• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.102-106
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• 2009

STATEMENT OF PROBLEM. Screw loosening has been a common complication and still reported frequently. PURPOSE. The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS. Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated poly-esther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS. TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION. Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.

• Journal of Korean Society for Quality Management
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• v.36 no.2
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• pp.59-66
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• 2008

Dental implant has recently become one of the most viable treatment options for regaining the oral function and dental aesthetics compared with conventional fixed or removable dentures. Dental implants vary in material, dimensions, geometries, surface properties, and interface geometries. It has been reported that there has been a proliferation of manufacturers who produce implants using various materials and surface treatments, and the dentist needs to select from over 2,000 different dental implants and abutments in a specific treatment situation. Unfortunately, however, no metrics have been specifically identified for the purpose of quality assessment and selection of an appropriate dental implant. This study aims to provide practical guidelines for quality assessment of dental implant based on clinical data. Like other medical devices and materials, the superiority related to specific characteristics of the dental implant needs to be verified through extensive clinical studies. The procedures of clinical monitoring for dental implants have been proposed along with a case study to exemplify the usefulness of clinical monitoring for the purpose of continuous quality improvement in medical industry.

• Journal of Korean Dental Science
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• v.2 no.2
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• pp.31-34
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• 2009

The survival rate of the OSSTEM GS II Implant 1 year after serving the prosthetic function in 2 domestic and foreign medical institutes was 97.57%; the success rate was 95.7%, and the average alveolar bone resorption was 0.24mm(n=389). In particular, the alveolar bone resorption occurred differently according to the placement location as well as whether or not the patient underwent bone grafting operation, but the implant s length and diameter did not have significant impact on alveolar bone resorption.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.258-265
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• 2008

Purpose. This multicenter retrospective study was performed to evaluate the survival and success rates of immediate placement of USII and SSII Osstem implant (Osstem implant Co, Korea) on the maxillary and mandibular anterior and premolar areas. Materials and methods. Dental records were obtained in 37 patients who were treated with immediate implantation on the maxillary and mandibular anterior and premolar areas in 6 different clinics. The 98 implants were evaluated both clinically and radiographically using predefined success criteria. Results. There was no failed implant in all patients. The mean follow up period was 24.7 months (ranged from 12 to 58 months), and 25.1 months (ranged from 16 to 35 months) in USII and SSII implants, respectively. The crestal bone loss was 3 mm in 3 USII implants during 41 months, and in 1 SSII implant during 22 months. The overall success rate was 94.2% and 97.7% in USII and SSII implants, respectively. The age, gender, diameter, or length of implants, and type of surgery were not influenced to the success rate of immediate implantation. Conclusion. These results suggest that USII and SSII Osstem implant can be used successfully in immediate implantation on the maxillary and mandibular anterior and premolar areas.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.3
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• pp.325-340
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• 2008

The purpose of this study was to evaluate the artificial dental plaque by Streptococcus mutans on 4 different implant surfaces. In this study, the specimens were divided into 4 groups according to implant surface treatment. Uncoated implant group(n=5) which has an uncoated, smooth surfaced implant(Osstem, Korea), SLA implant group(n=5) which has an sandblasted large grit and acid-etched surface implant(Bicon, USA). Oxidized implant group(n=5) which has an oxidized surfaced implant (Osstem, Korea), and RBM implant group(n=5) which has resorbable blasting media(RBM) surfaced implant(Osstem, Korea). Acquired pellicle by human saliva and dental plaque by Streptococcus mutans were made on each implant surface. To analyze the plaque condition on implants surfaces, cell count and optical density were taken as a microbiologic method, and SEM(Scanning Electronic Microscope) findings was also taken for evaluation of surface condition. The following results were obtained. 1. Cell counting results of artificial dental plaque were Uncoated group($658.0{\pm}102.0$), RBM group($878.0{\pm}170.0$), SLA group ($946.0{\pm}42.0$), Oxidized group($992.0{\pm}40.0$), and there was difference between Oxidized group and Uncoated implant group(p<0.05). In case of modified cell counting results by v/w% were RBM group($197.8{\pm}45.2$), Oxidized group($207.04{\pm}8.34$), Uncoated group($261.6{\pm}40.6$), SLA group($315.4{\pm}14.0$), and there was difference between RBM group and SLA group(p<0.05). 2. Optical density results of artificial dental plaque after ultrasonic treatment was that there was difference among groups, and optical density of RBM group was higher than that of Uncoated group(p<0.05). In case of modified optical density results by v/w%, there was difference among groups, and the modified optical density of Uncoated group and SLA group was higher than those of Oxidized group and RBM group(P>0.05). 3. SEM findings of artificial dental plaque on the surfaces of implant as follows; there were artificial dental plaque on the surfaces of all test implants. Streptococcus mutans and by-product were observed at 10,000 times magnified condition on all test implants. Adhesion area of artificial dental plaque was about 1/2 of total surface after 24 hours incubate at $37^{\circ}C$. These results showed that there were differences among implant surfaces on the growth of Streptococcus mutans, and bacteria and by-product were covered about 1/2 area of total implant surfaces at 24 hours incubate at $37^{\circ}C$.

