Influence of chlorhexidine on the degree of conversion and E-modulus of experimental adhesive blends

M. Cadenaro, D. H. Pashley, G. Marchesi, M. Carrilho, F. Antoniolli, A. Mazzoni, F. R. Tay, R. Di Lenarda, L. Breschi

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Objectives: This study examined the effect of chlorhexidine (CHX) content on degree of conversion (DC) and E-modulus of experimental adhesive blends. The hypothesis tested was that increasing concentrations of CHX result in decreased DC and E-modulus in relation to adhesive hydrophilicity. Methods: Experimental adhesive blends with increasing hydrophilicity R2 (70% bisGMA, 28.75% TEGDMA); R3 (70% BisGMA, 28.75% HEMA); R4 (40% BisGMA, 30% TCDM, 28.75% TEGDMA); R5 (40% BisGMA, 30% BisMP, 28.75% HEMA) and different CHX concentrations (1 and 5%) were analyzed. 5% CHX could not be dissolved in R2. A differential scanning calorimeter was used to measure the DC of resin blends. Photopolymerized disks of the experimental comonomer mixtures (n = 10/gp) were used to measure the E-modulus of each specimen using a biaxial flexure test. Data were analyzed with two-way ANOVA (resin type and CHX concentration) and Tukey's post hoc test. Results: The addition of 1% CHX did not significantly alter the DC of R2 and R3. Significant decrease in R3 DC values was observed when 5% CHX was added. CHX significantly increased the DC of R4 and R5. 1% CHX reduced the E-modulus of all resins (p < 0.05) except for R2, in which the E-modulus was significantly increased (p < 0.05). 5% CHX significantly reduced the E-modulus of resins R3 to R5 (p < 0.05). Significance: In conclusion, increasing concentrations of CHX dissolved in resin blends had little adverse effect on DC but decreased the E-modulus 27-48% compared to controls. Solvation of CHX in ethanol prior to incorporation of CHX into R2 may permit higher CHX concentrations without lower polymer stiffness.

Original languageEnglish (US)
Pages (from-to)1269-1274
Number of pages6
JournalDental Materials
Issue number10
StatePublished - Oct 2009


  • Chlorhexidine
  • Degree of conversion
  • Dental bonding systems
  • E-modulus
  • Polymerization

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials


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