Biomedical subjects

K Nakanuma

Publications and source records attributed to K Nakanuma.

5 recordsLinked to original sources

PubMed2001

Synthesis of small multifunctional molecules having nucleic acid binding property.

We have previously reported that a multifunctional conjugate having the acridine derivative as an intercalative molecule and the polyamine moiety as an RNA cleaving molecule bound to a double helical RNA and cleaved the target efficiently. Along the study to develop a sequence and site specific artificial RNA cleaving molecule, we have development a novel intercalative molecule having polyamine moiety and DNA connecting function. The trisamine-acridine-tethered DNA is expected to bind to the complementary RNA and cleave the phosphodiester bond of the RNA near the position of the built-in interecalator.

Acridines↗

PubMed2000

Pulpal reactions to two experimental bonding systems for pulp capping procedures.

This study evaluated the pulpal responses induced by application of two types of bonding system to the exposed dental pulp. One consisted of the following steps: etching with neutralized EDTA, application of an experimental water-based photocuring bonding agent, and restoration with a commercially available photocuring resin composite (EDTA etching system). The other was treatment with an experimental water-based self-etching primer, application of a commercially available bonding agent, and restoration with a commercially available photocuring resin composite (self-etching system). These two systems of treatment were applied to the exposed pulp. Calcium hydroxide was used as a control for the direct pulp-capping material. The pulps in class V cavities in the anterior teeth of beagles were mechanically exposed and then filled using the etching, the self-etching, or the Ca(OH)2 system. The beagles were sacrificed on the 7th, 30th or 90th postoperative day, and pulpal responses were investigated histopathologically using light microscopy. The EDTA etching system induced severe pulp reactions at 7 days after the operation. These reactions did not completely diminish after 90 days. Reparative dentin formation was observed at day 90. The self-etching system showed moderate pulp reactions, which gradually decreased over the experimental period. Reparative dentin bridge formation was observed at day 90. No necrosis of the pulp was observed at any time. Calcium hydroxide induced both moderate and severe initial pulp reactions, with reparative dentin formation evident at day 30. Necrosis was observed in the superficial pulp. It is suggested that the EDTA etching agent caused not only pulpal damage but also re-bleeding because of rinsing and drying. The self-etching system is a promising system for direct pulp capping.

Acid Etching, Dental↗

PubMed1998

Effect of the application of dentin primers and a dentin bonding agent on the adhesion between the resin-modified glass-ionomer cement and dentin.

OBJECTIVES: This study was designed to evaluate the influence of the application of dentin primer and/or dentin bonding agent on the adhesion of a resin-modified glass-ionomer cement to dentin. METHODS: Bovine dentin was pretreated with Dentin Conditioner or EDTA 3-2 solution, primed by an experimental dentin primer, and applied with a dentin bonding agent. A resin-modified glass-ionomer cement, Fuji II LC, was then adhered to the dentin. The tensile bond strength between the light-cured glass-ionomer cement and the pretreated dentin was measured. The components of the experimental dentin primers were 2-hydroxyethyl methacrylate (HEMA), glyceryl methacrylate (GM) and a water-soluble photo-polymerization initiator, 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N, N-trimethyl-1- propanaminium chloride (OTX). Significant differences in the data were examined by an analysis of variance and Scheffe's test for multiple comparisons between the means at p = 0.05. RESULTS: A significantly higher mean bond strength between the Fuji II LC and dentin was obtained by EDTA 3-2 pretreatment, QTX/GM priming, and LB Bond application. This value was comparable with that obtained with the resin composite system. Scanning electron microscopy observation showed the formation of a hybrid layer with a thickness of 1-1.5 microns. SIGNIFICANCE: The data obtained in this investigation suggest that the adhesion of Fuji II LC to dentin is closer to that provided by a resin composite system than to that of conventional glass-ionomer cements.

Adhesiveness↗

PubMed1998

Clinical study of refractory apical periodontitis treated by apicectomy. Part 1. Root canal morphology of resected apex.

The morphology of the root apex was analysed by observation of the anatomy of specimens obtained by apicoectomy in cases of refractory apical periodontitis that did not respond to nonsurgical root canal treatment. Apical ramifications were present in 19 (70%) of the roots, while one were found in the remaining eight (3%) roots. This frequency is far higher than that reported by other investigators, suggesting that there is a close relationship between the anatomical complexity of the root canal and the occurrence of refractory apical periodontitis.

Apicoectomy↗

PubMed1990

[Study on prototype cylindrical HAP].

Hydroxyapatite (HAP) is currently utilized as biomaterials for implantation or reconstruction of bone defect in dentistry. In order to obtain better physical properties and biocompatibility, we have developed cylindrical sintered porous HAP which has longitudinal internal tubules. We measured compressive strength and specific surface area of cylindrical HAP. In the results, compressive strength was more 300MPa on average and specific surface area was 1.7-2.4 folds as HAP ceramics commercially available. This result indicates new bone formation. Cylindrical HAP used was subsequently applied to lower premolars and molars of male beagle dogs (1.5 years). We have implanted cylindrical HAP to bone defect of postextraction of tooth followed to sacrifice six months after. Specimens of bone block were stained with Villanueva bone stain and observed with fluorescence microscope and scanning electron microscope. New tissue formation was observed invading into tubules of 27 microns diameter of cylindrical HAP particles. This new tissue was confirmed to be bone tissue because the proportion of Ca to P was 1.616 obtained by energy dispersive X-ray analyzer.

Alveolar Bone Loss↗