Biomedical subjects

Junji Tagami

Publications and source records attributed to Junji Tagami.

At least 19 recordsLinked to original sources

PubMed2006

Effects of solvent drying time on micro-shear bond strength and mechanical properties of two self-etching adhesive systems.

OBJECTIVES: The all-in-one adhesives are simplified forms of two-step self-etching adhesive systems that must be air dried to remove solvent and water before curing. It was investigated whether those two systems perform equally well and if their performance is affected by air-drying of the solvent containing agent. METHODS: Two adhesive systems (both by Kuraray Medical) were evaluated; Clearfil Tri-S bond (TS) and Clearfil SE bond (SE). Micro-shear bond strengths to human dentin after solvent air-drying times of 2, 5 or 10 s for each group were measured (n=10). The indentation creep and hardness of the bonding layer were also determined for each group. RESULTS: The lowest micro-shear bond strength, nano-indentation hardness and creep stress exponents were obtained for 2 s air dried specimens of each material. After 10 s air blowing, SE showed superior properties compared to TS groups (p<0.05). SIGNIFICANCE: When properly handled, two step self-etching material performs better than the all-in-one adhesive. Air-drying is a crucial step in the application of solvent containing adhesives and may affect the overall clinical performance of them, through changes in the bond strength and altering nano-scale mechanical properties.

Acid Etching, Dental↗

PubMed2006

Effects of storage time and temperature on the properties of two self-etching systems.

OBJECTIVES: To evaluate the micro-shear bond strength to enamel and dentin, pH and hardness of two self-etching adhesives over a period of 60 weeks storage at different temperatures. MATERIALS AND METHODS: Two self-etching systems, an all-in-one adhesive, Clearfil Tri-S Bond (TS) and a two-step adhesive, Clearfil SE Bond (SE) were used in this study (both by Kuraray Medical, Osaka, Japan). Their micro-shear bond strengths to enamel and dentin were measured. The materials were then stored at 4, 23 or 37 degrees C. Their bond strengths were measured again after 1, 4, 16 and 60 weeks and compared to the base line. The nano-indentation hardness of the polymerized bonding, pH of SE primer and TS were also measured at the baseline and after 60 weeks of storage at three different temperatures. Bond-strength and hardness data were analyzed using ANOVA and post hoc tests at the significance level of 0.05. RESULTS: Two-way ANOVA analysis showed that both storage conditions and material type had significant effects on bond strength to enamel or dentin but the interactions of these factors were not significant for any of the substrates. One-way ANOVA post hoc tests revealed that the bond strength of adhesives stored at 37 degrees C significantly decreased during the storage period; with the earliest significant decreases observed at 4 weeks for TS and at 16 weeks for SE. After 60 weeks of storage, the hardness obtained for SE bonding resin was not significantly different with that at the baseline for 4, 23 and 37 degrees C groups, but there was a significant decrease observed in hardness for TS stored at 37 degrees C, compared to that at the baseline. The pH of both self-etching materials decreased when they were stored at 37 degrees C. CONCLUSION: Storage time and temperature significantly affected the bond strength of both materials through the time dependent hydrolysis and other changes that are likely to occur in the water-containing self-etching agents at high temperatures.

Dental Bonding↗

PubMed2006

Effect of simulated pulpal pressure on all-in-one adhesive bond strengths to dentine.

