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Biomedical subjects

K Hinoura

Publications and source records attributed to K Hinoura.

15 recordsLinked to original sources
PubMed1995

Influence of filler addition to bonding agents on shear bond strength to bovine dentin.

OBJECTIVES: The purpose of this study was to investigate the influence of adding filler particles to a bonding agent on dentin bond strength and of the temperature change during curing in order to determine the optimum filler level for an experimental bonding agent. METHODS: Experimental light-cured bonding agents with microfiller (average size: 0.05 micrometers) content of 0, 10, 20, 30, 40, 50, 60, and 70 wt% were used with the Imperva Bond / Lite-Fil II A (Shofu) restorative material. Bovine incisors were mounted in self-cured resin, and the facial surfaces were prepared with 600-grit SiC paper. After dentin surface pretreatment with dentin primer, experimental bonding agents were applied to the dentin surface and bonded with resin composite. Ten samples per test group were stored in 37 degrees C water for 24 h, then shear tested at 1.0 mm/min. The temperature change of the bonding agent was monitored during the exthothermic polymerization reaction according to the method of ISO standard #4049. The peak temperature and the time required to reach peak temperature were recorded. RESULTS: Bond strength to dentin and the temperature change were greatly affected by the filler level. Maximum dentin bond strength (14.3 +/- 2.3 MPa) was obtained with a filler level of 10 wt% and decreased with filler level higher than 30 wt% (10.4 +/- 1.7 MPa - 5.3 +/- 2.6 MPa). Peak temperature decreased and the time required to reach peak temperature increased with the higher filler levels. There were strong correlations between the bond strength and temperature change of experimental bonding agents. SIGNIFICANCE: The initial setting behavior of bonding agents containing filler particles may be one of the important factors influencing dentin bond strength. When bonding agents with filler particles are used, it is important to determine if optimum filler levels exist in order to optimize the dentin bond strength.

Analysis of Variance↗
PubMed1995

Influence of light irradiation of dentine primers on dentine-resin bond.

OBJECTIVE: The purpose of this study was to examine the influence of light irradiation of dentine primers that contain camphoroquinone (CQ) on the shear bond strength to dentine and their contact angle. METHOD: Three dentine bonding systems which contain CQ, Imperva Bond, OptiBond and XR-Bond; and Light Bond, which does not contain CQ, were employed. Labial surfaces of freshly extracted lower bovine incisors were ground with no. 600 grit SiC paper. Dentine primers were applied to the dentine surfaces in two groups, irradiated and non-irradiated. A shear bond strength test was performed and the direct contact angle was measured. RESULTS: Statistical analysis (Newman-Keuls multiple comparison P < 0.05) of the data indicated that light irradiation of the dentine primer for systems containing CQ resulted in increased bond strength and decreased contact angle. CONCLUSION: This study indicates that for these dentine bonding systems containing CQ in their primers, light irradiation of the dentine primer is effective in improving wettability and increasing the bond strength to dentine.

Analysis of Variance↗
PubMed1995

Influence of light intensity on shear bond strength to dentin.

PURPOSE: To investigate the influence of light intensity on dentin bond strength of five dentin bonding systems. MATERIAL AND METHODS: The light intensity used to polymerize specimens was controlled at the levels of 100, 200, 400, 600, 800, and 1000 W/m2 (470 +/- 40 nm). Labial surfaces of freshly extracted lower bovine incisors were ground with #600 grit SiC paper to expose dentin. After primer application, bonding agents were applied and bonded with resin composites. A shear bond strength test was performed and the data were analyzed by a one-way ANOVA followed by Newman-Keuls multiple comparison (P<0.05). RESULTS: Statistical analysis of the data indicated that light intensity affected the bond strength to dentin. The mean bond strength of all bonding systems decreased with lower light intensity. The tendency of decreasing bond strength was different among the test materials and each test material had a threshold light intensity that resulted in statistically the same bond strength obtained using a light intensity of 1000 W/m2.

Analysis of Variance↗
PubMed1993

Influence of argon laser curing on resin bond strength.

