jcda
News & Updates
ca
ESSENTIAL DENTAL KNOWLEDGE
Published by
Study Examines Bacteria’s Effect on
Composite Restorations
The Canadian Dental Association
jadc
DES CONNAISSANCES
DENTAIRES INDISPENSABLES
Publié par
l’Association dentaire canadienne
A
recent study1 by researchers at the University of Toronto
shows that a major cariogenic bacteria also produces
enzymes that hydrolyze resin components of adhesives and
composites, providing a possible contributing explanation
for the increased rate of secondary caries around resin
composite restorations.
The study examined the ability of S. mutans to degrade
resin composites and adhesives through the bacteria’s
esterase activities. Researchers assessed the degradation of resin composite, total-etch and self-etch adhesives
after incubation with S. mutans by measuring a Bis-GMAderived by-product, BisHPPP. BisGMA is a universal component of dental resin composites and adhesives.
The results suggest that S. mutans can degrade resin composites
and adhesives through the bacteria’s esterase activities. Esterasemediated degradation occurred in all materials used in the study, to
varying degrees. A critical factor in determining a restoration’s biochemical stability appeared to be the material’s chemistry.
A major reason for
dental resin composite
restoration replacement
is secondary caries
promoted by acidproducing bacteria,
including Streptococcus
mutans.
Dr. Yoav Finer, the study’s lead researcher and a member of CDA’s
Committee on Clinical and Scientific Affairs, explains how the findings might account for the higher incidence of failed resin composite
restorations compared to amalgam: “When present within the confined space of the restoration–tooth marginal interface, S. mutans
produces both acids and esterases, affecting the hybrid layer, tooth and
composite, ultimately compromising the integrity of the margins and
potentially reducing the longevity of the restoration.”
According to Dr. Finer, the study adds to the group’s previous work
with S. mutans that showed biodegradation of resin composites
increases bacterial virulence: “Our previous studies have shown that
resin composite degradation by-products released by salivary and bacterial esterase increase the ability of S. mutans to produce acids, survive in an acidic environment and form dental plaque,” says Dr. Finer.
The authors say that this study points to the need for manufacturers to
assess dental resin composites and adhesives for biostability—not only
their mechanical properties. a
Reference
1. Bourbia M, Ma D, Cvitkovitch DG, Santerre JP, Finer Y. Cariogenic Bacteria Degrade
Dental Resin Composites and Adhesives. J Dent Res. 2013; 92(11):989-94.
Cite this as: J Can Dent Assoc 2013;79:d179
• 22 •
| 2014 | Vol. 80, No. 1 |
jcda
ca
ESSENTIAL DENTAL KNOWLEDGE
Published by
The Canadian Dental Association
jcdaf
ca