• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.320-327
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• 2009

Statement of Problem: Although many efforts have been continually made to estimate long term prognosis of removable partial dentures, the complication of removable partial dentures was still found because of inaccurate fabrication procedure and improper maintenance care. Purpose: The purpose of this study was to evaluate the clinical status of removable partial dentures. Material and methods: A total of 112 individuals with 153 removable partial dentures (35 - 87 years, 64 women and 48 men) were examined by intra-oral examination, diagnostic cast and radiographic examination. Results and conclusion: The results of this study were as follows: 1. Length of service of removable partial dentures was $5.3{\pm}4.3$ years (mean), 4.0 years (median). 2. A total of 45 removable partial dentures were considered failures. The loss of 18 abutments of 369 was founded. 3. Type of arch, Kennedy classification and type of opposite dentition were found to have no influence on longevity and success rate of removable partial dentures (P > .05). 4. Most common major connector was the palatal plate in maxilla and the number of lingual bar and linguoplate designed in mandible were similar. 5. The circumferential type retainer was the most commonly used retainer. 6. Sixty-three percent of the class I and II removable partial dentures incorporated indirect retention into the design. 7. Approximately 81% of the removable partial dentures had at least one defect. Excessive wear of posterior teeth (27.9%), lack of integrity (23.2%), lack of stability (22.6%) were frequent defects of removable partial dentures.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.163-173
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• 2013

When the mandible performs opening movement, the condyle-disk complex conducts sliding movement along the articular eminence. Thus, anatomic configuration of articular eminence is very important to normal movement of TMJ. The purpose of this study was to measure the posterior slope of the articular eminence and evaluate the effect of a pathologic bone change in the condylar head on the stiffness of articular eminence, and compare the differences of the articular eminence slope by gender and age using dental cone-beam CT. As using i-CAT Cone-Beam Computed Tomography, the CT images of 204 TMJs of 102 patients(43 men and 59 women, mean age: 37.7 years) who were diagnosed at Wonkwang University Sanbon Dental Hospital were evaluated. All images were converted into a TMJ analysis mode to observe the continuous sagittal section images and coronal section images of the joints. To observe and assess bone changes in the condyle, three dentists measured the stiffness of the articular eminence on the same images, and when two of the three dentists agreed on their reading, these results were adopted and recorded. The articular eminence slope, considering the condylar anatomic configuration, was measured in three regions, namely, lateral part, central part, and medial part of the condyle. In the cases of a normal condyle(NCBC) and a condyle(CBC) with bone change, the articular eminence slopes were $57.0^{\circ}$(NCBC) and $51.8^{\circ}$(CBC) at the medial part, $57.9^{\circ}$(NCBC) and $52.4^{\circ}$(CBC) at the central part, and $55.1^{\circ}$(NCBC) and $49.5^{\circ}$(CBC) at the lateral part of the condyle. And the articular eminence slope of the condyle with bone change demonstrated less steepness than that of normal condyle (p<0.05). The articular eminence slope showed mediolaterally that it was the steepest at the central, followed by at the medial, and at the lateral (p<0.05). There were no significant differences by the gender and the age (p.0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.136-147
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• 2009

Statement of problem: Since the introduction of the concept of osseointegration in dental implants, high long-term success rates have been achieved. Though the use of dental implants have increased dramatically, there are few studies on domestic implants with clinical and objective long-term data. Purpose: The aim of this retrospective study was to provide long-term data on the $Implantium^{(R)}$ implant, which features a sandblasted and acid-etched surface and internal connection with microthreads. Material and methods: 106 $Implantium^{(R)}$ implants placed in 38 patients at Yonsei University Hospital were examined to determine the effect of various factors on implant success and marginal bone loss, through clinical and radiographic results during a 6 to 30 month period. Results: 1. Out of a total of 106 implants placed in 38 patients, one fixture was lost, resulting in a 99.1% cumulative survival rate. 2. Among the 96 implants which were observed throughout the study period, the survival rates were 97.0% in the maxilla and 100% in the mandible. The survival rate in the posterior regions was 98.9% and 100% in the anterior regions. 3. The mean bone loss during the first year after prosthesis placement was 0.17 mm, while the mean annual bone loss after the first year was 0.04 mm, which was statistically less than during the first year(P<.05). 4. There was no significant difference in marginal bone loss according to age during the first year(P>.05), but after the first year, the mean annual bone loss in patients above 50 years was significantly greater(P<.05) compared with patients under 50 years. 5. No significant difference in marginal bone loss was found according to the following factors: gender, jaw, location in the arch, type of implant(submerged or non-submerged), presence of bone grafts, type of prostheses, and type of opposing dentition(P<.05). Conclusion: Based on these results, the sole factor influencing marginal bone loss was age, while factors such as gender, jaw, location in the arch, type of implant, presence of bone grafts, type of prostheses and type of opposing dentition had no significant effect on bone loss. In the present study, the success rate of the $Implantium^{(R)}$ implant with a SLA surface and internal connection with microthreads was satisfactory up to a maximum 30 month period, and the marginal bone loss was in accord with the success criteria of dental implants.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.99-107
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• 2009

