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

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*

STATEMENT OF PROBLEM: The titanium has advantages of a high biocompatibility, a corrosion resistence, low density, and cheep price, so it is focused as a substituted alloy. But it is quite difficult to cast with the tranditional method due to the high melting point, reacivity with element at elevated temperature. By using the CAD-CAM system for the crown construction, it is possible to reduce the errors while proceeding the wax-up, investing, and casting procedure. PURPOSE: The purposes of this study were to measure the marginal adaptation of the casting titanium coping and machine-milled titanium coping according to the casting methods and the marginal configurations. MATERIAL AND METHOD: The marginal configurations were used chamfer, shoulder,and beveled shoulder. The total 30 copings were used, and these are divided into 6 groups according to the manufacturing method and marginal configuration. The gap between margin of the model and the restoration was measured with 3-dimensional measuring microscope. RESULTS: The following results were obtained; 1. casting gold coping demonstrated the best marginal seal, followed by casting titanium coping finally machine-milled titanium copings. 2. In casting titanium coping, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. There was no significantly difference in shoulder and beveled shoulder. But all margin form has clinically acceptable 3. In machine-milled titanium copings, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. Beveled shoulder show large and uneven marginal gap. CONCLUSIONS: Above result revealed that marginal adaptation of the titanim coping is available in the clinical range, it can be used as an alternative metal and it is prefered especially in chamfer or shoulder margin during implant superstructure fabrication. But there should be more research on machine-milled titanium in order to use it in the clinics.
Alloys ; Computer-Aided Design ; Corrosion ; Crowns ; Freezing ; Shoulder ; Titanium*

PURPOSE: The purpose of this study was to evaluate the efficacy and substitute possibility of a newly developed flowable composite resins as a luting cement for translucent fiber post. MATERIAL AND METHOD: Two kinds of 12 mm translucent fiber post (D.T. Light-Post (Bisco, USA) and FRC Postec (Ivoclar vivadent, Liechtenstein)) was inserted into the teflon mold (7 mm diameter, 9 mm long) and Filtek-Flow (3M ESPE, USA), a light activated flowable composite resin, was polymerized for 60 seconds through the post. Also, the post was cut from the tip to 9 mm, 6 mm, 3 mm, and Filtek-Flow was light cured according to each length. For comparison, 60 seconds light-cured and 24 hours self-cured two dual cured resin cement (Duo-cement (Bisco, USA) and 2 Panavia-F (Kuraray, Japan)) samples were prepared as control group. Also cavities (1 mm in width, 1 mm in depth, and 12 mm in length) were prepared using acrylic plate and aluminum bar, and flowable composite resin was filled and light cured by the diffused light from the fiber post's side wall. The degree of polymerization was measured according to the distance from curing light using Vickers' hardness test. RESULT: Within the limitation of this study, the following conclusions were drawn: 1. Vickers'hardness of light cured dual cured resin cement and flowable composite resin decreased from Panavia-F, Filtek-Flow, and Duo-cement accordingly (p<0.05). In the dual curing resin cement, light curing performed group showed higher surface hardness value than self cured only group (p<0.05). 2. Surface hardness ratio (light cured through fiber post /directly light cured) of D.T. Light-Post using Filtek-Flow showed about 70% in the 6 mm deep and about 50% in the 12 mm deep. FRC Postec showed only 40% of surface hardness ratio. 3. Surface hardness ratio by diffused light from the post's side wall showed about 50% at 6 mm and 9 mm deep, and about 40% at 12 mm deep in D.T. Light-Post. However, FRC Postec showed about 40% at 6 mm deep, and almost no polymerization in 9 mm and 12 mm deep.
Aluminum ; Composite Resins* ; Fungi ; Hardness ; Hardness Tests ; Polymerization ; Polymers ; Polytetrafluoroethylene ; Resin Cements

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*

STATEMENT OF PROBLEM: The titanium has advantages of a high biocompatibility, a corrosion resistence, low density, and cheep price, so it is focused as a substituted alloy. But it is quite difficult to cast with the tranditional method due to the high melting point, reacivity with element at elevated temperature. By using the CAD-CAM system for the crown construction, it is possible to reduce the errors while proceeding the wax-up, investing, and casting procedure. PURPOSE: The purposes of this study were to measure the marginal adaptation of the casting titanium coping and machine-milled titanium coping according to the casting methods and the marginal configurations. MATERIAL AND METHOD: The marginal configurations were used chamfer, shoulder,and beveled shoulder. The total 30 copings were used, and these are divided into 6 groups according to the manufacturing method and marginal configuration. The gap between margin of the model and the restoration was measured with 3-dimensional measuring microscope. RESULTS: The following results were obtained; 1. casting gold coping demonstrated the best marginal seal, followed by casting titanium coping finally machine-milled titanium copings. 2. In casting titanium coping, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. There was no significantly difference in shoulder and beveled shoulder. But all margin form has clinically acceptable 3. In machine-milled titanium copings, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. Beveled shoulder show large and uneven marginal gap. CONCLUSIONS: Above result revealed that marginal adaptation of the titanim coping is available in the clinical range, it can be used as an alternative metal and it is prefered especially in chamfer or shoulder margin during implant superstructure fabrication. But there should be more research on machine-milled titanium in order to use it in the clinics.
Alloys ; Computer-Aided Design ; Corrosion ; Crowns ; Freezing ; Shoulder ; Titanium*