OBJECTIVES: To evaluate the durability of all-in-one adhesive systems bonded to dentine with and without simulated hydrostatic pulpal pressure (PP). METHODS: Flat dentine surfaces of extracted human molars were prepared. Two all-in-one adhesive systems, One-Up Bond F (OBF) (Tokuyama Corp., Tokyo, Japan), and Fluoro Bond Shake One (FBS) (Shofu Co., Kyoto, Japan) were applied to the dentine surfaces under either a PP of 0 or 15cm H(2)O. Then, resin composite build-ups were made. The specimens bonded under pressure were stored in 37 degrees C water for 24h, 1 and 3 months under 15cm H(2)O PP. Specimens not bonded under pressure were stored under zero PP. After storage, the specimens were sectioned into slabs that were trimmed to hourglass shapes and subjected to micro-tensile bond testing (muTBS). The data were analysed using two-way ANOVA and Holm-Sidak HSD multiple comparison tests (alpha=0.05). RESULTS: The muTBS of OBF fell significantly (p<0.05) when PP was applied during bonding and storage, regardless of storage time. In contrast, although the muTBS of OBF specimens bonded and stored without hydrostatic pressure storage fell significantly over the 3 months period, the decrease was less than half as much as specimens stored under PP. In FBS bonded specimens, although there was no significant difference between the muTBS with and without hydrostatic pulpal pressure at 24h, by 1 and 3 months of storage under PP, significant reductions were seen compared with the control group without PP. CONCLUSION: The muTBS of OBF bonded specimens was lowered more by simulated PP than by storage time; specimens bonded with FBS were not sensitive to storage time in the absence of PP, but showed lower bond strengths at 1 and 3 months in the presence of PP.

Composite Resins↗

PubMed2006

Qualitative analysis of adhesive interface nanoleakage using FE-SEM/EDS.

OBJECTIVES: The purpose of this study was to evaluate the quality of short term sealing of current adhesives. METHODS: Five adhesive systems were used and evaluated in this study; two kinds of two-step adhesives (Single Bond and Clearfil SE Bond) and three one-step adhesives (Clearfil S3 Bond, G Bond and One-Up Bond F-plus). Flat occlusal superficial dentin surfaces from extracted human third molars were finished with wet 600-grit silicon-carbide paper and bonded with one of the adhesives. After 24h storage at 37 degrees C in water, the bonded assemblies were sectioned into approximately 1mm thick slabs. Two central slabs from each tooth were chosen and immersed into 50% (w/v) solution of silver ammoniacal nitrate for 18 h and exposed to photodeveloping solution for 6h. The specimens were then slightly polished, argon ion-etched. In order to examine the nanoleakage within the resin/dentin interface, penetration of silver was observed in a field emission (FE)-SEM using yttrium-aluminium-garnet (YAG) backscattered electron mode. EDS analysis was also carried out in parallel to identify the existence of metallic silver particles. RESULTS: The penetration pattern of silver depended on the adhesive used, indicating different nanoleakage in different adhesive systems. Single Bond, One-Up Bond F-plus and G Bond showed clear silver uptake in both the adhesive and hybrid layer. Clearfil SE Bond showed less silver penetration and slight silver peak on the elemental energy spectroscopy of EDS. Clearfil S3 Bond did not display clear silver penetration under 2000x magnification by FE-SEM, and no existence of metallic silver of the Clearfil S3 Bond group by EDS, could be detected. SIGNIFICANCE: The nanoleakage, as well as its location depends on the adhesives. Different nanoleakage expressions were revealed between two-step and one-step adhesives and also among one-step adhesives themselves.

Adhesives↗

PubMed2006

The effects of cavity size and incremental technique on micro-tensile bond strength of resin composite in Class I cavities.

OBJECTIVE: The purpose of this study was to investigate if incremental-filling technique and cavity size would affect the bond strength of resin composite. METHODS: Two sizes of Class I cavities were prepared in bovine dentin (large cavities: pi x (5/2)2 x 5 mm3; small cavity: pi x (3/2)2 x 3 mm3). Light-cure resin composite (Clearfil Photocore) with a self-etching primer adhesive (Clearfil SE Bond) was placed into the cavities by bulk filling (C-factor=5) or incremental filling (two layers, C-factor=3) and light-cured. As a control, 3 or 5mm thick resin composite was bonded to the flat dentin surface. After 24h storage in 37 degrees C water, the micro-tensile bond strength was measured at a crosshead speed of 1mm/min. The results obtained were statistically analyzed using two-way ANOVA and t-test at a significance level of P=0.05. RESULTS: The results obtained showed that there was no significant difference among the filling techniques in small cavities (P>0.05). However, in large cavities, bulk filling presented the lowest bond strength (P<0.05). SIGNIFICANCE: Not only the filling technique affected the bonding strength to the cavity floor, but the cavity size was also an influential factor in Class I cavities.

