• 소성∙가공
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• 제8권2호
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• pp.200-207
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• 1999

To increase dimensional accuracy of strip width, model to compensate width spread during roughing mill has been developed. To measure the amount of width spread during the production rolling more precisely, special roughing rolling procedures for the horizontal rolling and dog-bone rolling were designed in the actual production mill. From the operational data analysis, it is known that the prime factors influencing on the width spread were strip width, strip thickness, edging amount, number of pass and type of edger roll etc., Based upon the statistical analysis of rolling data, new models which can predict width spread during horizontal rolling and dog-bone rolling were developed and tested on the actual processing conditions for the reliability. The application test showed that newly developed model gave fairly accurate predictions on the width spread during roughing passes.

• 대한치과교정학회지
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• 제46권6호
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• pp.379-385
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• 2016

Objective: Forced eruption has been proposed for the reconstruction of deficient bone and soft tissue. The aim of this study was to examine the changes in the alveolar ridge width and the vertical levels of the interproximal bone and papilla following forced eruption. Methods: Patients whose hopeless maxillary anterior teeth were expected to undergo severe bone resorption and soft tissue recession upon extraction were recruited. In addition, patients whose maxillary anterior teeth required forced eruption for restoration due to tooth fracture or dental caries were included. Before and after forced eruption, the interproximal bone height was measured by radiographic analysis, and changes in the alveolar ridge width and the interproximal papilla height were measured with an acrylic stent. Results: This prospective study demonstrated that the levels of the interproximal alveolar bone and papilla were significantly increased by 1.36 mm and 1.09 mm, respectively, in the vertical direction. However, the alveolar ridge width was significantly reduced by an average of 0.67 mm in the buccolingual direction. The changes in the level of the interproximal alveolar bone and papilla were positively correlated. Conclusions: Although the levels of the interproximal bone and papilla were significantly increased, the alveolar ridge width was significantly decreased following forced eruption. There was a modest positive and significant correlation between the changes in the height of the interproximal alveolar bone and the papilla. Based on our findings, modification of vertical forced eruption should be considered when augmentation of the alveolar ridge width is required.

• 대한구순구개열학회지
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• 제4권2호
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• pp.69-78
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• 2001

Alveolar cleft exists in 75% of cleft patients, In alveolar cleft patients, alar base is widening, palatal fistular formation, maxillary growth disturbance & tooth loss of adjacent area is raised, Alveolar bone grafting, especially iliac bone grafting, is a general treatment method. As operation timing, bone grafting is classified with primary, early secondary, secondary, & late secondary, Here we report cleft width, marginal bone height, bone resorption rate, grafted shape & bone densities after secondary iliac bone grafting was done in the Dept. of oral and maxillofacial surgery of chonbuk national university hospital. We compared cleft width to bone resorption rate and grafted shape. Also, alveolar bone densities of grafted and contralateral site was compared with Emago 3 package? (Oral Diagonostic System, The Netherlands), The data obtained were analyzed using Spearman's rho coefficients and sign test with SPSS for window, The results were obtained as follows. 1. As alveolar cleft width is increase, bone resorption rate is, too. This relation showed significant difference(P<.01). 2, In proximal & distal area, alvolar cleft width and bone graft contour after bone grafting had a reverse proportional difference. It was not significant difference(P>.05). 3. After 3 month, in bone density results by using Emago 3 package? with periapical standard view, occlusal view & panoramic view, differences between grafted bone and alveolar bone of contralateral site didn't show a significant difference(P>.05). Thus, differences of bone densities in the alveolar bones didn't exist.

• 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 Periodontal and Implant Science
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• 제35권1호
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• pp.187-197
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• 2005

The aim of this study was to investigate the influence of peri-implant soft tissue and bone thickness on the early dimensional change of peri-implant soft tissue. Seventy-seven non-submerged implants of 39 patients which had been loaded more than 6 months were selected for the study. Following clinical parameters were measured; bucco-lingual bone width of the alveolar bone for implant placement before implant surgery; distance between implant shoulder and the first bone/implant contact at the surgery; presence of plaque, probing depth, bleeding on probing, width of keratinized mucosa, mucosa thickness, distance between implant shoulder and peri-implant mucosa, crown margin location at follow-up examination. The results showed that distance between implant shoulder and peri-implant mucosa (DIM) was correlated with probing depth and width of keratinized mucosa (p < 0.05). In addition, mucosa thickness was also correlated with probing depth (p<0.05). However, the bone width of alveolar bone and soft tissue thickness were not found to be correlated with DIM. It is important to understand the meaning of peri-implant tissue dimension in relation to dimensional changes of peri-implant soft tissue which designates appearance of implant-supported restorations. Future study is needed to elucidate the significance of the buccal bone thickness and soft tissue thickness with respect to the change of peri-implant soft tissue margin with the use of an instrument capable of measuring buccal bone thickness directly.

