• Maxillofacial Plastic and Reconstructive Surgery
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• 제33권4호
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• pp.352-358
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• 2011

Purpose: This study evaluated the prognosis and survival rate of SLA (Sandblasted, Large-grit and Acid-etched) implants and it also evaluated the prosthodontic complications and the associated factors. Methods: Twenty seven patients (14 men and 13 women, mean age: 54.9) who visited Chosun University Hospital Implant Center with the chief desire for placement of an implant in an edentulous area from March, 2008 to December 2008 and who received placement of a SLA implant ($Implantium^{(R)}$, Dentium Co., Korea) were selected for this study. Results: The average follow-up period was 15 months and the study was based on the treatment records, radiographs and clinical examinations. A total of 69 implant cases were retrospectively assessed for the width and length of the implant, the primary and secondary stability, the combined surgery, the employed bone graft material and barrier membrane, the status of the opposing tooth, implant failure and the prosthetic complications. During the follow-up period (average: 15 months), the accumulative survival rate of the 69 implants in 27 patients was 100%. Complications such as infection, sinusitis and fixture exposure after surgery were seen for 5 implants in 4 patients. Complications such as screw loosening, contact loosening and peri-implant gingivitis after prosthodontic treatment occurred in 7 cases (10.14%). Conclusion: This study reports placement of SLA implants may cause various complications, yet the final accumulative survival rate was 100%. The SLA implant ($Implantium^{(R)}$) has an excellent clinical survival rate and outcome.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제32권3호
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• pp.207-217
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• 2010

The purpose of this study was to evaluate the effects of the stress distribution and displacement in mandible according to treatment modalities of mandibular angle fractures, using a three dimensional finite element analysis. A mechanical model of an edentulous mandible was generated from 3D scan. A 100-N axial load and four masticatory muscular supporting system were applied to this model. According to the number, location and materials of titanium and biodegradable polymer plates, the experimental groups were divided into five types. Type I had a single titanium plate in the superior border of mandibular angle, type II had two titanium plates in the superior tension border and in the inferior compression border of mandibular angle, type III had a single titanium plate in the ventral area of mandibular angle, type IV had a single biodegradable polymer plate in the superior border of mandibular angle, type V had a single biodegradable polymer plate in the ventral area of mandibular angle. The results obtained from this study were follows: 1. Stress was concentrated on the condylar neck of the fractured side except Type III. 2. The values of von-Mises stress of the screws were the highest in the just-posterior screw of the fracture line, and in the just-anterior screw of Type III. 3. The displacement of mandible in Type III was 0.04 mm, and in Type I, II, IV, and V were 0.10 mm. 4. The plates were the most stable in the ventral area of mandibular angle (Type III, V). In conclusion, the ventral area of mandibular angle is the most stable location in the fixation of mandibular angle fractures, and the just- posterior and/or the just-anterior screws of the fracture line must be longer than the other, and surgeons have to fix accurately these screws, and the biodegradable polymer plate also was suitable for the treatment of mandible angle fracture.

• The korean journal of orthodontics
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• 제28권3호
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• pp.453-459
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• 1998

The dental implants for edentulous Patients have been used for more than 20 years. After the introduction of osseointegration by $Br{\aa}nemark$, the commercially pure titanium implants were accepted by most practitioners. Recently dental implants are used for orthodontic anchorages as well as prosthetic abutment. Many researchers have reported implants as a good orthodontic anchorage through basic research and clinical evaluation. But previous researches were done after the healing time for osseointegration of inserted implants. If dental implants are to be used for prosthetic abutment the healing time for osseointegration is necessary, but orthodontic forces to implants are different from bite force regarding its amount of force, duration and direction. The authors evaluated the effect of orthopedic force to implants on bone tissue before osseointegration. 48 implants were placed at 12 rabbits. 2 implants into left side and 2 implants into right side were inserted along the long axis of femur respectively 2 weeks (2 weeks group), 4 weeks (4 weeks group) and 6 weeks (6 weeks group) after implants placement, 300g force had been applied to the implants at left side femur by Ni-Ti close coil spring for 4 weeks (experimental group) and no force applied to implants at right side femur (control group). After the force application for 4weeks, rabbits were sacrificed and microscopic evaluation was done by hematoxylin-eosin stain and Masson trichrome stain. The result3 were followed. 1. All implants in experimental group remained rigid after the force application for 4 weeks. 2. More fibrous tissue between bone and implants were noticed at 2 weeks experimental group than 2 weeks control group 3. More bone remodeling was noticed at 4weeks group than 2 weeks group and it was difficult to find out fibrous tissue between bone and implants at both experimental and control group of 4 weeks group. 4. It was hard to distinguish experimental group from control group at 6 weeks group. Therefore if initial stability can be obtained on implant insertion, it can be possible to use implants as a orthodontic anchorage before the healing time for osseointegration.

