No abstract available.
Suicide, Attempted*

STATEMENT OF PROBLEM: When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered. PURPOSE: The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment. MATERIAL AND METHODS: The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera(TM), Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at 25degrees C for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-5(R), United Calibration, USA). These values were statistically analyzed. RESULTS: 1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order. CONCLUSION: Within the limitations of this study, all methods of surface treatment used in this study are clinically available.
Alloys ; Calibration ; Collodion ; Crowns ; Tin ; Titanium ; Water

STATEMENT OF PROBLEM: The microbial adhesion on the surface of materials used in prosthodontics and restorative dentistry significantly influences microbial infection. PURPOSE: The purpose of this study was to evaluate the effect of how the degree of surface roughness of acrlyic resin affect the adhesion of bacteria. MATERIAL AND METHODS: Resins were finished with 50micrometerand 250micrometeraluminium oxide particles by using sandblaster, by using stone point, and high polished with Opal(R) and Lace motor(R). The surface of acrylic resin attached by bacteria was directly touched on the surface of BHI agar, which was incubated. Bacteria colonies formed on BHI agar were counted in accordance with the degree of the surface roughness. RESULTS: 1. The viable cell number of Streptococcus mutans increased on the acrylic resins incubated in BHI broth than in PBS. 2. The viable cell number of Streptococcus mutans increased on the acrylic resins incubated without agitation than with agitation, washed three times than six times, and incubated in broth added with 5% sucrose than without sucrose. 3. When Streptococcus mutans incubated in BHI broth, the number of Streptococcus mutans colonies formed on BHI agar was the largest on the acrylic resins finished with 250micrometeraluminium oxide particle using sandblaster. But when incubated in BHI broth containing sucrose, the number of colonies formed on that was the largest on the acrylic resins high polished using Opal(R) and Lace motor(R). 4. When Streptococcus sanguis was incubated in BHI broth with or without sucrose, the number of Streptococcus mutans colonies formed on BHI agar was the largest on the acrylic resins finished with 250micrometeraluminium oxide particle using sandblaster. 5. When Actinomyces viscous was incubated in BHI broth with or without sucrose, the number of Streptococcus mutanscolonies formed on BHI agar was the largest on the acrylic resins high polished using Opal(R) and Lace motor(R). CONCLUSION: These results indicated that when acrylic resins attached by bacteria were touched on the surface of BHI agar, the number of bacterial colonies formed on the agar was dependent on the bacterial species. Also, the result of this study was showed that increase in the surface roughness and the addition of sucrose increased retention of microbial cells.
Acrylic Resins ; Actinomyces ; Agar ; Bacteria* ; Cell Count ; Dentistry ; Dihydroergotamine ; Prosthodontics ; Streptococcus ; Streptococcus mutans ; Streptococcus sanguis ; Sucrose

The purposes of this study were to evaluate the adherence of bacteria on various denture base resin materials and effects of chitosan, added to denture base materials on bacterial adherence. PMMA denture base resin such as heat-cured Vertex-RS, self-cured Vertex-SC and 4-META denture base resin such as heat-cured Meta-Dent, self-cured Meta-Fast were used in this study. Samples were divided into two groups: the denture base resin with chitosan, without chitosan. Streptococcus mutans and Lactobacillus casei were used in this study. The surface of samples was observed by SEM. When chitosan was added to M17 and MRS broth, viable cell count of bacteria was reduced. Viable cell count of Streptococcus mutans on the samples decreased as follows: Meta-Dent, Vertex-SC, Meta-Fast, Vertex-RS. Viable cell count of Lactobacillus casei on the samples decreased as follows: Vertex-RS, Meta-Dent, Meta-Fast, Vertex-SC. The resin with chitosan showed lower adherence of bacteria than without chitosan. The images of SEM showed that the surface of the resin with chitosan was rougher than that of without chitosan. These results showed that the denture base resin materials with chitosan have rougher surface than without chitosan,but less bacteria adhered on them.
Bacteria* ; Cell Count ; Chitosan* ; Denture Bases* ; Dentures* ; Lactobacillus casei ; Polymethyl Methacrylate ; Streptococcus mutans

