Biomedical subjects

M Atsuta

Publications and source records attributed to M Atsuta.

At least 91 records · Page 5Linked to original sources

PubMed1998

A two-stage resin-bonded fixed partial denture seated in conjunction with postextraction healing of the alveolar socket: a clinical report.

A patient treatment modality that involved a two-stage resin-bonded FPD was presented in this clinical report. During recovery of the alveolar socket, a direct bonded acrylic pontic was seated with an adhesive resin (Super-Bond C&B Clear). This primary prosthesis provided service for 6 months without trouble and was effective for maintaining the open space and recovery of oral functions. The secondarily seated resin-bonded FPD, which was made of silver-palladium-copper-gold alloy and bonded with a primer for noble alloys (V-Primer) and an adhesive resin (Super-Bond Opaque), has been functioning satisfactorily for more than 5 years. This two-stage procedure is useful in situations that require conservative or periodontal treatment before seating final prostheses.

Acrylic Resins↗

PubMed1998

Phosphate and thiophosphate primers for bonding prosthodontic luting materials to titanium.

STATEMENT OF PROBLEM: When resin-bonded prostheses are constructed with titanium, they must be strongly bonded with luting materials for the prostheses to withstand the oral environment over the long term. However, limited information is available about the bond durability between luting materials and titanium. PURPOSE: This study determined whether a phosphate and two thiophosphate primers increase bond strength and durability between a commercially available pure titanium and four luting agents. MATERIAL AND METHODS: Three primers and four luting agents were divided into three groups according to the type of acidic monomers: carboxylic acid derivatives (4-META, 4-AET, and MAC10), a phosphoric acid derivative (MDP), and a thiophosphoric acid derivative (MEPS). Disk specimens were bonded with 16 combinations of 3 primers and 4 luting agents, including 4 controls. Shear bond strengths were determined after 1-day immersion in water and after thermocycling for 100,000 cycles. RESULTS: Bond strengths were influenced by thermocycling, primer, luting agent, and their combinations. After thermocycling, the groups that demonstrated the highest bond strengths were six combinations of two primers (Cesead Opaque Primer and Metal Primer II) and three luting agents (Imperva Dual, Panavia 21, and Super-Bond C&B).

Analysis of Variance↗

PubMed1998

Effect of ceramic surface treatments on the bond of four resin luting agents to a ceramic material.

PURPOSE: This study evaluated the effect of various ceramic surface treatments on the shear bond strengths of four resin luting agents to Cerec 2 ceramic material. MATERIAL AND METHODS: Four ceramic surface treatments were performed. All groups were subjected to the control treatment, which was abrasion with No. 600 silicon carbide paper. The other three group treatments were etching with phosphoric acid gel, application of bonding agent containing silane coupler, and application of silane coupling agent after etching with phosphoric acid gel. Cerec 2 ceramic specimens were treated with one of the four methods and then cemented together with each of the four resin luting agents (Super-Bond C&B, Panavia 21, Clapearl, and Vita Cerec Duo Cement). Half of the specimens were stored in water and the other half were thermal cycled before shear bond strength testing. RESULTS: Treatment with the silane coupler improved the shear bond strength compared only with the abrasion with carbide paper (control). When the ceramic material was treated with the silane coupler or the silane coupling agent after etching with phosphoric acid gel, no significant differences in bond strength were noted between water storage and 20,000 thermal cycles for any of the four resin luting agents. After 20,000 thermal cycles, all specimens treated with the silane coupling agent with phosphoric acid gel except those cemented with Super-Bond C&B resin luting agent after etching showed cohesive failures within the ceramic. CONCLUSION: Combined surface treatment of etching with phosphoric acid and application of silane coupling agent provides the highest bond strengths of resin luting agents to Cerec 2 ceramic material after thermal cycling.

Acid Etching, Dental↗

PubMed1998

Adhesive bonding to dentin with iron (II) perchlorate primers and a tri-n-butylborane-initiated luting agent.