Adhesives↗

PubMed2006

Quantitative assessment for stimulated saliva flow rate and buffering capacity in relation to different ages.

OBJECTIVES: To evaluate salivary flow rate and buffering capacity using a quantitative pH measurement among three broad age groups. METHODS: The population consisting of 117 patients was classified into three age groups: young, middle-aged, and elderly group. The volume of stimulated saliva after chewing gum was measured. Saliva samples were titrated with 0.1N HCl to evaluate the buffering capacity. Saliva pH change was measured directly using a hand-held pH meter. At the point of 50 microL of titrated HCl, individual salivary buffering capacities were ranked into one of the following three categories; high buffering capacity (above pH 5.5), medium buffering capacity (from pH 5.5 to 4.5), and low buffering capacity (below pH 4.5). RESULTS: Chi(2)-test showed that the proportional distribution of individuals in the three buffering capacity groups was not statistically different among the age groups (p>0.05). One-way ANOVA and Tukey's HSD test showed the flow rate of stimulated whole saliva in the young group was significantly greater than that of the middle-aged and elderly groups (p<0.05). Two-way ANOVA showed there was no significant interaction between the independent variables buffering capacity and age group (F=0.419, p=0.7950). One-way ANOVA and Tukey's HSD test indicated the flow rate showed significant differences among the three age and buffering capacity groups. CONCLUSIONS: Although a limited number of subjects were investigated in this study, the quantitative saliva assessment is useful as a screening method for different ages to identify patients with a low saliva flow rate and/or buffering capacity.

Adult↗

PubMed2006

Mechanical properties and bond strength of dual-cure resin composites to root canal dentin.

OBJECTIVES: To evaluate the regional mechanical properties of dual-cure resin composites and their regional bond strengths to root canal dentin. METHODS: One of the following dual-cure resin composites was placed in artificial post spaces: Unifil Core (UC), Clearfil DC Core (DC), Build-It FR (BI), Clearfil DC Core-automix (DCA), and photo-cured for 60s. After 24h storage, each specimen was serially sliced to harvest eight hour-glass shaped specimens for measurement of regional ultimate tensile strength (UTS), and the remaining eight semi-circular slabs were polished for the measurement of Knoop Hardness Number (KHN). For the microtensile bond strength (muTBS) test, post cavities were prepared in human premolar roots, and the cavity surfaces treated with Clearfil SE Bond and photo-cured for 10s. The post spaces were then filled with one of the above resin composites and photo-cured for 60s. After 24h storage, each specimen was serially sliced into 8, 0.6x0.6 mm-thick beams for the muTBS test. The data were divided into coronal and apical regions and analyzed using ANOVA and post hoc test (alpha=0.05). RESULTS: UTS and KHN were affected by the type of dual-cure resin composite and region (p<0.0001). There was no relationship between UTS and KHN for each material. The auto-mix type of resin composite possessed superior UTS to that of the hand-mix type. muTBS among the four composite materials were not significantly different at both apical and coronal regions (p>0.05). Regional differences in bond strengths were found for all materials (p<0.05). SIGNIFICANCE: The UTS and KHN of the dual-cure resin composites varied among each material, however, differences in the mechanical properties of the resin core materials did not affect their adhesion to root canal dentin.

Composite Resins↗

PubMed2006

Age-related changes in hardness and modulus of elasticity of dentine.

