• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.356-359
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• 1999

To obtain a biomaterial that has both biological affinity and high mechanical strength, hydroxyapatite granules were implanted into the surface of pure titanium film coated titanium alloy. The film was coated by reactive DC sputtering method on the alloy substrate. Hydroxyapatite granules (32- $38\mu\textrm{m}$ in diameter)were spread over titanium alloy substrate and pressed to implant the granules in the substrate. They can be implanted into substrate under 17MPa at $800^{\circ}C$ for 10minutes. The only tops of the granules were exposed and they were firmly stuck in substrate. The hydroxyapatite implanted titanium alloy composites were expected to be useful for biomaterials as artificial bones and dental roots.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.400-410
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• 1993

Dental implants have been widely used in the treatment of esthetic and functional problems of the mouth due to alveolar bone loss, after tooth extraction. The success of implantation strongly depends on osseointegration. For osseointegration, implant material, methodology, and design have been investigated. For materials, two popular materials at present are titanium and hydroxyapatite. For methods, immediate implantation is being used recently. The purpose of this study is to evaluate osseointegration between the unthreaded cylindrical TPS implant and the HA-coated implant by a histomorphometric analysis. For this analysis, experimental periodontits was induced on the 3, 4 premolars of adult dogs by the ligation of orthodontic threads. Thereafter, each tooth was extracted. TPS. Implants and HA-coated implants were immediately inserted in the extraction socket. In control group, TPS implants were immediately inserted, and In experimental group, HA implants were immediately inserted. The dogs were sacrificed after 12 weeks, then the specimens were prepared for LM and histomorphometric analysis. The conclusion of this study is as follows l. In both control and experimental group, no inflammatory cells were observed. 2. The results of the histomorphometric analysis showed that the total osseointegration was 48.5% in control group, and 68.8% in expermental group. The experimental group was higher than the control group, and the difference was not statistically significant (p<0.05). 3. The results of the histomorphometric analysis showed that the osseointegration in the hole was 40.6% in control group, and 70.2% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). In both control and experinental group, no inflammatory cells were observed. 4. The results of the histomorphometric analysis showed that the osseointegration in the lower part was 52.1% in control group, and 73.3% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). 5. In experimental group, the bone to HA interface seemed to be mixed of bone and HA. We could not distinguish HA from the bone. The HA coating was detached from the titanium surface.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.41-57
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• 2001

It is well known that the apposition of bone at implant surface would be influenced by the microstructure of titanium implants. The purpose of this study was to compare bone healing around the screw-shaped titanium implant with three different surface topographies in the canine mandibles by histological and biomechanical evaluation. All mandibular premolars of six mongrel dogs were extracted and implants were placed one month later. The pure titanium implants had different surface topographies: smooth and machined ($Steri-OSS^{(R)}$: Group II); sandblasted and acid-etched ($ITI^{(R)}$, SLA: Group III) surface. The fluorescent dyes were injected on the 2nd (calcein), 4th (oxytetracycline HCI) and 12th (alizarin red) weeks of healing. Dogs were sacrificed at 4 and 12 weeks after implantation. The decalcified and undecalcified specimens were prepared for histological and histo-metrical evaluation of implant-bone contact. Some specimens at 12 weeks after implantation were used for removal torque testing. Histologically, direct bone apposition to implant surface was found in all of the treated groups. More mature and dense bone was observed at the implant-bone interface at 12 weeks than that at 4 weeks after implantation. Under the fluorescent microscope, thick regular green fluorescent lines which mean early bone apposition were observed at the implant-bone interface in Group III, while yellow and red fluorescent areas were found at the implant-bone interface in Group I and II. The average implant-bone contact ratios at 4 weeks of healing were 54.3% in Group I, 57.7% in Group II and 66.2% in Group III. In Group I, implant-bone contact ratio was significantly lower than Group II and III(p<0.05). The average implant-to-bone contact ratios at 12 weeks after implantation were 64.3% in Group I, 66.7% in Group II and 71.2% in Group III. There was no significant difference among the three groups. In Group I and II, the implant-bone contact ratio at 12 weeks increased significantly in comparison to ratio at 4 weeks(p<0.05). The removal torque values at 12 weeks after implantation were 90.9 Ncm in Group I, 81.6 Ncm in Group II and 77.1 Ncm in Group III, which were significantly different(p<0.05). These results suggest that bone healing begin earlier and be better around the surface-treated implants compared to the smooth surface implants. The sandblasted and acid-etched implants showed the most favorable bone response among the three groups during the early healing stage and could reduce the waiting period prior to implant loading.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.821-836
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• 2000