OBJECTIVES: This study was conducted to measure the tensile bond strength of a resin to dentin when the dentin was primed with iron (II) perchlorate modified aqueous 2-hydroxyethyl methacrylate (HEMA) or an iron (II) perchlorate modified commercial self-etching primer (ED primer, Kuraray Co.). METHODS: Bovine dentin surfaces were ground flat and each specimen underwent one of the following two treatments: (1) priming with 2.0 x 10(-6) to 5.0 x 10(-4) mol/g iron (II) perchlorate in aqueous HEMA solutions after etching with 10 wt% phosphoric acid; (2) priming with self-etching primers containing 4.0 x 10(-7) to 2.0 x 10(-4) mol/g iron (II) perchlorate. Each specimen was then bonded to a stainless-steel rod with a luting agent (MMA-TBB resin) consisting of methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), and tri-n-butylborane (TBB) initiator. Tensile strengths of the bonded tooth specimens were then determined after 1 day immersion in water. Results were analyzed using ANOVA and Duncan's new multiple range test (p < 0.05). RESULTS: Tensile testing revealed the maximum mean bond strengths (22.5 MPa) when the dentin was primed with 2.0 x 10(-4) mol/g iron (II) perchlorate after etching with 10 wt% phosphoric acid aqueous solution. The highest level of bond strength with self-etching primer (19.6 MPa) was achieved using 1.0 x 10(-4) mol/g iron (II) perchlorate. SIGNIFICANCE: These bonding techniques, combining the use of iron (II) perchlorate modified HEMA primers with MMA-TBB resin, are potentially applicable for seating resin-bonded restorations.

Adhesiveness↗

PubMed1998

Influence of surface oxidation of titanium on adhesion.

OBJECTIVES: The adhesive bonding of titanium was investigated using a methacrylate-phosphate primer and a luting agent. The present study investigates the influence of heat oxidation as well as a suitable durable bonding method for treating the surface of titanium. METHODS: Two groups of disc specimens were fabricated by milling and casting, respectively. Machine-milled specimens were subjected to heat treatment, and three groups of cast metal specimens underwent following respective treatments: (1) as-cast, (2) emery-polishing, (3) alumina-blasting after emery-polishing. The primer contained 10-methacryloyloxydecyl dihydrogen phosphate (MDP); the luting agent was based on methyl methacrylate (MMA), and was initiated with tri-n-butylborane derivative (TBB). Each specimen was primed and bonded to an acrylic rod. Shear bond strengths were determined before and after thermocycling. RESULTS: The mean bond strength of the machine-milled emery-polished group was 32.5 MPa after 5000 thermocycles with only a slight decrease in bond strength. A decrease in the bond strength occurred when the heat-treatment temperature was above 400 degrees C. Although both emery-polishing and alumina-blasting were effective, the minimum decrease in bond strength was obtained with alumina-blasting. CONCLUSIONS: The excess surface oxide layer may be of great concern as a possible cause of decreased bonding durability. Sufficient bonding durability for clinical use was obtained when the titanium was alumina-blasted.

Adhesiveness↗

PubMed1998

Effect of different etching periods on the bond strength of a composite resin to a machinable porcelain.

OBJECTIVES: The purpose of this study was to evaluate microstructure changes of Cerec 2 Vitablocs Mark II porcelain etched by a 5% hydrofluoric acid and examine the effect of different etching times on the bond strength between the porcelain and a composite resin. METHODS: Six different etching times (0, 5, 30, 60, 120 and 180 s) were used to etch the surfaces of the porcelain, respectively. Etched relief patterns were observed by means of a scanning electron microscope and the bond strength was determined between a dual-cured composite luting agent and the porcelain. RESULTS: The results showed that composite resin did not bond to unetched porcelain but bonded to etched porcelain, the 120 s etch giving the highest bond strength. CONCLUSION: The bond strength values corresponded well to the microstructure changes caused by etching.