• Journal of Dental Rehabilitation and Applied Science
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• 제27권4호
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• pp.393-403
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• 2011

The purpose of this study was to analyze and compare survival rates of resorbable blast media(RBM) surface and acid-etched surface implants being usually used in clinics. RBM surface implants (USII, Osstem, Busan, Korea) or acid-etched surface implants ($Osseotite^{(R)}$, Biomet $3i^{[TM]}$, FL, USA) were placed in edentulous area of 140 patients between January of 2005 and March of 2007. The number of implants was 304, and 152 out of them were RBM surface implants while another 152 were acid-etched surface implants. According to the evaluation items, the survey was performed before and after the implants installations. The 3-year survival rates of both kind of implants were calculated. 1. Total of 152 RBM surface implants were placed. Among them, one implant was failed, which was implanted in the posterior mandible with D2 bone quality. The failure was resulted from fracture of the fixture. Others showed good results and survival rate of RBM surface implant was 99.34%. 2. Total of 152 acid-etched surface implants were placed. Seven implants of them were failed, thus, survival rate was 95.39%. The causes of the failures were considered as infection, overheat and the lack of initial stability. In this research, both implants showed good 3-year survival rate, although RMB surface implant represented a better result.

• Journal of Dental Rehabilitation and Applied Science
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• 제27권4호
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• pp.437-447
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• 2011

In patients who used removable partial dentures for a long period of time, gradual alveolar bone resorption occurs in edentulous area. However, in residual teeth area, alveolar bone is maintained sound. This causes an imbalance in intermaxillary distance between a maxillae and a mandible which is intensified due to expansion in vertical and horizontal bone amount difference between the two area as time passes. As the result, this shows a substantial difference in vertical position according to the period of teeth loss even after residual teeth loss. As in this situation, a patient with bilaterally and anterio-posteriorly different intermaxillary distance, various prosthodontic problems can be caused in fixed implant prosthodontics and implant overdenture. This study shows a case in which implant-supported removable partial denture was fabricated considering residual alveolar bone height after teeth loss in a patient who had been using a distal extension removable partial denture for a long period of time. In anterior area with short intermaxillary distance, fixed prosthodontics were fabricated with implant placement and in posterior area with long intermaxillary distance, a removable partial denture was fabricated. Finally, a small number of implants were placed without additional surgery and economical and comfortable treatment results were shown.

• Journal of Dental Rehabilitation and Applied Science
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• 제26권1호
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• pp.59-68
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• 2010

Recently, dental implants extensively inserted on edentulous area show highly clinical success rate. However, clinicians cannot exclude the possibility of failure and it often unexpectively occures. Many possible factors associated with failure of dental implants have been reported but controversy exists over the extent to them. In this study, we collected 212 patients who had been inserted 358 dental implants on mandibular premolar and molar area from 2005 to 2006. The survival rate of fixtures was recorded according to age of patients, implantation site, implant system, diameter and length of fixtures. Multi-variable analysis using SPSS chi-square test was operated to verify relation of each factors and survival rates. Accumulative survival rate was 98.3% for 3 years. Only diameter of fixtures was related to the implant survival rate. This may be thought that wider fixtures had been chosen to rescue implants or used in sites of poor bone quality. Further continuous study will be needed for direct guidance associated with survival rate of implants.

• Journal of Dental Rehabilitation and Applied Science
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• 제33권3호
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• pp.189-198
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• 2017

Purpose: This study aims to analyze the stress distribution of mandibular molar restoration supported by the implants with external hex and internal taper abutment connection design. Materials and Methods: Models of external connection (EXHEX) and internal connection (INCON) implants, corresponding abutment/crowns, and screws were developed. Supporting edentulous mandibular bony structures were designed. All the components were assembled and a finite element analysis was performed to predict the magnitude and pattern of stresses generated by occlusal loading. A total of 120 N static force was applied both by axial (L1) and oblique (L2) direction. Results: Peak von Mises stresses produced in the implants by L2 load produced 6 - 15 times greater than those by L1 load. The INCON model showed 2.2 times greater total amount of crown cusp deflection than the EXHEX model. Fastening screw in EXHEX model and upside margin of implant fixture in INCON model generated the peak von Mises stresses by oblique occlusal force. EXHEX model and INCON model showed the similar opening gap between abutment and fixture, but intimate sealing inside the contact interface was maintained in INCON model. Conclusion: Oblique force produced grater magnitudes of deflection and stress than those by axial force. The maximum stress area at the implant was different between the INCON and EXHEX models.

