Biomedical subjects

Junji Tagami

Publications and source records attributed to Junji Tagami.

At least 73 records · Page 4Linked to original sources

PubMed2004

Growth-inhibitory effect of antibacterial self-etching primer on mutans streptococci obtained from arrested carious lesions.

BACKGROUND: An antibacterial self-etching primer has been developed to inhibit bacterial attachment and plaque accumulation on the tooth surfaces. The purpose of this study was to evaluate the growth-inhibitory effect of an antibacterial self-etching primer on mutans streptococci obtained from arrested carious lesions. MATERIALS AND METHODS: Softened dentin specimens were obtained from arrested carious lesions with an excavator or a round steel bur. The effect of a commercial antibacterial self-etching primer and a commercial self-etching primer on the total streptococci on Mitis-Salivarius (MS) agar plates and on Streptococcus mutans on MS agar plates containing 0.02 M bacitracin (MSB) was evaluated. Specimens with no primer were used as controls. The number of colonies of both total streptococci and S. mutans were compared statistically with two-way analysis of variance and Fisher's Protected Least Squares Differences (PLSD) test (p < .05). RESULTS: The number of colonies of total streptococci (CFU/mL) for the two methods (excavator and round steel bur) were as follows: for the control, 5.0 x 10(6) and 5.0 x 10(6); for the self-etching primer, 1.0 x 10(5) and 1.0 x 10(5); and for the antibacterial self-etching primer, 0 and 0. The number of colonies of S. mutans for the two methods (excavator and round steel bur) were as follows: for the control, 5.0 x 10(6) and 1.8 x 10(5); for the self-etching primer, 3.5 x 10(4) and 5.0 x 10(3); and for the antibacterial self-etching primer, 0 and 0. Regardless of the method of softened dentin removal, the antibacterial effect was significantly higher for the group that had antibacterial self-etching primer compared with that of the control group and the group that had commercial self-etching primer (p < .05). CLINICAL SIGNIFICANCE: The antibacterial self-etching primer showed a high level of antibacterial activity against mutans streptococci obtained from the arrested carious lesions.

Adult↗

PubMed2004

Molecular interactions of surface protein peptides of Streptococcus gordonii with human salivary components.

Oral streptococci play a large role in dental biofilm formation, and several types interact as early colonizers with the enamel salivary pellicle to form the primary biofilm, as well as to incorporate other bacteria on tooth surfaces. Interactions of surface molecules of individual streptococci with the salivary pellicle on the tooth surface have an influence on the etiological properties of an oral biofilm. To elucidate the molecular interactions of streptococci with salivary components, binding between surface protein (SspB and PAg) peptides of Streptococcus gordonii and Streptococcus sobrinus were investigated by utilizing BIAcore biosensor technology. The analogous peptide [change of T at position 400 to K in SspB(390-402), resulting in the SspB(390-T400K-402) peptide] from S. gordonii showed the greatest response for binding to salivary components and inhibited the binding of Streptococcus sanguis by more than 50% in a competitive inhibition assay in a comparison with other SspB and PAg peptides. This peptide also bound to the high-molecular-weight protein complex of salivary components and the agglutinin (gp340/DMBT1) peptide (scavenger receptor cysteine-rich domain peptide 2 [SRCRP 2]). In addition, the SspB(390-T400K-402) peptide was visualized by two surface positive charges in connection with the positively charged residues, in which lysine was a key residue for binding. Therefore, the region containing lysine may have binding activity in S. gordonii and S. sanguis, and the SRCRP 2 region may function as a receptor for the binding. These findings may provide useful information regarding the molecular mechanism of early biofilm formation by streptococci on tooth surfaces.

Adhesins, Bacterial↗

PubMed2004

Microhardness and Young's modulus of a bonding resin cured with different curing units.

