Biomedical subjects

Junji Tagami

Publications and source records attributed to Junji Tagami.

102 records · Page 6Linked to original sources

PubMedDate not supplied

Effects of regional enamel and prism orientation on resin bonding.

Human enamel, with its prismatic, rod-like apatitic morphology, is an anisotropic material. Because of this structural anisotropy, variation in enamel bonding sites might influence the bonding ability of current adhesive systems. This study investigated the effects of regional enamel and the direction of enamel sectioning on the bonding ability of two commercially available resin adhesives: a self-etching primer system (Clearfil SE Bond) and a one-bottle adhesive system intended for use with a total-etch wet bonding technique (Single Bond). Two regions of enamel, cuspal and mid-coronal enamel, were chosen, then sectioned in three different directions, horizontally, axially and tangentially. Slices of the sectioned enamel were then bonded with each adhesive system and submitted to a micro-shear bond test. The results of a micro-shear bond testing showed that the bonding of a one-bottle adhesive system (Single Bond) to enamel was high at the surface perpendicular to the enamel prisms (40 MPa to 51 MPa) and low at the surface parallel to the enamel prisms (24 MPa to 27 MPa). In the case of a self-etching primer system (Clearfil SE Bond), 35 MPa to 45 MPa bond strengths were obtained from all surfaces. The bond strengths of the two adhesive systems were significantly influenced by the anisotropic structure of enamel (p < 0.05). However, the effect of a self-etching primer system was less influenced by the orientation of the prismatic structure of enamel than that of a one-bottle adhesive system (p < 0.05). SEM and CLSM microphotographs showed that the self-etching primer effectively modified the smear layer without being excessively destructive to the enamel.

Acid Etching, Dental↗

PubMedDate not supplied

The effect of a "resin coating" on the interfacial adaptation of composite inlays.

The relatively low bond strengths of resin cements to dentin may result in poor interfacial adaptation of composite inlays. This study determined whether the interfacial adaptation of composite inlays could be improved by applying an adhesive system and a low viscosity microfilled resin to the prepared cavity walls before making an impression. Ten MOD cavities were prepared on extracted human premolars with gingival margins located above and below the cemento-enamel junction. A "resin coat" consisting of a self-etching primer system (Clearfil SE Bond) and a low viscosity microfilled resin (Protect Liner F) was applied to the cavities of half of the prepared teeth, while the remaining teeth served as non-coated control specimens. All the teeth were restored with composite inlays (Estenia) fabricated by the indirect method and cemented with a dual-cured resin cement (Panavia F). After finishing the margins with superfine burs, the bonded inlays were thermocycled between 4 degrees C and 55 degrees C for 400 cycles. Specimens were sectioned with a diamond saw and the tooth-restoration interfaces were observed with a confocal laser scanning microscope. The data were analyzed with two-way ANOVA and Fisher's PLSD test (p < 0.05). The percentage length of gap formation at the dentin-restoration interface of the "resin coated" teeth (7.1 +/- 3.5) was significantly less than that of the non-coated teeth (85.7 +/- 6.7) (p < 0.05). The concept of coating the prepared cavity with an adhesive system and a low viscosity microfilled resin resulted in observing fewer gaps at the internal dentin-restoration interface compared with the non-coated specimens.

Analysis of Variance↗

PubMedDate not supplied

The durability of a fluoride-releasing resin adhesive system to dentin.

The durability of a fluoride-free (SE Bond) and a fluoride-containing (KBF) self-etching primer/ adhesive system were compared by measuring the microtensile bond strengths (microTBS) of these adhesive systems to human dentin in vitro. After bonding, the restored teeth were serially sectioned into multiple slabs that were trimmed to a 1 mm2 cross-sectional area at the bonded interface. For the three and six month specimens, half were fully covered with nail varnish (SE+, KBF+), while the other half were incubated at 37 degrees C in water without any protective varnish (SE-, KBF-). The microTBS of the one-day specimens were 44.6 +/- 11.2 MPa for SE Bond and 39.8 +/- 8.0 MPa for KBF (p > 0.05). When unprotected specimens were incubated in water for three and six months, the microTBS fell to 26.3 +/- 8.8 MPa and 23.6 +/- 10.7 MPa for SE-, respectively, but did not change in the specimens protected with nail varnish (SE+, 41.9 +/- 12.8 MPa and 41.8 +/- 9.8 MPa, respectively). In contrast, in specimens bonded with a fluoride-containing resin, KBF, the bond strengths of the unprotected specimens did not change over three and six months KBF-. Values were 32.4 +/- 6.1 MPa and 36.8 +/- 2.3 MPa, respectively. Similarly, varnish-protected KBF+ specimens did not change over three and six months (39.3 +/- 13.6 MPa and 40.9 +/- 14.7 MPa, respectively). The results indicate that decreases in bond strength over six months' storage are water-dependent but can be prevented by using fluoride-containing resins.

