87 Evaluation of Streptococcus Mutans on Dental Composite Resins

Thursday, March 22, 2012: 8 a.m. - 9:30 a.m.
Presentation Type: Oral Session
B. STONER1, J. PIASCIK2, E. SWIFT JR.3, B. BYERS4, L. NISTICO4, G. EHRLICH5, and W. COSTERTON4, 1Research Triangle Institute, Durham, NC, 2RTI International, Research Triangle Park, NC, 3Operative Dentistry, University of North Carolina, Chapel Hill, NC, 4Center for Genomic Sciences, Allegheny-Singer Research Institute, Pittsburgh, PA, 5Center for Genomic Sciences, Allegheny-Singer Research Institute, Pittsburgh

Objective: á Over the past decade, the clinical placement of dental composites for posterior restorations has dramatically increased as amalgam use has declined.á Dental composites have evolved both chemically and physically; however, they still have some drawbacks, including polymerization shrinkage, potential failure at resin-dentin interfaces leading to secondary caries, and relatively high coefficient of thermal expansion.á Recently, attention has shifted towards deleterious effects of dental biofilms on the potential accelerated degradation of resin-based composites

Methods: Composite discs were formed in Teflon molds and light-activated according to the manufacturers' recommended procedures. Cured specimens were then wet-polished with 3 mm diamond paste to replicate clinical polishing procedures.á Specimens were then exposed to Streptococcus mutans (biofilm-forming strain of this organism (UA159-BS480)) and bacterial adhesion was quantified using confocal scanning laser microscopy (CLSM) after period of 1, 4, 7, 11, 13, and 15 days.á Additionally, stylus profilometry, AFM, and SEM were used to analysis composite degradation.
Dental Composite AFM Initial Ra (nm) AFM Final Ra (nm) Profilometry Initial Ra (nm) Profilometry Final Ra (nm)
Filtek Supreme Ultra 10.5 29.5 10.0 47.3
Premise 22.3 37.9 22.0 58.9
Kalore 35.1 74.9 37.9 214.8
Esthet-X 77.0 276.9 44.5 368.5

áResults: CLSM revealed that surfaces exhibited an increase in biofilm thickness (from 2-4 Ám at 1 day to 5-30 Ám at 13 days) and the onset of concavities indicating foci of microbial attack and potential sites of material degradation.á Surface roughness analysis showed that all composite surfaces increased in Ra indicating biofilm-driven degradation.   Conclusions: Dental composites provide a novel substrate in the oral environment that is colonized by complex microbial communities which can further accelerate degradation and promote secondary caries. áBy characterizing biofilm-enhanced degradation may lead to the development of new composites with increased restoration lifetime.á This research was supported through NIH/NIDCR Grant NIH - R56 DE021387-01.


This abstract is based on research that was funded entirely or partially by an outside source: NIH/NIDCR Grant NIH - R56 DE021387-01

Keywords: Adhesion, Biofilm, Composites, Dental materials and Surfaces