• Imaging Science in Dentistry
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• 제49권2호
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• pp.123-130
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• 2019

Purpose: This study was conducted to characterize the relationship of the angulation between the tooth root axis and alveolar bone axis with anterior alveolar(AA) arch forms and sagittal root position (SRP) in the anterior esthetic region using cone-beam computed tomography (CBCT) images. Materials and Methods: CBCT images that met the inclusion and exclusion criteria were categorized using a recent classification of AA arch forms and a SRP classification. Then, the angulation of the root axis and the alveolar bone axis was measured using mid-sagittal CBCT images of each tooth. The relationships of the angulation with each AA arch form and SRP classification were evaluated using 1-way analysis of variance and a linear regression model. Results: Ninety-eight CBCT images were included in this study. SRP had a greater influence than the AA arch form on the angulation of the root axis and the alveolar bone axis(P<0.05). However, the combination of AA arch form and SRP was more predictive of the angulation of the root axis and the alveolar bone axis than either parameter individually. Conclusion: The angulation of the root axis and alveolar bone axis demonstrated a relationship with the AA arch form and SRP in teeth in the anterior esthetic region. The influence of SRP was greater, but the combination of both parameters was more predictive of root-to-bone angulation than either parameter individually, implying that clinicians should account for both the AA arch form and SRP when planning implant placement procedures in this region.

• Journal of Periodontal and Implant Science
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• 제50권3호
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• pp.146-158
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• 2020

Purpose: The aim of this study was to investigate and identify the main causes of periodontal tissue change associated with labial gingival recession by examining the anterior region of patients who underwent orthodontic treatment. Methods: In total, 45 patients who had undergone orthodontic treatment from January 2010 to December 2015 were included. Before and after the orthodontic treatment, sectioned images from 3-dimensional digital model scanning and cone-beam computed tomography images in the same region were superimposed to measure periodontal parameters. The initial labial gingival thickness (IGT) and the initial labial alveolar bone thickness (IBT) were measured at 4 mm below the cementoenamel junction (CEJ), and the change of the labial gingival margin was defined as the change of the distance from the CEJ to the gingival margin. Additionally, the jaw, tooth position, tooth inclination, tooth rotation, and history of orthognathic surgery were investigated to determine the various factors that could have affected anterior periodontal tissue changes. Results: The mean IGT and IBT were 0.77±0.29 mm and 0.77±0.32 mm, respectively. The mean gingival recession was 0.14±0.57 mm. Tooth inclination had a significant association with gingival recession, and as tooth inclination increased labially, gingival recession increased by approximately 0.2 mm per 1°. Conclusions: In conclusion, the IGT, IBT, tooth position, tooth rotation, and history of orthognathic surgery did not affect labial gingival recession. However, tooth inclination showed a significant association with labial gingival recession of the anterior teeth after orthodontic treatment.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.303-312
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• 2023

Purpose: This study investigated the prevalence of developmental and acquired pathologic conditions associated with impacted third molars (3Ms) in a Southern Brazilian population and evaluated whether demographic and tooth characteristics were correlated with the presence of bone or tooth lesions. Materials and Methods: Panoramic radiographs were assessed for developmental (bone-related) or acquired (tooth-related) pathoses associated with impacted upper or lower 3Ms. Data on tooth positioning, tooth development, and patient demographics were collected. A trained, calibrated postgraduate student evaluated all images. Binary and multivariate logistic regression models were used to assess associations between outcomes and the demographic and radiographic variables. The threshold for statistical significance was set at 5% (P<0.05). Results: The sample comprised panoramic radiographs from 2054 patients, predominantly female (59.2%), with a mean age of 27.2±11.5 years. Overall, 4066 impacted 3Ms were evaluated, revealing 471 (11.6%) developmental and 710 (17.5%) acquired pathoses. Among the developmental pathoses, 460 (95.2%) were indicative of dentigerous cysts. Male sex, lower 3M location, vertical or distoangular positioning, and incomplete root formation were associated with an elevated likelihood of developmental pathology. Lower tooth position, complete root formation, and partial eruption were linked to an increased probability of an acquired pathology in the third or second molar. Conclusion: The prevalence of pathologic conditions associated with impacted 3Ms was low. Male sex, lower 3M placement, horizontal or distoangular positioning, and incomplete root formation were associated with developmental pathoses, while lower tooth position, complete root formation, and partial eruption were related to acquired pathoses.