• Journal of Korean Dental Science
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• v.2 no.2
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• pp.35-41
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• 2009

Objective : This study sought to investigate the clinical survival rate of two implants with different surfaces: resorbable blasting media (RBM)-treated and calcium metaphosphate (CMP)-coated implant. Study design : SSII non-submerged implants (Osstem, Seoul, Korea) were placed in a total of 48 patients with mean age of 38.8. At least 31 patients in the experimental group had a CMP-coated implant, and 1 patient in the control group received a, RBM surface implant. The evaluation period was between April 2006 and December 2007. Radiographs, periotest, clinical periodontal examination, and prosthetic adjustment and occlusion were used. Results : The survival rate of the experimental and control groups after 1 year was 97.2% and 100%, respectively. The Wald confidence interval reported for the experimental group was not inferior to the control group. Conclusion : No significant differences were found between the RBM and CMP groups. The observed data suggest that CMP-coated methods can provide favorable clinical results for the functioning and healing of dental implants.

• The Journal of the Korean dental association
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• v.50 no.12
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• pp.743-754
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• 2012

urpose : The purpose of this study was to evaluate the US II plus/GS II Osstem$^{(R)}$ implants through the study for the clinical success rate during the installation of the Osstem¢Á implants after bone graft. Materials and Methods : This study was researched in the 4 medical institutions: Chonnam National University, Chosun University, Bundang Seoul National University Hospital, and FM dental clinic from May, 2002 to September, 2009. Based on the total number of 60 patients whose treatment was the installation of the US II plus/GS II Osstem¢Á implants after bone graft, we evaluated success rate of implants. We analysis the distribution of patient's age and gender, edentulous area, bone type, fixture length and diameter, installation and loading time, donor site, bone graft material and method, antagonistic teeth, and survival and success rate. From these analyses we got the following results. Results : 1. In this study, the total number of patients who have been installed with US II plus implant was 27, and total of 52 implants were installed. The average age was 38.9, with 16 male, and 11 female patients. 2. The total number of patients who have been installed with GS II implant was 33, and total of 54 implants were installed. The average age was 49.7, with 24 male, and 9 female patients. 3. As for bone graft method, either autogenous bone or a mix of autogenous and heterogenous bone was used(88.4%) for US II plus. Chin, iliac, and Maxillary tuberosity were the donor sites for autogenous bone graft, and onlay method of bone graft was performed. 4. Allogenic bone or a mix of autogenous and heterogenous bone was used(77.8%) for GS II. Chin, ramus, and tibia were the donor sites for autogenous bone graft, and GBR method of bone graft was performed. 5. The duration from the installation of implants to setting of final prosthesis was average of 16 months and 10 months for US II plus and GS II respectively. Also, the final follow up period was average of 31 months and 28 months respectively. During this period, one GS II implant was removed from 1 patient due to failure of early osteointegration. 6. The survival rates were 100% and 98.1%, and success rates were 94.2% and 94.4% for US II plus and GS II implant respectively. Conclusion : On the evaluation of our clinical study, both US II plus and GS II Osstem¢Á implants showed the excellent clinical results after bone graft.

• Journal of Periodontal and Implant Science
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• v.43 no.1
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• pp.41-46
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• 2013

