Biomedical subjects

Junji Tagami

Publications and source records attributed to Junji Tagami.

At least 55 records · Page 3Linked to original sources

PubMed2005

Shear bond strengths of indirect resin composites to hybrid ceramic.

A hybrid ceramic, Estenia, is a highly-filled composite for indrect use. The purpose of this study was to measure the shear bond strength between Estenia and six incremental materials: Estenia, Cesead II, Epricord, Gradia, Prossimo, and Solidex. Five specimens were prepared for each group, and all specimens were subjected to shear bond strength testing at a cross-head speed of 1 mm/min. Data were analyzed using two-way ANOVA and Dunnett's T3 test at 95% confidence level. The results indicated that the shear bond strength of Estenia to Estenia was significantly lower than that of any other combinations. Apart from storage condition that was found to influence shear bond strength statistically, thermal cycling of the specimens also tended to decrease the bond strength between Estenia and the incremental materials. It was concluded that regularly-filled composites are suitable to be used as an incremental material facing Estenia in combination technique.

Analysis of Variance↗

PubMed2005

Regional bond strength of four self-etching primer/adhesive systems to root canal dentin.

The purpose of this study was to evaluate the regional bond strength of a dual-cure resin core material to root canal dentin using four self-etching primer/adhesive systems. Post spaces were prepared in extracted premolars, and their root canal dentin was treated with one of the following self-etching primer/adhesive systems: ED Primer II and Clearfil Photobond, photo-cure/dual-cure systems of Clearfil Liner Bond 2V, or Clearfil SE Bond. Post spaces were filled with the dual-cure resin core material, and microtensile bond strength (microTBS) at the coronal and apical regions was measured after 24-hour storage. There were no regional differences in microTBS of the photo-cure and dual-cure systems of Clearfil Liner Bond 2V, while microTBS at the coronal region of Photobond and SE Bond groups were higher than those at the apical region. At the apical region, photo-cured Clearfil Liner Bond 2V exhibited significantly higher bond strength than those of the other systems.

Adolescent↗

PubMed2005

Effect of air-powder polishing on dentin adhesion of a self-etching primer bonding system.

The purpose of this study was to evaluate the effect of air-powder polishing with sodium bicarbonate (SB) or crystalline cellulose (CC) on the bond strength of a self-etching primer bonding system to dentin. Ground human dentin surfaces were prepared using 600-grit SiC paper. The teeth were divided into three groups according to dentin treatment: control, air-powder polishing with SB, and air-powder polishing with CC. The dentin surfaces were bonded with a self-etching primer bonding system, followed by a light-cured resin composite. microTBS test and SEM analysis were performed. The results of microTBS test indicated that air-powder polishing with SB affected bond strength to dentin, while that with CC did not influence bond strength. SEM observation of air-polished dentin surfaces showed that dentin surfaces air-polished with SB were roughened and covered with a smear layer, while those with CC were smooth and the smear layer was removed.

Air Abrasion, Dental↗

PubMed2005

Hardness and Young's modulus of transparent dentin associated with aging and carious disease.

This study investigated the changes in hardness and Young's modulus of the transparent layer of dentin associated with aging and the carious process. Eighteen extracted human molars with or without coronal caries were used in this study. The normal teeth were divided into two groups by age, and the carious teeth were divided into two groups of active or arrested caries. After polishing the specimens parallel to the long axis of the tooth, both hardness and Young's modulus were measured using a nanoindentation tester. The hardness and Young's modulus of the transparent layer in aged dentin were higher than the other portions of aged dentin. The transparent layer under carious lesions had a significantly lower hardness than the underlying normal dentin, whereas its Young's modulus was not significantly reduced. The hardness and Young's modulus of the transparent layer in active carious lesions were lower than those in arrested carious lesions.

Aging↗

PubMed2005

Influence of curing method and storage condition on microhardness of dual-cure resin cements.

