No abstract available.
Dental Alloys* ; Dental Porcelain*

No abstract available.
Dental Implants* ; Prostheses and Implants* ; Tooth*

No abstract available.
Incisor*

Dental implant may be immediately placed in postextraction socket which has alveolar bone defect. The purpose of this study was to compare the bone regeneration and bone quality around defects adjacent to implants that were placed into extraction sockets according to EFEB, GTAM barrier and GTAM barrier with DFDB. Mandibular P2, P3 and P4 were extracted bilaterally in dogs, and buccal defects were created about 4mm in depth and 3.3mm in width. Screwed pure titanium implants, 3.8mm in diameter and 10mm in length, were placed into the extraction sockets. The experimental groups were divided into four groups : the G group was covered with a GTAM barrier on the defective area, the D+G group was filled with DFEB and covered with a GTAM barrier, the D group was filled with DFDB only and the control group was sutured without any special treatment on the defective area. The experimental animals were killed after 12 weeks and specimens were prepared for light microscopic evaluation and fluorescent dyes were administered daily for 2 weeks after implantation, and injected on the 4th and 11th week for fluorescent microscopic examination to observe new bone formation and bone remodeling. The new Bone height of the buccal defect was measured and compared with the another for bone gain and the removal torque for the implant was measured for the comparison of bone density and bone-implant osseointegration. Results obtained were as follows : 1. Experimental groups showed bone regeneration in oder from D+G, G, D group and control. D+G and G group was significantly from D group and control(P<0.01). 2. In the defective area of control the regenerated alveolar bone showed poorly developed lamellated structure and fibrous tissue intervention into the bone-implant interface but the others showed well developed lamellated structure and osseointegration. 3. All implant groups showed no significant difference in the removal torque for implant(P>0.05) These results suggest that immediate implants placed in defective sockets were successfully osseointegrated and utilizing placed in defective sockets were successfully osseointegrated and utilizing not only the combination of GTAM and DFDB but also only the GTAM was favorable for the predictable regeneration of the defective area.
Animals ; Bone Density ; Bone Regeneration* ; Bone Remodeling ; Dental Implants ; Dogs ; Fluorescent Dyes ; Osseointegration ; Osteogenesis ; Regeneration ; Titanium ; Torque

STATEMENT OF PROBLEM: There has been a great interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However, the melting temperature and chemical reactivity of titanium necessities casting system different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new development in Ti casting system, inadequate mold filling and internal porosity are frequently observed casting defects. PURPOSE: The purposes of this study were to compare the castibility and reaction layer of the casting titanium under the two casting machines and their investment condition. MATERIAL AND METHOD: coping and machine-milled titanium coping according to the casting methods and the marginal configurations. The total 28 specimens were used, and these are divided into 4 groups according to 2 casting machines and 2 investments. The castings were analyzed using x-ray microanalysis and microhardness testing. The reaction layer between margin of titanium casting and the investments was observed and analyzed with scanning electron microscope. RESULT: 1. Castabiliy of casting titanium specimen was best in the group of centrifugal casting machine and Selevest CB(R) and good that of Selevest CB and pressure differential casting machine, Rematitan plus and centrifugal casting machine, Rematitan plus and pressure differential casting machine in order. 2. There was no significanct correlation in titanium castability in respect of casting machine. However ANOVA indicated that Selevest CB(R) groups had significantly better castability than Rematitan plus(R) groups.(p<0.05) 3. There was a significant microhardness difference between cetrifugal casting machine groups and pressure differential groups.(p<0.05) Titanium castings in centifugal groups had significantly harder than those in pressure differential groups. 4. The addition of zirconia decreased interfacial reactivity. CONCLUSION: above result revealed that of the castability of titanium casting specimens had little correlation in casting machines and was better in magnesia-based investment contained ZrO2 groups. However in order to practice casting titanium in clininic, its castability should be improved, also there should be more research on factor of castability so that long-span prothesis and removable partial denture metla frame may be casted completly.
Alloys* ; Argon ; Atmosphere ; Denture, Partial, Removable ; Electron Probe Microanalysis ; Freezing ; Fungi ; Investments* ; Porosity ; Prostheses and Implants ; Titanium*

STATEMENT OF PROBLEM: A number of studies about the nano-treated surfaces of implants have been conducting along with micro-treated surfaces of implants. PURPOSE: The purpose of this study was to get information for the clinical use of nano-treated surfaces compared with micro-treated surfaces by measuring removal torque and analyzing histological characteristics after the placement of various surface-treated implants on femurs of dogs. MATERIAL AND METHODS: Machined surface implants were used as a control group. 4 nano-treated surface implants and 3 micro-treated surface implants [resorbable blast media surface (RBM), sandblast and acid-etched surface (SAE), anodized RBM surface] were used as experimental groups. Removal torque values of implants were measured respectively and the histological analyses were conducted on both 4weeks and 8weeks after implant surgery. The surfaces of removed implants after measuring removal torque values were observed by scanning electron microscopy (SEM) at 8 weeks. RESULTS: 1. Removal torque values of the nano-treated groups were lower than those of micro-treated groups. 2. Removal torque values were similar in the anodized RBM surface groups. 3. On the histological views, there was much of bone formation at 8 weeks, but there was no difference between 4 and 8 weeks, and between the types of implant surfaces as well. CONCLUSION: It is suggested that implant topography is more effective in removal torque test than surface chemistry. To get better clinical result, further studies should be fulfilled on the combined effect of surface topography and chemistry for the implant surface treatments.
Animals ; Dogs ; Femur ; Microscopy, Electron, Scanning ; Osteogenesis ; Titanium ; Torque