The Peri-implantitis causes inflammation of periodontal tissue and bone loss. It contaminates surface of implants. Therefore, guided bone regeneration has been used for the treatment of this disease. For the reosseointegration of the exposed surface, various mechanical and chemical methods have been used for cleaning and detoxication of implant surface. Among these methods, air-powder abrasive and oversaturated citrate are known to be most effective. However, these treatments may deform implant surface. In this research, changes of surface roughness they were examined. 10 experimental machined titanium cylinder models were fabricated to be used for control groups. Each of them was air powder abraded for 1 minute and they were named group 1. And then, group 1 were burnished with cotton pellets soaked with citrate for 30 seconds(Group 2), 1 minute(Group 3), 3 minutes(Group 4), and 5 minutes(Group 5) burnishing were applied for grouping respectively. Each group were examined with SPM, and their surface roughness were measured and analyzed. 1. Surface roughness of titanium decreased when it was air-powder abraded for 1 minute. It was statistically significant. 2. When Air-powder abraded titanium were treated with citrate for 3 minutes, Their surface roughness was the lowest. Titanium treated for 1 minute was the second lowest and 30 seconds was the third and titanium burnished for 5 minutes was the highest. 3. Surface roughness of titanium which was treated with citrate was decreased till 3 minutes, which was statistically significant. There was no statistical significance from 30 seconds to 1 minute and from 1 minute to 3 minutes, and there was statistical significance from 30 seconds to 3 minutes. 4. Oxide layer was formed when titanium is exposed to air, and it was removed when air-powder abraded. It was made when treated with citrate. It is thought that citrate treatment is necessary after the air-powder abrasion, and 1 minute is clinically and qualitatively adequate for burnishing time of citrate.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.193-204
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• 2019

Purpose: The reaction of cells to a titanium implant depends on the surface characteristics of the implant which are affected by decontamination. The aim of this study was to evaluate the cytocompatibility of titanium disks treated with various decontamination methods, using salivary bacterial contamination with dental pellicle formation as an in vitro model. Methods: Sand-blasted and acid-etched (SA) titanium disks were used. Three control groups (pristine SA disks [SA group]; salivary pellicle-coated SA disks [pellicle group]; and biofilm-coated, untreated SA disks [NT group]) were not subjected to any decontamination treatments. Decontamination of the biofilm-coated disks was performed by 14 methods, including ultrasonic instruments, rotating instruments, an air-powder abrasive system, a laser, and chemical agents. MG63 cells were cultured in the presence of the treated disks. Cell proliferation assays were performed on days 2 and 5 of cell culture, and cell morphology was analyzed by immunofluorescence and scanning electron microscopy (SEM). A vascular endothelial growth factor (VEGF) assay was performed on day 5 of culture. Results: The cell proliferation assay revealed that all decontaminated disks, except for the 2 groups treated using a plastic tip, showed significantly less cell proliferation than the SA group. The immunofluorescence and SEM analyses revealed that most groups showed comparable cell density, with the exception of the NT group, in which the cell density was lower and bacterial residue was observed. Furthermore, the cells grown with tetracycline-treated titanium disks showed significantly lower VEGF production than those in the SA group. Conclusions: None of the decontamination methods resulted in cytocompatibility similar to that of pristine SA titanium. However, many methods caused improvement in the biocompatibility of the titanium disks in comparison with the biofilm-coated, untreated titanium disks. This suggests that decontamination is indispensable for the treatment of peri-implantitis, even if the original biocompatibility cannot be restored.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.246-254
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• 2008