This study evaluated the influence of curing method and storage condition on the microhardness of dual-cure resin cements: Panavia F 2.0 (PF) and Nexus 2 (NX). The specimens were either light-cured (LC) or chemically cured in darkness (CC). After 24 hours of storage in dry chamber (Dry) or distilled water (DW), the specimens were sectioned and polished. The microhardness of resin cement matrix was measured using a nanoindentation tester (ENT-1100). The data (n = 6) were statistically analyzed with t-test, two-way ANOVA (p < 0.05), and Tukey HSD test (alpha = .05). It was found that the factors of curing method and storage condition had significant effect on microhardness. For both PF and NX, LC presented higher microhardness than CC, while DW showed higher microhardness than Dry. In conclusion, dual-cure resin cements could achieve high degree of cure when light-cured. In addition, the microhardness of the resin cements evaluated did not decrease when kept in water.

Analysis of Variance↗

PubMed2005

Effect of various grit burs on marginal integrity of resin composite restorations.

The purpose of this study was to evaluate the generation of enamel cracks and gaps at the cavosurface margin of resin composite restorations using various burs. Saucer-shaped cavities with a bevel were prepared on mid-coronal buccal or lingual surfaces of extracted human molars using a regular-grit round diamond bur, a fine-grit diamond bur, a superfine-grit diamond bur or a six-bladed tungsten carbide bur with an air turbine handpiece. The enamel margin of the cavity in each group was observed by a light microscope. Cavities were restored with a self-etching adhesive and a light-cured composite resin. After thermocycling, enamel cracks and gaps at the cavosurface margins were observed and scored. Specimens were sectioned longitudinally in two halves, and the resin-cavity interface was observed by means of a light microscope. In cavity preparation, the regular-grid diamond bur and the tungsten carbide bur caused more cracks in the marginal enamel than other groups. From the surface and sectioned surface observation of restored teeth, the superfine-grit diamond bur generated fewer cracks and gaps than the other burs.

Analysis of Variance↗

PubMed2005

Simplified and quantitative saliva buffer capacity test using a hand-held pH meter.

PURPOSE: To evaluate and compare saliva buffer capacity using a hand-held pH meter and a commercial buffer strip in patients at risk of caries. METHODS: To obtain stimulated saliva, 109 patients were given a paraffin wax to chew for 5 minutes. After reading the pH value of 0.5 ml of tested saliva using a portable hand-held pH meter (B-212), 10 microl of 0.1N HCl was titrated into the obtained saliva up to a total titration of 160 microl, and then the pH value read each time. The commercial buffer strip (CRT) was also evaluated. The correlation in ranking results (high, medium, low) between the B-212 pH meter and CRT buffer were statistically analyzed by the Bartlett's test (P < 0.001). RESULTS: At the point of 50 microd of titrated HCl, the individual saliva buffer capacities were ranked into one of the following three categories; high (above pH 5.5), medium (pH from 5.5 to 4.5) and low (below pH 4.5). The percentages of the tested patients for the different ranks (high, medium, low) of buffer capacity were 50%, 17% and 33% respectively for the B-212 pH meter, and 56%, 17% and 27% respectively for the CRT. For the CRT buffer, 23 out of 109 cases showed inconclusive color change under the colorimetric test. There was significant correlation between ranking buffer capacity measured by the B-212 pH meter and the CRT buffer (P < 0.001).

Adult↗

PubMed2005

Bonding of resin to artificially carious dentin.

