• Journal of Dental Rehabilitation and Applied Science
• /
• v.29 no.3
• /
• pp.209-223
• /
• 2013

This study was to evaluate the stress distributions of prefabricated, customized abutments and fixtures according to their material and shape by three-dimensional finite element analysis. And to investigate the fatigue life and fracture characteristics. Mandibular models were fabricated by reconstruction of the CT scan of patients with normal occlusion. A total of six finite element models were designed, a load of 100 N was applied on the buccal cusps vertically, and 30 degree obliquely. 10 specimens each were fabricated for the more clinically widely used 4 type abutments and were loaded according to ISO 14801. Differences in stress distribution patterns were not found according to the materials of the abutments and fixtures. But a slight difference in the stress level was detected. Customized abutment groups showed lower crown stress levels. One-piece zirconia implant showed the lowest bone stress levels. In the fatigue test, highest values were measured in group 7. Prefabricated abutments showed less variation of fatigue life (P<0.05). Use of customized abutments can improve the fracture resistance of restorations. Especially, use of customized zirconia abutments reinforced by titanium screw connecting parts is recommended.

• Clinics in Shoulder and Elbow
• /
• v.12 no.1
• /
• pp.44-52
• /
• 2009

Purpose: We assessed the radiographic and clinical results of one surgeon's experience treating proximal humerus fractures with a locked proximal humeral plate. Materials and Methods: Twenty patients with unstable proximal humerus fractures were treated with a locking compression plate between February 2005 and September 2007. The average age of the patients was 60.6 years, and the average postoperative follow-up period was 22.3 months. The clinical results were evaluated using the Constant and DASH scores. The radiologic results were evaluated by the Paavolainen method, which measures the neck shaft angle and humeral head height. Results: At the last follow-up examination, the mean Constant score was 75.3 and 15 cases (75%) had excellent or good results; the mean DASH score was 16.4. The mean neck shaft angle was $137.1^{\circ}$, and 19 cases (95%) had good results by the Paavolainen method. There was one delayed union, malunion, and screw loosening. Conclusion: The patients treated with a locking compression plate had relatively good clinical and radiologic results, and a low complication rate. Moreover, the patients could exercise earlier due to good reduction and initial stability. Treatment of unstable proximal humerus fractures with a locking compression plate is a reliable method.

• Composites Research
• /
• v.30 no.2
• /
• pp.145-148
• /
• 2017

Wood powders were surface-modified by plasma-treating propylene to make them compatible with PP matrix in WPC(wood powder composite). The plasma treatment of propylene resulted in the deposition of an ultrathin hydrophobic film which had the chemical structure similar to that of polypropylene. Wood powder and polypropylene were mixed to pellets by twin screw extruder and then 50 wt% wood powder/PP composites were produced by an injection machine. Tensile strength and flexural strength were improved by 7.59% and 12.43% at the maximum respectively. SEM (Scanning Electron Microscopy) observation on the fracture surface revealed that the treatment improved the interfacial bonding and the mechanical properties of the composites.

• Clinics in Shoulder and Elbow
• /
• v.20 no.4
• /
• pp.217-221
• /
• 2017

Background: The purpose of this study was to evaluate the clinical and radiographic outcomes of internal fixation with locking T-plates for osteoporotic fractures of the proximal humerus in patients aged 65 years and older. Methods: From January 2007 through to December 2015, we recruited 47 patients aged 65 years and older with osteoporotic fractures of the proximal humerus. All fractures had been treated using open reduction and internal fixation with a locking T-plate. We classified the fractures in accordance to the Neer classification system; At the final follow-up, the indicators of clinical outcome-the range of motion of the shoulder (flexion, internal rotation, and external rotation) and the presence of postoperative complications-and the indicators of radiographic outcome-the time-to-union and the neck-shaft angle of the proximal humerus-were evaluated. The Paavolainen method was used to grade the level of radiological outcome in the patients. Results: The mean flexion was $155.0^{\circ}$ (range, $90^{\circ}-180^{\circ}$), the mean internal rotation was T8 (range, T6-L2), and the mean external rotation was $66.8^{\circ}$ (range, $30^{\circ}-80^{\circ}$). Postoperative complications, such as plate impingement, screw loosening, and varus malunion were observed in five patient. We found that all patients achieved bone union, and the mean time-to-union was 13.5 weeks of the treatment. The mean neck-shaft angle was $131.4^{\circ}$ at the 6-month follow-up. According to the Paavolainen method, "good" and "fair" radiographic results each accounted for 38 and 9 of the total patients, respectively. Conclusions: We concluded that locking T-plate fixation leads to satisfactory clinical and radiological outcomes in elderly patients with proximal humeral fractures by providing a larger surface area of contact with the fracture and a more rigid fixation.

