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Biomedical subjects

Yuichi Kitasako

Publications and source records attributed to Yuichi Kitasako.

At least 19 recordsLinked to original sources

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↗

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↗

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↗

Migration and particle clearance from hard-setting Ca(OH)2 and self-etching adhesive resin following direct pulp capping.

PURPOSE: To evaluate the migration and particle clearance from a hard-setting calcium hydroxide (HSCH) and self-etching adhesive resin (SEAD) following direct pulp capping using the light and electron microscope. METHODS: Exposed monkey pulps were capped with a hard-setting calcium hydroxide (Dycal) or adhesive resin (Clearfil SE Bond), and histopathologically evaluated at 14 and 21 days using light and transmission electron microscopy (n = 14). RESULTS: At 14 days, both HSCH and SEAD materials showed no severe inflammatory reactions of the pulp (necrosis and abscess formation). The main reaction was slight inflammatory cell infiltration consisting of leukocytes. A number of HSCH particles were entrapped by macrophages and observed in the small capillaries similar to blood or lymphatic vessels. For SEAD, slight hemorrhage was observed at the exposed surface. At 21 days, for both HSCH and SEAD, a few cases showed minimal inflammatory response which was limited to the area beneath the exposure. Some macrophages entrapping the HSCH particles in vacuoles within the cytoplasm were arranged at the surface of the capping layer. HSCH particles were also observed in the vessels similar to blood or lymphatic vessels. A few macrophages entrapped filler-like particles of SEAD adjacent to the capping material, but there was no evidence of any SEAD in the vessels.

Animals↗

Elemental distributions and microtensile bond strength of the adhesive interface to normal and caries-affected dentin.

The aim of this study was to evaluate the microtensile bond strength (microTBS) and the elemental contents of the adhesive interface created to normal versus caries-affected dentin. Extracted human molars with coronal carious lesions were used in this study. A self-etching primer/adhesive system (Clearfil Protect Bond) was applied to flat dentin surfaces with normal and caries-affected dentin according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were cross-sectioned and subjected to a microTBS test and electron probe microanalysis for the elemental distributions [calcium (Ca), phosphorus (P), magnesium (Mg), and nitrogen (N)] of the resin-dentin interface after gold sputter-coating. The microTBS to caries-affected dentin was lower than that of normal dentin. The demineralized zone of the caries-affected dentin-resin interface was thicker than that of normal dentin (approximately 3 microm thick in normal dentin; 8 microm thick in caries-affected dentin), and Ca and P in both types of dentin gradually increased from the interface to the underlying dentin. The caries-affected dentin had lost most of its Mg content. The distributions of the minerals, Ca, P, and Mg, at the adhesive interface to caries-affected dentin were different from normal dentin. Moreover, a N peak, which was considered to be the collagen-rich zone resulting from incomplete resin infiltration of exposed collagen, was observed to be thicker within the demineralized zone of caries-affected dentin compared with normal dentin.

Dental Caries↗

Seven-year dentin bond strengths of a total- and self-etch system.

The aim of this study was to determine the durability of tensile bond strengths of a conventional 3-step bonding system (Superbond D-liner Plus) and a self-etching priming bonding system (Clearfil Liner Bond II) to bovine dentin over a 7 yr period. Superficial bovine dentin finished with 600-grit SiC paper was bonded with one of the two adhesive materials. A 4 mm diameter area was bonded, covered with resin composite and stored in 37 degrees C deionized water containing gypsum chips and 0.4% sodium azide as an antibacterial. Bonds were stressed in tension at a crosshead speed of 1 mm min(-1). Mean bond strengths were observed at 1 d, at 1, 3, and 6 months, and at 1, 2, 3, 6 and 7 yr. Ten specimens were tested for the first 3 yr and 15 specimens were tested for 6 and 7 yr. The bond strength of Superbond D-liner Plus significantly decreased over the 7 yr period, whereas Liner Bond II showed a slight but, insignificant, decrease. The fracture mode changed with time for Superbond D-liner Plus, but not for Liner Bond II. It was concluded that systems which use a strong acid for demineralizing the dentin may show greater deterioration of the bond to dentin compared with a self-etching priming system.

