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S Imazato

Publications and source records attributed to S Imazato.

35 records · Page 2Linked to original sources
PubMed1999

Water sorption and colour stability of composites containing the antibacterial monomer MDPB.

OBJECTIVES: Previously, we have reported that composites incorporating the newly developed antibacterial monomer methacryloyloxydodecylpyridinium bromide (MDPB) inhibited bacterial growth and plaque accumulation on their surfaces without releasing antibacterial components, and that the antibacterial effect was not lost even after ageing in a wet environment for a long period. The purpose of this study was to investigate the influence of the incorporation of MDPB on the water sorption characteristic and colour stability of Bis-GMA based composites. METHODS: Cured disc-shaped specimens of composites containing 0.4% or 0.5% MDPB were fabricated, and water uptake, the diffusion coefficient and the surface contact angle for water were determined. Discoloration of MDPB-containing composites was evaluated after immersion in water at 37 degrees C and 60 degrees C for 4 weeks and compared with that of the control composite without MDPB. RESULTS: There were no significant differences in water uptake, diffusion coefficient and contact angle between the control and MDPB-containing composites. Although composites incorporating MDPB showed greater discoloration than the control when maintained at 37 degrees C, no difference was found after 4 weeks of immersion in water at 60 degrees C. CONCLUSIONS: Incorporation of small amounts of the antibacterial monomer MDPB showed no influence on the water sorption characteristic and affected a little the colour stability of the Bis-GMA based composite, causing rapid discoloration.

Absorption↗
PubMed1998

Antibacterial activity of cured dental resin incorporating the antibacterial monomer MDPB and an adhesion-promoting monomer.

In this study, the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) and an adhesion-promoting phosphoric monomer were incorporated into Bis-GMA-based dental resin and its antibacterial activity after curing was investigated. The experimental resin containing MDPB and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was polymerized and washed with methanol, and the bacteriostatic and bactericidal effects against Streptococcus mutans were determined. Growth of S. mutans was strongly inhibited by contact with the surface of cured MDPB/MDP-containing resin, although the bactericidal effect was small. Cured MDPB/MDP-containing resin also showed an inhibitory effect against in vitro plaque formation on its surface by S. mutans. The bactericide immobilized in Bis-GMA-based resin demonstrated bacteriostatic activity as a contact antimicrobial even when adhesion-promoting phosphoric monomer was incorporated into the materials.

Adhesives↗
PubMed1998

Antibacterial activity of dentine primer containing MDPB after curing.

OBJECTIVES: A monomer methacryloyloxydodecylpyridinium bromide (MDPB) has antibacterial activity before polymerization. Furthermore, the antibacterial agent is immobilized by the polymerization of MDPB and the resin-based material incorporating MDPB is able to show an antibacterial effect even after being cured. The purpose of this study was to investigate the antibacterial effect of a dentine primer containing MDPB after curing. METHODS: The inhibitory effect of a cured MDPB-containing primer on the growth of Streptococcus mutans, Actinomyces viscosus and Lactobacillus casei was determined by the agar-disc method. The bactericidal activity of cured primer during a 1-h contact period was assessed using S. mutans, and the elution of unpolymerized MDPB was measured with high performance liquid chromatography. RESULTS: Cured MDPB-containing primer showed an inhibitory effect on the growth of all species which were in contact with the specimen surface, and displayed a little bactericidal effect on S. mutans without releasing any unpolymerized antibacterial components. CONCLUSION: Incorporation of antibacterial monomer MDPB into dentine primer is beneficial for providing antibacterial activity after curing.

Actinomyces viscosus↗
PubMed1998

Antibacterial activity of proprietary self-etching primers.