The purpose of this study was to estimate the effect of a bleaching agent on tooth surfaces and to evaluate the resin bond strength according to different surface treatments on bleached teeth.To prepare for the experimental samples,first,extracted human third molars were used and the body portions of the crowns were cut into four equal-sized specimens.Next,each specimen was mounted in an plastic bottle with self-cured resin and highly polished to have them reveal the enamel or dentin surfaces.Then,the enamel(E)and dentin(D)specimens were divided into four; 1) non-bleached,laser-treated(NBLA)group 2)bleached,laser-treated(BLLA)group 3)non-bleached,acid-treated(NBAC)group and 4)bleached,acid-treated(BLAC)group.Here,opales-cence(R)(10%carbamide peroxide)was used for bleaching agent.The treated specimens were observed by confocal laser scanning microscopy and bonded with composite resin for shear bond test. The following results were obtained from this experiment : 1. Compared with the ENB group,the EBL group was shown to be dyed about 20 micrometer deeper with rhodamine B.The DBL group appeared to be caved in at the entry part of the dentinal tubules, was dyed about 20 micrometer deeper and 5 micrometer wider in diameter,compared with the DNB group. 2. In comparison with the EBLAC group,the ENBAC group looked evenly bonded with the resin, while the DNBAC group,compared to DBLAC group,was observed to have its resin tags penetrated about 50 micrometer deeper.Other than those,however,no observable differences between ENBLA and EBLLA group or between DNBLA and DBLLA group were found. 3. At the shear bond test,the ENBAC group was shown to have statistically significant higher shear bond strength than the EBLAC group(p<0.05).No statistically significant differences between the ENBLA and the EBLLA groups were observed(p>0.05). 4. At the shear bond test,the DNBAC group was shown to have statistically significant higher shear bond strength than the DBLAC group(p<0.05).No statistically significant differences between the DNBLA and the DBLLA groups were observed(p>0.05). The in vitro observations above suggest that tooth-bleaching procedure brings a certain change on enamel and dentin surfaces and it weakens the shear bond strength with composite resin when the bleached tooth was acid-treated.
Crowns ; Dental Enamel* ; Dentin* ; Humans ; Microscopy, Confocal* ; Molar, Third ; Plastics ; Rhodamines ; Tooth

STATEMENT OF PROBLEM: Titanium has many advantages of high biocompatibility, physical porperties, low-weight, low price and radiolucency, but it is incompatible with conventional dental porcelain due to titanium's oxidative nature. Many previous studies have shown that they used the method of sandblast for surface treatment prior to porcelain application, the researchs are processing about the method of acid etching or surface coating. PURPOSE: The purpose of this research is to study the effect on bond strength between titanium and porcelain when using macro-surface treatment and micro-surface treatment and macro and micro surface treatment . MATERIAL AND METHOD: In this study, we evaluated the bond strength by using 3-point bending test based on ISO 9693 after classified 7 groups - group P : polished with #1200 grit SiC paper, group SS : sandblasted with 50 micrometer aluminum oxides, group LS : sandblasted with 250 micrometer alumium oxides, group HC : treated with 10 % hydrochloric acid, group NF : treated with 17% solution of fluoric acid and nitric acid, group SHC : treated with 10 % hydrochloric aicd after sandblsting with 50 micrometer alumium oxides, group SNF : treated with 17 % solution of fluoric acid and nitric acid. RESULTS: Within the confines of our research, the following results can be deduced. 1. Group SS which was sandblasted with 50 micrometer aluminum oxides showed the highest bond strength of 61.74 MPa and significant differences(P<0.05). The bond strengths with porcelain in groups treated acid etching after sandblasting decreased more preferable than the group treated with sandblasting only. It gives significant differences(P<0.05). 2. After surface treatments, the group treated with sandblasting showed irregular aspect formed many undercuts, in the SEM photographs. The group treated with hydrochloric acid had the sharp serrated surfaces, the group treated with the solution of fluoric acid and nitric acid had the smooth surfaces, the group with sandblasting and hydrochloric acid had irrigular and porous structure, the group with sandblasting and the solution of fluoric acid and nitric acid had craterlike surfaces. But all of the groups treated with acid etching was not found and undercut. CONCLUSION: In above results, average surface roughness increase, bond strength also increase, but surface topographs influences more greatly on bond strengths.
Aluminum ; Dental Porcelain ; Hydrochloric Acid ; Nitric Acid ; Oxides ; Titanium