STATEMENT OF PROBLEM: The cast abutment has advantages of overcoming angulation problem and esthetic problem. However, when a gold-machined UCLA abutment undergoes casting, the abutment surfaces in contact with the implant may change. PURPOSE: The purpose of this study was to compare the detorque values of prefabricated machined abutments with gold-premachined cast-on UCLA abutments before and after casting in two types of internal implant-abutment connection systems: (1) internal hexagonal joint, (2) internal octagonal joint. Furthermore, the detorque values of two implant-abutment connection systems were compared. MATERIALS AND METHODS: Twenty internal hexagonal implants with an 11-degree taper and twenty internal octagonal implants with an 8-degree taper were acquired. Ten prefabricated titanium abutments and ten gold-premachined UCLA abutments were used for each systems. Each abutment was torqued to 30 N㎝ according to the manufacturer's instructions and detorque value was recorded. The detorque values were measured once more, after casting with gold alloy for UCLA abutment, and preparation for titanium abutments. Group means were calculated and compared using independent t-test and paired t-test (${\alpha}$=0.05). RESULTS: The results were as follows: 1. The detorque values between titanium abutments and UCLA-type abutments showed significant differences in internal octagonal implants (P<0.05), not in internal hexagonal implants (P>0.05). 2. In comparison of internal hexagonal and octagonal implants, the detorque values of titanium abutments had significant differences between two connection systems on the initial analysis (P<0.05), not on the second analysis (P>0.05) and the detorque values of UCLA-type abutments were not significantly different between two connection systems (P>0.05). 3. The detorque values of titanium abutments and UCLA-type abutments decreased significantly on the second analysis than the initial analysis in internal hexagonal implants (P<0.05), not in internal octagonal implants (P>0.05). CONCLUSION: Casting procedures of UCLA-type abutments had no significant effect on screw loosening in internal implant-abutment connection systems, and UCLA-type abutments showed higher detorque values than titanium abutments in internal octagonal implants.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.296-326
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• 1994

The purpose of this study was to evaluate the mechanical effects when one implant fixture was connected to the natural teeth with reduced alveolar bone height. This study also examined the effects of increasing the number of abutment teeth and the effects of the intramobile connector and the titanium connector as they were inserted between the implant superstructure and the fixture. The distribution and concentration load was applied to the fixed partial denture(FPD) supported by implant and the natural teeth with reduced alveolar bone height. The stress and displacement of each element was observed and compared by the two-dimensional finite element method. The following results were obtained : 1. The greater the loss of alveolar bone in natural teeth area, the greater the displacement of FPD and the stress concentration in alveolar bone around implant, especially at the stress concentration in the mesial alveolar bone crest around implant fixture. 2. The displacement of FPD was increased more and that of implants fixture was decreased more when intramobile connector was used than titanium connector was used. Also the stress concentration in alveolar bone around implant fixture was greater when intramobile connector than titanium connector. One implication of this finding was that the difference in stiffness of implant and the natural teeth with reduced alveolar bone height could be partially compensated in case of the POM intramobile connector. 3. The amount and direction of displacement and the stress distribution of the 4-unit FPD was better than those of the 3-unit FPD. It implied that the difference of stiffness of implant and natural teeth with reduced alveolar bone height could be partially compensated in case of the 4 unit FPD.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.2
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• pp.123-130
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• 2005

Many of the molecular and genotypic events taking place at the osteoblast cell level during bone-implant integration are still largely unknown. The objective of this study was to examine expression patterns of TGF-$\beta$ and IGF-I related genes during bone-implant integration. Titanium implants with machined surface were placed into 8 rabbit tibias. At 3rd, 7th, 14th, 28th day after implantation, the expression pattern of TGF-$\beta$ and IGF-I genes in bone with or without implant was examined using reverse transcriptase-polymerase chain reaction (RT-PCR). At the same time, histomorphometric analysis was evaluated, respectively. The bone-to-implant contacts (BIC) of experimental groups were 5.2%, 6.2%, 6.6%, 24.6% at 3rd, 7th, 14th, 28th day. This indicated that newly formed bone increased at the implant surface in bone marrow space after implantation. The expressions of TGF-$\beta$ and IGF-I were higher in implantation groups than untreated control groups during all experimental days. The increased expression of TGF-$\beta$ and IGF-I genes may be associated with the increased bone-to-implant contact. This result provided the evidence for existing biologic differences in tissue response after implantation and helped us to understand molecular biologic processes in tissue-implant integration.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.112-123
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• 2006