• The Journal of Korean Academy of Prosthodontics
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• 제42권4호
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• pp.425-442
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• 2004

Statement of problem: A difficulty in achieving a passive-fitting prosthesis can be overcome by individual crown restoation of multiple implants. But individualized crown has another difficulty in control of contact tightness and stress distribution. Purpose: This in vitro study is to evaluate the stress distribution and the magnitude in the supporting tissues around Endopore implants with different crown lengths, interproximal contact tightness, and the splinting effects. Material & methods: Three Endopore implants($4.1{\times}9mm$) were placed in the mandibular posterior edentulous area distal to the canine and photoelastic model was made with PL-2 resin(Measurements Group, Raleigh, USA). Restorations were fabricated in two crown lengths: 9, 13 mm. For non-splinted restorations, individual crowns were fabricated on three custom-milled titanium abutments. After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal($8{\mu}m$ shim stock drags without tearing), medium($40{\mu}m$), and heavy($80{\mu}m$). For splinted restorations, 3-unit fixed partial dentures were fabricated. This study was examined under simulated non-loaded and loaded conditions(6.8 kg). Photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure. Results: 1. When restorations were not splinted, the more interproximal contact tightness was increased among the three implants, the more stress was shown in the cervical region of each implant. When crown length was increased, stresses tended to increase in the apex of implants but there were little differences in stress fringes. 2. When nonsplinted restorations were loaded on the first or third implant, stresses were increased in the apex and cervical region of loaded implant. Regardless of interproximal contact tightness level, stresses were not distributed among the three implants. But with tighter interproximal contact, stresses were increased in the cervical region of loaded first or third implant. 3. When the nonsplinted restorations were not loaded, there were little stresses on the supporting structure of implants, but low level stresses were shown in the splinted restorations even after sectioning and soldering. 4. With splinted restorations, there were little differences in stresses between different crown lengths. When splinted restorations were loaded, stresses were increased slightly on the loaded implant, but relatively even stress distribution occurred among the three implants. Conclusions: Splinting the crowns of adjacent implants is recommended for Endopore implants under the overloading situation.

• The Journal of Korean Academy of Prosthodontics
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• 제42권4호
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• pp.397-411
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• 2004

Purpose: The purpose of this study was to determine the effect of anchorage systems and palatal coverage of denture base on load transfer in maxillary implant-supported overdenture. Material and methods: Maxillary implant -supported overdentures in which 4 implants were placed in the anterior region of edentulous maxilla were fabricated, and stress distribution patterns in implant supporting bone in the case of unilateral vertical loading on maxillary right first molar were compared with each other depending on various types of anchorage system and palatal coverage extent of denture base using three-dimensional photoelastic stress analysis. Two photoelastic overdenture models were fabricated in each anchorage system to compare with the palatal coverage extent of denture base, as a result we got eight models : Hader bar using clips(type 1), cantilevered Hader bar using clips(type 2), Hader bar using clip and ERA attachments(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4). Result: 1. In all experimental models, the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. In every experimental models with or without palatal coverage of denture base, maximum fringe orders on the distal ipsilateral implant supporting bone in an ascending order is as follows; type 3, type 1, type 4, and type 2. 3. Each implants showed compressive stresses in all experimental models with palatal coverage of denture base, but in the case of those without palatal coverage of denture base, tensile stresses were observed in the distal contralateral implant supporting bone. 4. In all anchorage system without palatal coverage of denture base, higher stresses were concentrated on the most distal implant supporting bone on loaded side. 5. The type of anchorage system affected in load transfer more than palatal coverage extent of the denture base. Conclusion: To the results mentioned above, in the case of patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant, and poor bone quality, selecting a resilient type attachment or minimizing the distal cantilevered bar is considered to be an appropriate method to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.

• Journal of Periodontal and Implant Science
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• 제34권1호
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• pp.101-112
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• 2004

Osseointegrated implnats have proven to be successful in both full and partial edentulous patients since the 1960s and recently have shown successful results when used to restore single tooth missing. However, in most studies reporting the success of single implants, single implants replacing anterior teeth are more frequently mentioned than posterior single implants. Moreover, in studies regarding posterior single implants, the replaced region seemed to be variable; the maxilla, mandible and areas from the first premolar to the second molar were mentioned. However, considering the difference in bone quality in the mandible and maxilla, and the increased occlusal force in the posterior region, the success rates in each region may be different. In this study, the cumulative success rates and amount of bone loss of single implants replacing the mandibular first and second molar, respectively, were compared and analyzed to come to the following conclusion. 1. The 20 (20 persons) single implants that were placed in the mandibular first molar region were all successful and showed a 100% 5 year cumulative success rate. Among the 27 (24 persons) single implants replacing the mandibular second molar, 8 failed (27.63%) showing a 5 year cumulative success rate of 70.37%. 2. Among the 8 failed implants, one showed symptoms of postoperative infection and one complained of parenthesia. 6 implants failed after functional loading; 5 showed mobility and one resulted in fixture fracture. 3. After the attachment of the prosthesis, there was no significant statistical difference regarding the marginal bone loss in group 1 and group 2 during the checkup period (P>0.05). In conclusion, restoration of the mandibular first molar using single implants was found to be an excellent treatment modality, and when replacing mandibular second molars with single implants, poor bone quality and risk of overloading must be considered.