• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.28-37
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• 2020

Purpose: The aim of our study was to determine the prevalence and degree of lingual concavities in the first molar region of the mandible to reduce the risk of perforating the lingual cortical bone during dental implant insertion. Methods: A total of 163 suitable cross-sectional cone-beam computed tomography images of edentulous mandibular first molar regions were evaluated. The mandibular morphology was classified as a U-configuration (undercut), a P-configuration (parallel), or a C-configuration (convex), depending on the shape of the alveolar ridge. The characteristics of lingual concavities, including their depth, angle, vertical location, and additional parameters, were measured. Results: Lingual undercuts had a prevalence of 32.5% in the first molar region. The mean concavity angle was 63.34°±8.26°, and the mean linear concavity depth (LCD) was 3.03±0.99 mm. The mean vertical distances of point P from the alveolar crest (Vc) and from the inferior mandibular border were 9.39±3.39 and 16.25±2.44, respectively. Men displayed a larger vertical height from the alveolar crest to 2 mm coronal to the inferior alveolar nerve (Vcb) and a wider LCD than women (P<0.05). Negative correlations were found between age and buccolingual width at 2 mm apical to the alveolar crest, between age and Vcb, between age and Vc, and between age and LCD (P<0.05). Conclusions: The prevalence of lingual concavities was 32.5% in this study. Age and gender had statistically significant effects on the lingual morphology. The risk of lingual perforation was higher in young men than in the other groups analyzed.

• Imaging Science in Dentistry
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• v.37 no.3
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• pp.133-138
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• 2007

Purpose: The purpose of this study was to evaluate the morphologic features of posterior edentulous mandible for Korean patients using cross-sectional CT images. Materials and Methods: Computed tomographic cross-sectional views taken in 2004 and 2005 at Seoul National University Dental Hospital were analyzed by an oral and maxillofacial radiologist. Four indices were measured to meet the purpose of this study: 1) the horizontal distance between the alveolar crest and mandibular canal (Type), 2) the angle of the mandibular long axis (Angle), 3) the bucco-lingual location of mandibular canal, and 4) the depth of the submandibular fossa. The averages and standard deviations of the measurements were compared according to the location (the first and second molar area) and sex of the patients. Results: Statistically significant difference was found in Type, Angle, and submandibular fossa depth between the first and second molar area (p<0.05). However, there was no significant difference between men and women in any of the measured indices. Most of the mandibular canals were located in lingual side of posterior mandible. Conclusion: More care should be taken when an implant is installed on the mandibular second molar area.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.633-643
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• 2007

Statement of problem: Recently there are on an increasing trend of using implants-especially in edentulous mandible of severly alveolar bone recessed. Purpose: The aim of this study was to analyze the displacement and stress distribution of various mandibular implant-retained overdenture models supported by two implants in interforaminal region under the occlusion scheme load. Material and method: FEA models were made by the 3D scanning of the edentulous mandibular dentiform. The three models were named as Model M1, M2, and M3 accord ing to the position of implants: M1, Lt. incisor area, M2, Canine area, and M3, 1st Premolar area. Inter-implant angulation model was named as M4. Conventional complete denture was named M5 and used as a control group. Ball implant and Gold matrice were used as a retentive anchors. The occlusion type loads were applied horizontally over each tooth. Results: 1. In mandibular implant retained overdenture Canine Protected Occlusion type load resulted in higher levels of stress to the implants and female matrices than other types of loads. 2. The overdenture model M1, with implants in lateral incisor areas resulted in lower stress concentration to the implants and female matrices than other models. 3. In mandibular implant retained overdenture the stresses of the implant and female matrice were lower in mesially inclined implant than these of parallel installed implant. Conclusion: Lateral incisor areas could be the best site for the implants in mandibular implant-retained overdenture. The mandibular implant retained overdenture models mentioned above showed to the lowest stress to the implants and female matrices.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.25-30
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• 2018

In edentulous patients, the advantages of prosthodontic therapy using oral implants include both stability and comfort. Advantages suggested for this approach include the prevention of mandibular bone resorption and increased masticatory function. Implant hybrid prostheses place 4 to 6 implants between the mental foramens, and cantilevers are used to replace the posterior teeth at both ends. The 85 - year - old female patient visited our clinic with complete edentulism in the maxilla and mandible. This article reports a satisfactory clinical and esthetic outcome of full mouth rehabilitation using removable complete denture in the maxilla and implant hybrid prosthesis in the mandible.