PURPOSE: We aimed to identify a more esthetic width-to-length ratio by analyzing maxillary central incisor of Korean adult population. Information regarding tooth ratio in the Korean population may be useful to clinicians when restoring anterior teeth. MATERIALS AND METHODS: A total of 40 men and 40 women were included in this study. The NON-MEDIA group included 40 non-celebrities, who were healthy and 25 to 39 years old, with normal dentofacial appearance. The MEDIA group consisted of 40 celebrities selected only on the basis of their soft-tissue facial appearance. The facial photographs of 40 celebrities were collected from the Internet websites. The width and length of the maxillary central incisor were measured using Adobe Photoshop(R) 7.0, a software for analysis, measurement and edition of photographs. Data were analyzed statistically using the Independent t-test at 5% statistical significance level. RESULTS: The mean ratio for the MEDIA group was 0.77, whereas that of the NON-MEDIA group was 0.88. The difference between the two groups was statistically significant. No significant gender differences were found in the width-to-length ratio in MEDIA group. In NON-MEDIA group, however, there were significant differences between female and male. CONCLUSION: After analyzing maxillary anterior teeth of Korean adults, our results were in accordance with the general Western standards of esthetics. A dentist restoring the natural look and beauty of teeth will have to consider those standards.
Adult ; Anodontia ; Beauty ; Dentists ; Esthetics ; Female ; Humans ; Incisor ; Internet ; Korea ; Male ; Tooth

PURPOSE: We aimed to identify a more esthetic width-to-length ratio by analyzing maxillary central incisor of Korean adult population. Information regarding tooth ratio in the Korean population may be useful to clinicians when restoring anterior teeth. MATERIALS AND METHODS: A total of 40 men and 40 women were included in this study. The NON-MEDIA group included 40 non-celebrities, who were healthy and 25 to 39 years old, with normal dentofacial appearance. The MEDIA group consisted of 40 celebrities selected only on the basis of their soft-tissue facial appearance. The facial photographs of 40 celebrities were collected from the Internet websites. The width and length of the maxillary central incisor were measured using Adobe Photoshop(R) 7.0, a software for analysis, measurement and edition of photographs. Data were analyzed statistically using the Independent t-test at 5% statistical significance level. RESULTS: The mean ratio for the MEDIA group was 0.77, whereas that of the NON-MEDIA group was 0.88. The difference between the two groups was statistically significant. No significant gender differences were found in the width-to-length ratio in MEDIA group. In NON-MEDIA group, however, there were significant differences between female and male. CONCLUSION: After analyzing maxillary anterior teeth of Korean adults, our results were in accordance with the general Western standards of esthetics. A dentist restoring the natural look and beauty of teeth will have to consider those standards.
Adult ; Anodontia ; Beauty ; Dentists ; Esthetics ; Female ; Humans ; Incisor ; Internet ; Korea ; Male ; Tooth

STATEMENT OF PROBLEM: Major objective in making on implant-supported prosthesis is the production of superstructure that exhibits a passive fit when connected to multiple abutments. One requirement to ensure passive fit is to make an accurate impression. 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 FIXM) 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. CONCLUSION: An impression method have more effect on accuracy of master model than an impression level. A modified indirect method showed smallest vertical and horizontal error.
Prostheses and Implants*

PURPOSE: Four finite element models were constructed in the mandible having a single implant fixture connected to the first premolar-shaped superstructure, in order to evaluate how the shape of the fixture and the implant-abutment connection would influence the stress level of the supporting tissues, fixtures, and prosthethic components. MATERIAL AND METHODS: The superstructures were constructed using UCLA type abutment, ADA type III gold alloy was used to fabricate a crown and then connected to the fixture with an abutment screw. The models BRA, END, FRI, ITI were constructed from the mandible implanted with Branemark, Endopore, Frialit-2, I.T.I systems respectively. In each model, 150 N of vertical load was placed on the central pit of an occlusal plane and 150 N of 40.oblique load was placed on the buccal cusp. The displacement and stress distribution in the supporting tissues and the other components were analysed using a 2-dimensional finite element analysis. The maximum stress in each reference area was compared. RESULTS: 1. Under 40.oblique loading, the maximum stress was larger in the implant, superstructure and supporting tissue, compared to the stress pattern under vertical loading. 2. In the implant, prosthesis and supporting tissue, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA and END). 3. In the superstructure and implant/abutment interface, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA and END). 4. In the implant fixture, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA and END). 5. The stress was more evenly distributed in the bone/implant interface through the FRI of trapezoidal step design. Especially Under 40.oblique loading, The maximum stress was smallest in the bone/implant interface. 6. In the implant and superstructure and supporting tissue, the maximum stress occured at the crown loading point through the ITI. CONCLUSION: The stress distribution of the supporting tissue was affected by shape of a fixture and implant-abutment connection. The magnitude of maximum stress was reduced with the internal connection type (FRI) and the morse taper type (ITI) in the implant, prosthesis and supporting tissue. Trapezoidal step design of FRI showed evenly distributed the stress at the bone/implant interface.
Alloys ; Crowns ; Dental Occlusion ; Finite Element Analysis ; Mandible ; Prostheses and Implants