OBJECTIVETo compare the difference in strength degradation and morphology damage of two dental ceramic materials after Hertzian contact cyclic fatigue.

METHODSHertzian contact technique was used to investigate the response of Empress II glass ceramic and GI- II glass-infiltrated alumina ceramic to cyclic fatigue. Critical loads of specimens after different fatigue cycles were recorded.

RESULTSFor Empress II glass ceramic, critical load had significantly difference between specimens after 10(5) cycles loading. No significant difference of critical load was found in GI- II glass-infiltrated alumina ceramic after cycles loading.

CONCLUSIONGI- II glass-infiltrated alumina ceramic has better capability in resistance to cyclic loading. It may attribute to microstructure of material. Empress II glass ceramic shows a brittle damage model.

No abstract available.
Aluminum Oxide* ; Dental Porcelain*

The purpose of this experiment was to determind whether the gold electrodeposit on Pd-Ag and Ni-Cr alloys influences on the shear bond strength between veneering resin and silicoated metal surface. All the metal specimens were sandblasted with 250microneter aluminum oxide and followed by silicoating and resin veneering. According to the metal surfaces to be veneered, experimental groups were divided into five. Group Prec : Gold alloy without gold coating Group Semi : Pd-Ag alloy without gold coating Group Base : Ni-Cr alloy without gold coating Group Semi-G : Pd-Ag alloy with gold coating Group Base-G : Ni-Cr alloy with gold coating All specimens were thermocycled 1,000 times at temperature of 5degrees C to 55degrees C. The effects of gold electrodeposit on the shear bond strength between resin and metal interface were measured and fractured surface of the resin veneered metal was examined under the scaning electron microscope. The following results were obtained 1. The shear bond strength between resin and metal was 64.51+/-11.11Kg/cm2in Prec group, 62.77+/-11.23Kg/cm2in Base group and 58.97+/-9.20 Kg/cm2in Semi Group. There was no significant difference among the groups. 2. The bond strength in groups Semi-G and Base-G decreased about 17%, compared to the non-gold-electrodeposit groups(Semi, Base). 3. In groups of non electrodeposit(Prec, Semi, Base), fracture occurred at the interface between alloy and resin, while fracture interface was observed between gold coating and resin in group Semi-G, and between metal substrate and gold coating in group Base-G resp[ectively.
Alloys* ; Aluminum Oxide

PURPOSE: The purpose of this study was to investigate the impact of different surface treatment methods and thermal ageing on the bond strength of autopolymerizing acrylic resin to Co-Cr. MATERIALS AND METHODS: Co-Cr alloy specimens were divided into five groups according to the surface conditioning methods. C: No treatment; SP: flamed with the Silano-Pen device; K: airborne particle abrasion with Al2O3; Co: airborne particle abrasion with silica-coated Al2O3; KSP: flamed with the Silano-Pen device after the group K experimental protocol. Then, autopolymerized acrylic resin was applied to the treated specimen surfaces. All the groups were divided into two subgroups with the thermal cycle and water storage to determine the durability of the bond. The bond strength test was applied in an universal test machine and treated Co-Cr alloys were analyzed by scanning electron microscope (SEM). Two-way analysis of variance (ANOVA) was used to determine the significant differences among surface treatments and thermocycling. Their interactons were followed by a multiple comparison' test performed uing a post hoc Tukey HSD test (alpha=0.05). RESULTS: Surface treatments significantly increased repair strengths of repair resin to Co-Cr alloy. The repair strengths of Group K, and Co significantly decreased after 6,000 cycles (P<.001). CONCLUSION: Thermocycling lead to a significant decrease in shear bond strength for air abrasion with silica-coated aluminum oxide particles. On the contrary, flaming with Silano-Pen did not cause a significant reduction in adhesion after thermocycling.
Alloys* ; Aluminum Oxide ; Water

The aim of this study was to compare the compositions and cytotoxicity of white ProRoot MTA (white mineral trioxide aggregate) and 3 kinds of Portland cements. The elements, simple oxides and phase compositions of white MTA (WMTA), gray Portland cement (GPC), white Portland cement (WPC) and fast setting cement (FSC) were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD). Agar diffusion test was carried out to evaluate the cytotoxicity of WMTA and 3 kinds of Portland cements. The results showed that WMTA and WPC contained far less magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn) than GPC and FSC. FSC contained far more aluminum oxide (Al2O3) than WMTA, GPC, and WPC. WMTA, GPC, WPC and FSC were composed of main phases, such as tricalcicium silicate (3CaO.SiO2), dicalcium silicate (2CaO.SiO2), tricalcium aluminate (3CaO.Al2O3), and tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3). The significance of the differences in cellular response between WMTA, GPC, WPC and FSC was statistically analyzed by Kruskal-Wallis Exact test with Bonferroni's correction. The result showed no statistically significant difference (p > 0.05). WMTA, GPC, WPC and FSC showed similar compositions. However there were notable differences in the content of minor elements, such as aluminum (Al), magnesium, iron, manganese, and zinc. These differences might influence the physical properties of cements.
Agar ; Aluminum ; Aluminum Oxide ; Calcium Compounds ; Diffusion ; Glutamates ; Guanine ; Humans ; Iron ; Magnesium ; Manganese ; Oxides ; Plasma ; Silicates ; Spectrometry, X-Ray Emission ; Spectrum Analysis ; Zinc ; Pemetrexed