• 대한치과보철학회:학술대회논문집
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• 2001.11a
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• pp.47-47
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• 2001

• The Journal of the Korean dental association
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• v.57 no.11
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• pp.654-663
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• 2019

This case report describes the management of a 30-year-old woman with hopeless mandibular first molars and right maxillary second premolar. The treatment plan included mandibular second and third molar protraction after extraction of mandibular first molars. Mini-implants were placed between roots of first and second premolar. Sliding mechanics with lever arm was used to prevent inclination of molars. A good functional occlusion was achieved in 38 months without clinically significant side effects. Most of the extraction space of mandibular first molar was closed by protraction of second and third molars. The skeletal Class II pattern was improved by counterclockwise rotation of mandible through reduction of wedge effect. Mandibular molar protraction with orthodontic mini-implants in adequate cases would be a great alternative to prosthetic implant and reduce the financial and surgical burden of patients.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.259-269
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• 1992

The author has examined the abnormalities in panoramic radiographs of 668 edentulous patients. The distribution, type, incidence, and location of all abnormalities were analized, and the distances between alveolar crest and anatomical structures were measures. (Maxillary measurements were performed between alveolar crest and lower margin of the maxillary sinus and mandibular measurements between alveolar crest and upper edge of the mental foramen.) The obtained results were as follows: 1. Of the 668 panoramic radiographs examined, 103(15.4%) showed one or more abnormalities. 2. The incidence of abnormalities was decreased by years, which was 22.0% in 1970's and 16.8% in 1980's and 12.1 % in 1990's. 3. The distribution of abnormalities as follows; 43 (40.2%) superficial root fragments, 24(22.4%) impacted teeth, 9(8.4%) imbedded root fragments, 7 (6.5%) cysts, 7(6.5%) fractures, 5(4.7%) foreign bodies, 5(4.7%) abnormal radiolucencies, 4(3.7%) abnormal radiopacities, 2(1.9%) bony defects, 1(0.9%) tumor. 4. In the location of abnormalities, 42 cases (35.3%) were in the maxillary posterior region, 26 cases(21.8%) were in the maxillary anterior region, 20 cases(24.4%) were in the mandibular posterior region and 18 cases(15.1%) were in the mandibular anterior region. 5. In the distance between alveolar crest and maxillary sinus, 109 cases(9.7%) were below 0.5㎜, 757 cases(67.6%) were between 0.5㎜ and 10㎜, 254 cases(22.7%) were above 10㎜. In the distance between alveolar crest and mental foramen, 73 cases (8.8%) were below 0.5㎜, 501 cases (60.7%) were between 0.5㎜ and l0㎜ and 252 cases(30.5%) were above 100㎜.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.339-346
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• 2022

Compared with traditional full dentures, mandibular implant overdentures have the advantage in that good support and retention can be obtained even with two implants. When manufacturing a mandibular implant overdenture using two implants, it is important to place the implant in the correct position. The long-term prognosis of overdenture is good when two implants are placed in the direction vertical to the occlusal plane and parallel to each other at the canine position. However, it is difficult to place two implants in the correct position in edentulous patients, and if you use surgical guides in these cases, you can get help in placing the implants in a prosthetically advantageous position. This case, a 57-year-old male patient, came to our hospital with all upper and lower teeth removed due to periodontal disease. Therefore, the maxilla was restored with a traditional full denture and the mandible was restored with an implant overdenture using two implants, which resulted in satisfactory functional and esthetic results.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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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).

• The Journal of Korean Academy of Prosthodontics
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• v.26 no.1
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• pp.153-169
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• 1988

There is a little scientific documentation reporting the stress, distribution to the edentulous mandible by different concepts of occlusal scheme. So, this study was to investigate the hypothesis that the magnitude and distribution of the occlusal stresses, transmitted through a mandibular complete denture base to the edentulous mandible, would be influenced by the lingualized occlusion. This investigation was performed to analyze the stresses induced in a three-dimensional photoelastic edentulous mandible, when a load is applied to the denture arranged into lingualized occlusion in centric relation, lateral and protrusive functional position. The mounted denture on a Dentatus Type ARO articulator was loaded in a pure vertical direction with 15kgs on the center of articulator in each case and the stresses were frozen into epoxy edentulous model at $127^{\circ}C$ in the stress freezing furnace. The stress-frozen epoxy models were sliced with diamond disc saw into 4mm thick. The slices were examined with a circular polariscope. The results were as follows: 1. In centric relation, the stresses were low at anteriors, and gradually increase to the premolar, molar area and highest at the first molar and gradually decrease from the second molar and lowest at the retromolar pad region. The lingual side showed higher stresses than labiobuccal side. 2. In lateral functional position, the working side showed higher stresses than the balancing side. In working side, the lingual side showed higher stresses than the buccal side and in balancing side, the buccal side showed higher stresses than the lingual side. 3. In protrusive position, stress distribution was symmetrical on the posteriors and the stresses were concentrated at the labial side of the anteriors.