• 대한치과보철학회지
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• 제29권3호
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• pp.1-32
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• 1991

Tho osseointegrated dental prosthetic treatment has develped for the edentulous patient with severely resorbed alveolar ridge, and has given us a successful clinical results to date. Nowadays the partially edentulism is included among the indications of the osseointegrated prosthetic treatment. The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstructure. Two dimensional finite element stress analysis was applied for this study. FEM models were created using software Super SAP for MBM 16bit personal computer. Three modalities of connection were modeled and analyzed under load condition. The results were as follws: 1. The stress develped at tooth and implant in the cancellous bone was lower in the case of rigid connection than in the case of norigid connection, but higher between the two implants in the case of rigid connection than in the case of nonrigid connection. 2. The stress developed at the cortical bone and at the supporting bone interface was lower in the case of rigid connection than in the case of nonrigid connection 3. The stress developed at the supporting tissue interface of the implant nearby the tooth, was lower in the case of rigid connection than in the case of nonrigid connection. 4. The stress developed at the supporting tissue interface of posteriormost implant, was same between the cases of rigid and nonrigid connection. 5. The stress distribution related to the freestanding case was generally similar to the stress distribution pattern of nonrigid connection case. 6. The magnitude of applied load which produces deformation within elastic limit, had influence on the absolute value of stress, but had no influence on the pattern of stress distribution of the same case.

• Journal of Periodontal and Implant Science
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• 제38권3호
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• pp.475-482
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• 2008

Purpose: To evaluate the safety and efficiency of bone regenerative abilities of silk fibroin nanomembrane(Nanoguide-S) Material and Methods: The objects were 38 patients who had large defect at extraction sockets caused by chronic periodontitis and silk fibroin nano matrix were used on experimental group(N=19) and PLA/PLGA matrix were used on control group(N=19). The width, height, and length by crown-apical direction(socket depth) of defects were measured with the occlusal plane as a reference plane, and tooth axis direction, perpendicular to tooth axis direction were measured on radiographs at 3 months pre-operative, 3 months post-operative. Result: Tissue response to silk fibroin nano matrix and Biomesh were clinically satisfactory and complications such as swelling, exudation, ulceration and vesicles were not found except the ordinary discomfort of operated portion. 3 months later, the width, height, and length by crown-apical direction (socket depth) of defects were clinically improved in both groups with no significant difference. 3 months later radiolucency of tooth axis direction and perpendicular to tooth axis direction were all increased in both groups with no significant difference. Conclusion: By these results biodegradadable silk fibroin nano matrix was efficient in GBR on alveolar bone resorption caused by periodontitis compared to Biomesh.

• Journal of Periodontal and Implant Science
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• 제51권2호
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• pp.100-113
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• 2021

Purpose: Previous studies have solely focused on fresh extraction sockets, whereas in clinical settings, alveolar sockets are commonly associated with chronic inflammation. Because the extent of tissue destruction varies depending on the origin and the severity of inflammation, infected alveolar sockets may display various configurations of their remaining soft and hard tissues following tooth extraction. The aim of this study was to classify infected alveolar sockets and to provide the appropriate treatment approaches. Methods: A proposed classification of extraction sockets with chronic inflammation was developed based upon the morphology of the bone defect and soft tissue at the time of tooth extraction. The prevalence of each type of the suggested classification was determined retrospectively in a cohort of patients who underwent, between 2011 and 2015, immediate bone grafting procedures (ridge preservation/augmentation) after tooth extractions at Seoul National University Dental Hospital. Results: The extraction sockets were classified into 5 types: type I, type II, type III, type IV (A & B), and type V. In this system, the severity of bone and soft tissue breakdown increases from type I to type V, while the reconstruction potential and treatment predictability decrease according to the same sequence of socket types. The retrospective screening of the included extraction sites revealed that most of the sockets assigned to ridge preservation displayed features of type IV (86.87%). Conclusions: The present article classified different types of commonly observed infected sockets based on diverse levels of ridge destruction. Type IV sockets, featuring an advanced breakdown of alveolar bone, appear to be more frequent than the other socket types.

• 대한치과교정학회지
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• 제34권1호
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• pp.71-81
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• 2004

치아의 맹출 과정과 치간이개로 유도된 치아 및 치조골의 흡수 과정에서 치주인대 세포와 치주인대 단백질의 기능을 알아보기 위하여, 발육 중인 흰쥐를 치근 형성 전, 치근 형성 시작과 치근 형성 및 맹출 시기로 구분하여 조직 표본을 제작하고, 또한 성 장 중인 흰쥐를 2주간 치간 이개시켜 조직표본을 제작하였다. 치주인대 섬유모세포에서 특이적으로 발현되며 치주인대의 분화와 성숙에 관여하는 PDLs22단백질과 치아와 치조골의 파괴와 흡수를 조절하는 것으로 알려진 RANKL과 OPG의 발현을 면역 조직화학적으로 연구하였다. PDLs22 단백질은 치근 형성이 시작되면서부터 치낭세포와 골모세포에서 발현되어, 치아가 맹출하는 과정에서도 그 발현이 계속 유지되었으나, 치간이개에 의하여 치주인대가 개조되는 부위에서는 발현이 감소하였다. RANKL은 치근형성 과정에서는 미약한 발현을 나타내었으나, 치아가 맹출하면서 발현이 증대되었으며, 치간이개에 의한 치근과 치조골 흡수과정에서는 치주인대세포, 골모세포, 치수세포 및 파치세포에서 발현이 증대되었다. OPG는 치근이 형성되는 시기에는 강한 발현을 보였으나, 치아가 맹출하면서 발현이 현저히 감소하였고, 치아와 치조골의 흡수가 진행됨에 따라서 발현이 다소 감소하였다.

