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International Journal of Dentistry
Volume 2012, Article ID 452108, 4 pages
http://dx.doi.org/10.1155/2012/452108
Clinical Study

Relationship between Cariogenic Bacteria and pH of Dental Plaque at Margin of Fixed Prostheses

Department of Fixed Prosthodontics and Occlusion, Osaka Dental University, 1-5-17, Otemae, Chuo-ku, Osaka 540-0008, Japan

Received 30 June 2011; Revised 13 September 2011; Accepted 1 October 2011

Academic Editor: Alexandre Rezende Vieira

Copyright © 2012 Junko Tanaka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. The purpose of this study was to investigate whether teeth that have undergone prosthetic restoration are under conditions that promote caries recurrence. Methods. The subjects were 20 dentate adults with both a healthy tooth and an affected tooth entirely covered with a complete cast crown in the molar regions of the same arch. The pH was measured in plaque adhering to the margin of the tooth covered with a complete cast crown and adhering to the cervicobuccal area of the natural tooth. In addition, the numbers of cariogenic bacteria (mutans streptococci and lactobacilli) were measured employing the saliva test. The relationships between the number of cariogenic bacteria and plaque pH of the natural tooth and between the number of cariogenic bacteria and plaque pH of the tooth covered with a complete cast crown were investigated. Results. The plaque pH of the tooth covered with a complete cast crown decreased as the numbers of SM and LB increased. The natural tooth were also influenced by the number of SM. Conclusion. Secondary caries are likely to develop from the marginal region of the crown in the oral cavity with a high caries risk unless a preventive program is prepared and the oral environment is improved following the program.