This study evaluated the microhardness and Young's modulus of a photocurable bonding resin, Clearfil SE Bond (SE), cured with four curing units at different distances. The curing units used were: Candelux (Quartz-tungsten halogen), Lux-O-Max (Blue light emitting diode), Arc-light (Plasma-arc), and Rayblaze (Metal halide). Discs of bonding resin were prepared using vinyl molds and were photocured at the top surface with light tip at three different distances (contact, 2 and 4 mm). After 24 hours of storage in water at 37 degrees C, the specimens were sectioned into halves, embedded in epoxy resin, and polished. The microhardness and Young's modulus of this bonding resin were measured using a nanoindentation tester. Six specimens were prepared for each group. The data was statistically analyzed using two-way ANOVA test and Tukey multiple comparison test (p < 0.01). The microhardness of SE was affected by light source and distance, as was Young's modulus. Candelux and Rayblaze presented the highest hardness and Young's modulus results. Both properties presented high values when the curing unit tip was maintained in contact with the irradiated surface. Increasing the distance between the curing unit tip and the irradiated surface decreased the hardness and Young's modulus of SE.

Analysis of Variance↗

PubMed2004

Microtensile bond strength of dual-cure resin cement to root canal dentin with different curing strategies.

The purpose of this study was to measure the bond strength of dual-cure resin cement at different regions of root canal dentin using three kinds of curing method. Thirty-six extracted bovine teeth were used. Each root was sectioned vertically into halves. Their pulpal dentin walls were polished flat and then applied with two dual-cure resin cements (Bistite II, Panavia F), and divided into three curing strategy groups: multi-direction light, one-direction light and no-light. The bonded specimens were sectioned perpendicularly to the long axis of the root into approximately 0.7 mm thick slabs within two-third of the root from the coronal end, and prepared for microtensile bond strength (muTBS) test. Knoop hardness of the cements was also measured. Within each curing strategy for both dual-cure resin cements, there were no significant differences between the muTBS values at the coronal third and mid third regions. The effect of curing method on bond strength and KHN was found to be dependent on the material.

Acid Etching, Dental↗

PubMed2004

Surface analysis of dentinal caries in primary teeth using a pH-imaging microscope.

The aim of this in vitro study was to evaluate the pH value of intact and carious dentin in primary teeth using a pH-imaging microscope (SCHEM-100, HORIBA Ltd., Kyoto, Japan). Bucco-lingual cut sections of extracted human primary teeth, which had either mild or severe dentinal caries lesions, were placed on the pH-imaging sensor of the microscope. The pH values were compared statistically by Levene's test for equality of variances and Tukey HSD multiple comparison test (p < 0.05). For both mild and severe lesions in primary dentin, the lowest pH values in the carious lesions were lower than those of intact dentin (6.6, range 6.3-6.9). There were statistical differences between the lowest pH value within the mild lesions (6.2, range 5.8-6.4) and that of the severe lesions (6.0, range 5.9-6.2) (p < 0.05). It was concluded that SCHEM-100 was able to distinguish the pH-value distribution of intact and carious dentin in primary teeth.

Analysis of Variance↗

PubMed2004

Histologic evaluation of adhesive restorations on dentin caries in rat molar teeth.

OBJECTIVE: The aim of this study was to evaluate the progress of dentin caries under resin composite and glass-ionomer cement restorations in vivo. METHOD AND MATERIALS: Sixteen rats were subjected to oral inoculation of the bacterial strain, Streptococcus mutans, and experimental dental caries was induced in the rats' molars. The dental caries induced in rat molars was sealed with resin composite or glass-ionomer cement without removal of the caries; the depth and width of bacterial penetration in the lesion were measured from histopathologically stained sections. Inflammatory cell infiltrations within the pulp were also examined. RESULTS: Both bacterial penetration into dentin and caries spread were significantly reduced by sealing with glass-ionomer cement or resin composite. No significant differences in bacterial penetration and caries spread were seen between the sealing materials. Regarding the pulpal reactions, moderate to severe inflammatory cell infiltration was observed even in the sealed teeth. CONCLUSION: The caries lesions could not be completely arrested by sealing alone, although their progress was slowed from an active to a chronic status.

Animals↗

PubMed2004

Comparison of PAC and QTH light sources on polymerization of resin composites.

