• 대한치과보철학회지
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• 제45권2호
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• pp.274-282
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• 2007

Statement of problem: Main consideration was given to the stresses at the site of implant entry into the cortical bone at the alveolar crest. As a suspectible factor affecting the occurrence of stress concentrations, the contact angle between the implant and the alveolar crest bone was addressed. Purpose: The purpose of this study is to evaluate angles between the alveolar crest bone and the implant effect on the implant crestal area induced stresses using a finite element method. Material and methods: Cylindrically shaped, standard size ITI implants entering into alveolar crest with four different contact angles of 0, 15, 30, and 45 deg. with the long axis of the implant were axisymmetrically modelled. Alterations of stresses around the implants were computed and compared at the cervical cortical bone. Results and conclusion: The results demonstrated that regardless of the difference of the implant/alveolar crest bone contact angles, stress concentration occurred at the cervical bone and the angle differences led to insignificant variations in stress level.

• Journal of Periodontal and Implant Science
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• 제41권2호
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• pp.60-66
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• 2011

Purpose: The aim of this study is to evaluate the buccal and lingual bone thickness in the anterior teeth and the relationship between bone thickness and the tissue biotype. Methods: Three male and two female human cadaver heads (mean age, 55.4 years) were used in this study. First, the biotype of periodontium was evaluated and categorized into a thick or a thin group. Next, full thickness reflections of the mandible and the maxilla to expose the underlying bone for accurate measurements in the anterior regions were performed. After the removal of the half of the alveolar bone, the probe with a stopper was used to measure the thickness of bone plate at the alveolar crest (AC), 3 mm apical to the alveolar crest (AC-3), 6 mm apical to the alveolar crest (AC-6), and 9 mm apical to the alveolar crest (AC-9). The thickness of the buccal plates at the alveolar crest were $0.97{\pm}0.18\;mm$,$0.78{\pm}0.21\;mm$, and $0.95{\pm}0.35\;mm$ in the maxillary central incisors, lateral incisors, and canines, respectively. The thickness of the labial plates at the alveolar crest were $0.86{\pm}0.59\;mm$, $0.88{\pm}0.70\;mm$, and $1.17{\pm}0.70\;mm$ in the mandibular central incisors, lateral incisors and canines, respectively. Conclusions: The thickness of the labial plate in the maxillary anteriors is very thin that great caution is needed for placing an implant. The present study showed the bone thickness of maxillary and mandibular anteriors at different positions. Therefore, these data can be useful for the understanding of the bone thickness of the anteriors and a successful implant placement.

• Journal of Periodontal and Implant Science
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• 제51권2호
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• pp.88-99
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• 2021

Purpose: Direct intraoral scanning and superimposing methods have recently been applied to measure the dimensions of periodontal tissues. The aim of this study was to analyze various correlations between labial gingival thickness and underlying alveolar bone thickness, as well as clinical parameters among 3 tooth types (central incisors, lateral incisors, and canines) using a digital method. Methods: In 20 periodontally healthy subjects, cone-beam computed tomography images and intraoral scanned files were obtained. Measurements of labial alveolar bone and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0-5 mm from the alveolar crest on the superimposed images. Clinical parameters including the crown width/crown length ratio, keratinized gingival width, gingival scallop, and transparency of the periodontal probe through the gingival sulcus were examined. Results: Gingival thickness at the alveolar crest level was positively correlated with the thickness of the alveolar bone plate (P<0.05). The central incisors revealed a strong correlation between labial alveolar bone thickness at 1 and 2 mm, respectively, inferior to the alveolar crest and the thickness of the gingiva at the alveolar crest line (G0), whereas G0 and labial bone thickness at every level were positively correlated in the lateral incisors and canines. No significant correlations were found between clinical parameters and hard or soft tissue thickness. Conclusions: Gingival thickness at the alveolar crest level revealed a positive correlation with labial alveolar bone thickness, although this correlation at identical depth levels was not significant. Gingival thickness, at or under the alveolar crest level, was not associated with the clinical parameters of the gingival features, such as the crown form, gingival scallop, or keratinized gingival width.

