No evidence for the growth-stimulating effect of monomers on cariogenic Streptococci

Ivana Nedeljkovic, Kumiko Yoshihara, Jan De Munck, Wim Teughels, Bart Van Meerbeek, Kirsten L. Van Landuyt

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Background: In spite of contradicting results, the high susceptibility of composites for secondary caries is still often associated with the bacterial growth-stimulating effect of released methacrylate monomers. However, most studies that showed this effect were performed with techniques having inherent limitations (spectrophotometry). Objectives: Therefore, our objective was to determine the effect of four methacrylate monomers (2-Hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA), ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate (DEGDMA)) on the growth of two caries-associated bacteria, Streptococcus mutans and sobrinus, and one non-cariogenic species, Streptococcus sanguinis, using TaqMan quantitative polymerase chain reaction (qPCR) to quantify bacterial DNA. Materials and methods: Cultures were exposed to monomer solutions selected after spectrophotometric growth measurements. At baseline and predetermined time intervals, bacterial DNA was extracted and quantified with TaqMan qPCR. Biofilms grown in the presence of monomers were analyzed with scanning electron microscopy (SEM). Results: Spectrophotometry indeed showed increased growth rates of all three strains with 5 mM TEGDMA, EGDMA, and DEGDMA and increased total biomass of S. sanguinis with 5 mM TEGDMA. However, qPCR failed to show any growth-stimulating effect of these monomers on S. mutans and S. sobrinus. In contrast, some monomers exhibited a growth-inhibiting effect on S. sanguinis. SEM revealed extracellular matter in S. sobrinus and S. sanguinis biofilms, which might be attributed to polymer formation. Conclusions: Techniques which quantify bacterial DNA are more appropriate to evaluate bacterial growth in the presence of monomers than spectrophotometry. Clinical relevance: Even though methacrylate monomers did not affect the growth of cariogenic species, growth inhibition of S. sanguinis, a non-cariogenic antagonistic species, may lead to ecological shifts towards higher cariogenicity.

Original languageEnglish
Pages (from-to)1861-1869
Number of pages9
JournalClinical Oral Investigations
Volume21
Issue number5
DOIs
Publication statusPublished - Jun 1 2017

Keywords

  • Bacterial growth
  • Dental composite
  • Methacrylate monomers
  • Oral streptococci
  • RT PCR
  • Spectrophotometry
  • Streptococcus mutans
  • Streptococcus sanguinis
  • Streptococcus sobrinus
  • qPCR

ASJC Scopus subject areas

  • Dentistry(all)

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