The microbiota of root caries lesions of different grades of severity were studied. Fourteen lesions were examined. The experimental design of the study allowed correlation of histopathologically distinguishable stages with specific and distinct microbial populations. Dentin samples were ground in a sterile mortar and cultured anaerobically on nonselective Columbia blood agar plates supplemented with 5% hemolyzed human blood and on media selective for Lactobacillus spp. and streptococci. The cultivable microbiota were quantitatively speciated using Rapid ID 32A, Rapid ID 32 Strep, API 20 Strep, API ZYM, and API 50 CH tests and SDS-PAG electrophoresis. In initial as well as in advanced lesions gram-positive bacteria accounted for approximately 90% of the CFUt. The proportion of Actinomyces, and in particular A. naeslundii was significantly higher (p < 0.05) in initial lesions than in advanced lesions. In contrast, the percentage of Streptococcus and especially S. mutans was higher (p < 0.05) in advanced than in initial lesions. Surprisingly low (0.8% of the CFUt) was the percentage of lactobacilli in advanced lesions. Gram-negative bacteria formed a minor part of the microbiota in both initial and advanced lesions. Among the gram-negative isolates, Prevotella, Selenomonas, and Bacteroides spp. were most noticeable. In advanced lesions, only the outermost layer of 0.5 mm thickness was populated by a high number of bacteria; the following segments harbored a negligible number of bacteria only. It is concluded that root caries is a continuous destruction process which is restricted to a subsurface zone of limited depth. The necrotic dentin is successively worn away, leading to a saucer-shaped cavitation which is repopulated by plaque. The creation of cavitations favors an aciduric flora. This might explain the succession of bacterial populations observed during the destruction process.

Keywords:
Dentin, Microbiology, Root caries
This content is only available via PDF.
© 1996 S. Karger AG, Basel
1996
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.