• 대한치과교정학회지
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• 제30권5호
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• pp.599-611
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• 2000

교정치료에 의해 빚어지는 치조골 소실의 정도를 좌, 우측 제1대구치의 근, 원심면에서 치료 전, 후의 파노라마 필름을 이용하여 비교평가하고 치조골 소실에 미치는 영향 요소들을 알아보고자 하였다. 고정식 교정장치 치료를 받은 216명의 환자들은 104명의 성장군과 112명의 성인군으로 나뉘어 졌으며 4개 소구치의 발거가 이루어진 경우는 각각 50명씩이었다. 치료 전, 후 파노라마 사진에서 상하 좌우 제1대구치의 근심 및 원심 부위의 치조골 높이를 백악법랑질경계에서 치조골의 최첨점까지 치아 장축에 평행하게 계측하여 다음과 같은 결론을 얻었다. 1. 치료 시작시, 성인군은 성장군보다 유의하게 치조골 수준이 낮았다. 2. 치료 후 치조골 수준은 치료 전 수준보다 유의하게 낮았다. 3. 성장군과 성인군 간에 치조골 변화량의 유의한 차가 없었다. 4. 성인발치군은 비발치군보다 유의하게 더 많은 치조골 소실을 모든 원심면에서 보였다. 5. 상악은 하악보다 통계적으로 유의하게 더 많은 치조골 소실을 근심면에서 보였다. 6. 성인군은 원심면에서 근심면보다 유의하게 더 많은 치조골 소실을 보였다.

• Journal of Periodontal and Implant Science
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• 제35권1호
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• pp.251-261
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• 2005

Alveolar ridge defects may limit or restrict placement of implants. The purpose of this study was to evaluate clinical and histopathologic results which occur following guided bone regeneration using platelet-rich plasma, bovine bone powder and e-PTFE membrane in the localized alveolar bone defects. Ten patients who required guided bone regeneration in implant placemnet, were slelected. Alveolar crest height and width were measured at baseline and, afer 2nd surgery 5 months later At 5 months , we obtained histopathological results as follows: 1. Alveolar crest height was an average of $8.20{\pm}3.74$ mm preoperatively and decreased to an average of $7.40{\pm}1.84$ mm postoperatively. There was no significant difference. 2. Alveolar crest width was an average of $4.25{\pm}2.03$ mm preoperatively and significantly increased to an average of $7.20{\pm}2.44$ mm postoperatively (P<0.01) 3. The change of Alveolar crest height and width were $0.80{\pm}1.40$ mm, $2.95{\pm}1.09$ mm 4. Histopathological evaluations revealed new bone formation with graft material and laminated bone containing the presence of osteocyte-like cell In conclusion, guided bone regeneration using platelet-rich plasma, bovine bone powder and e-PTFE membrane would provide a viable therapeutic alternative for implant placement in the localized alveolar defect or implant failure

• 대한치과교정학회지
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• 제48권6호
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• pp.349-356
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• 2018

Objective: This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images. Methods: CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > $38.0^{\circ}$), normal ($30.0^{\circ}$ < SN-MP < $37.0^{\circ}$), and low (SN-MP < $28.0^{\circ}$) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance. Results: Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness. Conclusions: Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

• Journal of Periodontal and Implant Science
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• 제45권6호
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• pp.216-222
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• 2015

Purpose: After extraction, the alveolar bone tends to undergo atrophy in three-dimensions. The amount of alveolar bone loss in the horizontal dimension has been reported to be greater than the amount of bone loss in the vertical dimension, and is most pronounced in the buccal aspect. The aim of this study was to monitor the predictive alveolar bone level following the extraction of anterior teeth seriously involved with advanced chronic periodontitis. Methods: This study included 25 patients with advanced chronic periodontitis, whose maxillary anterior teeth had been extracted due to extensive attachment loss more than one year before the study. Periapical radiographs were analyzed to assess the vertical level of alveolar bone surrounding the edentulous area. An imaginary line connecting the mesial and the distal ends of the alveolar crest facing the adjacent tooth was arbitrarily created. Several representative coordinates were established in the horizontal direction, and the vertical distance from the imaginary line to the alveolar crest was measured at each coordinate for each patient using image analysis software. Regression functions predicting the vertical level of the alveolar bone in the maxillary anterior edentulous area were identified for each patient. Results: The regression functions demonstrated a tendency to converge to parabolic shapes. The predicted maximum distance between the imaginary line and the alveolar bone calculated using the regression function was $1.43{\pm}0.65mm$. No significant differences were found between the expected and actual maximum distances. Likewise, the predicted and actual maximum horizontal distances did not show any significant differences. The distance from the alveolar bone crest to the imaginary lines was not influenced by the mesio-distal spans of the edentulous area. Conclusions: After extraction, the vertical level of the alveolar ridge increased to become closer to the reference line connecting the mesial and distal alveolar crests.

