Biomedical subjects

Hiroyasu Koizumi

Publications and source records attributed to Hiroyasu Koizumi.

8 recordsLinked to original sources

PubMed2006

Effect of metal priming agents on bonding characteristics of an acrylic resin joined to SUS XM27 steel.

The purpose of the current study was to evaluate the effect of functional monomers contained in the primers on adhesive bonding of a steel alloy. SUS XM27 steel was primed with one of the following materials; Alloy Primer, Estenia Opaque Primer, and V-Primer. The functional monomers in the primers were a phosphate (10-methacryloyloxydecyl dihydrogen phosphate; MDP) and a thione (6-(4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione, -dithiol tautomer; VTD) for Alloy Primer, MDP alone for Estenia, and VTD alone for V-Primer. The steel disks were bonded with an acrylic resin (Unifast Trad), and bond strength was determined. Of the three primers, both the Alloy Primer (33.3 MPa) and Estenia Opaque Primer (33.9 MPa) materials exhibited far better post-thermocycling bond strength than V-Primer (0 MPa). It can be concluded that the phosphate MDP is effective, whereas the thione VTD is ineffective for bonding SUS XM27 steel.

Acrylic Resins↗

PubMed2006

Bond strength to primed Ti-6Al-7Nb alloy of two acrylic resin adhesives.

This study aimed to evaluate the bonding behavior of two acrylic resin adhesives joined to titanium-aluminum-niobium (Ti-6Al-7Nb) alloy primed with two metal conditioners. Cast Ti-6Al-7Nb alloy disks were air-abraded with alumina and bonded with six combinations of two resin adhesives (Super-Bond C&B and Multi Bond) and three surface conditions (Alloy Primer, M.L. Primer, and unprimed control). Shear bond strengths were determined both before and after 20,000 thermal cycles. The tri-n-butylborane initiated Super-Bond C and B resin exhibited greater bond strength than the BPO-amine initiated Multi-Bond resin. Both the Alloy Primer with a hydrophobic phosphate and the M.L. Primer with a phosphonoacetate effectively improved the 24-hour bond strength of Multi-Bond resin as well as the post-thermocycling bond strength of Super-Bond C and B resin.

Acid Etching, Dental↗

PubMed2005

Systemic administration of argatroban reduces secondary brain damage in a rat model of intracerebral hemorrhage: histopathological assessment.

This study investigated the effects of argatroban, a thrombin inhibitor, on brain edema and inflammation in a rat intracerebral hemorrhage (ICH) model. ICH was induced by injecting collagenase IV into the right caudate nucleus. Argatroban was administered intraperitoneally. Argatroban reduced brain edema from 44.6 to 14.3 microl at 72 h. Infiltration of polymorphonuclear leukocytes at 24 h and monocyte/macrophage at 24 and 72 h was significantly suppressed by argatroban. Argatroban did not increase the volume of hematoma. Systemic administration of argatroban reduced secondary brain damage including edema and inflammation in a rat ICH model.

Animals↗

PubMed2005

Effect of metal halide light source on hardness, water sorption and solubility of indirect composite material.

This study evaluates the effects of a metal halide light source on the post-polymerization properties of the Sinfony indirect composite material. Two polymerization systems were employed: the Hyper LII system, comprising a metal halide polymerization unit, and the Visio system, comprising two proprietary units designed for polymerizing the Sinfony composite. The composite material was polymerized for 60, 120 or 180 s with the LII system. As a control, the composite was polymerized for 15 min with the Visio system. Knoop hardness, water sorption and solubility were determined. The results were analyzed by Dunnett's T3 multiple comparison test (P<0.05). Knoop hardness was greater for polymerization with the LII unit than for that with the Visio system. Water sorption was greater for polymerization with the Visio system than that with the LII unit. For polymerization with the LII unit for 180 s, solubility was significantly reduced as compared with the Visio system. Within the limitations of the current experiment, it can be concluded that the metal halide unit exhibited better polymerizing performance for the composite material than the proprietary units.

Composite Resins↗

PubMed2005

Properties of an indirect composite material polymerized with two different laboratory polymerizing systems.