Light cured resin composites are usually cured with halogen lamps whose light output decreases with time and distance to the resin surface. This study compared bond strengths of resins to tooth structure cured with either an argon laser or a conventional halogen light. The enamel and dentin of bovine incisors were ground on the buccal surface with wet #600 grit SiC paper. A 4 x 2 mm mold was placed on the tooth surface and Scotchbond 2/Silux and Clearfil Photobond/Photo Clearfil A were placed into the molds and cured using a Quick Light or an argon laser for exposure times of 10, 20, and 30 seconds, and distances of 0.0, 0.5, 1.0, and 1.5 mm from the resin surface. The intensity of the Quick Light was measured as 510 mW/cm2 at 470 +/- 15 nm and the intensity of the argon laser was adjusted to 510 mW/cm2 before curing. Shear bond tests at a crosshead speed of 1.0 mm/min were performed after 24 hours of storage in water. The bond strengths obtained with the halogen lamp and the laser were not significantly different at the same exposure times and at 0.0 or 0.5 mm from the resin surface. The laser cured bond strengths did not decrease with increasing distance whereas there was a significant decrease in halogen bond strengths at distances greater than 0.5 mm for both resins. The use of the laser might provide a clinical advantage in cases where the curing light source cannot be brought into proximity to the surface of the resin.

Animals↗
PubMed1991

Effect of filler content of light-cured composites on bond strength to bovine dentine.

The bonding of light-cured composites to tooth tissues is known to be disturbed by polymerization shrinkage, and polymerization shrinkage is affected by the filler content of composites. This in vitro research examined the relationship between the filler content and bond strength to dentine of light-cured composites. Experimental light-cured composite systems with filler contents of 45, 55, 65 and 75 per cent by volume were used in both bond strength to dentine and shrinkage tests. The surfaces selected as substrates were a flat surface and a box-shaped cavity prepared in bovine dentine. The lowest bond strength was obtained with the 45 per cent filler content composite in the box-shaped cavity. Bond strength increased with increasing filler content. Volumetric polymerization shrinkage decreased with increasing filler content. The polymerization shrinkage at 120 s after light curing was 5.24 per cent for the 45 per cent filler content system, 4.77 per cent for the 55 per cent, 2.14 per cent for the 65 per cent and 1.68 per cent for the 75 per cent. The correlation between bond strength and shrinkage was greater for the cavity than it was for the flat surface. This implies that bond strength in the box-shaped cavity may have been affected more by polymerization shrinkage than with the flat surface. The findings lend support to the view that filler content is one of the important factors influencing the physical properties of composites.

Acid Etching, Dental↗
PubMed1991

Dentin bond strength of light-cured glass-ionomer cements.

The purpose of this study was to investigate the influence of surface treatments and irradiation conditions on the bond strength of light-cured glass-ionomer cements to dentin. The light-cured glass-ionomer cements used in this study were Vitrabond, XR Ionomer, and Fuji Lining LC. Three experiments were designed to study the influence of the following factors on bond strength to dentin: (1) effect of the surface treatment of the dentin, (2) effect of the irradiation time, (3) effect of an increase in the interval between mixing of the cement and irradiation. Samples were stored in water for 24 hours, after which shear bond testing was performed at a cross-head speed of 1 mm/min. For Vitrabond, the Scotchprep and Gluma 2 treatments gave the greatest shear bond strengths. For XR Ionomer and Fuji Lining LC, the Scotchprep treatment gave the greatest shear bond strengths. The bond strengths for all cements increased with prolonged irradiation time. Bond strengths decreased with a longer elapsed time between mixing and light-curing. This means that light-curing should be done soon after the cement is placed. The failure mode was found to be cohesive in the ionomer.

Acid Etching, Dental↗
PubMed1991

Effect of irradiation time to light-cured resin composite on dentin bond strength.

This study examined the relationship between the irradiation time of three light-cured resin composites and their bond strength to dentin using two adherend surfaces. The light-cured resin composite systems selected were: Scotchbond/Silux, Scotchbond 2/Silux, and Clearfil Photo Bond/Photo Clearfil A. The adherend surfaces selected were a flat dentin surface and a box-shaped cavity. The greatest bond strength for all resin systems was recorded using the longest irradiation time. The bond strengths increased with an elevated irradiation time. When comparing the flat surface and a box-shaped cavity, the bond strength of the box cavity was greater than the flat surface with similar conditions except for 20 and 30 seconds of Scotchbond and 30 seconds of Clearfil. The correlation between bond strength and irradiation was greater for the flat surface than for the box-shaped cavity. This implied that the bond strength of the box-shaped cavity may be more susceptible to polymerization shrinkage.

Animals↗
PubMed1990

Factors of glass-ionomer cements influencing the bond strength to resin composites.

