Objective: The use of chlorhexidine (CHX) as therapeutic primer has been reported to stabilize the adhesive interface over time. This study examined the effect of CHX content on E-modulus of experimental adhesive blends using a biaxial flexure test. The hypothesis tested was that E-modulus of resin blends is affected by CHX content in relation to adhesive hydrophilicity.
It was hypothesized that resins having higher CHX diluition result in decreased E modulus.
Methods: Light-curing experimental adhesive blends with increasing hydrophilicity and different CHX diacetate concentrations were analyzed: R2 (70% bisGMA, 28.75% TEGDMA); R2+1%CHX; R3 (70% BisGMA, 28.75% HEMA); R3+1%CHX; R3+5%CHX; R4 (40% BisGMA, 30% TCDM, 28.75% TEGDMA); R4+1%CHX; R4+5%CHX; R5 (40% BisGMA, 30% BisMP, 28.75% HEMA); R5+1%CHX; R5+5%CHX. All blends included 1% EDMAB and 0.25% CQ. CHX in higher percentages than 1% could not be dissolved in R2. The experimental comonomer mixtures (n=10/gp) were placed in wells made in teflon molds to form disks 6.0±0.1mm in diameter and 0.5±0.02 mm thick. Disk surface was covered with a Mylar film to exclude oxygen and the resin was fully cured. The E-modulus of each specimen was measured using a biaxal flexure test (universal testing machine SUN 500 Galdabini). Data were analyzed with two-way ANOVA (resin type and CHX concentration) and Tukey's post hoc test.
Results:
|
| R2 | R3 | R4 | R5 |
| Neat resin | 908.59 (30.69)aMPa | 1383.10 (21.27)dMPa | 844.60 (2.59)fMPa | 640.14( 8.61)gMPa |
| 1% CHX | 1068.38 (8.48)bMPa | 762.01 (1.50)eMPa | 648.57 (2.49)gMPa | 372.56 (2.12)iMPa |
| 5% CHX | --- | 724.67 (16.69)cMPa | 621.37( 6.08)hMPa | 346.93 (24.03)iMPa |
Different superscript letters indicate statistical differences (p<0.05), n = 10.
Conclusions: E-modulus decreased by adding increasing concentration of CHX for R3-R5,while it increased with 1% CHX in R2. In conclusion CHX dissolved in resin blends affected the E-modulus in relation to its concentration and resin type.