• Imaging Science in Dentistry
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• 제36권3호
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• pp.145-149
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• 2006

Purpose : To assess the width of the labial alveolar bone of the incisive canal and the width of the incisive canal on spiral computed tomographic images of the anterior portion of the maxilla. Materials and Methods : Study materials included 38 CT scans taken for preoperative planning of implant placement. Axial cross-sectioned image entirely showing the incisive canal was selected and scanned with 600 DPI resolution. The width of the labial alveolar bone of the incisive canal at an orifice to the oral cavity, middle portion, and an orifice to the nasal cavity and the diameter of the incisive canal at the middle portion were determined by two specialist using Digora for Windows 2.1 The statistical analyses were carried out using SPSS 12.0.1. Results : When the maxillary central incisors remained, the mean labial alveolar bone width were $6.81{\pm}1.41mm,\;6.46{\pm}1.33mm$, and $7.91{\pm}1.33mm$. When the maxillary central incisors were missed the mean width were $5.42{\pm}2.20mm,\;6.23{\pm}2.29mm$, and $7.89{\pm}2.13mm$. Conclusions : The labial alveolar bone width at middle portion and an orifice to the nasal cavity were of no statistical significant difference according to presence of the maxillary central incisors (P>0.05). The width between oral cavity and nasal cavity, middle portion and to nasal cavity revealed statistically significant difference (P<0.05).

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.33.1-33.7
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• 2019

Background: The concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone. Methods: This study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed. Results: The horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level. Conclusions: The results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.43-49
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• 2003

Purpose : To evaluate the differences in bone height, bone width, and visibility of posterior spiral tomographic images according to various exposure directions, image layer thickness, and inclination of the mandibular inferior border. Materials and Methods: Six partially and completely edentulous dry mandibles were radiographed using Scanora spiral tomography. Spiral tomography was performed at different exposure directions (dentotangential and maxillotangential projection), image layer thicknesses (2 mm, 4 mm and 8 mm), and at various inclinations to the mandibular border (+ 100, 00 and -10°). The bone height and width was measured using selected tomographic images. The visibility of mandibular canal, crestal bone, and buccal and lingual surfaces were graded as 0, 1, or 2. Results : The bone width at the maxillo-tangential projection was wider than at the dento-tangential projection (p < 0.05). The visibility of buccal and lingual surface at the maxillo-tangential projection was higher than at the dento-tangential projection (p<0.05). Thinner image layer thicknesses resulted in greater visibility of buccal and lingual surfaces (p < 0.05). Bone height was greatest in the -10° group, and at the same time the bone width of the same group was the narrowest (p < 0.05). The visibility of alveolar crest and buccal surface of the + 10° group was the highest, while the visibility of the mandibular canal was greatest in the 00 group. Conclusion: When spiral tomography is performed at the mandibular posterior portion for visualization prior to implant surgery, it is important that the inferior border of mandible be positioned as parallel as possible to the floor. A greater improvement of visibility can be achieved by maintaining a thin image layer thickness when performing spiral tomography.

• 대한치과보철학회지
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• 제41권5호
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• pp.674-688
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• 2003

Statement of Problem : With increasing demand of the implant-supported prosthesis, it is advantageous to use the different platform width of the fixture according to bone quantity and quality of the patients. Purpose : The purpose of this study was to assess the loading distributing characteristics of two implant designs according to each platform width of fixture, under vertical and inclined loading using finite element analysis. Material and method : The two kinds of finite element models were designed according to each platform width of future (4.1mm restorative component x 11.5mm length, 5.0mm wide-diameter restorative component x 11.5mm length). The crown for mandibular first molar was made using UCLA abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction, 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction and 200N at the buccal cusp in a 300 transverse direction individually Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment screw. Results : The stresses were concentrated mainly at the cortex in both vertical and oblique load ing but the stresses in the cancellous bone were low in both vertical and oblique loading. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading. Increasing the platform width of the implant fixture decreased the stress in the supporting bone, future and abutment screw. Increased the platform width of fixture decreased the stress in the crown and platform. Conclusion : Conclusively, this investigation provides evidence that the platform width of the implant fixture directly affects periimplant stress. By increasing the platform width of the implant fixture, it showed tendency to decreased the supporting bone, future and screw. But, further clinical studies are necessary to determine the ideal protocol for the successful placement of wide platform implants.

• Journal of Periodontal and Implant Science
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• 제39권2호
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• pp.129-138
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• 2009

Purpose: This study was designed to compare the bond regeneratiom effects of treatment using silk fibroin membrane ( Nanogide-S$^{(R)}$ ) resorbable barrier with control group treated by polyactic acid / polylacticglycolic acid membrane(Biomesh$^{(R)}$ ) Methods: 44 severe bone loss on extraction socket from 44 patients were used in this study. In experimental group 22 sites of them were treated by silk fibrin membrane as and the other 22 sites were treated by polyactic acid/ polylacticglycolic acid membrane as a control group. Clinical parameters including recovered bone width, length and radiographic parameter of vertical length were evlauated at base line and 3 months after surgery. Results: 1) Severe bone width, length was significantlly decreased in two group. 2) Bone width, length was significantlly decreased in two group. 3) Decreased bone width, length and radiographic examination differences between group. Conclusions: On the basis of these results, silk fibrin resorbable membrane has similar bone regeneration ability to polyactic acid / polylacticglycolic acid membrane in guided bone regeneration for severe bone loss defect on extraction socket.