과, 모두에서 방사선적으로 골재생이 관찰되었다. 이를 통하여 유구치 치근분지부 병소나 누공을 보이는 모든 경우가 발치의 적응증은 아니며, 이 방법이 치근분지부 병소를 가진 유구치를 잔존시킬 수 있는 하나의 대안이 될 수 있음을 알 수 있었다. 그러나 이 방법이 객관적 인 타당성을 얻기 위해서는, 병소의 크기와 진행정도, 계승 영구치의 성숙도, 환아의 연령 등 적응증에 대한 보다 심층적인 검토와 연구가 필요할 것으로 사료되었다.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.6.1-6.9
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• 2022

Objectives: This study investigated the internal morphology of mesiobuccal (MB) roots of maxillary molars with a second mesiobuccal (MB2) canal. Materials and Methods: Forty-seven maxillary first or second molars from Brazilians were scanned using micro-computed tomography. The following measurements were obtained from the MB roots: root thickness, root width, and dentin thickness of the buccal aspect of the first mesiobuccal (MB1) canal, between the MB1 and MB2 canals, and the palatal aspect of the MB2 and MB1 canals at 3 mm from the root apex and in the furcation region. For statistical analysis, the Student's t-test and analysis of variance with the post-hoc Tukey test were used (α = 0.05). Results: In maxillary molars with an MB2 canal, MB roots were significantly thicker (p = 0.0014) and narrower (p = 0.0016) than in maxillary molars without an MB2 canal. The dentin thickness of the palatal aspect of the MB1 canal was also significantly greater than that of MB roots without an MB2 canal at 3 mm from the root apex (p = 0.0007) and in the furcation region (p < 0.0001). In the furcation region of maxillary molars with an MB2 canal, the dentin thickness between the MB1 and MB2 canals was significantly smaller than that in the buccal and palatal aspects (p < 0.0001). Conclusions: The internal morphology of MB roots of maxillary molars with an MB2 canal revealed differences in dentin thickness, root diameter, and distance between the canals when compared with maxillary molars without an MB2 canal.

• Journal of Periodontal and Implant Science
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• 제50권1호
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• pp.38-47
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• 2020

Purpose: The aim of this study was to investigate the available alveolar bone height between the maxillary molars and the sinus floor according to their anatomical relationship using cone-beam computed tomographic (CBCT) images. Methods: A total of 752 maxillary first (M1) and second molars (M2) on CBCT scans of 188 patients were selected. First, each maxillary molar was categorized as type 1, 2, 3, or 4 according to the relationship of the molar root with the maxillary sinus floor. The frequency distribution of each type was analyzed. Second, the shortest vertical distance (VD) of each molar was measured from the furcation midpoints of the roots to the lowest point of the sinus floor by 2 observers. Intraclass correlation coefficients and the t-test were calculated for the VD measurements. Results: For M1, type 3 was the most frequent, followed by type 2. For M2, type 3 was the most common, followed by type 1. The VD measurements of type 1 were 9.51±3.68 mm and 8.07±2.73 mm for M1 and M2, and those of type 3 were 3.70±1.52 mm and 4.03±1.53 mm for M1 and M2, respectively. The VD measurements of M2 were significantly higher in female patients than in male patients. Conclusions: Type 3 was the most frequent anatomical relationship in the maxillary molars, and showed the lowest alveolar bone height. This information will help clinicians to prevent complications related to the maxillary sinus during maxillary molar treatment and to predict the available bone height for immediate implant planning.

• 대한치과교정학회지
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• 제41권3호
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• pp.191-199
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• 2011

Objective: The purpose of this study was to investigate the stress distribution on the orthodontic mini-implant (OMI) surface and periodontal ligament of the maxillary first and second molars as well as the tooth displacement according to the OMI position in the dragon helix appliance during scissors-bite correction. Methods: OMIs were placed at two maxillary positions, between the first and the second premolars (group 1) and between the second premolar and the first molar (group 2). The stress distribution area (SDA) was analyzed by three-dimensional finite element analysis. Results: The maximal SDA of the OMI did not differ between the groups. It was located at the cervical area and palatal root apex of the maxillary first molar in groups 1 and 2, respectively, indicating less tipping in group 2. The minimal SDA was located at the root and furcation area of the maxillary second molar in groups 1 and 2, respectively, indicating greater palatal crown displacement in group 2. Conclusions: Placement of the OMI between the maxillary second premolar and the maxillary first molar to serve as an indirect anchor in the dragon helix appliance minimizes anchorage loss while maximizing the effect on scissors-bite correction.

• 대한치과교정학회지
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• 제45권5호
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• pp.236-244
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• 2015

Objective: The aim of this study was to investigate three-dimensional molar displacement after distalization via miniscrews and a horizontal modification of the trans-palatal-arch (TPA). Methods: The subjects in this clinical trial were 26 Class II patients. After the preparation of a complete set of diagnostic records, miniscrews were inserted between the maxillary 2nd premolar and 1st molar on the palatal side. Elastic modules connected to the TPA exerting an average force of 150-200 g/side parallel to the occlusal plane were applied. Cone-beam computed tomography was utilized to evaluate the position of the miniscrews relative to the adjacent teeth and maxillary sinus, and the direction of force relative to molar furcation. The distances from the central point of the incisive papilla to the mesiopalatal cusps of the 1st maxillary molars and the distances between the mesiopalatal cusps of the left and right molars were measured to evaluate displacement of the maxillary molars on the horizontal plane. Interocclusal space was used to evaluate vertical changes. Results: Mean maxillary 1st molar distalization was $2.3{\pm}1.1mm$, at a rate of $0.4{\pm}0.2mm/month$, and rotation was not significant. Intermolar width increased by $2.9{\pm}1.8mm$. Molars were intruded relative to the neighboring teeth, from 0.1 to 0.8 mm. Conclusions: Distalization of molars was possible without extrusion, using the appliance investigated. The intrusive component of force reduced the rate of distal movement.