PURPOSE: To determine and compare the in vitro antibacterial activity of three self-etching primers. MATERIALS AND METHODS: LB primer (Liner Bond 2), FB primer (Fluoro Bond), and MB conditioner (Tokuso Mac Bond) were evaluated. The antibacterial activity against Streptococcus mutans, Lactobacillus casei, and Actinomyces viscosus was assessed using the agar disc-diffusion method. Twenty microliters of each primer were impregnated into a paper disc and placed on a Brain Heart Infusion agar plate inoculated with a bacterial suspension. The size of inhibition zones produced around the specimens was measured after 48 hours of incubation of the plate. In addition, 20 microliters of each primer was added to a 1 ml suspension of S. mutans adjusted to 1 x 10(6), 1 x 10(5), or 1 x 10(4) CFU/ml in phosphate buffered saline and kept in contact for 30 seconds. The number of viable bacteria after contact with each primer was determined. The results were analyzed by ANOVA and Fisher's PLSD test (P < 0.05). RESULTS: LB primer and FB primer produced inhibition zones against S. mutans and A. viscosus, and MB conditioner produced an inhibition zone only against A. viscosus. No inhibition zones were produced by any of the primers against L. casei. The three primers completely killed 1 x 10(4) CFU of S. mutans within 30 seconds of contact. When 1 x 10(5) or 1 x 10(6) CFU of bacterial cells were kept in contact, significant differences in the number of recovered viable cells were found among the three primers with MB conditioner being the most bactericidal. LB primer had little bactericidal activity and the mean reduction of viable bacteria by FB primer and MB conditioner was approximately 30% and 65%, respectively.

Actinomyces viscosus↗
PubMed1997

Incorporation of antibacterial monomer MDPB into dentin primer.

The polymerizable monomer methacryloyloxydodecylpyridinium bromide (MDPB) shows antibacterial activity when immobilized in a resin-based material. In this study, the antibacterial effect of a dentin primer incorporating MDPB was investigated. The influence of incorporation of MDPB on bond strength to dentin and on the curing performance of the adhesive system was also evaluated. Experimental primers were prepared by addition of MDPB into a proprietary primer at 1, 2, or 5%. Antibacterial effects of experimental primers were compared with those of control primer and two other proprietary primers by an agar disc-diffusion method and bactericidal activity test. Experimental primers produced greater inhibition zones against Streptococcus mutans, Actinomyces viscosus, and Lactobacillus casei than any of three proprietary primers, and inhibition increased as the concentration of MDPB was increased. Bactericidal activity of MDPB-containing primers against Streptococcus mutans was greater than those of the other three primers, with incorporation of MDPB at 5% showing complete killing of bacteria after 30 s contact. No decrease in tensile bond strength was observed for materials containing MDPB. On the contrary, the primer incorporating 1 and 2% MDPB showed higher bond strength than all the others, including the control (p < 0.05). When the degree of conversion of the complex of primer and adhesive resin was determined with Fourier Transform Infrared Spectroscopy, there were no significant differences between any of the experimental primers and the control (p > 0.05). These results indicate that incorporation of the antibacterial monomer MDPB enhanced the antibacterial effect of a proprietary dentin primer before curing, and had no adverse influence on bond strength to dentin and curing of the adhesive system.

Actinomyces viscosus↗
PubMed1995

Antibacterial activity of MDPB polymer incorporated in dental resin.

OBJECTIVES: Previously, we have reported that dental composite incorporating the new monomer methacryloyloxydodecylpyridinium bromide (MDB) showed no release of antibacterial components after being cured but still exhibited antibacterial activity against Streptococcus mutants on its surface. In this study, in order to elucidate the mechanism of the antibacterial effect of immobilized MDPB, the bactericidal activity of MDPB polymer in water-soluble and -insoluble form was investigated, and the effect of MDPB polymer on bacterial attachment was estimated. METHODS: Solutions of homo-polymer of MDPB and co-polymer of MDPB with acrylamide were prepared and the viability of seven major oral streptococci was determined after incubation with each polymer solution. For the estimation of bactericidal activity of insolubilized MDPB polymer, bacteria were kept in contact with cured unfilled Bis-GMA-based resin discs with or without MDPB, and the recovery of viable cells was measured. Attachment of streptococci to cured resin discs with or without MDPB was also compared using radiolabelled bacteria. RESULTS: Water-soluble homo-polymer of MDPB and co-polymer with acrylamide showed bactericidal activity against oral streptococci. However, cured resin incorporating MDPB, which is in water-insoluble form, had little bactericidal activity. Attachment of streptococci, including species which are early colonizers in dental plaque formation, to the cured resin containing MDPB was significantly less than to the control without MDPB. CONCLUSIONS: These results indicate that the bactericidal activity of MDPB polymer is reduced after immobilization, but MDPB on the surface of a resin-based material still shows a bacteriostatic effect and antiadhesion property against oral streptococci.