Analysis of Variance↗

PubMedDate not supplied

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↗

PubMedDate not supplied

Bonding of photo and dual-cure adhesives to root canal dentin.

This study evaluated the regional tensile bond strength of a dual-cure resin composite core material to root canal dentin using photo and dual-cure adhesives and different modes of polymerization. Nineteen extracted premolars were decoronated and their root canals prepared to a depth of 8 mm and a width of 1.4 mm using Para Post drills. For the microtensile bond strength (microTBS) test, 15 roots were randomly divided into five groups and their canal walls treated with a dual-cure self-etching primer (Clearfil Liner Bond 2V Primer, Kuraray Medical Co, Japan). Adhesive resin (Clearfil Liner Bond 2V Bond A) was applied to two of the groups and light cured for 20 seconds. A dual-cure adhesive resin (Clearfil Liner Bond 2V Bond A+B, Kuraray Medical Co, Japan) was applied to the remaining three groups, one of which was light cured. The post spaces of all the groups were filled with a dual-cure resin composite (DC Core) and three were light cured for 60 seconds from a coronal direction. Chemical-cure resin composite was placed on the outer surfaces of the roots, which were then stored in water for 24 hours. They were serially sliced perpendicular to the bonded interface into eight 0.6 mm-thick slabs, then transversely sectioned into beams approximately 8 x 0.6 x 0.6 mm for the microTBS test. All of the failure modes were observed under SEM and analyzed using the Kruskal-Wallis Rank test. For Knoop hardness testing, four specimens were prepared in a similar manner, two were light-cured and the other two chemically-cured. The specimens were longitudinally sectioned into two pieces, and three indentations were made at 100 microm intervals from a coronal to an apical direction in the eight halves. Data were divided into two groups (coronal/apical halves of post space) and analyzed using two-way ANOVA and Scheffe's test (p<0.05). For each curing strategy, there were no significant differences in microTBS and Knoop hardness between the coronal and apical regions (p>0.05). Light exposure of both the adhesive resin and resin composite resulted in significantly higher microTBS than chemical-cure alone (p<0.05). Light exposure also significantly increased Knoop hardness at both the coronal and apical regions (p<0.05). When the bonding resin and dual-cure resin composite were chemically-cured, failures occurred cohesively within the resin. Photo-initiated polymerization of the adhesive resin and dual-cure resin composite was necessary to achieve good bonding to root canal dentin, which was not dependent upon region.

Analysis of Variance↗

PubMedDate not supplied

Shear bond strength of current adhesive systems to enamel, dentin and dentin-enamel junction region.

This study investigated the bonding of current resin adhesives to the region approximating the dentin-enamel junction (DEJ), where the etch pattern to enamel or dentin may be different. Three kinds of tooth substrates were chosen for testing: enamel, dentin and the DEJ region. A self-etching primer system (Clearfil SE Bond) and two total-etch wet bonding systems (Single Bond and One-Step) were used. Each tooth region was bonded with one of the adhesive systems, and a resin composite and was subjected to a micro-shear bond test. In addition, morphological observations were performed on debonded specimens and etched surfaces using confocal laser scanning microscopy (CLSM). CLSM observations showed that the DEJ region was etched more deeply by phosphoric acid gel than enamel or dentin, suggesting that the action of acid etch seemed to be more intense on the DEJ. However, no statistically significant differences of shear bond strength values were observed between the DEJ region and enamel or dentin, or the adhesive systems used (p>0.05). Bonding to the DEJ is potentially as good as that to enamel or dentin.

Acid Etching, Dental↗

PubMedDate not supplied

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↗

PubMedDate not supplied

Evaluation of active and arrested carious dentin using a pH-imaging microscope and an X-ray analytical microscope.

A pH-imaging microscope was tested on carious teeth to examine the acid-base characteristics of active and arrested carious dentinal lesions and compared with an assessment of mineral loss in carious affected lesions using an x-ray analytical microscope. Extracted human molars, 22 active and 83 arrested carious teeth, were sliced vertically to maximize the presence of visible carious lesions. The pH change on the dentin surface was measured with a pH-imaging microscope, and the mineral loss was measured with an x-ray analytical microscope. The pH value of intact dentin and active and arrested carious dentinal lesions showed 7.0 (n=105), 5.8 (n=22) and 6.6 (n=83), respectively (analyzed by Kruskal-Wallis). The mineral loss was distinguishable in active dentinal lesions (4.92 times as much as intact dentin), while arrested lesions showed a slight mineral loss (2.19 times as much as intact dentin). The changes in pH value and mineral loss were significantly correlated (Pearson's correlation coefficients r=-0.8024) in active carious dentin lesions and weakly correlated (r=-0.1480) in arrested carious dentin lesions. Changes in tooth substance with the progression of the active carious process were reflected in a reduction in pH value and an increase in the amount of mineral loss.