PURPOSE: To evaluate the polymerization shrinkage, Knoop hardness number (KHN) and compressive strength and to suggest a suitable time for irradiating resin composite restorations, when using a high-intensity light source. METHODS: Two restorative resin composites, UniFil F, and Clearfil AP-X were employed. A high-intensity light unit (more than 1000mW/cm2) with a xenon discharge lamp (Apollo 95E), which is generally called a plasma arc light-curing unit (PAC), was compared with a conventional light-curing unit fitted with a quartz-tungsten-halogen lamp (QTH) (GC Newlight VL2). The resin composites were exposed to the light in four ways. For QTH, the irradiation time was for 40 seconds (QTH 40 seconds). For PAC, 3 seconds (PAC 3 seconds), 3+3 seconds (PAC 3+3 seconds) and 3+3+3 seconds (PAC 3+3+3 seconds) was used. Polymerization shrinkage using the bonded disk technique developed by Watts, Knoop hardness number (KHN), and compressive strength were then determined. RESULTS: Two-way ANOVA revealed that the two materials for PAC 3+3 seconds and PAC 3+3+3 seconds made no difference in polymerization shrinkage compared to QTH 40 seconds (P < 0.001). The polymerization shrinkage of the materials cured by PAC for 3 seconds was significantly lower than those cured by QTH for 40 seconds in a range from 61% to 72%, by the PAC for 3 + 3 seconds in a range from 65% to 88%, and those by PAC 3+3+3 seconds in a range of 61% to 72% (P < 0.001). With regard to microhardness, the composites in PAC 3+3+3 seconds exposure made no difference in hardness compared with QTH 40 seconds (P < 0.001). PAC 3+3 seconds exposure gave hardness at less than 3.0 mm depth equivalent to that of the QTH 40 seconds. PAC 3 seconds at 2.0 mm depth produced inferior hardness compared with the QTH 40 seconds. The compressive strength for the PAC 3 seconds exposure was significantly lower than that of PAC 3+3 seconds, PAC 3+3+3 seconds and QTH 40 seconds for each material. CLINICAL SIGNIFICANCE: Irradiation by the high-intensity light source for 3 seconds provided significantly lower microhardness and compressive strength for light-cured resin composites. The 3+3+3 seconds repeated irradiation with the PAC unit and QTH 40 second values were not significantly different.

Analysis of Variance↗

PubMed2004

Ultrastructure of the dentin-adhesive interface after acid-base challenge.

PURPOSE: To observe the ultrastructure of the dentin-adhesive interface after in vitro sequential challenge by acidic and basic chemicals around adhesive restorations. MATERIALS AND METHODS: Box-shaped cavities were prepared in bovine root dentin and restored as follows: Reactmer Bond and Reactmer Paste (RB/RP), Clearfil SE Bond and Clearfil AP-X (SE/APX), ABF (experimental) and APX (ABF/APX), Single Bond and APX (SB/APX). After the specimens were stored in water for 1 week, the integrity of the bonds tested by sequential immersion were placed in an artificial demineralizing solution (pH 4.5) for 20 min and in 5% NaOCl for 20 min. The specimens were sectioned, polished, then argon-ion etched for 7 min, and gold sputter coated for SEM examination of the dentin-adhesive interface. RESULTS: The morphological results indicated tight bonding between the cavity wall dentin and the adhesive. For the fluoride-releasing restoration, RB/RP, a thick acid-resistant zone was clearly observed adjacent to the restoration; however, the bonding resin, RB, was partially degraded by the acid-base challenge. For SE/APX, ABF/APX and SB/APX, the bonding resins were resistant to the acid-base challenge. With the self-etching adhesive systems, SE and ABF, a thin band of acid-base resistant dentin less than 1 microm thick was observed beneath the hybrid layer. With the wet bonding system, SB, the hybrid layer was partially degraded by the acid-base challenge. CONCLUSION: SEM observation is useful for observing the reactions of adhesives to acid-base challenge. Prevention of secondary caries around a restoration may be influenced by the physical properties of the restorative and adhesive materials, quality of the hybrid layer, and fluoride-release.

Acetic Acid↗

PubMed2004

Effects of light intensity through resin inlays on the bond strength of dual-cured resin cement.