• Imaging Science in Dentistry
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• 제33권2호
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• pp.71-77
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• 2003

Purpose : To evaluate and compare the efficacy of digital radiographic images in the detection of bone loss at the bifurcation area of the mandibular first molar with traditional film-based periapical radiographs, Materials and Methods : One dried human mandible with minimal periodontal bone loss around the first molar was selected and an artificial alveolar bone defect at the bifurcation area was serially prepared over 18 steps. Images were taken using a direct CCD-based system and with F-speed periapical films. The images were evaluated by seven interpreters (3 radiologists, 3 periodontologists, and 1 general dentist) using a 5-point confidence rating scale. Results : The readability of both periapical radiographs and digital image increased as the size of the artificial lesion and exposure time increased (p < 0.05). Periapical radiographs offered greater readability of smaller bone defects than digital images, and the coefficient of variation of mean score between periapical radiographs and digital images showed a significant difference. Conclusion : The experimental results indicate that a significant difference in the coefficient of variation of mean score exists between periapical radiographs and digital images, and that traditional film-based periapical images offer greater readability of smaller bone defects than digital images can presently offer.

• 대한치과교정학회지
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• 제25권3호
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• pp.299-310
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• 1995

이 연구의 목적은 교정치료시 제2대구치의 위치변화를 알아보기 위함이다. 이를 위하여 제1대구치까지 banding하여 교정치료를 완료한 성인환자 64명을 Class I 발치군 15명, Class I 비발치군 12명, Class II 13명, Class III 14명으로 4개의 군으로 분류하고 치료전후의 두부방사선 계측사진을 분석하였다. 이 연구로부터 얻어진 결과는 다음과 같다. 1. Class I 발치군에서 하악 제2대구치는 제1대구치보다 적은 정출과 더 많은 원심경사를 보였고, 상악 제2대구치는 제1대구치와 유사한 정출과 근심경사를 보였다. 2. Class I 발치군에서 하악 제2대구치는 제1대구치에 비해 함입되고 유사한 원심경사를 보였으며, 상악 제2대구치는 제1대구치와 비슷하게 정출되었다. 3. Class II군에서 하악 제2대구치는 제1대구치에 비해 적은 정출을 보였고, 상악 제2대구치는 제1대구치보다 많은 정출을 보였다. 4. Class III군에서 하악 제2대구치는 제1대구치와 유사한 정출과 더 많은 원심경사를 보였으며, 상악 제2대구치는 제1대구치에 비해 적은 정출을 보였다. 5. 제2대구치 위치변화에 대한 각 군간의 비교시 FH plane에서 상악 제2대구치 치근 분기점까지 거리 변화는 Class I 발치군과 Class II, Class I 발치군과 Class III군에서 차이를 보였으며, 구개평면과 교합평면에 대한 상악 제2대구치의 각도 변화는 Class I 발치군과 Class III군에서 차이를 보였으며, 하악평면에 하악 제2대구치 치근분기점까지 거리변화는 Class I 발치군과 비발치군, Class I 비발치군과 Class II군, Class I 비발치군과 Class III군에서 차이를 보였으며, 하악 평면과 교합평면에 대한 하악 제2대구치의 각도 변화는 각 군간에 차이를 보이지 않았다.

• Restorative Dentistry and Endodontics
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• 제39권2호
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• pp.115-119
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• 2014

As long as the prognosis of teeth remains a matter of concern, the endodontic-periodontal relationship will be considered a challenge for the clinician. Many etiologic factors, including bacteria, fungi, and viruses, plus other contributing factors, such as trauma, root resorptions/perforations, and dental malformations, play a role in the co-occurrence of endodontic and periodontal lesions. Whatever the cause, a correct diagnosis on which to base the treatment plan is the key to successful maintenance of the tooth. This article reports the successful endodontic management of a furcation lesion in a mandibular molar that was nonresponsive to a previous periodontal surgical graft. The case had presented a diagnostic challenge for the clinicians, and this article reviews the key points that can lead to a correct diagnosis and treatment planning.

• Journal of Periodontal and Implant Science
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• 제32권1호
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• pp.61-68
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• 2002

The objective of this study was to determine the incidence and distribution of root fusion as well as its sexlinkage in maxillary and mandibular molars. One hundred fifty patients who had eight maxillary and mandibular molars (third molars excluded) were consecutively selected for the study subjects. The subjects provided a total of 1200 molars, i.e., 600 maxillary and 600 mandibular molars. A decision about root fusion was made on the radiographic examination. If a molar had one root and/or roots fused at any part in the root surface, it was considered as having root fusion. The results showed that : (1) 14.1 % of the maxillary molars and 5.8 % of the mandibular molars had a fused root, (2) the prevalence of root fusion in the male was 33 % and 56.4 % in the female, (3) 60 % in the male and 48.8 % in the female had bilaterally paired root fusion, (4) the root fusion was most frequently observed in the maxillary second molar position, but none in the mandibular first position in this study. Within limitations of this study, it can be concluded that, in management of molars with a furcation problem, treatment options such as hemisection and root amputation should be chosen after careful evaluation of root fusion. Further studies are needed to investigate a possible relationship between root fusion and periodontal disease progression.