Adolescent↗

PubMedDate not supplied

Biocompatibility of a flowable composite bonded with a self-etching adhesive compared with a glass lonomer cement and a high copper amalgam.

This study evaluated the pulpal response and in-vivo microleakage of a flowable composite bonded with a self-etching adhesive and compared the results with a glass ionomer cement and amalgam. Cervical cavities were prepared in monkey teeth. The teeth were randomly divided into three groups. A self-etching primer system (Imperva FluoroBond, Shofu) was applied to the teeth in one of the experimental groups, and the cavities were filled with a flowable composite (SI-BF-2001-LF, Shofu). In the other groups, a glass ionomer cement (Fuji II, GC) or amalgam (Dispersalloy, Johnson & Johnson) filled the cavity. 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 and Brenn gram stain for bacterial observation. No serious inflammatory reaction of the pulp, such as necrosis or abscess formation, was observed in any of the experimental groups. Slight inflammatory cell infiltration was the main initial reaction, while deposition of reparative dentin was the major long-term reaction in all groups. No bacterial penetration along the cavity walls was detected in the flowable composite or glass ionomer cement except for one case at 30 days in the glass ionomer cement. The flowable composite bonded with self-etching adhesive showed an acceptable biological com- patibility to monkey pulp. The in vivo sealing ability of the flowable composite in combination with the self-etching adhesive was considered comparable to glass ionomer cement. Amalgam restorations without adhesive liners showed slight bacterial penetration along the cavity wall.

Analysis of Variance↗

PubMedDate not supplied

The bond of resin to different dentin surface characteristics.

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.

Analysis of Variance↗

PubMedDate not supplied

Bonding to sound vs caries-affected dentin using photo- and dual-cure adhesives.

This study aimed to evaluate the microtensile bond strength (microTBS) of photo- and dual-cure adhesives to sound and caries-affected dentin using total- and self-etch techniques. Human third molars with occlusal caries were prepared as previously described by Nakajima and others (1995). Dentin surfaces were bonded with Optibond Solo Plus (Kerr; photo-cure adhesive) or Optibond Solo Plus + Dual-cure activator (Kerr; dual-cure adhesive) with total- and self-etch technique. Clearfil AP-X (Kuraray) was used for composite buildups. Following storage in distilled water at 37 degrees C for 24 hours, the teeth were sectioned into 0.7-mm thick slices to obtain sound and caries-affected dentin slabs, then trimmed to form hour glass shapes with a 1 mm2 cross-sectional area. The specimens were subjected to microtensile testing using EZ-test (Shimadzu) at 1 mm/minute. Data were analyzed using three-way ANOVA and Student's t-Test (p<0.05). Bond strengths to sound dentin with photo- and dual-cure adhesives using total- and self-etch techniques were significantly higher than those to caries-affected dentin. Dual-cure adhesive significantly decreased bond strengths both to sound and caries-affected dentin. The total-etch technique showed no beneficial effect on caries-affected dentin compared with the self-etch technique. Scanning electron microscopic observation of the resin-dentin interfaces revealed that hybrid layers in caries-affected dentin were thicker than those observed in sound dentin with photo- and dual-cure adhesives. Resin infiltration into dentinal tubules of caries-affected dentin was hampered by the presence of mineral deposits.

Acid Etching, Dental↗

PubMedDate not supplied

Shear bond strength of tooth-colored indirect restorations bonded to coronal and cervical enamel.

This study evaluated the shear bond strength of resin inlays bonded with resin cement to cervical and mid-coronal enamel. Two regions of enamel, cervical and mid-coronal, were chosen from the buccal surface of extracted molars. Composite "inlays" (Estenia, Kuraray Medical Inc) were fabricated indirectly and cemented with a dual-cured resin cement (Panavia Fluoro Cement II, Kuraray Medical Inc). The resin cement was cured with or without light irradiation for 30 seconds. After 24-hours or one-week's storage in 37 degrees C water, the bonded inlays were subjected to a microshear bond test, whereby a shear force was applied to the inlays at a crosshead speed of 1 mm/minute. The data were statistically analyzed using ANOVA and Fisher's PLSD test, with significance defined as p<0.05. Observations using confocal laser scanning microscopy were also performed after debonding the specimens. The light-cure method showed significantly higher bond strengths to both enamel regions compared with self-cure, especially at 24 hours (p<0.05). However, bond strength of the self-cured resin cement significantly improved after one week's storage (p<0.05; cervical enamel: p=0.022, midcoronal enamel: p=0.0024). The cervical enamel showed significantly lower bonding than midcoronal enamel (p<0.05), except for the self-cured specimens at 24 hours. Light curing of resin cement is a better choice than self-curing for luting of indirect restorations. The bond strength of indirect restorations to cervical enamel was lower than mid-coronal enamel.

Composite Resins↗