• Journal of Korean Neurosurgical Society
• /
• v.51 no.3
• /
• pp.135-140
• /
• 2012

Objective : To evaluate radiographic results of anterior fusion methods in two-level cervical disc disease : tricortical autograft and plate fixation (ACDF-AP), cage and plate fixation (ACDF-CP), stand-alone cage (ACDF-CA), and corpectomy and plate fixation (ACCF). Methods: The numbers of patients were 70 with a minimum 6 month follow-up (ACDF-AP : 12, ACDF-CP : 27, ACDF-CA : 15, and ACCF : 16). Dynamic simple X-ray and computed tomography were evaluated preoperatively, postoperatively, 6 month, and at the final follow-up. The fusion and subsidence rates at the final were determined, and global cervical lordosis (GCL), cervical range of motion, fused segment angle (FSA), and fused segment height (FSH) were analyzed. Results: Nonunion was observed in 4 (25%) patients with ACDF-CA, 1 (8%) patient with ACDF-AP, 1 (4%) patient with ACDF-CP. The number of loss of FSH (%) more than 3 mm were 2 patients (16%) in ACDF-AP, 3 patients (11%) in ACDF-CP, 5 patients (33%) in ACDF-CA, and 3 patients (20%) in ACCF. The GCL was decreased with ACDF-CA and increased with others. The FSA was increased with ACDF-AP, ACDF-CP, and ACCF, but ACDF-CA was decreased. At the final follow-up, the FSH was slightly decreased in ACDF-CP, ACDF-AP, and ACCF, but ACDF-CA was more decreased. Graft related complication were minimal. Screw loosening, plate fracture, cage subsidence and migration were not identified. Conclusion: ACDF-CP demonstrated a higher fusion rate and less minimal FSH loss than the other fusions in two-level cervical disc disease. The ACDF-AP and ACCF methods had a better outcome than the ACDF-CA with respect to GCL, FSA, and FSH.

• Composites Research
• /
• v.26 no.5
• /
• pp.328-333
• /
• 2013

In this study, bone plate made of glass/polypropylene composite material which was applied to an artificial bone was tested to check the service ability under fatigue loading. To check serviceability of composite bone plates fatigue test was carried out considering changes in the moisture absorption rate, locking position of screws and loading condition. Test results showed that all the tested specimens had the fatigue life more than one million cycles which was much higher fatigue life than the expected value of 650,000 cycles. Screw position was not critical impact on the deformation of the fracture site. In this paper, the mechanical performance of the glass/polypropylene composite was verified by fatigue test under various water absorption conditions, and this result may give useful information on the design of composite bone plate.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.23 no.3
• /
• pp.270-276
• /
• 2001

The treatment of mandibular subcondylar fractures is a matter of controversy. The majority of mandibular subcondylar fracture are treated by closed reduction, but the displaced or dislocated mandibular subcondylar fractures may be treated by open reduction. The characteristics of open reduction are the anatomical reduction, the functional restoration, the rapid function, the maintenance of vertical ramus dimension, the better appearance and the less resultant TMJ problem etc. When an open reduction is considered, the wire, miniplate, lag screw and Kirschner wire are available with internal fixation. Of these, Kirschner wire is a simple method relatively and correct positioning of the wire achieves rigid fixation. But many open reduction methods for mandibular subcondylar fractures require extraoral approach. The extraoral approach has some problems, the facial scar and the risk of facial nerve injury. On the other hand, the intraoral approach eliminates the potency of the facial scar and the facial nerve injury, but is difficult to access the operation site. Since the intraoral approach was first described by Silverman (1925), the intraoral approach to the mandibular condyle has been developed with modifications. The purpose of this article is to describe the intraoral technique with the Kirschner wire on mandibular subcondylar fractures. Conclusion : The intraoral reduction with Kirschner wire on mandubular subcondylar fractures avoids the facial scar and facial nerve injury and is simple method to the extraoral approach. And it has minimal morbidity and better esthetics.