The bond strength between composites and various particle sizes of glass-ionomer cements was investigated. The best bond strength was obtained after use of a small-particle cement and with the highest powder-to-liquid ratio employed for mixing the cement. In addition, use of a small-particle cement and the highest powder:liquid ratio produced cements with significantly stronger tensile strengths. Failure usually occurred within the cement. Consequently, the recorded bond strength actually reflected the tensile strength of the relevant cement.

Composite Resins↗
PubMed1987

Tensile bond strength between glass ionomer cements and composite resins.

Etching or roughening the surface of glass ionomer cement before use of composite resins and bond agents produces bond strengths comparable to the bond strength between glass ionomers and dentin. Bond failure at such surfaces occurs within the glass ionomer. Adequate washing with water after acid etching the glass ionomer is essential to obtain optimal bond strength. Apparently, some combinations of ionomer cements and resins are more effective than are others in providing a good bond in the "sandwich technique".

Acid Etching, Dental↗
PubMedDate not supplied

Factors influencing bond strengths between unetched glass ionomers and resins.

The use of glass-ionomer cements as a base beneath composite resins has become a popular restorative procedure often referred to as the "sandwich technique." Originally etching of the glass-ionomer surface was recommended to help create the necessary bond between glass-ionomer cement and composite resin. This study investigated the bond strength of various composite resins and their bond agents to unetched glass ionomer. The pH of the bond agents was measured and related as bond strength. The influence of time elapsed between mixing the glass-ionomer cement and placement of the bond agent was also studied. Bond strengths varied from 65.5 kg/cm2 for G-C Dentin Cement with Pyrofil Light Bond A to 3.2 kg/cm2 for G-C Dentin Cement with Bis-Fil-M. The pH range was from 2.28 for Pyrofil Light Bond to 7.62 for Durafill Bond. Low correlation coefficients between bond strength values and pH indicated only limited relationship between the two. The bond strength decreased as the time lapse between the end of the mix and application of the bond agent increased.

Composite Resins↗
PubMedDate not supplied

Effect of die material hue and value on polymerization of indirect resin inlays.

This study investigated the effects of hue and value of mold materials on the polymerization of resin composite inlays fabricated by an indirect process. Three colors of molds were used, and 10 specimens each of three resin composite materials were light polymerized on each of the die materials for each test. The specimens were postirradiation heat polymerized. Compressive strength, flexural strength, Knoop hardness, and bond strength to enamel and dentin were measured. Although differences in properties between specimens polymerized on different die materials were not always significant, the values obtained from the white mold were highest in all tests followed by those obtained on the gray and then the black molds. Correlations (r2) between lightness or value and compressive and flexural strength, hardness, and bond to enamel and dentin values were greater than 0.90. Die color and value appear to be important factors influencing the properties of indirect resin composite inlays even though they are heat polymerized after light activation.

Analysis of Variance↗
PubMedDate not supplied

Influence of irradiation sequence on dentin bond of resin inlays.

The relationship between the order in which a dual-cured resin cement is light activated and the bond strength of resin inlay materials to dentin was examined. Also evaluated was the setting time with various irradiation sequences. Lite-Fil CR/Imperva Bond (Shofu) and Clearfil CR/CR Cement (Kuraray) were employed. Ten specimens, 4 mm in diameter by 4 mm deep, were made with each material for each condition and bonded to bovine dentin with the respective bonding agent and cement. Order of light activation was: 1) no light activation; 2) premix activation of only the liquid prior to mix, 3 seconds for Lite-Fil and 25 seconds for Clearfil; 3) postplacement activation, 30 seconds for Lite-Fil and 40 seconds for Clearfil; and 4) premix and postplacement activation, 3 seconds and 30 seconds for Lite-Fil and 25 seconds and 40 seconds for Clearfil. Samples were stored in water for 24 hours and shear strength tested. The setting time with no activation and premix activation was measured according to the ISO #7489 standards. Bond strengths (MPa) were 1) 4.41, 2) 13.07, 3) 6.34, and 4) 14.81 for Lite-Fil, and 1) 0.37, 2) 2.44, 3) 0.52, and 4) 2.51 for Clearfil. No light activation or only postplacement activation resulted in lower bond strengths with a 4.0 mm-thick specimen. The setting time of the cement mix with premix activation was shorter than with no activation. Light activation of these dual-cure cements is essential. Premix activation of only the liquid resulted in bond strengths similar to those obtained with combined pre- and postplacement activating.

Analysis of Variance↗