Su-Jong Lee

A study on the hemolytic properties of Prevotella nigrescens

Hemolytic property is a specific feature of bacteria to obtain iron which is essential for its survival in host tissues. Therefore, it is thought to be one of several factors of virulence. The purpose of this study was to investigate the hemolytic properties of Prevotella nigrescens isolated from the teeth diagnosed as pulp necrosis and apical periodontitis under the presence of hemolysin inhibitors such as and dithiothreitol. heat, various pH and cultural conditions. The results were as follows; 1. Clinically isolated P. nigrescens strains and standard P. nigrscens ATCC 33563 showed hemolytic activity. 2. P. nigrescens showed higher hemolytic activity against human erythrocytes than sheep or horse erythrocytes. 3. and dithiothreitol (DTT) reduced the hemolytic activity of P. nigrescens in a dose dependent manner (p, but the hemolytic activity was significantly decreased at . 5. P. nigrescens cultured in condition showed higher hemolytic activity than the bacteria cultured in the anaerobic condition.

The effects of surface contamination by hemostatic agents on the shear bond strength of compomer

One of the latest concepts in bonding are “total etch” , in which both enamel and dentin are etched with an acid to remove the smear layers, and “wet dentin”in which the dentin is not dry but left moist before application of the bonding primer. Ideally, the application of a bonding agent to tooth structure should be insensitive to minor contamination from oral fluids. Clinically, contaminations such as saliva, gingival fluid, blood and handpiece lubricant are often encountered by dentists during cavity preparation. The aim of this study was to evaluate the effect of contamination by hemostatic agents on shear bond strength of compomer restorations. One hundred and ten extracted human maxillary and mandibular molar teeth were collected. The teeth were removed soft tissue remnant and debris and stored in physiologic solution until they were used. Small flat area on dentin of the buccal surface were wet ground serially with 400, 800 and 1200 abrasive papers on automatic polishing machine. The teeth were randomly divided into 11 groups. Each group was conditioned as follows: Group 1: Dentin surface was not etched and not contaminated by hemostatic agents. Group 2: Dentin surface was not etched but was contaminated by Astringedent � (Ultradent product Inc.,

Cytotoxic effects of prevotella nigrescens on cultured cells

Infection of the dental pulp commonly occurs as a consequence of caries. Pulpal infections often progress to pulp necrosis and periapical lesion development with periapical bone destruction. The severity of pulpal/periapical inflammation has been directly correlated with the total microbial content within root canals, and with the length of time the periapical tissues were exposed to the infecting microorganisms. Microbial studies of endodontic infections have revealed that gramnegative anaerobic bacteria are the prominent microorganisms. Some combinations of bacterial species present in root canals are more pathogenic in inducing periapical inflammation and bone destruction. Species of Prevotella, Porphyromonas, Fusobacterium, and Peptostreptococcus are strongly linked to increased periapical destruction. Sunqvist et al identified 25 strains of black pigmented Bacteroides in 22 of 72 infected root canals and Jin-Soon Han, Eun-Sook Kim, Su-Jong Lee, Yong-Ouk You*, Kyung-Soo Han**, Mi-Kyung Im Department of Conservative Dentistry, College of Dentistry, Wonkwang University Department of Oral Biochemistry, College of Dentistry, Wonkwang University* Department of Oral Medicine, College of Dentistry, Wonkwang University** Cytotoxic Effects of Prevotella nigrescens on Cultured Cells

Detection of black-pigmented bacteria in infected root canals

Black-pigmented bacteria have been implicated in the endodontic infections. This group of microorganisms includes Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, and Prevotella nigrescens. The organisms display a wide variety of virulence factors that may be pertinent to acute endodontic infections. The aim of this study was to identify P. endodontalis, P. gingivalis, P. intermedia, and P. nigrescens by using special potency disk test, filter paper spot test, 165 rRNA gene-directed PCR, and API 32A. Microbial samples were collected from root canals of 33 intact teeth with necrotic pulp and/or apical periodontitis. Conventional laboratory methods were used for identification of the strains of black pigmented bacteria. Eighteen of 33 samples were positive for the growth of black-pigmented bacteria Five colonies were cultured from each pure cultured colonies from Brucella agar plate. Seventy seven colonies were positive for the growth of black-pigmented bacteria. Thirty three of 77(42.6%) were identifed as P. nigrescens, 10 of 77(12.9%)were P. gingivalis, 6 of 77(7.8%) were P. endodontalis, 10 of 77(12.9%) were P. intermedia. On the contrary the reference strains of P. nigrescens, experimental strains of P nigrescens was sensitive to kanamycin in special potency disk test. 165 rRNA gene PCR and API test after rapid presumptative identification methods, such as special potency disk test and filter paper spot test, would be accurate detection methods for black-pigemented bacteria.