Acid Etching, Dental↗

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↗

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↗

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↗

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↗

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↗

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↗

Effect of resin-coating technique on dentin tensile bond strengths over 3 years.

PURPOSE: The resin-coating technique has been developed to protect prepared dentin and underlying pulp tissue. The purpose of this study was to evaluate the resin-coated dentin bond durability over a period of 3 years of a resin cement and to compare it with two representative resin cements. MATERIALS AND METHODS: Ten bovine dentin specimens were tested for tensile bond strengths with each of the following three materials: CLAPEARL DC with a resin-coating technique (CDRC), Panavia 21 (PA21), and Super Bond C&B (SBCB) at 1 day, 6 months, 1 year, and 3 years. Mean bond strengths were compared statistically by two-way analysis of variance and Fisher's PLSD test (p < .05). The mode of failure was classified by scanning electron microscope observation and analyzed using the Mann-Whitney U-test. RESULTS: The 3-year bond strengths of all resin cements were significantly lower than those at the other experimental periods except for 1 year (p < .05). There was no significant difference in mean bond strength between CDRC and SBCB (p > .05). Regarding the fracture modes, in the case of CDRC, an increase in adhesive failure at the resin-dentin interface was observed as the time period lengthened. Statistical differences were observed between SBCB and the other materials at 1 year (p < .05) and between PA21 and the other materials at 3 years (p < .05). CLINICAL SIGNIFICANCE: The mean tensile bond strengths of the three resin cements to dentin decreased at different rates during the study; the rate at which the bond decreases is likely to affect the long-term durability of restorations.

Acid Etching, Dental↗

Histomorphometric analysis of dentinal bridge formation and pulpal inflammation.

OBJECTIVE: The purpose of this study was to evaluate pulpal responses to the use of four resin composite materials as direct pulp capping agents. The importance and effects of individual pulp capping variables are not well understood; consequently histomorphometric analysis was used to analyze these variables. METHOD AND MATERIALS: Two hundred fifty standardized pulp-exposed cavities were prepared in nonhuman primate teeth. Exposed pulps were capped with calcium hydroxide and multistep and self-etching primer resin composites. Teeth were collected from 3 to 60 days to observe pulpal reactions. Following perfusion fixation, tissues were demineralized, sectioned, stained, and histomorphometrically measured. Bridge area, diameter of pulpal exposure, and cavity floor width were measured. Tunnel defects, operative debris, and pulpal inflammation were graded according to defined criteria. RESULTS: The variables correlated to dentinal bridge area were, in decreasing order of significance, time elapsed since exposure, diameter of pulpal exposure, pulp capping material, and tunnel defects. The variables correlated to pulpal inflammation were the type and curing of pulp capping material. Other variables were not statistically significant. CONCLUSION: Pulp capping with resin composite materials provided acceptable pulpal inflammatory and dentinal bridge repair responses, comparable with those of calcium hydroxide. Although resin composites are promising as direct pulp capping agents, further investigations are required to optimize their application protocols to reduce the penetration of potentially cytotoxic monomers into pulpal tissue.

Acid Etching, Dental↗

Pulpal response to a fluoride-releasing all-in-one resin bonding system.

Pulp tissue reactions to a fluoride-releasing all-in-one resin bonding system (Reactmer Bond and Reactmer Paste) in non-exposed monkey teeth were histopathologically evaluated at three, 30, and 90 days after restoration. No serious inflammatory reactions of the pulp, such as necrosis or abscess formation, were observed. At 90 days in the Reactmer group, odontoblastic change and inflammatory cell infiltration were not observed, and slight irritation dentin formation was formed. The pulpal response of the Reactmer group was minimally different from that of the control group. Consequently, the Reactmer system was determined as being biologically compatible with vital pulps.

Abscess↗

In vitro surface analysis of active and arrested dentinal caries using a pH-imaging microscope.