Statement of problem: Restoring and replacing teeth with fixed prostheses commonly used in dental practice. Because of improper oral hygiene care and inaccurate laboratory procedure, complications of fixed prostheses were found in the mouth of patients. Although many efforts have been continually made to obtain the data of long term prognosis of fixed prostheses, it was difficult to do it. Purpose: The purpose of this study was to evaluate the clinical status of fixed prostheses. Material and methods: In order to assess the clinical status of fixed prostheses, a total of 161 individuals(aged 17-85, 99 women and 62 men with 1596 unit of fixed prostheses, and 1169 abutments) who first visited the Department of Prosthodontics, Pusan National University Hospital, between April to September, in 2007 were examined. Results and conclusion: The results of this study were as follows: 1. Length of service of fixed prostheses was $8.6{\pm}0.6$ years(mean), 10.0 years(median). 2. Location of fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in posterior region and in mandible where the failure rate was high in combination(P<.05). 3. Longevity of fixed prostheses made of metal was longest(mean: $13.0{\pm}9.3$, median: 14.0), gold, precious ceramic, non-precious ceramic trailing behind(P<.05). 4. Number of units in fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in Single-unit and the failure rate was high in over 3-unit(P<.05). 5. Condition of opposing dentition was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in natural dentition(P<.05). 6. Defective margin(28.2%), dental caries(23.0%), periodontal disease(19.3%), periapical disease(16.9%) were frequent complications. In 30.1% of the cases, abutment state after removing fixed prostheses was needed to be extracted.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.381-395
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• 2008

Purpoose: For decades dental implants have been used widely in the field of prosthetic dentistry. However there is confusion when establishing treatment plans in cases where some teeth are remained but an insufficient number of implants can be used due to limited anatomical status and ecomomical problems. Many clinicians have tried to connect natural teeth and implants, and it still has controversy. But, there have been few studies on mechanical analysis of connecting natural teeth and implants with konus telescopic removable partial dentures. The purpose of this study was to analyze the stress distribution of prosthesis, abutment and alveolar bone when teeth and implants were connected with the konus telescopic denture, by means of 3-dimensional finite element analysis. Material and methods: The assumption of this study was that there were 2 mandibular canine (11 mm in length, 4 mm in diameter) and 2 implants(10 mm in length, 4 mm in diameter) which are located in the second premolar region. The mandible, teeth, implants, abutments, and connectors are modeled, and analyzed with the commercial software, ANSYS Version 8.1(Swanson, Inc., USA). The control group used implants instead of natural teeth. 21038 elements, 23544 nodes were used in experimental group and 107595 elements, 21963 nodes were used in control group, Stress distribution was evaluated under 150 N vertical load on 3 experimental conditions - between teeth and implants (Load case 1), posterior to implants (Load case 2), between natural teeth (Load case 3). Results: 1. In all load cases, higher von mises stress value was observed in the experimental group. 2. Maximum von miss stress observed in all load cases and all locations were as follows ; a. 929.44 Mpa in the experimental group, 640.044 Mpa in the control group in outer crown and connector - The experimental group showed 1.45 times high value compared with the control group. b. 145,051 Mpa in the experimental group, 142.338 Mpa in the control group in abutment - The experimental group showed 1.02times high value compared with the control group. c. 32.489 Mpa in the experimental group, 25.765 Mpa in the control group in alveolar bone - The experimental group showed 1.26times higher value compared with the control group. 3. All maximum von mises stress was observed in load case 2, and maxim von mises stress in alveolar bone was 32.489 Mpa at which implant failure cannot occur. 4. If maximum von mises stress is compared between two groups, the value of the experimental group is 1.02 times higher than the control group in abutment, 1.26 times higher than the control group in alveolar bone. Conclusion: If natural teeth and implants are connected with the konus telescopic denture, maximum stress will be similar in abutment, 1.26 times higher in alveolar bone than the control group. With this result, there may be possible to make to avoid konus telescopic dentures where natural teeth and implants exist together.