The purpose of the current study was to evaluate the performance of two laboratory light polymerization systems used to polymerize an indirect composite (Sinfony). A two-step polymerization system (Visio-Alfa and Beta) and a halogen-metal halide unit (Twinkle MIII) were assessed. The composite was polymerized either with the Visio units or with the MIII unit for different exposure periods. Knoop hardness, water sorption, and solubility in water of the composite polymerized with the following modes were determined: Visio, 15 minutes; MIII, 30, 60, 90, 120, and 180 seconds. Extension of light exposure time to the MIII unit improved the hardness of the composite from 30.5 (30 s) to 40.7 (180 s), whereas hardness obtained with the Visio units resulted in 24.8 (15 minutes). Water sorption and solubility of the composite were greater when it was polymerized with the Visio units than with the MIII unit.

Absorption↗

PubMed2005

A new laboratory polymerizing apparatus equipped with halogen and metal halide light sources.

We developed a new laboratory polymerizing unit (Twinkle MIII: M3) equipped with different light sources (a metal halide and two halogen lamps) that could illuminate independently. This study introduced the structure of the curing unit and examined the curing depth of a representative indirect composite (Artglass). The composite material was cured with the following modes: 1) M3 - halogen only; 2) M3 - metal halide only; 3) M3 - both halogen and metal halide (HM); 4) conventional xenon; and 5) preliminary halogen. The results obtained from analysis of variances and post-hoc tests revealed that curing depth was affected significantly (p < 0.05) by both exposure mode and time, and that HM mode exhibited the most favorable curing performance (p < 0.05) among the curing units and polymerization modes. In conclusion, the M3 unit was found to be well suited to polymerizing the composite material tested.

Analysis of Variance↗

PubMed2005

Effect of acidic primers on bonding three magnetic steel alloys with tri-n-butylborane initiated methacrylic resin.

The purpose of this study was to evaluate the effect of acidic primers on bonding magnetic steel alloys. Three alloys (XM27, 447J1, and AUM20) were primed with one of the following materials: Acryl Bond, Estenia Opaque Primer, Eye Sight Opaque Primer, M. L. Primer, or Super-Bond liquid. The specimens were bonded with a tri-n-butylborane initiated resin, and bond strength was determined both before and after thermocycling in water. Unprimed specimen was considered as the control. Average bond strength varied from 0 to 45.3 MPa for the XM27 alloy, 0.3 to 43.6 MPa for the 447J1 alloy, and 0.5 to 41.1 MPa for the AUM20 alloy. Of the five primers, Estenia Opaque Primer exhibited better adhesive performance than the other materials regardless of the type of steel alloy. It can be concluded that the use of the Estenia Opaque Primer, which contains an adhesive monomer (10-methacryloyloxydecyl dihydrogen phosphate; MDP), is recommended for bonding the three magnetic steel alloys with TBB-initiated resin.

Acid Etching, Dental↗

PubMed2004

Effect of noble metal adhesive systems on bonding between an indirect composite material and a gold alloy.

In this study, the bond strength between an indirect composite and a gold alloy was determined for the purpose of evaluating noble metal bonding systems. A single liquid primer designed for conditioning noble metal alloys (Infis Opaque Primer) and tri-n-butylborane-initiated adhesive resins (Super-Bond C & B), with or without the powder component, were assessed. Cast gold alloy disks (Casting Gold type IV) were air-abraded with alumina, followed by six surface preparations, and were then bonded with a light-activated composite material (New Metacolor Infis). Shear testing was performed both before and after thermocycling for evaluation of bond durability. The results showed that three primed groups improved post-thermocycling bond strengths compared to each of the corresponding unprimed groups (P < 0.01). The bond strength was reduced for all six groups by the application of thermocycling (P < 0.01). After thermocycling, the group primed with the Infis Opaque Primer material and bonded with the Super-Bond C & B resin exhibited the greatest bond strength (23.4 MPa). The Infis Opaque Primer and Super-Bond bonding system increased the post-thermocycling bond strength of the control group by a factor of approximately ten. This simple technique is applicable in the fabrication of composite veneered restorations and cone-telescope dentures.

Adhesives↗