Naoki Horiba

The relationship between clinical symptoms and anaerobic bacteria from infected root canals.

The purpose of this study was to investigate the correlation between the composition of bacterial flora from infected root canals and clinical symptoms. The materials evaluated consisted of 28 teeth from 25 patients with apical periodontitis. Eubacterium were found to be significantly related to acute or chronic clinical symptoms and Peptococcus, Peptostreptococcus, and Porphyromonas gingivalis to subacute clinical symptoms. We suggested that Peptococcus, Peptostreptococcus, Eubacterium, Porphyromonas, and Bacteroides were significantly related to percussion pain; Porphyromonas and Bacteroides were significantly related to odor in the infected root canals. Many Bacteroides were isolated from most of the infected root canals.

Correlations between endotoxin and clinical symptoms or radiolucent areas in infected root canals.

Samples were collected from the root canals of 30 teeth of patients with apical periodontitis and assayed for endotoxin content. The detection rates of endotoxin and endotoxin content were higher in symptomatic teeth, teeth with radiolucent areas, and teeth with exudation than in those without them.

Factors affecting successful prognosis of root canal treatment

The purpose of this study was to investigate the correlation between prognosis and various factors influencing repair by using clinical and roentgenographic follow-up evaluations of endodontically treated teeth. There was no statistically significant difference between success of repair in teeth yielding positive canal cultures at the time of filling and those yielding negative cultures. Underfilled root canals were highly successful. Factors influencing failure included deep periodontal pockets, apical rarefactions, occlusal trauma, and teeth with only one or no adjacent teeth.

A study of the distribution of endotoxin in the dentinal wall of infected root canals

Samples of dentinal walls from the pulpal surface of the root canal to the cementum side were prepared by an abrasive microsampling method from teeth extracted from patients diagnosed as having apical periodontitis. Endotoxin was extracted with citric acid, and endotoxin content was quantified using a colorimetric method. Endotoxin content was significantly higher in samples from the pulpal surface of root canals to 300 microns in depth than in those taken from farther toward the cementum side. Endotoxin was detected from all of a series of samples obtained from infected root canals.

Endotoxin and Gram-negative bacteria in the rat periapical lesions

The purpose of this study was to measure the amount of endotoxin as well as to identify Gram-negative bacteria in experimental periapical lesions in rats. Molar pulps were exposed and infected and the amount of endotoxin in the periapical tissue of the right mandibular first molar was measured by Endospecy, while the colony number of Gram-negative bacteria was determined in the same region of the left mandibular first molar. In the control animals, the amount of endotoxin in the periapical tissues did not change at all during the experimental period, and no Gram-negative bacteria were isolated. In the experimental animals, the amount of endotoxin in the periapical tissues increased gradually from 1 to 70 days, and its level was significantly greater than that of control animals after 7 days. Gram-negative bacteria were isolated from the periapical tissues and their number gradually increased from 1 to 14 days (26 to 82%), but decreased at 21 days. It was approximately 60% from 28 to 70 days. The results of this study showed that the amount of endotoxin in the periapical tissues gradually increased with increasing time and that Gram-negative bacteria were isolated from the same region but did not increase in number concurrently with the increase in the amount of endotoxin.

Bactericidal effect of electrolyzed neutral water on bacteria isolated from infected root canals

OBJECTIVE The purposes of this study were to examine the time-related changes in pH, oxidation-reduction potential, and concentration of chlorine of electrolyzed neutral water and to evaluate the bactericidal effect of electrolyzed neutral water against bacteria from infected root canals. STUDY DESIGN Various properties of electrolyzed neutral water--pH value, oxidation-reduction potential, and concentration of chlorine--were measured at different times after storage of the water in the open state, the closed state, or the closed-and-dark state. The bactericidal effect of the various electrolyzed neutral water samples was then tested against 17 strains of bacteria, including 15 strains isolated from infected canals, as well as against 1 strain of fungus. Each bacterial or fungal suspension was mixed with electrolyzed neutral water, and the 2 substances were reacted together for 1 minute. After incubation for 1 to 7 days, the bactericidal effect of the electrolyzed neutral water was determined. RESULTS The pH value and oxidation-reduction potential of electrolyzed neutral water remained almost unchanged when the water was stored in a dark, closed container. However, the concentration of chlorine decreased from 18.4 ppm to 10.6 ppm. Electrolyzed neutral water showed a bactericidal or growth-inhibitory effect against the bacteria. CONCLUSIONS The results indicate that electrolyzed neutral water maintains a constant pH and oxidation-reduction potential when kept in a closed container without light and that it exhibits a bacteriostatic/bactericidal action against isolates obtained from infected root canals.

A pilot study of Japanese green tea as a medicament: Antibacterial and bactericidal effects

Antibacterial and bactericidal actions of extracts of four kinds of Japanese green tea were tested against 24 bacterial strains isolated from infected root canals. The extracts of all four teas had antibacterial and bactericidal actions against many of the bacteria.

Cytotoxicity against various cell lines of lipopolysaccharides purified from bacteroides, fusobacterium, and veillonella isolated from infected root canals

The cytotoxicity against two mesenchymal cell lines, L-929 and WI-38, and two epithelial cell lines, KB and HeLa S-3, of lipopolysaccharide (LPS) purified from strains of Bacteroides gingivalis, Fusobacterium nucleatum, and Veillonella parvula isolated from infected root canals was investigated. The inhibition of cell growth by these LPSs was considerable for mesenchymal cell lines, but mild for epithelial cell lines. The cytotoxic effect of F. nucleatum LPS was the greatest and that of B. gingivalis LPS was the least.

Relationship between clinical symptoms and enzyme-producing bacteria isolated from infected root canals

The object of this study was to determine the correlation between clinical symptoms and the activity of enzymes such as collagenase, chondroitinase, and hyaluronidase produced by bacteria isolated from infected root canals. The materials examined consisted of 28 teeth with apical periodontitis from 25 patients. Bacteria producing collagenase or chondroitinase and hyaluronidase were found to be significantly related to subacute clinical symptoms involving percussion pain. The frequency of bacteria producing collagenase was higher in isolates from root canals with a radiolucent area over 5 mm in diameter than in those from canals having a radiolucent area less than 5 mm in diameter.

Effects of lipopolysaccharides on human dental pulp cells

Human dental pulp cells were treated with 1, 10, and 100 micrograms/ml of lipopolysaccharide (LPS). The effects of treatment were examined by measurement of the DNA content, protein content, and alkaline phosphatase activity of the cells. LPS samples were purified from Porphyromonas gingivalis, Porphyromonas endodontalis, and Fusobacterium nucleatum isolated from root canals, and Escherichia coli 0111:B4 LPS was used as a positive control. At a concentration of 1 microgram/ml, none of the LPSs caused any change in the production of DNA or protein, whereas the amount of DNA was increased at 10 micrograms/ml and inhibited at 100 micrograms/ml. Protein synthesis was decreased by LPSs at both 10 and 100 micrograms/ml. Alkaline phosphatase activity was not changed at any concentration of LPS tested.