• Journal of Oral Medicine and Pain
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• 제8권1호
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• pp.77-82
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• 1983

The author measured the degree of alveolar bone resorption around mandibular central incisors in Korean female(254). Mandibulr central incisors were selected from the females who do not have periodontal disease or malocclusion. The selected radiograms were enlarged in the $5"\times7"$ printing papers for the precise measuring. The obtained results were as follows : 1. The average alveolar bone resorption around mandibular central incisors in Korean women were 1.91mm in 3rd decade, 2, 16mm in 4th decade, 2.51mm in 5th deacade, 2.70mm in 6th decade, 2.94mm in older age group. 2. Alveolar bone resorption and age were in positive correlation; there is a tendency that the alveolar bone resorption increase with aging. 3. The regression equation is as follows. Y=13.57x + 7.06(r=0.60, n=254) (Y=estimated age, x=Length(C-E Junction alveolar crest)lar crest)

• 대한치과교정학회지
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• 제50권5호
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• pp.314-323
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• 2020

Objective: To identify the available evidence on the effects of rapid maxillary expansion (RME) with three-dimensional imaging and provide meta-analytic data from studies assessing the outcomes using computed tomography. Methods: Eleven electronic databases were searched, and prospective case series were selected. Two authors screened all titles and abstracts and assessed full texts of the remaining articles. Seventeen case series were included in the quantitative synthesis. Seven outcomes were investigated: nasal cavity width, maxillary basal bone width, alveolar buccal crest width, alveolar palatal crest width, inter-molar crown width, inter-molar root apex width, and buccopalatal molar inclination. The outcomes were investigated at two-time points: post-expansion (2-6 weeks) and post-retention (4-8 months). Mean differences and 95% confidence intervals were used to summarize and combine the data. Results: All the investigated outcomes showed significant differences post-expansion (maxillary basal bone width, +2.46 mm; nasal cavity width, +1.95 mm; alveolar buccal crest width, +3.90 mm; alveolar palatal crest width, +3.09 mm; intermolar crown width, +5.69 mm; inter-molar root apex width, +2.85 mm; and dental tipping, +3.75°) and post-retention (maxillary basal bone width, +2.21 mm; nasal cavity width, +1.55 mm; alveolar buccal crest width, +3.57 mm; alveolar palatal crest width, +3.32 mm; inter-molar crown width, +5.43 mm; inter-molar root apex width, +4.75 mm; and dental tipping, 2.22°) compared to pre-expansion. Conclusions: After RME, skeletal expansion of the nasomaxillary complex was greater in most caudal structures. Maxillary basal bone showed 10% post-retention relapse. During retention period, uprighting of maxillary molars occurred.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권2호
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• pp.85-93
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• 2022

Objectives: The aim of this study was to compare morbidities and duration of surgery, as well as bone formation in alveolar defects reconstructed with symphysis bone combined with allograft and iliac crest bone graft in patients with cleft palate. Patients and Methods: This randomized clinical trial was performed with 22 patients with unilateral alveolar cleft with a follow-up period of 12 months. In 12 patients, alveolar defects were reconstructed with chin bone graft plus allograft (Group A), while for the other 10 patients, iliac bone crest was used as donor site (Group B). Duration of surgery as well as occurrence of morbidities and complications were recorded. In addition, cone-beam computed tomographic (CBCT) scans were performed before surgery and 12 months after surgical procedures in order to compare bone formation between the two groups. Results: Postoperative CBCT demonstrated a mean bone fill percentage of 76.9% of the alveolar defect in Group A, compared with 77.0% in Group B. Paresthesia in the lower lip or chin did not occur in any patients of Group A. The mean duration of the surgical process was significantly shorter for Group A (40 minutes vs 76 minutes, P<0.001). In addition, patients in Group A regained normal gait faster than patients in Group B (1 day vs 9.5 days). Conclusion: Mandibular symphysis bone graft in combination with allograft results in favorable outcomes in patients with unilateral alveolar clefts.