Acid Etching, Dental↗

PubMed1998

Spectroscopic studies of three osseointegrated implants.

OBJECTIVES: The purpose of this study was to investigate the surface characteristics of titanium implants. METHODS: The chemical state of the surfaces of three types of osseointegrated titanium implant, Brånemark (Nobelpharma, Göteborg, Sweden), IMZ (Friatec, Mannheim, Germany) and ITI-Bonefit (Straumann, Waldenburg, Switzerland), were analysed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). RESULTS: The outermost layers of the implants investigated were speculated to be TiO2. In the Brånemark implants pure titanium was found under the TiO2 layer. By contrast, in the IMZ and ITI-Bonefit implants which are titanium plasma spray coated, oxygen atoms were observed at considerable depths by AES, and the material under the TiO2 layer showed a chemical shift by XPS. Furthermore, shifted peaks were not of pure titanium or of titanium oxide. CONCLUSION: The three titanium implants investigated were found to have different surface characteristics when examined by spectroscopy. As these implants show similar osseointegration it is suggested that they may be found to interact differently with vital bone.

Biocompatible Materials↗

PubMed1998

Metal chloride primers for bonding dentine with tri-n-butylborane-initiated luting agents.

OBJECTIVES: The bonding of resin to dentine is dependent largely on surface modifications. The purpose of the present study was to test the hypothesis that a role of the metal chlorides used as primers is to initiate polymerization of resin at the resin-dentine interface, thereby affecting bond strength. METHODS: Nine primers were evaluated, comprising aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing AICl3, CeCl3, CoCl2, CuCl2, FeCl3, NiCl2, MgCl2, SnCl2 or ZnCl2, respectively. One of the two luting agents (Super-Bond resin) consisted of methyl methacrylate (MMA), 4-methacryloyloxyethyl trimellitate anhydride (4-META) and tri-n-butylborane (TBB) initiator. The other luting agent (MMA-TBB resin) consisted of MMA and TBB without 4-META. Extracted bovine teeth were ground to expose the dentine, etched with an aqueous solution of 10% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1-day immersion in water. Data were analysed by ANOVA and Duncan's new multiple range test (P < 0.05). RESULTS: Four of the metal chlorides (CuCl2, FeCl3, MgCl2 and ZnCl2) enhanced the bond strengths of MMA-TBB resin to dentine. With Super-Bond resin, maximum bond strengths of 15.6 MPa and 19.0 MPa were recorded with primer containing 2.0 x 10(-5) mol g(-1) FeCl3 and 2.0 x 10(-6) mol g(-1) CuCl2, respectively. CONCLUSIONS: Bonding techniques, combining the use of either cupric primer or ferric primer with 10% phosphoric acid etchant may be suitable for application in seating resin-bonded prostheses with TBB-initiated luting materials.

Acid Etching, Dental↗

PubMed1998

Use of 2-isocyanatoethyl methacrylate and iron (II) perchlorate for bonding tri-n-butylborane-initiated luting agents to dentin.

The present study investigated the effect of 2-isocyanatoethyl methacrylate (IEM) and iron (II) perchlorate on dentin adhesion. Four primers were evaluated, consisting of aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing 5, 10, 20 or 50 micromol/g iron (II) perchlorate. Five luting agents were prepared with methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), tri-n-butylborane (TBB) initiator and IEM. The concentrations of IEM in the luting agents were 0.2, 0.4, 0.8, 2.0 and 4.0 wt%. Extracted bovine teeth were ground to expose the dentin, etched with an aqueous solution of 10 wt% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1 d immersion in water. The highest bond strength (20.7 MPa) was recorded for the group using 10 micromol/g iron (II) perchlorate and 2.0 wt% IEM. The use of IEM was effective in decreasing the optimal concentration of iron (II) perchlorate, and this may contribute to the color stability of iron-containing pretreatment agents.

