• Imaging Science in Dentistry
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• 제32권3호
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• pp.141-145
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• 2002

Purpose : The purpose of this study was to propose standard values for alveolar and basal bone in normal adult mandibles, and radiologically analyze the remodeling process of the edentulous mandible by examining molar areas and comparing them to the established normal values. Materials and Methods : Panoramic and CT scans of mandible were performed on 20 normal adults and 20 edentulous or partially edentulous adults. In both groups, arch half diameter and distance of alveolar bone were measured. Also the distance from the mandibular canal to the caudal edges, the buccal and lingual external borders of basal bone, were measured. A statistical comparison between the mean values of normal and edentulous mandibles was carried out in the selected areas. Results : There was evidence of decreasing arch half diameter and distance in the edentulous mandible, but statistically no significant change was seen between the normal and edentulous alveolar bone. There was evidence of decreasing buccal basal bone and increasing in the lingual basal bone in the edentulous mandible. A statistically significant difference between normal and edentulous mandibles was noted in the buccal basal bone. Conclusion: There was an inward and forward atrophic change of the edentulous mandibular molar area compared to the control. CT scanning required the use of sophisticated and expensive procedures to analyze the remodeling process of edentulous mandibles. Consequently, the development and application of a more simplified and objective radiographic procedure for broad and long-term study of remodeling procedures of edentulous mandible was recommended.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권5호
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• pp.207-213
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• 2014

Fractures of the mandible occur with a greater frequency in the elderly. This study reports three cases of edentulous atrophic mandible fracture in elderly patients treated with open reduction technique. Three patients who presented with edentulous atrophic mandible fractures underwent surgical management using open reduction and internal fixation. After treatment, clinical evaluations and postoperative complications were examined with postoperative x-ray. Patients were followed with clinical and radiographic examinations. In the postoperative clinical evaluation, two male patients healed well, but one female patient complained of pain and swelling. In radiographic examinations, no union delay or lack of fusion was observed in the edentulous area. Open reduction technique is a viable treatment option for the edentulous atrophic mandible fractures in geriatric patients.

• 대한치과보철학회지
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• 제38권3호
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• pp.360-365
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• 2000

The completely edentulous patient has few treatment options in conventional dentistry. When implants are considered, treatment plans range from a 2-implant overdenture to a completely implant-supported prosthesis. Fixed prosthesis is often the preferred selection of the edentulous patient. fixed full-arch cert amo-metal restorations can be a predictable implant treatment modality for the edentulous patient. Implant-supported fixed prosthesis has several advantages: predictability, fixedness, retrievability, improved function, lower maintenance of prosthesis, long-term published success. Edentulous patients with a severely resorbed mandible often experience problems with their dentures. Treatment concepts involving two to four implants for the support of an overdenture have been proposed. There seems to be no need to insert more than two endosteal implants to support an overdenture, however, long-term prospective studies are needed to support this notion. Using short endosseous implants and an overdenture in the extremely resorbed mandible is a justified treatment option because of the relative simplicity and low morbidity of this treatment strategy. Implant-supported overdenture has several advantages: Cost, retrievability, hygiene access, profile and contour control, increased retention and stability, implant installed in a predicted region(ant. mandible).

• 치과방사선
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• 제29권1호
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• pp.43-53
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• 1999

Purpose: The aim of this study was to analyze radiologically the location and course of the mandibular canal and to observe the alveolar and basal bone changes during the remodeling procedures of atrophic mandible. Materials and Methods: CT scanning was performed on dry 30 edentulous or partially dentulous mandibles. In 48 edentulous lower halves, measuring areas were determined by three points in the length of the mandibular canal. The distance from the mandibular canal towards cranial and caudal edges, buccal and lingual external borders of the body of the mandible were measured. A statistical comparison between the mean values of different classes of mandibular body was carried out in the selected areas. Results: The distance between the mandibular canal and caudal borders of the body of the mandible and lingual borders dose not change in the atrophic process of mandible. The mandibular canal within the mandible courses downwards from mandibular foramen towards mesial and subsequently it gets to the mental foramen. The distance between the mandibular canal and buccal external border of basal bone changes similar to the change of cranial borders of alveolar bone in the atrophic process of mandible. Conclusion: CT scanning was very effective and practicable to analyze the location and course of the mandibular canal and to observe the alveolar and basal bone changes of atrophic mandible. Also more detailed investigation of basal bone changes observed during the remodeling procedures of atrophic mandibles seems reasonable to rely on the massive anthropologic collections of atrophic mandibles combined with CT scanning.