OBJECTIVES: Little knowledge has been clarified about the relationship between the morphological and physical changes of dentine during aging. The purpose of this study was to clarify the modulus of elasticity and hardness related to the morphological changes of dentine by aging using a transmitted light microscope (TLM) and a nano-hardness tester (NHT). METHODS: Aged human molars and young third molars were used. The dentine morphology was observed under a TLM. The hardness and Young's modulus of elasticity related to the morphologic study were evaluated with an NHT. RESULTS: The thickness of mantle dentine and globular dentine of aged teeth were less than that of young teeth. Transparent dentine was observed only underneath the attrition of young teeth. Reactionary tertiary dentine formed and a "dark zone" was found at the junction between physiologic secondary and reactionary dentine only in aged teeth. At the mantle dentine, hardness and modulus of elasticity of aged dentine were higher than those of young dentine. The reactionary dentine in aged teeth and newly developed secondary dentine in young teeth demonstrated lower modulus of elasticity and hardness than those of other circumpulpal dentine. Relatively low modulus of elasticity and hardness were observed at the zone between secondary and reactionary dentine. CONCLUSIONS: Changes in dentine due to aging resulted in transformation of morphological features causing changes to their hardness and modulus of elasticity at the explicit areas such as the increase of hardness and modulus of elasticity at mantle dentin and the reduction of these properties at the "dark zone" that found in aged teeth.

Adolescent↗

PubMed2006

Short- and long-term in vitro study of the bonding of eight commercial adhesives to normal and deproteinized dentin.

OBJECTIVE: The aims of this study were to investigate the influence of deproteinization of dentin on the shear bond strength (SBS) mediated by eight dentin adhesives, and to evaluate the long-term durability of the SBSs. The hypotheses were that deproteinization of dentin would not affect the capacity for adherence, and that in contrast to the SBSs to collagen-rich surfaces, the SBSs to deproteinized surfaces would be stable during a 1-year period of storage in water. MATERIAL AND METHODS: Ground surfaces of human dentin were either rinsed with water (normal dentin) or treated with sodium hypochlorite (deproteinized dentin). The dentin surfaces were analyzed by Fourier transform-infrared spectroscopy (FT-IR) using horizontal attenuated total reflectance (HATR). In addition, the SBS to normal and deproteinized dentin treated with the adhesives was measured after 24 h or 1 year of storage in water. RESULTS: The IR absorption peaks at approximately 1,640, 1,560, and 1,240 cm(-1) were assigned to the collagen matrix and peaks at about 1,000 cm(-1) were assigned to the phosphate group in hydroxyapatite. From the relative magnitude of the peaks, it was determined that the utilized deproteinization method was effective. Furthermore, the normal dentin group showed SBS values ranging from 10 to 39 MPa and the deproteinized dentin group showed SBS values ranging from 13 to 30 MPa. CONCLUSIONS: According to the statistical analysis, the results only partly supported the hypotheses: it was found that the influence on bond strength of deproteinization of dentin surfaces and the effect of 1 year of storage in water depended on the composition of the dentin adhesive.

Acid Etching, Dental↗

PubMed2006

Effect of curing method and storage condition on fluoride ion release from a fluoride-releasing resin cement.

The purpose of this study was to evaluate fluoride ion release from a resin-modified glass ionomer cement (Fuji IILC improved, FLC) and a fluoridated resin cement (Panavia F, PF) following different curing methods and storage conditions. The specimens, which were either light-cured (LC) or chemical-cured (CC), were stored in either distilled water (DW) or demineralizing solution (DS; pH 4.5) for 1, 3, 7, 15, 30, 60, and 90 days. Fluoride ion release was measured using a fluoride ion-specific electrode. Data (n = 5) were statistically analyzed using one- and three-way ANOVA (p = 0.05). A "burst effect" was observed in the first week from both materials. However, fluoride ion release from FLC was seven times higher than that from PF. Storage in demineralizing solution accelerated the amount of fluoride release from both materials. In addition, LC yielded a lower amount of fluoride ion release from both materials, as compared to CC. It was concluded that both curing mode and storage medium influenced the amount of fluoride release from the tested materials.