Acid Etching, Dental↗

PubMed1998

Curing depth of a composite veneering material polymerized with seven different laboratory photo-curing units.

Properties of laboratory-cured composite materials are affected by the type of activation system as well as by the photo-curing unit light source. This study examined curing depth of a composite veneering material polymerized by means of various photo-curing units with the aim of evaluating the curing performance of the light sources. A microfilled composite material designed for prosthetic veneer was cured with seven photo-curing units. The light sources of the units were halogen/fluorescent, xenon, metal halide, fluorescent, halogen, halogen and mercury lamps. Exposure periods were 20, 30, 60 and 90 s. The curing depth of the material was determined using the method described by the International Organization for Standardization (ISO 4049). Two-factor analysis of variance revealed that the depth of cure was influenced both by the type of curing unit and by the exposure period (P = 0.0001). Among the seven photo-curing units, a metal halide curing unit consistently exhibited the greatest depth of cure. For all units, longer exposure increased the depth of cure.

Analysis of Variance↗

PubMed1998

Properties of four composite veneering materials polymerized with different laboratory photo-curing units.

This study examined properties of four composite veneering materials polymerized with two different photo-curing units for the purpose of evaluating curing performance of the combination of composite material and curing unit. Two microfilled (Dentacolor and Thermoresin LC II) and two hybrid (Cesead II and Solidex) composite materials designed for prosthetic veneer were selected. The respective light sources of the units were a xenon (Dentacolor XS) and a metal halide (Hyper L II) lamp. The composite materials were exposed with the photo-curing unit for 60 s on each side (i.e. from top and bottom). Knoop hardness, compressive strength, flexural strength, flexural modulus, water absorption and water solubility were determined according to standardized testing methods. The specimens exposed with the metal halide unit generally exhibited greater Knoop hardness number, and compressive strength and lower solubility than those exposed with the xenon unit. A microfilled material (Thermoresin LC II) cured with the metal halide unit exhibited significantly improved results for all tests as compared with the same material cured with the xenon unit.

Absorption↗

PubMed1998

Curing depth of four composite veneering materials polymerized with different laboratory photo-curing units.

Post-curing properties of composite materials are influenced by the type of base monomer, activation system, filler content, and also by the type of light source employed. This study examined curing depth of four composite veneering materials polymerized by means of two different high-intensity photo-curing units for the purpose of evaluating the curing performance of the combinations of composite material and photo-curing unit. Two microfilled and two hybrid composite materials designed for prosthetic veneer were assessed. The composite materials were cured using two photo-curing units, one with a xenon light source and one with two metal halide light sources, and exposure periods varied from 20 to 90 s. Curing depth of the materials was determined with a scraping technique described by the International Organization for Standardization (ISO 4049). Three-factor analysis of variance revealed that the depth of cure was influenced by the type of composite material as well as by the photo-curing unit, and also by the exposure period (P = 0.0001). A microfilled composite material (Dentacolor) demonstrated the greatest depth of cure (4.69 mm) after 90 s irradiation with a metal halide unit (Hyper LII). Of the two photo-curing units, the metal halide curing unit consistently exhibited greater depth of cure than the xenon curing unit (Dentacolor XS). Longer exposure increased the depth of cure for all combinations.

Analysis of Variance↗

PubMed1998

In-vitro solubility of three types of resin and conventional luting cements.