This study investigated the effects of surface treatment for filling resins on the surface texture of denture resin teeth by the use of scanning electron microscope. This study also evaluated the bond strength of filling resins to denture resin teeth. The denture resin teeth in this study was Endura Posterio(Shofu Co., Japan). The filling resins used were Coe-cure(Coe Co., USA), Vertex RS (Dentimax Ziest, Holland), and light cured resin Z-100(3M Co., USA). The test sample were divided into 3 parts. Group 1 : Sandblasted with 50micrometer Aluminum oxide. Group 2 : Treated with #60 silicone carbide paper. Group 3 : Treated with monomer brush application. Control Group : No Treatment. The results were as follows; 1.The bond strength of filling resins to denture resin teeth is increased by surface treatment. 2.Regardless of the filling resins, there was a significant difference with # 60silicone carbide paper treated group. 3.Regardless of each group, the bond strength according to the filling resins were decreased in the following order: Vertex RS, Coe-cure and Z-100.
Aluminum Oxide ; Dentures* ; Silicones ; Tooth*

STATEMENT OF PROBLEM: Preparation of implant beds with lasers is considered a safe and reliable method, but the accuracy of this technique has not been examined. PURPOSE: The purpose of this study was to evaluate the accuracy and effectiveness of implant bed preparation using an Er,Cr:YSGG laser. MATERIAL AND METHODS: An Er,Cr:YSGG laser was applied to pig rib bone. The laser was employed at a 5.75 W power setting, 30 Hz/sec pulse repetition, and 70 micro sec pulse duration with 50 % water and 60% air spray. According to laser tips the groups were divided as follows; Group 1: paralleled - shaped sapphire tip (0.6 mm phi), Group 2: paralleled - shaped zirconia tip (0.6 mm phi), Group 3: tapered sapphire tip (0.4 mm phi). The Er,Cr:YSGG laser tip was separated by 1 mm from the bone and applied for 15 seconds in a non-contact mode. After the application, the bone was sectioned for specimens. Histologic measurements were determined by computerized morphometry. The length of the prepared bone surface was measured and the width of the entrance was measured. The results were analyzed with one-way ANOVA (P<0.05). RESULTS: The prepared length of group 3 was longer than that of group 2. The prepared bone width was larger than the width of the laser tip in every group. Additional bone removal was observed adjacent to the prepared area and displayed an irregular surface. CONCLUSION & DISCUSSION: Different cutting effects were observed according to the laser tip, emphasizing the importance of proper tip selection in the clinical setting. This preliminary study supported the existence of hydrokinetic effects.
Aluminum Oxide ; Ribs ; Water ; Zirconium

PURPOSE: Many studies have shown that airborne-particle abrasion of fiber post can improve the bonding strength to resin cement. But, airborne-particle abrasion may influence the property of fiber post. The purpose of this study is to evaluate the influence of airborne-particle abrasion on flexural strength of fiber post. MATERIALS AND METHODS: Two fiber-reinforced posts; DT Light Post Size 2 (1.8 mm diameter, Bisco Inc) and RelyX Fiber Post Size 3 (1.9 mm diameter, 3M ESPE); were used in this study. Each group was divided into 3 subgroups according to different surface treatments; without pretreatment: 50 µm aluminum oxide (Cobra®, Renfert): and 30 µm aluminum oxide modified with silica (Rocatec Soft®, 3M ESPE). After airborne-particle abrasion procedure, three-point bending test was done to determine the flexural strength and flexural modulus. The diameter of each posts was measured to an accuracy of 0.01 mm using a digital micrometer. There was no diameter change before and after airborneparticle abrasion. The mean flexural moduli and flexural strengths calculated using the appropriate equations. The results were statistically analyzed using One-way ANOVA and Scheffe's post-hoc test at 95% confidencial level. RESULTS: There was no significant difference on flexural strength between groups. CONCLUSION: In the limitation of this study, flexural strength and flexural modulus of fiber post are not affected by airborne-particle abrasion.
Aluminum Oxide ; Resin Cements ; Silicon Dioxide

The success of an implant is determined by its integration into the tissue surrounding the biomaterial. Surface roughness is considered to influence the behavior of adherent cells. The aim of this in vitro study was to determine the effect of surface roughness on Saos-2 osteoblast-like cells. Titanium disks blasted with 75 micrometer aluminum oxide particles and machined titanium disks were prepared. Saos-2 were plated on the disks at a density of 50,000 cells per well in 48-well dishes. After 1 hour, 1 day, 6 days cell numbers were counted. One day, 6 days after plating, alkaline phosphatase(ALPase) activity was determined. Compared to experimental group, the number of cells was significantly higher on control group. The stimulatory effect of surface roughness on ALPase was more pronounced on the experimental group than on control group. These results demonstrate that surface roughness alters proliferation and differentiation of osteoblasts. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells.
Aluminum Oxide ; Cell Count ; Osteoblasts* ; Titanium*

PURPOSE: Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core. MATERIALS AND METHODS: Fifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 microm aluminum oxide particles (Al2O3), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 microm Al2O3 + Al coating and air particle abrasion with 50 microm Al2O3 + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (alpha=.05). RESULTS: The highest bond strengths were obtained by air abrasion with 50 microm Al2O3, the lowest bond strengths were obtained in polishing + Al coating group (P<.05). CONCLUSION: Al and AlN coatings using the reactive magnetron sputtering technique were found to be ineffective to increase the bond strength of adhesive resin cement to zirconia core.
Adhesives ; Aluminum Oxide* ; Collodion ; Resin Cements ; Zirconium