Purpose: The biocompatibility and bio-adhesive property of a dental implant abutment are important for proper soft tissue healing and maintenance of osseointegration of implant. However, studies of soft tissue healing and mucosal attachment of various materials of implant abutment other than titanium are still needed. In this study, cell attachment, proliferation, cytotoxicity of human gingival fibroblast for ceramic, gold alloy, Ni-Cr alloy and, commercially available pure titanium as a control were evaluated, using MTS and scanning electron microscopy. Materials and Methods: Specimen was designed to disc, 4mm diameter and 1mm thickness, made of ceramic, gold alloy, Ni-Cr alloy and commercially available pure titanium. Primary culture of human gingival fibroblasts were grown in Dulbecco's modified Eagle's medium with 10% fetal bovine serum and 1% antibiotics. Cells were inoculated in the multiwell plates placed the specimen disc. Cell Titer 96 AQucous One Solution Cell Proliferation Assay were done after 1hour 3hours, 24hours, 3days, 5days of incubation. The discs were processed for scanning electron micrography to evaluate cell attachment and morphologic change. Results: The results were obtained as fellows. 1. The ceramic showed high cell attachment and proliferation and low cytotoxicity, which is as much bioadhesive and biocompatible as titanium. 2. The gold alloy represented limited proliferation of human gingival fibroblast and the highest cytotoxicity among tested materials (p<0.05). 3. The Ni-Cr alloy limited the proliferaion of the human gingival fibroblast compared to titanium(p<0.05) but cytotoxicity on the bottom of well was not so considerable, compared to titanium. 4. On the scanning electron micrographs , the ceramic showed good attachment and proliferation of human gingival fibroblast, which was similar to titanium. But gold alloy and Ni-Cr alloy showed the shrinkage of gingival fibroblast both after 24 hours and 3 days. On 5th day, small amount of the human gingival fibroblast proliferation was observed on the Ni-Cr alloy, while the shrinkage of gingival fibroblast was still observed on the gold alloy. Conclusions: These results suggest that the ceramic abutment is as biocompatible as titanium to make proper mucosal seal. The gold alloy has a high cytotoxicity to limit proliferation of gingival fibroblast, which suggest limited use on the anterior tooth where soft tissue healing is recommeded.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.295-313
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• 2006

Statement of problem. Higher fracture rates were reported for Branemark implants placed in the maxilla and for 3.75 mm diameter implants installed in the posterior region. Purpose. The purpose of this study was to investigate the fracture of a fixture by finite element analysis and to compare different diameter of fixtures according to the level of alveolar bone resorption. Material and Methods. The single implant and prosthesis was modeled in accordance with the geometric designs for the 3i implant systems. Models were processed by the software programs HyperMesh and ANSA. Three-dimensional finite element models were developed for; (1) a regular titanium implant 3.75 mm in diameter and 13 mm in length (2) a regular titanium implant 4.0 mm in diameter and 13 mm in length (3) a wide titanium implant 5.0 mm in diameter and 13 mm in length each with a cementation type abutment and titanium alloy screw. The abutment screws were subjected to a tightening torque of 30 Ncm. The amount of preload was hypothesized as 650 N, and round and flat type prostheses were 12 mm in diameter, 9 mm in height were loaded to 600 N. Four loading offset points (0, 2, 4, and 6 mm from the center of the implants) were evaluated. To evaluate fixture fracture by alveolar bone resorption, we investigated the stress distribution of the fixtures according to different alveola. bone loss levels (0, 1.5, 3.5, and 5.0 mm of alveolar bone loss). Using these 12 models (four degrees of bone loss and three implant diameters), the effects of load-ing offset, the effect of alveolar bone resorption and the size of fixtures were evaluated. The PAM-CRASH 2G simulation software was used for analysis of stress. The PAM-VIEW and HyperView programs were used for post processing. Results. The results from our experiment are as follows: 1. Preload maintains implant-abutment joint stability within a limited offset point against occlusal force. 2. Von Mises stress of the implant, abutment screw, abutment, and bone was decreased with in-creasing of the implant diameter. 3. With severe advancing of alveolar bone resorption, fracture of the 3.75 and the 4.0 mm diameter implant was possible. 4. With increasing of bending stress by loading offset, fracture of the abutment screw was possible.