Triclosan-loaded chitosan as antibacterial agent for adhesive resin

Objectives: The aim of this study was to formulate and to evaluate the immediate and long-term physical, chemical and antibacterial properties of an experimental adhesive resin with chitosan or triclosan-loaded chitosan. Materials and methods: Chitosan, triclosan and triclosan-loaded chitosan were evaluated for scanning electron microscopy (SEM) and micro-Raman spectroscopy. An experimental adhesive resin was formulated with methacrylate monomers and photoinitiators. Chitosan or triclosan-loaded chitosan were added at 2 (G(Q2%) and G(QT2%)) or 5 (G(Q5%) and G(QT5%)) wt.% in the base resin. The base resin was used as control (G(CTRL)). The adhesives were evaluated for degree of conversion (DC), Knoop hardness (KHN), softening in solvent (Delta KHN), immediate and long-term microtensile bond-strength (mu-TBS) and antibacterial activity. Results: SEM indicated triclosan sticks and chitosan porosity. Triclosan-loaded chitosan presented structures on chitosan. Micro-Raman indicated no chemical interaction between chitosan and triclosan. There was no difference among groups for DC (p > 0.05). Initial KHN ranged from 17.36 (+/- 1.56) to 20.38 (+/- 1.72), with higher value for G(QT5%) compared to G(CTRL) (p < 0.05). G(CTRL) presented the lowest Delta KHN% (p < 0.05). There were no differences in the immediate or long-term mu-TBS (p > 0.05). G(CTRL) and G(Q2%) decreased the mu-TBS after storage (p < 0.05). Chitosan groups showed higher biofilm formation (p < 0.05). Triclosan-loaded chitosan groups presented lower biofilm formation (p < 0.05). There was no activity against planktonic bacteria regardless the time of evaluation (p > 0.05). Conclusion: Triclosan-loaded chitosan at 5 wt.% addition in an experimental adhesive resin showed reliable properties, with the highest antibacterial activity immediately and after six months, and induced dentin/adhesive interface stability over time. Clinical significance: Triclosan-loaded chitosan groups showed antibacterial activity immediately and over time and induced dentin/adhesive interface stability, may positively affecting long-lasting marginal sealing.