PURPOSE: To evaluate the bond strength of adhesive resins to artificially carious dentin specimens which were previously exposed to an acid buffer solution for various periods. MATERIALS AND METHODS: Flat dentin disks were obtained from superficial occlusal dentin of extracted human third molars and polished with wet silicon carbide paper. Dentin disks were immersed in acid buffer solution for different periods to create the demineralized dentin layer. The first group of demineralized specimens was used for the evaluation of demineralization depth under SEM and the second group was used for the bond strength measurement. Shear bond strengths mediated by three dentin adhesives (Clearfil SE Bond, OptiBond Solo Plus Total-Etch, and OptiBond Solo Plus Self-Etch) were examined. A 0.75-mm-diameter area of dentin was bonded according to the manufacturers' instructions before placing a 0.5-mm-high resin composite cylinder. The bonds were stressed in shear at a crosshead speed of 1 mm/min. All data were analyzed using ANOVA and LSD multiple comparison test. RESULTS: Depth of demineralization increased with the prolongation of demineralizing time. After dentin specimens were demineralized for up to 24 h, bond strengths of the self-etching adhesives were significantly higher than those of the total-etch adhesive. However, for longer demineralization periods, no statistical differences in bond strengths were observed. SEM photographs showed that resins cannot thoroughly infiltrate through the whole depth of the demineralized dentin layer. CONCLUSION: Bond strengths to demineralized, artificially carious dentin were affected by the depth of demineralization and adhesive resins used.

Adhesives↗

PubMed2005

Effect of a fluoride-releasing one-step adhesive system on monkey pulp tissue.

PURPOSE: The purpose of this study was to evaluate the pulpal response of a fluoride-releasing one-step adhesive in nonexposed monkey teeth. MATERIALS AND METHODS: Cervical Class V cavities were prepared in monkey teeth. The cavities were divided into three groups of different restorative materials. A one-step adhesive (SI-IB551, Shofu) was applied to the teeth, and the cavities were filled with a resin composite (Beautifil, Shofu). In the other two groups, a two-step adhesive (Imperva FluoroBond, Shofu) together with either a resin composite (Beautifil) or a glass-ionomer cement (Fuji II, GC) was placed in the cavities. The teeth were then extracted after 3, 30, and 90 days, fixed in 10% buffered formalin solution, and prepared according to routine histological techniques. Five-micrometer sections were stained with hematoxylin and eosin, or Brown & Brenn gram stain for bacterial observation. Four histological features, odontoblastic change, inflammatory cell infiltrate, reparative dentin formation, and the bacterial staining, were evaluated and compared. The results were compared statistically with significance defined as p < 0.05 (Kruskall-Wallis test). RESULTS: Disarrangement of the odontoblasts and slight inflammatory cell infiltrations were the main initial reactions, while deposition of reparative dentin was the major long-term reaction in all groups. No statistically significant differences in the four histological features were seen among the restorative materials placed in the cavities (p > 0.05). No serious pulpal inflammatory reactions, such as necrosis or abscess formation, were observed in any of the experimental groups. CONCLUSION: The one-step adhesive showed acceptable biological compatibility with the monkey pulp, whereas the pulpal response to the system was minimally different from that of the glass-ionomer cement or the two-step self-etching adhesive.

Animals↗

PubMed2005

Monkey pulpal response to an MMA-based resin cement as adhesive luting for indirect restorations.

PURPOSE: The objective of this study was to evaluate the pulpal response to a newly-developed MMA resin cement (MultiBond, Tokuyama) when used for adhesively luting composite resin inlays. MATERIALS AND METHODS: Cervical cavities were prepared in monkey teeth. The teeth were randomly divided into 3 groups. In the experimental group, a self-etching primer and a resin cement were applied to the cavities, and then hybrid composite inlays (Estenia, Kuraray) were inserted using freshly mixed resin cement. In the other groups, a zinc oxide/eugenol cement (Eugedain, Showa Yakuhin Kakou) or a glass-ionomer cement (Fuji II, GC) was used to fill the cavity. The teeth were then extracted after 3, 30, and 90 days, fixed in 10% buffered formalin solution, and prepared using routine histological techniques. Five-mum-thick sections were stained with hematoxylin and eosin, or Brown & Brenn gram stain for bacterial observation. Histopathological reactions in the pulp tissue and bacterial penetration along the cavity walls were assessed using a standardized score. RESULTS: No serious inflammatory reactions in the pulp, such as necrosis or abscess formation, were observed in any of the experimental periods, except for 1 case after 30 days, in which a pulpal exposure was suspected. Disarrangement of the odontoblast layer and deposition of reparative dentin were the major reactions observed in this specimen. No bacterial penetration along the cavity walls was detected. The monkey pulpal response and in vivo sealing ability of the MMA resin cement in combination with the self-etching primer was considered as good as that of the glass-ionomer cement. CONCLUSION: The new MMA resin cement showed acceptable biological compatibility to the monkey pulp when used to adhesively lute composite resin inlays.