PURPOSE: To evaluate the influence of the light intensity, irradiation time, and thickness of the indirect restoration composite on the bond strength of dual-cured resin cement immediately after cementation, applying the resin coating technique. MATERIALS AND METHODS: Three hundred forty composite blocks as an adhesive surface and four thicknesses of indirect restoration composite disks were prepared. The surface of the composite blocks was coated with low-viscosity resin composite and immersed in water for 24 h. After immersion, dual-cured resin cement was applied to the resin-coated surface and the indirect restoration composite disks were placed on it. Light irradiation was performed through four thicknesses of indirect restoration composite disks with conventional halogen (40 s) and high intensity (10, 20, 40 s) light units. The specimens were stored in water at 37 degrees C for 10 min or 24 h, and the tensile bond test was performed. RESULTS: For the 1-mm composite thickness, there were no significant differences in the bond strengths between 10 min and 24 h after cementation with the four light curing methods. For the composite thicknesses of 3 or 4 mm, the bond strength 24 h after cementation was significantly higher than that at 10 min after cementation with conventional halogen (40 s) and high-intensity light units at 10 s and 20 s, but there was no significant difference with the high-intensity light unit applied for 40 s. CONCLUSION: The bond strength of dual-cured resin cement immediately after cementation could be greatly influenced by the irradiation time and the light intensity penetrating the indirect restoration composite.

Analysis of Variance↗

PubMed2004

Influence of activation mode of dual-cured resin composite cores and low-viscosity composite liners on bond strength to dentin treated with self-etching adhesives.

PURPOSE: The objective of this study was to investigate the effect of light- or chemical initiation on the polymerization reaction of dual-cured composite core buildup materials (CM) with respect to their shear bond strength to dentin treated with self-etching adhesives (SE), in the presence or absence of a low-viscosity composite liner (LI). MATERIALS AND METHODS: Two SEs (Clearfil SE Bond and Unifil Core Bond), their respective CMs (DC Core Paste and Unifil Core), and a LI (Protect Liner F) were tested. After removing the labial enamel surfaces of 8 bovine incisors, each flat dentin surface was sectioned into 4 pieces with similar surface areas (30 mm2). The dentin surfaces were wet abraded with 600-grit SiC paper and randomly divided into 8 groups. Experimental groups comprised the use of a SE and its respective CM with or without an intermediate application of the LI and with or without CM light activation. Three cylinders of CM (0.5 mm high and 0.75 mm in diameter) were applied to each bonded dentin surface (n = 12), using a tygon tubing mold. After water storage for 24 h, specimens were subjected to microshear testing. Data were statistically analyzed by two-way ANOVA and Tukey's test (5%). RESULTS: For both SEs, LI application and CM light activation showed significantly higher bond strengths than the groups in which an intermediate LI was not used or the CMs were only chemically cured. CONCLUSION: The bond strength of CM to dentin using SE is reduced if the LI and light activation are not employed.

Acrylic Resins↗

PubMed2003

Effect of artificial saliva contamination on pH value change and dentin bond strength.

OBJECTIVE: This study was to examine the effect of artificial saliva contamination on pH change of the dentin surface and the micro-shear bond strength (MSBS) of the two bonding systems to contaminated dentin. METHODS: Fifty-six human dentin disks were tested with two resin bonding systems: a self-etching primer system, Clearfil SE Bond (Kuraray Medical Inc., Tokyo, Japan), and a one-bottle adhesive system, Single Bond (3M-ESPE, St. Paul, MN). Dentin surfaces were conditioned with the self-etching primer (primer) or phosphoric acid (etchant) and divided into four groups: conditioning without contamination (conditioning), contamination with artificial saliva (contamination), re-conditioning the contaminated dentin (re-conditioning), water-rinsing the contaminated dentin and re-conditioning (rinsing and re-conditioning). The pH change on the dentin surface was measured using a pH-imaging microscope (SCHEM-100, Horiba Ltd, Kyoto, Japan) to estimate the acid-base characteristics of the conditioned and contaminated dentin surface. The MSBS to the dentin was examined after storage in distilled water at 37 degrees C for 1 week. RESULTS: The pH of intact dentin surfaces was 6.9. Conditioning with the primer and etchant decreased the pH to 5.4 and 5.9, respectively. Saliva contamination increased the pH slightly, and re-conditioning decreased the pH again. The MSBS of the two bonding systems decreased after contamination. Re-priming restored the MSBS to control values, while re-etching did not. Rinsing and re-priming produced a reduction in MSBS, and rinsing and re-etching did not increase the MSBS. SIGNIFICANCE: The conditioning and saliva contamination changed the pH value of dentin surface. The MSBS decreased after contamination; however, re-priming with SE Bond primer was an adequate treatment to restore the bond strength.