This in vitro study evaluated the pH value of active and arrested caries lesions in deep dentinal caries using a pH-imaging microscope (SCHEM-100, HORIBA Ltd, Kyoto, Japan). Buccal-lingual cut sections of extracted human teeth that had either active or arrested dentinal caries lesions were placed on the pH-imaging sensor of the microscope. The pH values were compared statistically by one-way ANOVA and Fisher's PLSD test (p<0.05). In addition, both types of caries lesions were compared with a caries detector solution for this pH-imaging characterization. For both active and arrested lesions in dentin, the lowest pH values in the caries lesions (range from 5.3 to 6.6) were lower than that of intact dentin (range from 6.8 to 7.4). There were statistical differences between the lowest pH value within the active lesion (range from 5.3 to 5.8) and the arrested lesion (range from 6.3 to 6.6) (p<0.05). Although the arrested lesion was unstainable and impermeable to the dye, there was a close relationship between dye staining and pH-imaging characterization within the active lesion from visual inspection.

Adult↗

Physiological remineralization of artificially demineralized dentin beneath glass ionomer cements with and without bacterial contamination in vivo.

This study evaluated the physiological remineralization of artificially demineralized dentin beneath glass ionomer cements with and without bacterial contamination. The artificially demineralized dentin was produced on 84 monkey teeth using a decalcifying solution. Half the samples were left open to the oral cavity for one week, then, all cavities were restored with two glass-ionomer cements: Fuji IX or Fuji II LC improved (n = 7). The nanohardness of the artificially demineralized dentin at 3, 90 and 360 days was measured using a nanoindentation tester (ENT-1100, Elionix) and compared statistically by two-way ANOVA and Fisher's PLSD test (p < 0.05). Each mineral (Ca, Mg, P, F) within the demineralized dentin was also analyzed using Electron Probe Microanalysis. For the samples, the mean nanohardness of the three-day samples was significantly lower than the 360-day samples (p < 0.05). Although there was no significant difference in the mean nanohardness within all the bacterially-contaminated groups through the experimental periods (p > 0.05), the mean nanohardness of the bacterial-contaminated samples were significantly lower than the non-bacteria-contaminated samples (p < 0.05). From the EPMA results, fluoride release from both cements to the bottom of the artificially demineralized dentin was detected within three days. Although Ca density was sparse within this demineralized dentin lesion, for the Fuji IX sample, a high Mg density within this lesion was detected at 360 days.

Analysis of Variance↗

Surface pH and bond strength of a self-etching primer/adhesive system to intracoronal dentin after application of hydrogen peroxide bleach with sodium perborate.

This study compared the dentin bond strength of a self-etching primer/adhesive system with dentin surface pH with or without bleaching and observed the morphological changes in bleached dentin treated with a self-etching primer. Dentin disks were prepared from the coronal-labial region of 32 human anterior teeth. The pulpal surfaces of the dentin disks were polished with 600-grit SiC paper under running water. The dentin surfaces on all specimens were bleached with a mixture of 30% hydrogen peroxide and sodium perborate in 100% humidity at 37 degrees C for one week. The bleaching agent was then rinsed off with water for 5, 15 or 30 seconds. All specimens were stored in water at 37 degrees C. Half of the five-second rinsing specimens were stored in water for an additional week. Dentin surface pH with or without bleaching was examined using a pH-imaging microscope (SCHEM-100). A self-etching primer/adhesive system (Clearfil SE Bond) was applied to bleached or unbleached dentin according to the manufacturer's instructions. After 24-hour water storage, the bonded specimens were prepared for microtensile testing. Microtensile bond strength (microTBS) to dentin was measured using a universal-testing machine (EZ test, Shimadzu, Japan) at a crosshead speed of 1.0 mm/minute. Data were analyzed by one-way ANOVA and Scheffe's test (alpha=0.05). The pH values of the dentin surfaces of the 5 and 15 second rinsing groups were significantly higher than the control group (p<0.05), while the 30-second rinsing and one-week water storage groups had similar surface pH values to the control group (p<0.05). The microTBS of 5, 15 and 30 second rinsing specimens after bleaching were significantly lower than the control specimens (p<0.05). However, after one-week of water storage, the microTBS returned to the control group. The application of a bleaching agent increased the pH value of the dentin surface and decreased the bond strength of the self-etching primer/adhesive system. One-week water storage after bleaching recovered the surface pH and the microTBS to dentin.

Analysis of Variance↗