Biomedical subjects

Koichi Shinkai

Publications and source records attributed to Koichi Shinkai.

4 recordsLinked to original sources

PubMed2006

Effect of high light intensity on cavity wall adaptation of a resin composite with a self-etching primer system.

This study evaluated the effect of high light intensity using a plasma arc lamp on the cavity wall adaptation of photo-polymerized composite restorations. Bowl-shaped cavities were prepared on the labial surfaces of extracted bovine teeth. Each cavity was restored with a resin composite restorative system (SE Bond & Clearfil AP-X) and then polymerized using a plasma arc lamp (Arc Light II) with a series of light intensities, including 1100, 1200, 1300, 1400, 1500, and 1600 mW/cm(2), and a halogen lamp (Candilux) with 400 mW/cm(2) light intensity (n = 10). The photo-irradiation time was adjusted for each group to receive a total energy output of approximately 16,000 mJ/cm(2). The specimens were subjected to 2500 cycles of thermal fatigue and sectioned bucco-lingually through the center of the restoration. Contraction gaps on the sections were measured using a replica-SEM observation technique. The degree of gap formation was determined as the ratio of the total length of the contraction gaps to the total length of the cavity wall on each sectioned specimen. The value was converted to a percentage. The data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests at a 0.05 level of significance. There were no significant differences (p > 0.05) in the cavity adaptation among the composites polymerized by the plasma arc lamp with high light intensities and the composite polymerized with the halogen lamp with 400 mW/cm(2) light intensity. There were no significant differences (p > 0.05) in the degree of cavity adaptation among the specimens polymerized with light intensities higher than 1100 mW/cm(2).

Animals↗

PubMed2002

Effect of surface conditioning and restorative material on the shear bond strength and resin-dentin interface of a new one-bottle nanofilled adhesive.

OBJECTIVES: To determine the effect of different combinations of surface conditioning (DeTrey Conditioner 36, NRC, no etching) and restorative materials (Dyract AP, Spectrum TPH) on the shear bond strength of Prime and Bond NT to enamel and dentin, and to characterize the resin-dentin interface produced by these combinations. METHODS: Shear bond strength was tested on 30 enamel and 30 dentin flat labial surfaces of extracted bovine teeth. The enamel and dentin specimens were randomly assigned to six groups of five teeth each and treated using different combinations of surface conditioners and restorative materials with Prime and Bond NT. Scanning electron microscope (SEM) observation of argon-ion-etched specimens was done to evaluate the resin-dentin interface. RESULTS: The type of surface conditioning and restorative material had significant effects on dentin bond strengths. Etching the dentin prior to application of Prime and Bond NT significantly increased bond strength and caused formation of a hybrid layer for Spectrum TPH. For Dyract AP, dentin etching generally did not improve bond strength despite the formation of a hybrid layer. On enamel, Prime and Bond NT had consistently high bond strengths on etched specimens. SIGNIFICANCE: The results showed that Dyract AP and Spectrum TPH, when used with Prime and Bond NT have different bonding mechanisms and the effect of surface conditioning on their shear bond strength differs. Clinicians should be aware of these effects in order to optimize bonding.

Acid Etching, Dental↗

PubMedDate not supplied

Histopathologic study on pulp response to single-bottle and self-etching adhesive systems.

This study compared the pulp response to seven adhesive resins (three single-bottle and four self-etching primers) and their companion resin composite systems with a commercial calcium hydroxide material when applied to exposed monkey pulps. The control group was capped with Dycal (DY), while the experimental groups were capped with one of the following adhesive resin systems: AQ Bond (AQ), Single Bond (SB), Imperva Fluorobond (IF), One Step (OS), Prime&Bond NT (PBNT), Perme Bond F (PBF) and One-up Bond F (OBF). Histopathologic evaluation of pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation and bacterial penetration at the 3rd, 30th and 90th post-operative days was done using light microscopy. Data were analyzed using the Kruskal-Wallis test followed by the Least Significant Difference Test to determine differences between the control group and the experimental groups at each observation period. The correlation of inflammatory cell infiltration and bacterial presence was investigated by the Kendall correlation analysis. All tests were performed at a 95% level of confidence. The pulpal responses of groups DY, SB, OS, PBF and OBF were generally characterized by none-to-mild pulp tissue disorganization and inflammatory cell infiltration. Also, initiation of reparative dentin formation was found earlier in Group DY, resulting in more complete dentin bridges at the 30- and 90-day observation periods. Groups AQ, IF and PBNT had significantly more inflammatory cell infiltration and a lower incidence of reparative dentin formation than Group DY. A significant correlation was detected between inflammatory cell infiltration and the presence of bacteria. It is concluded that the pulp response to SB, OS, PBF and OBF is not significantly different from the calcium hydroxide preparation. However, calcium hydroxide capping resulted in a higher incidence and faster rate of reparative dentin formation.

Acid Etching, Dental↗

PubMedDate not supplied

Two-year clinical performance of occlusal and cervical giomer restorations.

This study evaluated the two-year clinical performance of two types of giomers (Beautifil, a surface reaction giomer and Reactmer, a full-reaction giomer), in occlusal (Class I) and cervical (Class V) cavities using the USPHS criteria. Forty-two cervical erosion and carious lesions were restored using Beautifil and Reactmer following manufacturer's instructions. Twenty occlusal cavities were restored with Beautifil. Fifteen patients (mean age 35, ranging in age from 20 to 50 years) participated in the study. The success rate for cervical Beautifil restorations after two years was 80%, while the success rate for cervical Reactmer restorations was 71%. Occlusal Beautifil restorations had a 100% success rate.

Adult↗