• Journal of Periodontal and Implant Science
• /
• v.50 no.2
• /
• pp.97-105
• /
• 2020

Purpose: The present retrospective clinical study aimed to evaluate and compare the clinical and radiographic parameters, complications, and satisfaction in patients who received fixed prostheses supported by narrow-diameter implants (NDIs) in the anterior and posterior jaw. Methods: Patients aged ≥30 years who had NDI-supported fixed prostheses in the anterior or posterior region of either jaw for at least 2 years were included. Complications such as chipping of the crown; loosening or fracture of the screw, crown abutment, or implant; and loss of retention were recorded. Clinical peri-implant outcomes and crestal bone loss (CBL) were measured. A questionnaire was used to record responses regarding the aesthetics and function of the fixed restorations. Analysis of variance was used to assess the significance of between-group mean comparisons. The log-rank test was performed to analyze the influence of location and prosthesis type on technical complications. Results: Seventy-one patients (mean age: 39.6 years) provided informed consent with a mean follow-up duration of 53 months. Only bleeding on probing showed a statistically significant difference between NDIs in the anterior and posterior regions. The complication rate for NDIs in the posterior region was significantly higher than that for NDIs in the anterior region (P=0.041). For NDIs, CBL was significantly higher around splinted crowns than single crowns (P=0.022). Overall mean patient satisfaction was 10.34±3.65 on a visual analogue scale. Conclusions: NDIs in the anterior and posterior jaws functioned equally well in terms of periimplant soft and hard tissue health and offered acceptable patient satisfaction and reasonable complication rates.

• Journal of Korean Neurosurgical Society
• /
• v.60 no.2
• /
• pp.174-180
• /
• 2017

Objective : Proximal junctional kyphosis (PJK) is radiologic finding, and is defined as kyphosis of >$10^{\circ}$ at the proximal end of a construct. The aim of this study is to identify factors associated with PJK after segmental spinal instrumented fusion in adults with spinal deformity with a minimum follow-up of 2 years. Methods : A total of 49 cases of adult spinal deformity treated by segmental spinal instrumented fusion at two university hospitals from 2004 to 2011 were enrolled in this study. All enrolled cases included at least 4 or more levels from L5 or the sacral level. The patients were divided into two groups based on the presence of PJK during follow-up, and these two groups were compared to identify factors related to PJK. Results : PJK was observed in 16 of the 49 cases. Age, sex and mean follow-up duration were not statistically different between two groups. However, mean bone marrow density (BMD) and mean back muscle volume at the T10 to L2 level was significantly lower in the PJK group. Preoperatively, the distance between the C7 plumb line and uppermost instrumented vertebra (UIV) were no different in the two groups, but at final follow-up a significant intergroup difference was observed. Interestingly, spinal instrumentation factors, such as, receipt of a revision operation, the use of a cross-link, and screw fracture were no different in the two groups at final follow-up. Conclusion : Preoperative BMD, sagittal imbalance at UIV, and thoracolumbar muscle volume were found to be strongly associated with the presence of PJK.

• Journal of Korean Foot and Ankle Society
• /
• v.10 no.2
• /
• pp.201-206
• /
• 2006

Purpose: To evaluate the advantages of the antiglide plate fixation procedure for Danis-Weber type B lateral malleolar fractures of ankle compared to other methods of lateral plate fixation. Materials and Methods: We reviewed 70 cases that antiglide plate fixation and lateral plate fixation procedures were performed from Mar. 2001 through Mar. 2006. Of the total 70 cases, they were divided into two groups ; 22 cases were treated with the antiglide plate procedure (Group I) and 48 cases were treated with the lateral plate procedure (Group II). The results of the two groups were analyzed both radiographically and clinically using Ankle-Hindfoot scale of the American Orthopedic Foot and Ankle Society (AOFAS). Results: All fractures were healed at average of 8 weeks both radiographically and clinically. According to the Ankle-Hindfoot scale, all cases of Group I and 48 cases of Group II were above 80 points. 2 cases (9%) in Group I complained of peroneal tendinitis, while 19 cases (39%) in Group II showed skin irritation resulting from the screw or the plate. A total of 6 cases (27%) in Group I and 27 cases (55%) in Group II complained cosmetic problems. Conclusion: we concluded that the antiglide plate fixation for Danis-Weber type B lateral malleolar fractures is one of the good methods. But, further analysis will be need to find a solution for the peroneal tendinitis.