Acrylic Resins↗

PubMed2005

Influence of cavity configuration on the adhesion of two resin-based composites to pulpal floor dentin.

PURPOSE: To evaluate the effect of cavity configuration on microtensile bond strengths of two resin composites for core build-up to pulpal floor dentin. METHODS: Access cavity preparation and root canal filling with gutta percha were performed on extracted human molars. Following this, the gutta percha in the pulp chamber was completely removed to expose pulpal floor dentin. The cavity walls remained as a control group (Cavity). For another group, the cavity walls were removed to create a flat surface for bonding (Flat). For the Cavity group, Clearfil SE Bond was applied to the cavity according to the manufacturer's instructions, and either a light-cured resin composite (PH, Clearfil Photo Core) or a dual-cured resin composite (DC, Clearfil DC Core), was placed in the bonded cavity. Clearfil Photo Core was placed in three increments while bulk-filling was used for Clearfil DC Core. The application of the bonding system and the composites to the flat dentin surface was the same as that for cavity. Specimens were stored in water for 1 week, then sectioned vertically into 2 or 3 slabs (0.7 mm thick) and trimmed for the microtensile bond strength (MTBS) test. The MTBSs were measured with a universal testing machine at a crosshead speed of 1.0 mm/minute. RESULTS: The results (mean +/- SD, MPa, n=10) of PH/Cavity, PH/Flat and DC/Flat were 21.9 +/- 3.4, 28.9 +/- 4.0, and 27.6 +/- 6.1 respectively. The MTBS could not be determined in DC/Cavity because of debonding occurred during sample preparation.

Analysis of Variance↗

PubMed2005

Confocal laser scanning microscopic observations of secondary caries inhibition around different types of luting cements.

PURPOSE: To analyze in vitro artificial secondary caries inhibition around conventional luting cements and resin cements using a confocal laser-scanning microscope (CLSM). METHODS: Box shape cavities (approximately 3 mm long, 4 mm wide, and 1.5 mm deep) were prepared in bovine root dentin. One of five cements: Elite Cement 100 (EL) zinc phosphate cement, HY-Bond Carbo Cement (CA) polycarboxylate cement, Fuji I (FI) glass-ionomer cement, Fuji Luting (FL) GIC-based resin cement and Panavia F (PA) fluoride-releasing resin cement, was placed in the cavity. After polishing, the center of the cement surface was covered with an adhesive to preserve the original cement solubility. The specimens were stored in distilled water at 37 degrees C for 1 week, and stored in an artificial demineralizing solution for 3.5 days. Following this, each specimen was sectioned into two halves, trimmed, and polished. Thickness of inhibition zone, depth of outer lesion and cement solubility around each cement were determined by a CLSM. RESULTS: Inhibition zones were not seen in EL and CA, while they were found in FI, FL and PA. The depths of the outer lesions of CA and FI were significantly lower than those of EL, FL and PA (P< 0.05). The highest and the second-highest cement solubility were obtained in EL and CA, respectively. FI and FL indicated significantly lower cement solubility than EL and CA. PA tended to show the lowest cement solubility.

Analysis of Variance↗

PubMed2005

Micro-shear bond strength of adhesive systems to cementum.