Acid Etching, Dental↗

PubMed2003

Relationship between ceramic primer and ceramic surface pH on the bonding of dual-cure resin cement to ceramic.

OBJECTIVES: This study examined the relationship between a ceramic primer and ceramic surface pH on the microtensile bond strength of dual-cure resin cement to ceramic. METHODS: Ceramic blocks (Vita Celay Blanks) were cut into multiple 3mm-thick slices and polished using 600-grit SiC paper. Two pairs were left untreated (controls), six pairs were treated with 40% phosphoric acid (PA), six pairs were treated with 20% hydrofluoric acid (HFA), and rinsed with water for either 15, 30 or 60 s. Half the specimens were silanated with Tokuso ceramics primer (TCP) (Tokuyama) and the other half with TCP formulated without phosphate monomer (TCP-NoPM). All the pairs were bonded with Bistite II dual-cure resin cement (Tokuyama) and light-cured. After 24 h water storage at 37 degrees C, the bonded specimens were cut into 6x0.7x0.7 mm(3) beams and their microtensile bond strengths (micro TBS) determined. Failure modes were determined using a confocal laser-scanning microscope. For scanning chemical analysis, the polished slices were cut into quarters, divided into seven groups of six, and treated in a similar manner as described for the micro TBS test. Surface pH was then determined using a scanning chemical microscope. For SEM examination, one ceramic quarter from each of the seven groups was used. RESULTS: Three-way ANOVA revealed that the micro TBS of TCP was significantly higher than TCP-NoPM with no acidic treatment (p<0.05). However, after treatment of the ceramic surface with either PA or HFA, and 15 s rinsing, there was a significant reduction in surface pH (p<0.05), and no significant difference in micro TBS between TCP and TCP-NoPM (p>0.05). For TCP, there were no significant differences in micro TBS and failure mode between the control, PA, and HFA treated groups when the water rinsing time was increased. Whereas, for TCP-NoPM and surface treatment with PA, an increase in rinsing time resulted in a significant reduction in micro TBS and a significant increase in surface pH (p<0.05). SIGNIFICANCE: Acidic treatment of the ceramic surface did not significantly increase dual-cure resin/ceramic bond strengths when the ceramic primer, TCP, was used. It is suggested that when no phosphate monomer is present in a ceramic primer, dual-cure resin cement/ceramic bond strength is dependent upon the concentration of H(+) ions on the ceramic surface.

Acid Etching, Dental↗

PubMed2003

Efficacy of a resin coating on bond strengths of resin cement to dentin.

PURPOSE: The aims of this study were to (1) evaluate the effect of a resin coating consisting of a dentin bonding system and a flowable resin composite on the microtensile bond strength (micro-TBS) of a resin cement to dentin in indirect composite restorations and (2) compare the bond strengths of direct and indirect composite restorations. MATERIALS AND METHOD: Occlusal surfaces of human premolars were ground to obtain flat dentin surfaces and were divided into seven groups. For indirect restorations, the dentin surfaces of the experimental groups were bonded with a dentin bonding system (DBS), Clearfil SE Bond (SE) or Single Bond (SB) with and without a flowable resin composite, Protect Liner F (PLF), temporized for one day and cemented with a resin cement (Panavia F) according to the manufacturer's instructions. The dentin surfaces of the control group were temporized without prior treatment, and indirect composite (Estenia) was bonded with Panavia F. For the direct restorations, either SE or SB was applied to the dentin surface and the entire surface was built up with direct composite (Clearfil AP-X). After 24 hours in water storage, micro-TBS was measured at a crosshead speed of 1 mm/min. The data were analyzed with one-way analysis of variance and Fisher's protected least significant difference test (p < .05). RESULTS: The original bond strength of the resin cement (Panavia F) to dentin significantly improved with the use of a resin coating technique in indirect restorations (p < .05). The combination of DBS + PLF showed significantly higher bond strengths compared with the single use of DBS. The combination of SE + PLF as a resin coating provided the highest bond strengths in indirect restorations (p < .05). However, the best bond strengths were observed when SE and SB were used for direct composite restorations (p < .05). CONCLUSIONS: The application of a resin coating consisting of a dentin bonding system and a flowable resin composite on the dentin following cavity preparation significantly improved the micro-TBS of the resin cement Panavia F to dentin in indirect restorations. However, the bond strengths of indirect composite restorations were significantly lower than those of direct composite restorations even with the resin coating technique. CLINICAL SIGNIFICANCE: Indirect composite restorations may require a resin coating to improve the bonding performance of the resin cement Panavia F to dentin. However, adhesive systems with direct composite restorations still provide superior bond strengths compared with indirect restorations.

