Insights and relative effect of aspirin, naproxen and ibuprofen containing hydrogels: From design to performance as a functional dual capacity restorative material and build in free radical defense: <i>In-vitro</i>studies

Restorative materials in the new era aim to be “bio-active” and long-lasting. 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) and reactive nitrogen species (RNS), as well as to inhibit the respiratory burst of neutrophils triggered by various activating agents. 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 hydrogels containing krill oil (antioxidant containing material), naproxen, ibuprofen (non steroidal anti-inflammatory medication), aspirin (pain relieve medication and free radical scavengers) and combinations thereof (chitosan-H-krill oil, chitosan-H-krill oil-aspirin and chitosan-H-naproxen, chitosan-H-naproxen-krill oil, chitosan-H-krill oil-ibuprofen and chitosan-H-ibuprofen) as functional additive prototypes for further development of “dual function restorative materials”;secondly, determine their effect on the dentin bond strength of a composite and thirdly, evaluate the capability of newly designed hydrogels to play an integral role of “build in” free radical defense mechanism by using BSA solubility as a “molecular prototype” of the site of free radical attack in vitro. Materials and Methods: The above mentioned hydrogels were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan gelling agent. The surface morphology (SEM), release behaviors (physiological pH and also in acidic conditions), stability of the therapeutic agent-antioxidant-chitosan and the effect of the hydrogels on the shear bond strength of dentin were also evaluated. Results: The release of aspirin, ibuprofen and naproxen confers 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. Neither the release of aspirin, ibuprofen or naproxen nor the antioxidant stability was affected by storage over a 6- month period. The hydrogel formulations have a uniform distribution of drug content, homogenous texture and yellow color (SEM study). All chitosan dentin treated hydrogels gave significantly (P < 0.05;non-parametric ANOVA test) higher shear bond values (P < 0.05) than dentin treated or not treated with phosphoric acid. The model protein (BSA) was adopted to evaluate the chitosan-based functional biomaterials as defense for undesired free radical formation under in vitro conditions. Conclusion: The added benefits of the chitosan treated hydrogels involved positive influence on the aspirin, ibuprofen and naproxen release, increased dentin bond strength as well as demonstrated in vitro “build in” free radical defense mechanism, therefore acting as a “proof of concept” for the functional multi-dimentional restorative materials with the build in free radical defense mechanism.

Insights into Functional Tetracycline/Antioxidant Containing Chitosan Hydrogels as Potential Bio-Active Restorative Materials: Structure, Function and Antimicrobial Activity

The human inflammatory periodontal diseases are amongst the most common of chronic diseases to affect adults. Periodontitis is regarded as “an inflammatory lesion, mediated by complex host-parasite interactions, that leads to the loss of connective tissue attachment to root surface cementum and adjacent alveolar bone”. Substantial data are available in the literature on the role of reactive oxygen species (ROS) and antioxidants in disorders such as the inflammatory diseases. However, remarkably little information is available on the periodontal diseases, which show many of the pathological features of other chronic inflammatory diseases. The periodontal tissues also provide an ideal medium within which to study mechanisms of ROS mediated tissue damage and of antioxidant defense in response to bacterial colonisation, through the non-invasive collection of GCF. The objectives of this study are to evaluate the novel chitosan based functional drug delivery systems which can be successfully incorporated into “dual action bioactive restorative materials” containing common antibiotics such as tetracycline, krill oil, aloe and aspirin as commonly used antioxidant species. Methods: The novel hydrogels will be investigated with respect to the antioxidant capacity and drug release capacity of the tetracycline from the designer drug delivery system, the use of SEM imaging for the characterization of the surfaces and reactive features of novel materials with antimicrobial potential. Results: A steady slow release of tetracycline, while maintaining antibiotic effects against the tested bacteria, for at least 10 days was shown from designer chitosan-antioxidant hydrogels. Within the limitations of the study design chitosan-antioxidant hydrogels are suitable materials for functional restorative and periodontal applications in vitro. The addition of antioxidants to the tetracycline containing prototype delivery system had a beneficial effect on the design of the hydrogel by slowing down the release of tetracycline and thereby enabling a sustainable antifungal activity over time.

Bioinspired-Interpenetrating Network (IPNs) Hydrogel (BIOF-INPs) and TMD <i>in Vitro</i>: Bioadhesion, Drug Release and Build in Free Radical Detection and Defense

In this work, Bioactive-functionalized interpenetrating network (IPNs) hydrogel (BIOF-INPs) were prepared and investigated in vitro for the free radical detection/defense, therapeutic release as well as shear bond strength to dentine, ability to re-mineralize surface of the dentin after application of these bio-inspired materials using a biologically inspired mineralization process in vitro as well as investigating antimicrobial properties of the BIOF-INPs against S. aureous. The aim of this investigation was to evaluate the suitability and flexibility of the designer materials to act as an “in vitro” probe to gain insights into molecular origin of TMD and associated disorders.