PURPOSE: To investigate the micro-shear bond strength of current adhesive systems to human cementum and compare the results with those to dentin. METHODS: Two commercially available two-step adhesive systems were investigated; a self-etching primer system (Clearfil SE Bond) and a total-etch wet bonding adhesive system (Single Bond). The cementum and dentin surfaces were chosen from the mesial surfaces of extracted human molars and then bonded with each adhesive system. A micro-shear bond test was employed to evaluate the bond strength in this study. In addition, the etched cementum or dentin surfaces without any adhesive and the bonded interfaces between the adhesive and the cementum or the dentin were studied morphologically using scanning electron microscopy (SEM). RESULTS: No significant differences were found between the adhesive systems used (P> 0.05). However, both adhesive systems showed significantly lower bonding to cementum than to dentin (P< 0.05). The relatively lower bond strengths to cementum probably resulted from the existence of coarse collagen fibers, which may cause less or inhomogeneous penetration of resin monomers into the etched zone.

Analysis of Variance↗

PubMed2005

Effect of tooth age on microtensile bond strength of two fluoride-releasing bonding agents.

PURPOSE: The purpose of this study was to evaluate the effect of age of dentin and enamel on the microtensile bond strengths of a glass-ionomer based, all-in-one, single-step, self-etching adhesive system (Reactmer Bond, RB) and an antibacterial, two-step self-etching primer system (ABF Bond, ABF). MATERIALS AND METHODS: Extracted molars from 3 age groups (20 to 25, 35 to 40, and 50 to 55 years) were used. Enamel was removed from the occlusal surfaces of the teeth, and the entire flat surfaces were covered with composite resin (4 mm in height) following application of bonding agents. The bonded specimens were thinly sectioned parallel to the long axis of the tooth into 0.87 +/- 0.03 mm2 rectangular sections, resulting in 6 to 7 enamel specimens and 10 to 15 dentin specimens per tooth. The specimens were subjected to the microtensile test at a crosshead speed of 1 mm/min. The data were analyzed by Univariate ANOVA, Tukey HSD, and regression analysis. RESULTS: The bond strength of ABF to both enamel and dentin was higher than the bond strength of RB. Bond strengths of ABF to dentin were significantly higher than the bond strengths to enamel (p < 0.05). The 35- to 40-year age group of ABF showed the highest bond strength of all. In RB dentin groups, 34% of specimens showed cohesive failure in composite resin material. CONCLUSION: Bond strength values to enamel were not affected by age of teeth in either bonding system. Dentinal bond strength using ABF changed according to age of the teeth. Age did not affect bond strength values of RB to dental hard tissues. However, the high number of cohesive failures in Reactmer paste indicated low tensile strength of the material.

Adhesiveness↗

PubMed2005

Effect of cavity form on adhesion to cavity floor.

PURPOSE: To investigate the influence of cavity form, namely the C-factor, on adhesion at the interface on the cavity floor using light-cured resin-based composite. METHODS: Black ABS resin molds were used and were formed into five types of cavities having configuration factors that ranged from 0.5 to 5.0. The cavity size was standardized to cubes of 5 x 5 x 5 mm. Each cavity was treated using a bonding system (Clearfil SE Bond) and was filled with resin-based composite (Clearfil Photo Core). The composite was irradiated in the cavity and then cured for 40 seconds using a halogen light unit. Specimens were subjected to the microtensile test at a cross-head speed of 1 mm/minute. RESULTS: There was no significant difference in bond strength among the five different cavity forms. It was concluded that the difference of cavity forms had little effect on the adhesion to the cavity floor when using light-cured composites.

Acrylic Resins↗

PubMed2004

Microtensile bond strength of a dual-cure resin core material to glass and quartz fibre posts.