Analysis of Variance↗
PubMed1995

Relationship between the degree of conversion and internal discoloration of light-activated composite.

In order to elucidate the relationship between the degree of conversion and internal discoloration of light-activated composite, four experimental composites which contained different amounts of Bis-GMA and TEGDMA were prepared, and the degree of conversion and discoloration of each composite, with or without annealing, were determined. The degree of conversion was measured by Fourier transformation infrared spectroscopy and the color change was determined after 1, 2, 3 and 4 weeks of immersion in water at 60 degrees C. The non-annealed composites demonstrated a greater degree of conversion and less discoloration as the amount of TEGDMA was increased. Annealed composites showed a significantly greater degree of conversion and less discoloration compared with the non-annealed composites. The results indicate that the greater the degree of conversion, the less the discoloration of composite, and the correlation between the two factors was significant for light-activated composite.

Amines↗
PubMed1995

Antibacterial effect of composite incorporating Triclosan against Streptococcus mutans.

It has been shown that composite incorporating the antibacterial agent Triclosan (Irgasan DP 300, which is sparingly soluble in water, inhibited in vitro plaque formation by Streptococcus mutans, although the release of the agent was much less than the minimum inhibitory concentration for the bacterium. In this study, the inhibitory effect of the composite incorporating 1% Triclosan against growth and adherence of S. mutans was investigated. S. mutans was inoculated on the surface of a specimen made of control or Triclosan-incorporated composite and the number of bacteria was compared after 3, 6, 12 and 24 hr of incubation. The adherence of S. mutans to the control and experimental composite, with or without saliva treatment, was also examined by scanning electron microscopy. The composite incorporating Triclosan demonstrated significant inhibition of growth of S. mutans after 6, 12 and 24 hr of incubation. Adherence of S. mutans to the Triclosan-incorporated composite was less compared with control for both non-treated and saliva-treated specimens. It is concluded that the antiplaque effect of composite incorporating Triclosan depends upon its ability to inhibit bacterial growth and adherence, and Triclosan-incorporated composite is able to exhibit the antibacterial activity even after being treated with saliva.

Anti-Infective Agents, Local↗
PubMed1994

Incorporation of bacterial inhibitor into resin composite.

Attempts to produce resin composite with antibacterial properties by incorporation of an antibacterial agent such as chlorhexidine have been reported, but problems can arise due to release of the inhibitory agent from the composite. Such problems may include toxic effects, influence on mechanical properties, and loss of effectiveness. A new monomer, methacryloyloxydodecylpyridinium bromide (MDPB), was synthesized by combining an antibacterial agent and methacryloyl group. The monomer was incorporated into resin composite to develop a non-releasing antibacterial composite. The ability of composite incorporating MDPB to inhibit growth and plaque accumulation by Streptococcus mutans in vitro was assayed, elution of antibacterial components from the material was investigated, and the influence of incorporation of MDPB on the mechanical properties of composite was studied. Uncured MDPB revealed antibacterial activity against S. mutans and six other species of oral streptococci, with the minimum inhibitory concentration for S. mutans being comparable with that of triclosan. After composite incorporating MDPB was cured, no elution of the antibacterial components was observed from the material, even after 90 days' immersion in water or other solvents. Growth of S. mutans on agar under specimens of MDPB-containing composite was inhibited compared with controls. In a bacterial accumulation study, S. mutans accumulated to a lesser degree on the surface of composite incorporating MDPB (p < 0.05) than on control. Incorporation of MDPB had no significant influence on the mechanical properties of the composite.