Analysis of Variance↗

PubMed2006

Effect of resin coating on adhesion of composite crown restoration.

The purpose of this study was to evaluate the effect of a resin coating technique on the microtensile bond strength (microTBS) of resin cement to dentin in composite crown restorations. Crown preparations were done on human molars. A resin coating material, Hybrid Bond, was immediately applied to the prepared dentin and light-cured, while the tooth without resin coating acted as the control. An impression of the resin-coated tooth was taken, and a composite crown fabricated on the working cast. The composite crown was then bonded with a resin cement, Chemiace II. MicroTBSs were measured at a crosshead speed of 1 mm/min, and the resin-coated group yielded significantly higher microTBSs than the non-coated group (p < 0.05). In terms of microTBS values between the axial and occlusal surfaces, no regional differences in resin-dentin bond strength were detected (p < 0.05). It was concluded that resin coating with Hybrid Bond significantly improved the microTBS of resin cement to dentin in composite crown restorations.

Analysis of Variance↗

PubMed2006

Effects of smear layer and surface moisture on dentin bond strength of a waterless all-in-one adhesive.

The purpose of this study was to evaluate the microtensile bond strength (MTBS) of a waterless all-in-one adhesive system, Absolute, to dentin. Eighteen human molars were either ground with 600-grit SiC paper or cut with a diamond bur. The following dentin bonding procedures were then performed: dentin surface was kept moist; dentin surface was dried; or dentin surface was dried but equivalent amount of water was added to the adhesive (1:1 by volume). After adhesive curing, a resin composite was incrementally built up. After the specimens were kept in water for one day, MTBSs were measured at a cross-head speed of 1 mm/min. Two-way ANOVA (p = 0.05) indicated that the MTBS of the adhesive system was not influenced by surface texture, but enhanced by the presence of water on tooth surface. It was concluded that water is essential to obtaining good dentin bonding for this adhesive system.

Analysis of Variance↗

PubMed2006

In vitro pH analysis of active and arrested dentinal caries in extracted human teeth using a micro pH sensor.

The aim of this study was to evaluate the pH at the surface of active or arrested carious dentin using a micro pH sensor, and to compare the relationship between different pH measurement techniques. Twenty extracted carious teeth were divided into two groups, active or arrested caries, according to predefined clinical criteria before extraction. The surface pH values of carious dentin were measured using three methods: surface pH directly measured using a micro pH sensor (Direct); sectioned teeth measured using a pH-imaging microscope (Imaging) or micro pH sensor (Slice). For all techniques, statistically significant differences in pH values were observed between active and arrested dentinal caries (p<0.05). In addition, positive relations between the three pH measurement methods were found. In conclusion, Direct pH measurement using micro pH sensor might assist in caries lesion assessment and clinical treatment based on the concept of Minimal Intervention.

Adult↗

PubMed2006

The effect of bonding system and composite type on adaptation of different C-factor restorations.

This study evaluated the effect of two adhesive systems and four resin-based composites on the marginal sealing and cavity wall adaptation of restorations with different C-factors. Cylindrical cavities, 1 mm deep and 3 mm in diameter (C-factor=2.3) or 2 mm in diameter (C-factor=3), were prepared on superficial bovine dentin surfaces. The teeth were restored with Clearfil SE Bond or Single Bond adhesive system followed by hybrid (Photo Clearfil Bright or Z100) or flowable (Filtek Flow or Estelite LV) resin composite. After thermocycling, a dye penetration test was carried out to evaluate the degree of marginal leakage and cavity-wall gap formation. Cavity-wall gap formation increased when the C-factor increased from 2.3 to 3, except for Estelite LV resin composite. In terms of marginal sealing, Clearfil SE Bond showed better performance than Single Bond. When using Clearfil SE Bond, flowable composites improved resin composite adaptation to the cavity wall compared with hybrid composites.