The solubility of resin luting cement remains unknown although the use of resin luting cement for routine cementation of restorations has increased. The purpose of this in-vitro study was to compare the solubilities of three resin cements currently in clinical use with three brands of conventional luting agents. The three resin luting cements, All-Bond C&B (AB, Bisco) Panavia 21 (P21, Kuraray), and Super-Bond C&B (SB, Sun-Medical), and the three conventional luting agents, Elite Cement 100 (EC, zinc phosphate cement, GC), HY-Bond Carbo-plus Cement (HCP, polycarboxylate cement, Shofu), and Fuji I (FI, glass-ionomer cement, GC) were used in this study. A modification of the ADA specification test was adopted to evaluate the solubilities of luting cements. The two types of media (distilled water and pH 4.0 lactic acid solution) in which specimens were stored for 30 days were prepared. The four luting cements, EC, FI, AB, and P21, were more soluble in lactic acid solution than in distilled water. Resin luting cements were markedly less soluble than conventional luting agents when placed in fresh lactic acid solution (0.001 mol/L) at pH 4.0 every 24 h over a 30-day period. The solubility rates of luting cements could be fitted to mathematical expressions which indicated that the solubilities increased linearly or logarithmically with immersion period. Fixed prosthodontic restorations cemented with resin luting cement may be capable of withstanding long-term clinical use compared with conventional luting agents.

American Dental Association↗

PubMed1998

The influence of ultraviolet radiation intensity on curing depth of photo-activated composite veneering materials.

Light intensity and wavelength distribution affect post-cure properties of photo-activated composite materials. This study examined curing depth of composite veneering materials polymerized with a laboratory photo-curing unit for the purpose of evaluating the influence of ultraviolet radiation (UV) intensity on depth of cure. Three microfilled composite materials designed for prosthetic veneer were assessed. Two materials (Axis and Thermoresin LC II) were activated by both UV and visible radiation, whereas the other material (Dentacolor) was activated substantially by visible light. The light source of the photo-curing unit was a metal-halide lamp that radiates both UV and visible light. The unit was equipped with a removable UV-elimination filter capable of reducing the UV intensity from 1014.0 mW/cm2 to 574.0 mW/cm2. Each of the three materials was cured with the photo-curing unit for durations of 20, 30, 60 and 90 s both with and without the filter. The depth of cure of the materials was determined using a scraping technique described by the International Organization for Standardization (ISO 4049). Three-factor analysis of variance revealed that the depth of cure was influenced by the type of composite material, by the exposure period and also by the use of the filter (P < 0.01). Curing depth of one material (Thermoresin LC II) was significantly greater when the material was exposed without the filter than when the material was exposed through the filter. Among the three materials, the Axis composite demonstrated the greatest depth of cure regardless of exposure time period or filter use.

Analysis of Variance↗

PubMed1997

Effects of adhesive primers for noble metals on shear bond strengths of resin cements.

OBJECTIVES: The purpose of this study was to evaluate the durability and shear bond strengths of the different combinations of two adhesive primers and three resin cements to two types of noble metal alloys, silver-palladium copper-gold and type IV gold alloys. METHODS: The adhesive luting agents Imperva Dual, Panavia 21 and Super-Bond C&B, and the adhesive primers Metal Primer and V-Primer were used. Two sizes of casting alloy disks were nonprimed or primed and cemented with each adhesive luting agent. The specimens were stored in 37 degrees C water for one day and then immersed alternately in 4 degrees C and 60 degrees C water baths for 1 min each for up to 100,000 thermal cycles before shear mode testing at a cross-head speed of 0.5 mm/min. RESULTS: The application of Metal Primer was effective for improving the shear bond strengths between each of the three resin cements and both noble metal alloys compared with nonprimed specimens. When each noble metal alloy was cemented with Super-Bond C&B, there were no significant differences between the bond strengths with the use of Metal Primer and those with the use of V-Primer at 100,000 thermal cycles. However, V-Primer was ineffective for enhancing the shear bond strengths of Imperva Dual and Panavia 21 to noble metals. CONCLUSION: Metal Primer and V-Primer are clinically useful for strongly bonding adhesive resin cements to noble metal alloys.

Analysis of Variance↗

PubMed1997

Tensile strength of soldered gold alloy joints.