Insights into chitosan hydrogels on dentine bond strength and cytotoxicity

Contemporary dental adhesives show favorable immediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. Materials and Methods: Preparation of 3 chitosan-antioxidant hydrogels was achieved using modified hydrogel preparation method. Their effect on the bond strength to dentine both short term (after 24 hours) and long term (after 6 months) were evaluated using shear bond strength measurements using Instron Universal Testing Mascine). The SEM was used to study the surface of the hydrogels. The cell survival rate (cytotoxicity) of the antioxidants resveratrol, β-carotene and propolis towards Balb/c 3T3 mouse fibroblast cells was also assessed using the standard MTT assay. Results: It was found that chitosan-H treated dentine gives significantly (p β-carotene (92%) > propolis (68%) > resveratrol (33%). Conclusion: the antioxidant-chitosan hydrogels significantly improved bonding to dentine with or without phosphoric acid treatment. The pH of the growth medium had a high influence on the cell survival rate of Balb/c mouse 3T3 fibroblast cells. The release of the antioxidant β-carotene would not have an influence on the pulp cells. These materials might address the current perspectives for improving bond durability.

Cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells

Today it is generally accepted that most bonding agents are cytotoxic. In this study the relative cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells were investigated. Materials and Methods. Near-confluent mouse 3T3 fibroblast cells were exposed to Dulbecco Modified Eagle’s Medium containing extractions from the seven different bonding agents. The cell survival rate was then determined using the standard MTT assay. Results. The cell survival rate ranking is: iBond (94%) < Gbond (78%) < Xeno V (71%) < Adper Easy Bond (63%) < Xeno V+ (61%) < Adper Scotchbond SE (33%) < XP Bond (32%). Part A of Adper Scotchbond SE had a survival rate of 35% and part B 38%. These two parts did not differ significantly. Adper Scotchbond SE and XP Bond do not differ significantly. While Xeno V+, Xeno V and Adper Easy Bond do not differ. (p < 5%;Tukey-Kramer Multiple-Comparison Test). Conclusion. All of the tested adhesive bonding agents were cytotoxic with survival rate of 3T3 cells between 94% to 31%. Of the 7 bonding agents tested iBond was found to be only slightly toxic and by far the least toxic. The two bonding agents (XP Bond and Adper Scotchbond SE) containing UDMA plus TEGDMA plus HEMA plus camphorquinone were found to be the most toxic.

Insights into chitosan based gels as functional restorative biomaterials prototypes: <i>In vitro</i>approach

Restorative materials in the new era aim to be “bioactive” and long-lasting. The purpose of the study was to design and evaluate novel chitosan hydrogels containing melatonin and/or propolis (antioxidant containing material), nystatin (antifungal), naproxen (pain relieve medication) and combinations thereof (chitosan-H-melatonin, chitosan-H-melatonin-naproxen, chitosan-H-propolis, chitosan-H-propolisnaproxen, chitosan-H-naproxen-propolis-melatonin, Chitosan/Propolis/Nystatin, Chitosan/Melatonin/Propolis/Nystatin, Chitosan/Propolis/BSA/Nystatin, Chitosan/Melatonin/BSA/Nystatin) as functional additive prototypes for further development of “dual function restorative materials”, to determine their effect on the dentin bond strength of a composite, to evaluate stability of the encapsulated antioxidants as well as evaluate antimicrobial properties of the selected group of “designer” functional materials. Materials and Methods: The above mentioned hydrogels were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan gelling agent. The surface morphology (SEM), drug-polymer solid state interaction (FT-IR spectroscopy), released behaviours (physiological pH and also in acidic conditions), stability of the therapeutic agent-antioxidant-chitosan and the effect of the hydrogels on the shear bond strength of dentin were also evaluated. Results: The release of naproxen confers 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. Neither the release of naproxen or the antioxidant stability was affected by storage over a 6-month period. The hydrogel formulations have a uniform distribution of drug content, homogenous texture and yellow colour (SEM study). All chitosan dentin treated hydrogels gave significantly

Bio-Functional Nanodiamond Restorative Materials Containing Bio-Additives: In Vitro Approach

Restorative materials in the new era aim to be “bio-active”, bio-functional and long-lasting. As a part of our continuous interest of developing functional dual action restorative materials capable of being “bio-active” functional restorative materials, we designed and evaluated several novel nano-diamond:chitosan containing hydrogels as a prototype of molecular scaffold materials capable of free radical defense action containing propolis extract (antioxidant containing material) from 3 different regions namely, Green Brazilian Propolis, Uruguan Propolis and Australian Propolis. We evaluated 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, evaluated total phenol capacity of the materials as well as free radical defense capacity using BSA protein model as a quick and effective in vitro model. The hydrogels were prepared as previously reported by our protocol. The physico-chemical features including surface morphology (SEM), release behaviors, stability of the antioxidant-chitosan-nanodiamond and the effect of the hydrogels on the shear bond strength of dentin were measured. Structural investigations of the reactive surface of the hydrogel are reported. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defence and performance of the materials was evaluated using BSA and Folin Ciocalteu assay. Results: Within the limitations of the study design chitosan-antioxidant hydrogels are suitable materials for functional restorative and periodontal applications in vitro. The addition of propolis extracts nano-diamond chitosan prototype delivery system had a beneficial effect on the design of the hydrogel by increasing bioadhesive properties of the newly prepared hydrogels, increasing free radical defense properties of the biomaterials as well as increasing the dentin bond strength of the newly designed hydrogels. Conclusion: The added benefits of the chitosan treated hydrogels involved positive influence on the naproxen release as well as increased dentin bond strength as well as demonstrating good antimicrobial properties and enhanced antioxidant stability. The therapeutic polymer approach described here has a potential to provide clinical benefit, through the use of “designer” adhesive restorative materials with the desired properties.

Chitosan:Vitamin C Containing Hydrogels as a Prototype Functional Prolonged Pain Management Restorative Material <i>In-Vitro</i>Studies

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.