• The Journal of Advanced Prosthodontics
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• 제6권1호
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• pp.53-59
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• 2014

PURPOSE. The aim of this study was to obtain statistical data on the residual bone height at different natural tooth positions by panoramic radiography in edentulous Korean patients aged 60-90 years. MATERIALS AND METHODS. The study included the diagnostic panoramic radiographs of 180 randomly selected edentulous patients without systemic diseases affecting bone. The radiographic selection criteria included absence of obvious facial asymmetry, clearly visible anatomic structures, and no surgical and fracture history. The panoramic radiographs of 79 patients met these criteria and were used in the analysis. The same researcher processed all the radiographs by using a standardized method. The height of the residual bone was measured at 18 predetermined sites (7 in the maxilla and 11 in the mandible) on digitized and printed radiographs by using a Digimatic caliper, triangle, and ruler. Gender- and age-related differences were statistically analyzed by using the t-test and rank-sum test (${\alpha}=0.05$). RESULTS. The maxillary residual bone height did not show significant gender-related differences, but male patients had significantly higher residual bone in the mandible(P<.05). No significant height differences at the measured sites were noted among the 60s, 70s, and 80s age groups. CONCLUSION. Dentists should pay greater attention to older female edentulous patients because they are more prone to rapid residual bone resorption. Residual bone resorption may not be affected by age.

• Imaging Science in Dentistry
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• 제31권3호
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• pp.165-173
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• 2001

Objectives : To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. Materials and Methods: For radiographic projection, TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophagus. Effective dose was calculated, using the method suggested by Frederiksen et al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. Results: The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Conclusions: Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning.

• The Journal of Advanced Prosthodontics
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• 제14권3호
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• pp.143-149
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• 2022

PURPOSE. Masticatory loading triggers active bone remodeling, altering alveolar bone mineral density (BMD). While dental implants are placed to bear masticatory loading, their influence on changing bone properties has not been fully investigated. Objective of this pilot study was to examine whether the dental implantation has an effect on BMD distribution of bone by comparing dentate, edentulous, and edentulous patients with implants. MATERIALS AND METHODS. Cone beam computed tomography (CBCT) images of 19 partially edentulous patients (Dent), 19 edentulous patients (Edent), and 16 edentulous patients who received implants in the mandible (Edent+Im), were obtained. CBCT images were also obtained from 5 patients within Edent+Im group, before implant placement and after implant loading. Basal cortical bone region of the mandible was digitally isolated. A histogram of gray levels proportional to BMD was obtained to assess mean, histogram standard deviation (HSD), fifth percentile of low and high values (Low₅ and High₅) of the BMD distribution. Multivariate analysis of variance and paired t-test were used to compare the BMD parameters among the 3 dental status groups and between pre- and post-implantation, respectively. RESULTS. Edentulous patients with implants had significantly greater HSD and High₅ values compared to edentulous patients (P < .013). All other comparisons were not significant (P > .097). Mean, HSD, and High₅ values significantly increased after receiving implants (P < .022). CONCLUSION. The current findings suggested that receiving dental implants promoted oral bone mineralization for edentulous patients. The longitudinal investigation could provide valuable information on understanding the effects of implantation on the behavior of oral bone quality.

• 대한기계학회논문집A
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• 제32권3호
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• pp.290-296
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• 2008

After scientific verification of the osteointegration of dental implants, the overall efficiency of dental implants has been generally accepted. Thus, implants now play a major role in the clinical treatment of an edentulous mandible, and in the prosthetic maintenance equipment for partial edentulous mandible patients. Yet, for the successful long-term maintenance of implants, careful consideration of the bio-mechanics is needed to ensure that the maximum stress in the mandible as a result of chewing is maintained under a critical value. Accordingly, this study focuses on reducing the maximum stresses in an implanted mandible, especially in the cortical bone. Thus, the stresses in the implant and mandible are analyzed using finite element packages, including I-DEAS and NISA II/DISPLAY III, using a local zooming technique for a concentrated stress analysis. In addition, the von-Mises stress and principal stress in the mandible are both checked to determine the best combination.

• 대한치과의사협회지
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• 제54권9호
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• pp.692-702
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• 2016

A short dental implant is considered as possible solution in difficult clinical situations for the placement of a regular length implant. Using a short implant avoiding more invasive surgical procedures simplifies the treatment plan and shortenes the duration of treatment. In this case, 71-year-old female came up with discomfort from her old mandibular denture. As she had fully edentulous mandible and got a negative feedback from removable denture, implant-supported fixed prosthesis was planned. Six short implants were placed on her mandible with severe alveolar bone loss. After 1 year follow up period, implants were well retained with any other abnormal findings. The patient was satisfied with her prostheses and satisfactory outcomes were attained in terms of both esthetic and functional clinical results.

• 대한치과보철학회지
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• 제36권1호
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• pp.104-119
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• 1998

The purpose of this study was pertinent design of the framework of the fixed bone anchored bridge using implants in the edentulous mandible through analysis of stress distribution by the three dimensional finite element analysis method. The results were as follows: 1. The L-shaped framework was favorable in restoring the edentulous mandible by implants and fixed bone anchored bridge. 2. The structure of the framework should be designed to endure the occlusal load because of stress concentration at the most distal abutment of the framework. 3. The stress at the distal implant where cantilever starts was twice as much as that of other portions. 4. Compressive stress was generated on the framework of the mesial side of the distal implant and extrusive force was induced to the mesially positioned implants. 5. The height of vertical plate was high as possible as can be to distribute stresses concentrating bucco-lingually and labio-lingually in the framework between abutments, 6. Reinforcement of the horizontal plate thickness was needed because stress was loaded more on the horizontal plate than on the vertical plate of the framework. 7. Lengthening of the vertical plate can compensate for any limitations in horizontal plate width.