• Korean Journal of Head & Neck Oncology
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• v.6 no.2
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• pp.79-84
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• 1990

This paper is a review of our experience with radical resection for cancer of the oral cavity with particular emphasis upon the value of myocutaneous(i.e., musculocutanous) flaps employed in the surgical reconstruction in patient survival. During the past 15 years, 98 patients underwent resection of cancer arising in the oral cavity and oropharynx. Of these, 14 had composite resections in which the mandible was not sectioned, and 4 underwent en bloc resections without neck dissections in the face of post-radiation recurrence. When these excluded, 84 patients who underwent COMMANDO procedures with or without myocutaneous flaps were suitable for analysis of recurrence and survival according to the various surgical technics employed. 1) According to the surgical technic, there were 24 standard COMMANDO procedures in whom no regional or myocutanous flap was used; 12 patients who underwent reconstruction employing a forehead flap; 19 patients in whom a posterior cervical 'nape' flap was employed; 27 patients who underwent myocutaneous or osteo-myocutaneous flap repair; and two patients who had double flap repair. 2) The uncorrected two-year disease free survival was 41% for standard COMMANDOs, 17% for forehead flap COMMANDOs; 35% for nape flap COMMANDOs; and 35% for myocutaneous flap COMMANDO procedures. 3) The two-year disease-free survival by Stage was 100% in Stage I, 45% in Stage II, 41% in Stage III, and 18% in Stage IV. 4) When myocutanous flaps cases were compared with Group I, comprised of matched historical controls including both Standard COMMANDOs and those who had undergone regional flap repairs(that is, forehead and nape flap COMMANDOs)there was no difference, both groups showing a 40% 2-year disease-free survival. 5) When musculocutanous flap cases were compared with Goup II, which was composed of matched historical controis limited to patients who had undergone regional flap repairs(that is, forehead and nape flap cases only)there was no difference, both groups showing a 27% 2-year desease-free survival. 6) When musculocutanous flap cases were compared with Group III, composed of patients who had undergone classic COMMANDO procedures without any sort of flap repair, there was a striking difference; the patients undergoing MC flap repair showed 50% 2-year disease-free survival, whereas the classic COMMANDO cases showed a 25% survival free of disease. 7) Locoregional recurrence was also evaluated in the four categories; for standard COMMANDO cases it was 25%, for nape flap cases 26% ; for forehead flap cases, 33%, and for the musculocutaneous flap cases, the lowest recurrence rate, 22%. These results are of particular significance in view of the fact that the proportion of advanced cases(Stage III and IV)in each category was 67% of standard cases, 79% of nape flap patients, 100% of forehead flap cases, and 96% of musculocutaneous flap cases.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.157-168
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• 2008

Statement of problem: Over the past two decades, implant supported fixed prosthesis have been widely used. However, there are few studies conducted systematically and intensively on the splinting effect of implant systems in mandible. Purpose: The purpose of this study was to investigate the changes in stress distributions in the mandibular implants with splinting or non-splinting crowns by performing finite element analysis. Materials and methods: Cortical and cancellous bone were modeled as homogeneous, transversely isotropic, linearly elastic. Perfect bonding was assumed at all interfaces. Implant models were classified as follows. Group 1: $Br{{\aa}}nemark$ length 8.5mm 13mm splinting type Group 2: $Br{{\aa}}nemark$ length 8.5mm 13mm Non-splinting type Group 3: ITI length 8.5mm 13mm splinting type Group 4: ITI length 8.5mm 13mm Non-splinting type An load of 100N was applied vertically and horizontally. Stress levels were calculated using von Mises stresses values. Results: 1. The stress distribution and maximum von Mises stress of two-length implants (8.5mm, 13mm) was similar. 2. The stress of vertical load concentrated on mesial side of implant while the stress of horizontal load was distributed on both side of implant. 3. Stress of internal connection type was spreading through abutment screw but the stress of external connection type was concentrated on cortical bone level. 4. Degree of stress reduction was higher in the external connection type than in the internal connection type.