|
Overview
A recent study from the University of Heidelberg suggests that titanium, gold, natural enamel and amalgam alloy are superior to composite materials in reducing the adherence of Streptococcus mutans to dental restorations. This finding was presented in a poster session at the 2006 Interscience Conference on Antimicrobial Agents and Chemotherapy, and received online news coverage from MedPage Today  .
In the in vitro study, 73 restorative material specimens were coated with cultured S. mutans and then examined with a scanning electron microscope for bacterial adherence. The investigators reported that in the absence of saliva, samples of titanium, gold, natural enamel and amalgam alloy had significantly less S. mutans adherence than Herculite XRV, a composite material manufactured by Kerr Dental. However, in the presence of saliva, bacterial adherence of S. mutans was reduced on the titanium and amalgam samples but increased in most of the other tested materials.
Streptococcus mutans is a cavity-causing bacterium that grows on tooth surfaces and a primary microbial factor in the etiology of dental caries. The new study found that the least S. mutans bacteria adhered to specimens of titanium, a reactive metal that forms a passivating oxide layer. Titanium and titanium alloys are commonly used in dental implants and prostheses, crown fabrications, bridge frameworks, and denture frameworks.
The oral cavity is home to a diverse ecosystem of microorganisms, including dental plaque biofilms, the cariogenic S. mutans and oral bacteria that are associated with periodontal disease (e.g., Porphyromonas gingivalis). S. mutans is especially resilient in attaching to tooth surfaces and other S. mutans bacteria. However, numerous biological modifying factors, such as low salivary flow, diet, oral hygiene, acid reflux disease and other gastrointestinal conditions, can affect an individual patient’s risk of dental caries. Saliva plays a protective role by reducing exposure to the plaque acids that can demineralize tooth surfaces.
Although the laboratory study does not replicate bacterial exposure or normal salivary flow in the oral cavity, it offers preliminary evidence that S. mutans has variable levels of adhesion to restorative materials, which may have the potential to influence caries risk in adjacent dental surfaces. Further research is required to clarify the many factors linked with S. mutans acquisition, adherence and transmissibility, along with the specific properties of dental restorative materials that may influence the adherence of bacteria.
Regardless of the restorative material used in dental practice, the ADA recommends daily oral hygiene practices, including brushing and flossing, for effective plaque removal. The ADA will continue to monitor the scientific evidence on these areas of research to assist practitioners with the provision of optimal patient care.
Footnotes
1 Phend C. ICAAC: Amalgam Dental Fillings Fend Off Bacteria Better than Composite. MedPage Today, Sept. 29, 2006. Available at: “ http://www.medpagetoday.com/2005MeetingCoverage/2005ICAACMeeting/tb/4200 ”. Accessed Oct. 2, 2006.
Return to Top
Additional Resources
Journal of the American Dental Association
Return to Top
Science in the News is a service by the American Dental Association (ADA) to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.
Document Posted October 2006
To view a PDF file, you need Adobe Reader. Click on the logo to download.
| 
