Abstract
Restorative materials in the new era aim to be “bio-active” and long-lasting. As a part of our continuous interest of developing functional dual action restorative materials capable of being “bio-active” and wound healing, we design and evaluate several novel chitosan-vitamin C (5:1) containing hydrogels as a prototype of host:guest molecular free radical defense material containing hydroethanoic propolis extract (antioxidant containing material), naproxen, ibuprofen (non steroidal anti-inflammatory medication), or aspirin (pain relieve medication and free radical scavengers) as functional restorative materials. We will evaluate the physical properties, bonding to dentin as well as test the bioadhesion of the newly designed materials in order to access the suitability of these prototype materials as suitable restorative materials. Materials and Methods: The hydrogels were prepared by previously reported by us protocol. The physico-chemical features including surface morphology (SEM), release behaviors, stability of the therapeutic agent-anti-oxidant-chitosan and the effect of the hydrogels on the shear bond strength of dentin were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel were reported. Bio-adhesive studies were performed in order to assess the suitability of these designed materials. Results: Release of aspirin, ibuprofen and naproxen conferred the added benefit of synergistic action of a functional therapeutic delivery when comparing the newly designed chitosan-based hydrogel restorative materials to the commercially available products alone. Either the release of therapeutic agents or the antioxidant stability was affected by storage over a 12-month period. All chitosan:vitamin C hydrogels showed gave significantly higher shear bond values than dentin treated or not treated with phosphoric acid, which highlighted the feasibility. The bio-adhesive capacity of the materials in the 2 separate “in vitro” systems were tested and quantified. Additional action of chitosan:vitamin C pre-complex was investigated and it was found that favourable synergistic effect of free radical build-in defense mechanism of the new functional materials. Conclusion: Additional action of chitosan:vitamin C pre-complex was investigated and it was found that favorable synergistic effect of free radical build-in defense mechanism of the new functional materials, increased dentin bond strength, sustainable bio-adhesion, and acted as a “proof of concept” for the functional multi-dimensional restorative materials with potential application in wound healing in vitro.
Highlights
Many diseases and pathological syndromes are caused by oxidative stress, i.e. by an imbalance in favor of free radicals
The gel was brought into contact with the commercially available band aid, in order to simulate the skin attachment or the contact with slice of dentin was established in order to imitate adhesion of the gel to the tooth structure, after a preset contact time (1 min) under contact strength (0.5 N) the 2 surfaces were separated at a constant rate of displacement (1 mm/s)
The strength was recorded as a function of the displacement, which allowed to determine the maximal detachment force, Fmax, and the work of adhesion, W, which was calculated from the area under the strength-displacement curve
Summary
Many diseases and pathological syndromes are caused by oxidative stress, i.e. by an imbalance in favor of free radicals. The effect of free radicals, as one of the oldest chemical stimuli and the best organized biological structures such as the central nervous system (CNS), has been relatively seldom studied [1]-[4], of trauma and amyotropical lateral sclerosis. Information about the influence of free radicals and antioxidants in the CNS during pain is almost completely lacking [5]-[7]. Reactive oxygen species (ROS) are associated with all the stages of the healing process [8]. Antioxidants administration is beneficial for healing [13]. It has been suggested that the anti-inflammatory activity of some non-steroidal anti-inflammatory drugs (NSAIDs) may be partly due to their ability to scavenge reactive oxygen species (ROS) [14]. As a part of our continuous interest of developing functional dual action restorative materials capable of being “bio-active” and long-lasting, we design and evaluate novel chitosan:vitamin C hydrogels [15]-[21] as functional additive prototypes for further development of “dual function restorative materials”, with the build-in capability of secondly to determine their effect on the dentin bond strength of a composite and thirdly evaluate the bio-adhesive capability of newly designed hydrogels as a “molecular prototype of the site of free radical attack in vitro”
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