STATEMENT OF PROBLEM: Little information is available about the mechanical properties of soldered gold alloys after they have undergone various heat treatments. PURPOSE: This study investigated the influence of heat treating on the strength properties of soldered joints of two gold alloys (NC Type IV and Sofard), which can be age-hardened at intraoral temperature. MATERIAL AND METHODS: Dumbbell-shaped specimens were cast with each gold alloy and were cut at the center of the connecting bar for soldering. The two halves of the casting were then soldered with two different gold-based solders (Maingold and Degulor). Three different heat treatments were performed on the soldered gold alloy assemblies: solution heat treatment (ST) at 700 degrees C for 5 minutes (treatment A); aging at 37 degrees C for 7 days after ST (treatment B); and aging at 250 degrees C (Sofard) or 400 degrees C (NC type IV) for 15 minutes after ST (treatment C). The tensile strength, elongation and microhardness were evaluated after each heat treatment. RESULTS: The hardness values of Sofard significantly (p < 0.05) increased during aging at 37 degrees C (treatment B) and produced adequate strengths of the soldered joints, especially with the harder solder (645.7 MPa: Degulor [222 VHN] vs. 493.3 MPa: Maingold [165 VHN]). CONCLUSIONS: The results of this study indicated the possibility of strengthening soldered joints in the oral environment, thus eliminating the necessity for any additional hardening heat treatment.

Analysis of Variance↗

PubMed1997

Shear bond strength to feldspathic porcelain of two luting cements in combination with three surface treatments.

STATEMENT OF PROBLEM: Although selection of clinically reliable bonding system is essential, limited information concerning the combination of durable ceramic bonding and luting agents is available. PURPOSE: This in vitro study was conducted for the purpose of evaluating bond strengths of ceramic bonding materials in conjunction with their initiation and silane-activation modes. MATERIAL AND METHODS: Disk-shaped fired porcelain specimens were air-abraded with alumina, then bonded with six combinations of three silane priming and two luting agents; specimens were also bonded with two luting cements without priming. Shear bond strengths were determined both before and after thermocycling. RESULTS: For the two unprimed control groups, as well as two of the groups bonded with Panavia 21 cement (Clearfil Porcelain Bond and Panavia 21; Panavia Ceramic Primer and Panavia 21) the reduction in bond strengths after thermocycling was remarkable as compared with the corresponding prethermocycling groups (p < 0.05). A dual-cured luting cement (Clapearl DC) used with each of three silane priming materials (Clapearl Bonding Agent, Clearfil Porcelain Bond, and Panavia Ceramic Primer) exhibited consistent shear bond strength greater than 30 MPa after 20,000 thermocycles. CONCLUSION: The above three systems appeared to be useful for the long-term clinical success of feldspathic porcelain restorations.

Air↗

PubMed1997

Effects of adhesive primers on bond strength of self-curing resin to cobalt-chromium alloy.

PURPOSE: This study evaluated the effects of four adhesive primers on the shear bond strength of a self curing resin to cobalt-chromium alloy. MATERIAL AND METHODS: The adhesive primers Acryl Bond (AB), Cesead Opaque Primer (COP), Metal Primer II (MPII), and MR Bond (MRB) were used. A brass ring placed over the casting alloy disk surface nonprimed or primed with each primer was filled with the self-curing methyl methacrylate polymethyl methacrylate resin. The specimens were stored in water at 37 degrees C for 24 hours and then alternately immersed in water baths at 4 degrees C and 60 degrees C for 1 minute each for up to 20,000 thermal cycles before shear mode testing at a crosshead speed of 0.5 mm/min. RESULTS: All the primers examined improved the shear bond strength between the resin and cobalt chromium alloy compared with nonprimed specimens before thermal cycling. However, after 20,000 thermal cycles, the bond strengths of resin to cobalt chromium alloy primed with COP or MPII primers were significantly greater than those of specimens primed with AB or MRB primers and nonprimed controls. CONCLUSION: This study indicated that COP and MPII are effective primers to obtain higher bond strength between resin and cobalt-chromium alloy.

Adhesives↗