Analysis of Variance↗
PubMed1994

Influence of incorporation of antibacterial monomer on curing behavior of a dental composite.

A newly developed monomer, methacryloyloxdodecylpyridinium bromide (MDPB), has an antibacterial activity against oral streptococci, and this monomer can be active even after being immobilized as one component of a cured composite. The purpose of this study was to investigate the influence of incorporation of MDPB on the curing behavior of Bis-GMA-based composites. Depth of cure, degree of cure, light-attenuating effect, and surface hardness of composites incorporating 0.4 or 0.5% MDPB were measured and compared with those of a control material without MDPB. Depth of cure of composites with MDPB, measured by means of a penetrometer, was greater than for the control (p < 0.05). Differential thermal analysis showed that composites with MDPB had a significantly greater degree of cure than the control (p < 0.05). The light-attenuating effect of MDPB composites was less than for the control (p < 0.05). No significant difference between experimental and control was obtained with respect to Vickers hardness after both one day's and seven days' storage in water. These results indicate that the incorporation of small quantities of MDPB into Bis-GMA-based composites did not adversely affect the cure performance. On the contrary, a significant, though small, improvement was observed.

Analysis of Variance↗
PubMed1994

Shear bond strength of amalgam adhesives to dentin.

This study compared the bond strength of resinous adhesives used to bond amalgam to dentin. The adhesives were: All-Bond 2 (AB), Liner-F (LF), SuperBond C&B (SB), Amalgambond (AM), Photo Bond (PB), and Panavia (PA). Occlusal surfaces of non-carious molars were ground wet to 600 grit finish, exposing dentin. The dentin surfaces were conditioned and the adhesives were applied according to manufacturers' instructions. Dispersalloy amalgam (D) was condensed onto the adhesive immediately. For comparison, resin composite, Photo Posterior (PO) and Bis-Fil (BIS) were used. After 24 hours of storage in 100% humidity at room temperature, shear bond strengths were determined with a shear testing jig in an Instron testing machine at a crosshead speed of 0.5 mm/minute. The data were compared using ANOVA, P < 0.01. AB, LF, D had significantly higher bond strengths than other amalgam adhesives. There was no significant difference between SB, D and PB, PO. Bond strength of PB, PA, D was significantly higher than PA, D. Thus, there were significant differences among adhesives for bonding amalgams. Amalgam to dentin and composite to dentin bond strength were comparable except for the All-Bond groups. Fracture patterns at the dentin/restoration interfaces were examined by scanning electron microscopy (SEM).

Analysis of Variance↗
PubMed1990

Bonding ability of light cured composite resin to enamel and dentin promoted by various bonding systems--microleakage and bond strength studies.

The purpose of this study was to estimate bond strength between light cured composite resin and enamel or dentin, and marginal sealing ability of composite resin promoted by five commercial bonding systems. At first, tensile bond strength between light cured composite resin and enamel or dentin promoted by these bonding systems were measured. Next, class V cavities were prepared at cementoenamel junction of extracted human molars and filled with light cured composite resin, using the same bonding systems. Microleakage around the restoration was estimated by dye penetration test. All bonding systems presented high bond strength and good marginal sealing between composite resin and enamel. The bonding systems which presented high bond strength between composite resin and enamel or dentin inhibited microleakage around restoration effectively. However, no bonding system could inhibit microleakage completely at the cementum/dentin-composite resin interface.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Inhibition in vitro of caries around amalgam restorations by bonding amalgam to tooth structure.

Class 5 preparations in human molars were restored with amalgam. In half of the restorations, an experimental resin liner capable of bonding amalgam to tooth structure was used. The restored teeth were incubated in a bacterial medium containing sucrose and a culture of Streptococcus mutans. Artificial carious lesions were produced around all restorations. The experimental liner inhibited penetration of the lesions along the cavity wall. This inhibition was more effective at the occlusal side.

Dental Amalgam↗