Analysis of Variance↗

PubMed2003

Effect of depth and tubule direction on ultimate tensile strength of human coronal dentin.

The purpose of this study was to evaluate the effect of dentin depth and tubule direction on the ultimate tensile strength (UTS) of human dentin. Dentin slabs of 0.5-mm thickness were trimmed either from the mesial and distal (for specimens with the tubules parallel to the tensile force; parallel group) or from the occlusal and pulpal surfaces (perpendicular group) to reduce the cross-sectional area of the superficial, middle, and deep regions to 0.25 mm2, and subjected to microtensile testing. From SEM photomicrographs of the fractured specimens of the parallel group, the tubule density was investigated. For both parallel and perpendicular groups, superficial dentin showed a significantly higher UTS than deep dentin. The tubule density of superficial dentin was significantly lower than that of middle and deep dentin. When performing the microtensile bond test to deep dentin, it is possible that cohesive failure of dentin can occur at relatively low tensile stresses.

Dental Restoration Failure↗

PubMed2003

Direct pulp capping with an auto-cured sealant resin and a self-etching primer.

PURPOSE: To evaluate an auto-cured resin as a direct pulp capping material on exposed pulp with or without a self-etching primer. MATERIALS AND METHODS: Class V cavities were prepared on the facial surfaces of 90 intact monkey teeth, and the pulps were intentionally exposed with a carbide bur through the cavity floor. Each exposed pulp was capped with a commercially available adhesive resin system (Clearfil Liner Bond 2V: Group LB) or an auto-cured sealant resin (Teethmate-S) with and without the use of a self-etching primer (Group TMP and Group TM, respectively). The cavities were restored with an adhesive resin and a hybrid resin-based composite (Clearfil AP-X). Inflammatory cell infiltration and dentin bridge formation of the exposed pulp as well as protrusion of the exposed pulp tissue into the cavities were evaluated histologically at 3, 30 and 90 days. RESULTS: Slight inflammatory cell infiltration was the main inflammatory reaction of the exposed pulp, and the exposed area became occluded with dentin bridges as the observation period increased. However, significantly higher incidence of slight inflammatory cell infiltration was found in Group TM than in Group LB at 30 days (P<0.05). Group TM showed significantly higher incidence of protrusion of pulp tissue than Groups LB and TMP through all tested periods (P<0.05).

Acid Etching, Dental↗

PubMed2003

Effect of light source direction and restoration thickness on tensile strength of a dual-curable resin cement to copy-milled ceramic.

PURPOSE: To evaluate the effects of exposure duration and source direction on bond strength of a dual-curable resin cement to copy-milled ceramic MATERIALS AND METHODS: Ceramic blocks (Vita Celay Blanks) were cut into 1 mm, 2 mm and 3 mm thick slices. Following silanization (Tokuso Ceramic Primer), the slices were bonded using dual-cure resin cement (Bistite II) and subjected to one of four photo-curing strategies: no light-cure (control), 20 seconds light-cure from one direction, 120 seconds from one direction, and 20 seconds from each of six directions. After 24-hour water storage at 37 degrees C, the microtensile bond strengths and resin cement Knoop Hardness of the bonded specimens were determined. The data were analyzed using two-way ANOVA and Fisher's PLSD test at a confidence level of 95%. Specimen failure modes were determined using a laser-scanning confocal microscope. RESULTS: The KHN of the control group was significantly lower than those of the light-cured groups (P < 0.05). There were no significant differences in bond strength and microhardness when the 1 and 2 mm thick ceramic slices were light-cured for either 120 seconds from one direction, or for 20 seconds from six directions (P > 0.05). However, when ceramic thickness increased from 2 to 3 mm, significant reduction in bond strength occurred when light-cure was applied for 120 seconds from one direction, but not when applied for 20 seconds each from six directions (P < 0.05).