Purpose: The objective of this study was to evaluate the effect of microthreads on removal torque and bone-to-implant contact (BIC). Methods: Twelve miniature pigs for each experiment, a total of 24 animals, were used. In the removal torque analysis, each animal received 2 types of implants in each tibia, which were treated with sandblasting and acid etching but with or without microthreads at the marginal portion. The animals were sacrificed after 4, 8, or 12 weeks of healing. Each subgroup consisted of 4 animals, and the tibias were extracted and removal torque was measured. In the BIC analysis, each animal received 3 types of implants. Two types of implants were used for the removal torque test and another type of implant served as the control. The BIC experiment was conducted in the mandible of the animals. The $P_1-M_1$ teeth were extracted, and after a 4-month healing period, 3 each of the 2 types of implants were placed, with one type on each side of the mandible, for a total of 6 implants per animal. The animals were sacrificed after a 2-, 4-, or 8-week healing period. Each subgroup consisted of 4 animals. The mandibles were extracted, specimens were processed, and BIC was analyzed. Results: No significant difference in removal torque value or BIC was found between implants with and without microthreads. The removal torque value increased between 4 and 8 weeks of healing for both types of implants, but there was no significant difference between 8 and 12 weeks. The percentage of BIC increased between 2 and 4 weeks for all types of implants, but there was no significant difference between 4 and 8 weeks. Conclusions: The existence of microthreads was not a significant factor in mechanical and histological stability.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.365-375
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• 2009

Statement of problems: Stress analysis on implant components of the combined screw- and cement-retained implant prosthesis has not investigated yet. Purpose: The purpose of this study was to assess the load distribution characteristics of implant prostheses with the different prosthodontic retention types, such as cement-type, screw-type and combined type by using 3-dimensional finite element analysis. Material and methods: A 3-dimensional finite element model was created in which two SS II implants (Osstem Co. Ltd.) were placed in the areas of the first premolar and the first molar in the mandible, and three-unit fixed partial dentures with four different retention types were fabricated on the two SS II implants. Model 1 was a cement-retained implant restoration made on two cement-retained type abutments (Comocta abutment; Osstem Co. Ltd.), and Model 2 was a screw-retained implant restoration made on the screw-retained type abutments (Octa abutment; Osstem Co. Ltd.). Model 3 was a combined type implant restoration made on the cement-retained type abutment (Comocta abutment) for the first molar and the screw-retained type abutment (Octa abutment) for the first premolar. Lastly, Model 4 was a combined type implant restoration made on the screw-retained type abutment (Octa abutment) for the first molar and the cement-retained type abutment (Comocta abutment) for the first premolar. Average masticatory force was applied on the central fossa in a vertical direction, and on the buccal cusp in a vertical and oblique direction for each model. Von-Mises stress patterns on alveolar bone, implant body, abutment, abutment screw, and prosthetic screw around implant prostheses were evaluated through 3-dimensional finite element analysis. Results: Model 2 showed the lowest von Mises stress. In all models, the von Mises stress distribution of cortical bone, cancellous bone and implant body showed the similar pattern. Regardless of loading conditions and type of abutment system, the stress of bone was concentrated on the cortical bone. The von-Mises stress on abutment, abutment screw, and prosthetic screw showed the lower values for the screw-retained type abutment than for the cement-retained type abutment regardless of the model type. There was little reciprocal effect of the abutment system between the molar and the premolar position. For all models, buccal cusp oblique loading caused the largest stress, followed by buccal cusp vertical loading and center vertical loading. Conclusion: Within the limitation of the FEA study, the combined type implant prosthesis did not demonstrate more stress around implant components than the cement type implant prosthesis. Under the assumption of ideal passive fit, the screw-type implant prosthesis showed the east stress around implant components.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.491-497
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• 2014

PURPOSE. This study evaluated the influence of abutment materials on the stability of the implant-abutment joint in internal conical connection type implant systems. MATERIALS AND METHODS. Internal conical connection type implants, cement-retained abutments, and tungsten carbide-coated abutment screws were used. The abutments were fabricated with commercially pure grade 3 titanium (group T3), commercially pure grade 4 titanium (group T4), or Ti-6Al-4V (group TA) (n=5, each). In order to assess the amount of settlement after abutment fixation, a 30-Ncm tightening torque was applied, then the change in length before and after tightening the abutment screw was measured, and the preload exerted was recorded. The compressive bending strength was measured under the ISO14801 conditions. In order to determine whether there were significant changes in settlement, preload, and compressive bending strength before and after abutment fixation depending on abutment materials, one-way ANOVA and Tukey's HSD post-hoc test was performed. RESULTS. Group TA exhibited the smallest mean change in the combined length of the implant and abutment before and after fixation, and no difference was observed between groups T3 and T4 (P>.05). Group TA exhibited the highest preload and compressive bending strength values, followed by T4, then T3 (P<.001). CONCLUSION. The abutment material can influence the stability of the interface in internal conical connection type implant systems. The strength of the abutment material was inversely correlated with settlement, and positively correlated with compressive bending strength. Preload was inversely proportional to the frictional coefficient of the abutment material.