STATEMENT OF PROBLEM: The screws of dental implant, having various thread types, can be categorized into different classes by their geometrical form, and each type transmits dissimilar amount and form of stress to alveolar bone. PURPOSE: The purpose of this study was to find an inclination angle of the screw thread that is favorable in distributing the stresses to alveolar bone. MATERIAL AND METHODS: In this study, We used three dimensional finite element analysis with modeling having three types of thread inclination angles and fixed pitch-0.8 mm (single thread type with 3.8 degrees inclination, double thread type with 7.7 degrees inclination, triple thread type with 11.5 degrees inclination). RESULTS: The results obtained from this study were as follows; 1. When the number of thread increased, the amount of Von-Mises stress was reduced since the generated stress was effectively distributed. 2. Since the maximum principal stress affects on the alveolar bone can influence deeply on the longevity of the implants when comparing the magnitude of the maximum principal stress double thread had least amount of stress. This shows that the double thread screw gave best result. CONCLUSION: In conclusion, double, and triple thread screws were found to be more effective on distribution of the stress than the single thread screws. But, increasing in the thread inclination angle such as triple thread screw relate on the magnitude of the maximum principal stress affecting on the alveolar bone can become problematic. Thus, effective combination of thread number and thread inclination angle can help prolonging the longevity of implant.
Dental Implants ; Finite Element Analysis* ; Longevity

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 follows. 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.
Alloys ; Anti-Bacterial Agents ; Cell Proliferation ; Ceramics ; Dental Implants ; Fibroblasts* ; Humans* ; Microscopy, Electron, Scanning ; Osseointegration ; Titanium ; Tooth

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 follows. 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.
Alloys ; Anti-Bacterial Agents ; Cell Proliferation ; Ceramics ; Dental Implants ; Fibroblasts* ; Humans* ; Microscopy, Electron, Scanning ; Osseointegration ; Titanium ; Tooth

PURPOSE: The purpose of this study was to compare the accuracy of master cast fabricated by using different impression methods at the different impression levels. MATERIAL AND METHOD: The master model used in this study was resin block having four implant analogs. Impression method studied were 1) direct method on fixture level (Group FIX-D), 2) Indirect method on fixture level(Group FIX-I), 3) Modified indirect method on fixture level(Group FIX-M), 4) Direct method on abutment level(Group AB-D) and 5) Indirect method on abutment level(Group AB-I). Each of the five groups took 10 impressions. Fifty impressions were made for master cast by using Impregum F. impression material loaded on individual tray. Three dimensional measuring microscope was used to measure the inter-implant distance. Error rate of each inter-implant distance were calculated and evaluated. RESULTS: The results were as follows. 1. Group FIX exhibited higher accuracy than group AB. 2. In group FIX, modified indirect method showed the highest accuracy, while indirect method showed the lowest accuracy. In group Ab, indirect method showed the higher accuracy than direct method. 3. Group FIX showed larger horizontal error than group AB. But, group AB showed the larger vertical error than group FIX. 4. Group Fix-M showed smallest vertical and horizontal error.
Prostheses and Implants*