Acrylic Resins↗

PubMed2006

Effect of incremental filling technique on adhesion of light-cured resin composite to cavity floor.

The purpose of this study was to evaluate the effect of various incremental filling techniques on adhesion between composite and cavity floor using light-cured resin composite. Black ABS resin and hybrid resin composite were used as mold materials--instead of dentin--for the preparation of cavities, and standardized to 5x5x5 mm. Each cavity was then treated with a bonding system (Clearfil SE bond). Resin composite (Clearfil Photo Core) was placed on the bonding resin using different incremental filling techniques or in bulk and irradiated for a total of 80 seconds using a halogen light unit. Specimens were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. Data were analyzed by two-way ANOVA. The results indicated that an incremental filling technique was more effective in improving adhesion to the cavity floor than a bulk filling technique.

Acrylic Resins↗

PubMed2006

Influence of elasticity on gap formation in a lining technique with flowable composite.

The purpose of this study was to investigate the effect of flowable composites as liners for direct composite restorations, with key focus on the elastic moduli of flowable and condensable composites. After treating the composite mold cavity surface with an adhesive system, one of the flowable composites was placed as a 1 mm-thick layer on the cavity floor and irradiated for 20 seconds. The rest of cavity was subsequently filled with a condensable composite and irradiated for 40 seconds. Gap formation at both interfaces--between the cavity floor and flowable composite, and between the flowable and condensable composites--was examined. No gaps were detected at the interface between the cavity floor and flowable composite. Gap percentage at the interface between the flowable and condensable composites was dependent on the difference in elastic modulus. It was concluded that flowable composite with high elastic modulus could inhibit gap formation between flowable and condensable composites.

Acrylic Resins↗

PubMed2006

Evaluation of antibacterial and fluoride-releasing adhesive system on dentin--microtensile bond strength and acid-base challenge.

This study evaluated the influence of a fluoride-containing adhesive on microtensile bond strength (microTBS) to dentin, as well as analyzed the dentin-adhesive interface after acid-base challenge. Experimental groups were: G1--Clearfil SE Bond control (SE); G2--Clearfil Protect Bond control (PB); G3--Primer[SE]/Adhesive[PB]; G4--Primer[PB]/Adhesive[SE]. For microTBS evaluation, dentin surfaces were ground, bonded, and composite resin crowns were built up to obtain beams to be tested. For interfacial analysis, adhesive system was applied on dentin surface and a low-viscosity resin was placed between two dentin disks. Then, the specimens were subjected to acid-base challenge, sectioned, and polished to be observed by SEM. microTBS data showed no statistical differences among the groups (GI: 51.3, G2: 47.6, G3: 55.0, G4: 53.9; mean in MPa). Through SEM, it was observed that a thick acid-base resistant zone adjacent to the hybrid layer was created only when the fluoride-releasing adhesive was used. In conclusion, the presence of fluoride in an adhesive contributed significantly to preventing secondary caries, and did not interfere with dentin-adhesive bond strength.

Adhesives↗

PubMed2006

Retrospective study of five-year clinical performance of direct composite restorations using a self-etching primer adhesive system.

This study was conducted to assess the five-year clinical performance of composite restorations using a self-etching primer adhesive system, Clearfil Liner Bond II. Restorations were rated using the following scale: A--Good; B--Clinically acceptable; C--Clinically unacceptable; or D--Already replaced. The ratings were analyzed using Freedman's test (p=0.01) and Steel-Dwass test (p=0.05). A total of 83 restorations from 36 patients were identified from treatment records. Twenty-six restorations (31.3%) presented A rating and 36 restorations (43.4%) were clinically acceptable (B rating), while five (6.0%) received C rating and 16 (19.3%) had already been replaced (D rating). The mean survival rate of serviceable restorations (i.e., combined A and B ratings) after five years was 74.7%. It was found that cavity form, including cavity size, and occlusal contact seemed to influence longevity.

Acid Etching, Dental↗