Analysis of Variance↗

PubMed2003

Evaluation of in vitro secondary caries using confocal laser scanning microscope and X-ray analytical microscope.

PURPOSE: To evaluate in vitro secondary caries formation and inhibition by using a confocal laser scanning microscope (CLSM), and further map the calcium distribution with an X-ray analytical microscope (XAM). MATERIALS AND METHODS: 36 box-shaped cavities were prepared on bovine root dentin and restored with Fuji II, Fuji II LC (improved), or Clearfil Liner Bond 2V system with a non-fluoride releasing resin-based composite; Clearfil AP-X was used as a negative control. After immersion in a buffered demineralizing solution of 50 mmol/L of acetic acid adjusted to pH 4.5 for 3.5 days, longitudinal half sections were cut through each restoration and polished for analysis under CLSM. In order to confirm the CLSM results, the same samples were subsequently examined by means of the X-ray analytical microscope (XAM). The values of the outer lesions and the inhibition zones obtained by the two different CLSM and XAM measurements were then analyzed by one-way ANOVA, Fisher's PLSD Test at the 95% level of confidence and correlation coefficient. RESULTS: Inhibition zones and outer lesions were clearly detected under CLSM around the glass-ionomer and resin-modified glass-ionomer restorations. As expected, an inhibition zone was not detected adjacent to the resin-based composite restoration. Additionally, using the transmission x-ray images of XAM, the inhibition zones were observed as high density areas, and the outer lesions as low density areas. The width of the inhibition zones and the depth of the outer lesions measured under the CLSM were similar to those obtained from the XAM.

Acetates↗

PubMed2003

Tensile bond strengths of resin cements to bovine dentin using resin coating.

PURPOSE: To evaluate the effect of a resin coating technique on dentin tensile bond strengths of dual-cured resin cements. METHODS: 10 bovine dentin specimens were tested for tensile bond strengths of each of the following four materials: Panavia F, Link Max, Bistite II, Rely-X. Bovine dentin ground with 600-grit SiC was bonded with a resin cement according to the manufacturers' instructions or the resin coating technique, which was used in combination with one coat of a dentin adhesive; Clearfil SE Bond, Unifil Bond, One-Up Bond F or Single Bond, with one coat of a low viscosity micro-filled resin, Protect Liner-F. Each dentin adhesive and the low viscosity micro-filled resin were cured for 10 seconds and 20 seconds respectively. After 1 day storage in water, the specimens were subjected to the tensile bond test at a crosshead speed of 2 mm/minute. The data were analyzed by two-way ANOVA and Fisher's PLSD test (P < 0.05). The mode of failure after the tensile bond test was classified by visual inspection. The resin cement - dentin interfaces were examined by SEM. RESULTS: The tensile bond strengths (MPa +/- SD) of four resin cements to dentin with/without resin coating were: Panavia F (22.9 +/- 3.1; 10.2 +/- 2.5), Link Max (16.1 +/- 4.4; 9.6 +/- 3.2), Bistite II (14.8 +/- 3.2; 14.3 +/- 3.9), and Rely-X (15.7 +/- 4.7; 13.5 +/- 4.5), respectively. The resin coating significantly improved the bond strengths of resin cements to dentin in Panavia F and Link Max, while there were no significant differences of mean bond strengths between Bistite II or Rely-X with and without resin coating (P> 0.05). Regarding the fracture modes, complete and partial adhesive failures were observed in the cases without resin coating. For the resin coating groups, the fracture modes were much more complicated, although, adhesive failures rarely occurred. Hybrid layer formation was observed for all materials used.

Analysis of Variance↗