OBJECTIVES: To evaluate the microtensile bond strength (microTBS) of a dual-cure resin core material to different regions of fibre posts using different surface treatments. MATERIALS AND METHODS: Twenty-five silica zirconium glass fibre posts (Snowpost) and 25 quartz fibre posts (Aestheti-Plus) were used and randomly divided into five groups according to the surface treatments: (1) no surface treatment (Control) (2) dual-cure bonding agent, Clearfil Liner Bond 2V (LB) (3) LB followed by light curing for 20 s (LB and C) (4) silane coupling bonding agent agent, Clearfil Photobond with Porcelain Bond Activator (PB+PBA) (5) PB+PBA followed by light curing for 20 s (PB+PBA and LC). Treated posts were cemented into artificial post cavities using a dual-cure composite core material (Clearfil DC Core) and cured for 60 s from the top of the cavity. After 24 h storage in water, each specimen was serially sliced into 8, 0.6 x 0.6 mm2-thick beams for the microTBS test. The data were divided into three regions (upper/middle/bottom) and analyzed using three-way ANOVA and Dunnet's T3 multiple comparisons (alpha=0.05). RESULTS: There were no significant differences in bond strength between the three regions (p>0.05). The bond strengths were enhanced by the application of a silane coupling agent. For Snowpost, photoirradiation of the dual-cure bonding agent applied to the post surface significantly improved the bond strength (p<0.05) whereas it did not affect the bond strength of Aestheti-Plus post (p>0.05). CONCLUSION: The bond strength between fibre post and dual-cure resin core material depends upon the type of post and surface treatment. There were no regional differences in microTBS of the bonded post.

Composite Resins↗

PubMed2004

Effects of additional and extended acid etching on bonding to caries-affected dentine.

This study evaluated the effects of additional and extended acid etching on microtensile bond strength ( micro TBS) of two adhesive systems to sound (SD) and caries-affected dentine (CAD). Flat surfaces of CAD surrounded by SD of 36 extracted carious third molars were assigned to four treatments (i): self-etching adhesive system (Clearfil SE Bond) applied to dentine surfaces following manufacturer's instructions (MI); (ii) after additional etching for 15 s (35% phosphoric acid, PA); (iii) total-etch one-bottle adhesive (Single Bond) applied to dentine surfaces following MI; or (iv), after etching for 45 s with PA. Composite 'blocks' were built on bonded surfaces and restored teeth were vertically sectioned to obtain bonded slices of 0.7 mm thick. Slices were trimmed to create hourglass-shaped specimens (cross-sectional area of 1 mm(2)), which were tested under tension in a universal testing machine. Additional CAD and SD samples were prepared for scanning electron microscopy observations. Additional and extended etching significantly increased micro TBS to CAD; however, micro TBS of both adhesives to CAD were significantly lower than to SD. Additional and extended etching can improve bonding to CAD; however, adhesives applied on SD showed the best results for bonding.

Acid Etching, Dental↗

PubMed2004

Bond strengths of current adhesive systems on intact and ground enamel.

PURPOSE: The goal of this study was to compare the microshear bond strengths of current adhesive systems to intact and ground enamel surfaces. MATERIALS AND METHODS: Three commercially adhesive materials were examined: a two-step total-etching self-priming system (Single Bond, 3M ESPE, St. Paul, MN, USA), a two-step self-etching system (Clearfil SE Bond, Kuraray Co. Ltd., Osaka, Japan), and an all-in-one system (One-Up Bond F, Tokuyama Dental, Tokyo, Japan). The labial surfaces of extracted human incisors were used. For intact enamel surfaces, the teeth were polished with pumice. However, for the ground enamel, 0.5 mm deep, flat enamel surfaces at the midlabial aspect were ground with a no. 600 grit silicon carbide paper. Ground and intact enamel surfaces were bonded with one of three bonding systems and a resin composite and were subjected to a microshear bond test. RESULTS: The two self-etching systems demonstrated lower bond strengths than did the total-etching system on intact enamel (One-Up Bond F, 18.59 MPa; Clearfil SE Bond, 35.71 MPa; Single Bond, 47.20 MPa). No significant difference was found between the total-etching system and the two-step self-etching system on ground enamel (One-Up Bond F, 28.96 MPa; Clearfil SE Bond, 48.51 MPa; Single Bond, 51.07 MPa). Shear bond strengths on ground enamel were significantly higher than those on intact enamel except for the group that was bonded with the total-etching system. CONCLUSIONS: The two-step adhesives showed significantly higher bond strengths than did the one-step adhesive. When applying the total-etching system, no significant differences in bond strength were demonstrated between bonding to intact and to ground enamel.

Adhesives↗