• 대한치과교정학회지
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• 제14권2호
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• pp.187-202
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• 1984

There are evidences that exogenous electric currents are capable of enhancing bone formation and resolution, and that the conversion of the bioelectric response to biochemical activity provides the directional component of orthodontic tooth movement. In addition, evidence has implicated cyclic nucleotides in alveolar bone cellular activation mechanism during orthodontic tooth movement. In view of these evidences, this study was performed to investigate the effects of exogenous electric currents on cyclic nuclotide levels in feline alveolar bone and the possible clinical application of electric currents as an additional orthodontic tool. In the first study, three groups of three adult cats were subjected to application of a constant direct current of $10{\pm}2$ microamperes to gingival tissue near maxillary canine noninvasively for 1, 3, and 7 days respectively. In the second study, three groups of three adult cats each were treated by an electric-orthodontic procedure for 1, 3, and 7 days respectively. The left maxillary (control) canine received an orthodontic force of 80gm alone at time of initiation, while the right maxillary (experimental) canine received combined force-electric stimulation (80gm of force and $10{\pm}2$ microamperes of a constant D.C. currents). Alveola, bone samples were obtain from the mesial (tension and/or cathode) and the distal (compression and/or anode) sites surrounding maxillary canines as well as from contralateral control sites. The samples were extracted, boiled, homogenized, and the supernatants were assayed for cyclic nucleotides (cAMP, cGMP) by a radioimmunoassay method. And also the amount of tooth movement was measured in the second study. On the basis of this study, the following conclusions can be drawn: 1. The fluctuation pattern of cyclic nucleotide levels in alveolar bone treated by exogenous electric currents was similar to that treated by orthodontic force. 2. The cAMP levels in alveolar bone of electrically treated teeth significantly elevated above the control values. And of electrically treated teeth, the values of the anode sites were higher than those of the cathode sites. 9. The cGMP levels in alveolar bone of electrically treated teeth elevated above the control values at the initiation phase of treatment, but dropped below the control values at time of termination. And of electrically treated teeth, the values of the cathode sites were higher than those of the anode sites. 4. The rate of tooth movement in teeth . treated by force-electric combination increased with the length of treatment as compared to that treated by mechanical force alone.

• 대한심미치과학회지
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• 제25권1호
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• pp.15-24
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• 2016

전치부에서는 비록 임플란트가 기능적으로 문제가 없다고 하더라도 심미적인 문제가 있다면 실패로 간주한다. 2003년 Kan은 임플란트의 골 레벨은 인접치아의 골 레벨에 의해 결정된다고 보고하였다. 그 후로 많은 학자들이 인접치아의 골 소실이 있는 증례에서 어떻게 심미적 결과를 얻을 수 있는지에 대하여 연구해왔다. 2012년 Takino가 지금까지 여러 저널을 정리 및 분류하여 Class 1부터 4로 발표하였다. Class 1과 2는 인접치의 골소실이 없는 경우, Class 3,4는 인접치의 골소실이 있는 경우로 나누어서 각 분류마다 최적의 심미를 얻을 수 있는 방법에 대하여 설명하였다. 인접치의 골소실이 없는 경우에는 쉽게 심미적 결과를 얻을 수 있으나 인접치까지 골소실이 있는 경우는 수술이 복잡해지고 심미적 결과를 장담하기 힘들다. 따라서 장기적인 안정적 결과를 유지하기 위해서는 인접치에 대한 골재생술이 필요하다. 하지만 그 과정이나 치료법이 너무 복잡하여 이 저널에서는 기존의 수술법을 단순화하여 쉽게 비슷한 결과를 얻을 수 방법을 보고하고자 한다.

• 대한치과교정학회지
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• 제23권2호
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• pp.263-273
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• 1993

The purpose of this study was to analyse the center of resistance of the maxillary first molar using the 3-dimension finite element method. An extracted maxillary first molar of normal shape and average root length was selected and sectioned every 1.5mm parallel to the cementoenamel junction. Each section was traced and digitized to construct 3-D finite element model of the maxillary first molar. After a certain magnitude of counterbalancing moment(M) was applied to the tooth, a varying single force(F) of distomesial direction was applied to a certain point of th tooth until the tooth was translated. The force producing translation(Ft) was substituted to the equation ${\Delta}d=M/Ft$ to calculate the center of resistance of the maxillary first molar. And reducing the alveolar bone level 1.68mm, and 3.36mm below to the cementoenamel junction, the tooth movement was analysed to see the effect of reducing the alveolar bone level to the location of the center of resistance. The results were as follows ; 1. The center of resistance of the maxillary first molar was 3.72mm apical, 1.10mm buccal, and 0.71mm mesial to the geometric center of the horizontally sectioned surface at the cementoenamel junction. This point was 0.36mm apical, 1.20mm buccal, and 0.71mm mesial to the trifurcation point, indicating that it was not on the tooth root. 2. As the alveolar bone level was reduced, the center of resistance of the maxillary first molar was moved to the apical direction.