Vanessa Reher

Enamel demineralization and bracket bond strength when etching with acid and /or Er:YAG laser

BACKGROUND Enamel etching for brackets is usually done with phosphoric acid. Er:YAG lasers have been recently used for this purpose with conflicting results. The effects of lasers on tooth demineralization and the effects of different combinations of laser treatments and bonding agents were evaluated in this study. METHODS The enamel contents of fluorine, calcium oxide and phosphorus pentoxide (P(2) O(5)) were analysed using acid etching, laser treatment or both. The tensile bond strength of metallic and ceramic brackets using Transbond XT and Fuji Ortho LC were also tested, using acid etching, laser treatment or a combination of both. RESULTS All treatments reduced the contents of fluorine, P(2)O(5) and calcium oxide, and acid reduced P(2) O(5) levels more than laser. The bond strength with laser was weaker than with acid, and stronger when combining both. When using laser, the best adhesive was the Fuji Ortho LC. The combination of laser and acid produced the best results when using Transbond XT. CONCLUSIONS The demineralization promoted by laser was lower than the one produced with acid. Laser treatment produced lower tensile stress strength than acid, but still enough to produce clinically efficient retention. The combination of laser and acid produced the best retention results.

Understanding the early transition needs of diverse commencing university students in a health faculty: informing effective intervention practices

The engagement and retention of commencing students is a longstanding issue in higher education, particularly with the implementation of the widening student participation agenda. The early weeks of the first semester are especially critical to student engagement and early attrition. This study investigated the perceived early transition needs of three cohorts of commencing students in their first three weeks of university study in a Health Faculty. A short survey was developed based on a systematic understanding of student transition and supplemented by open-ended qualitative data. The results showed a stable, consistent pattern of early transition needs across the cohorts, with commencing students expressing most concern about accessing resources, balancing work, family and study commitments, establishing peer relationships, and understanding the requirements and standards for early assessment tasks, particularly group tasks. Findings are discussed in terms of implications for early co-curricular and curricular interventions to enhance early student engagement and retention.

Bioactive-Functionalized Interpenetrating Network Hydrogel (BIOF-IPN): A Novel Biomaterial Transforming the Mechanism of Bio-Repair, Bio-Adhesion and Therapeutic Capability – An In Vitro Study

The purpose of this investigation was to evaluate and report the in vitro performance of a few selected Bioactive- Functionalized Interpenetrating Network Hydrogels (BIOF-IPN); a novel biomaterial with a build-in mechanism of biorepair capacity, bio-adhesion and therapeutic capability. The study also evaluates the cytotoxicity of the newly developed material, and its ability to be used in the dental field. In this study, four bioactive-functionalized interpenetrating network hydrogels (BIOF-IPN) were prepared by dispersion of different therapeutic agents. The dentin bond strength is tested, the bio-adhesivity, modulus of elasticity and cytotoxicity of the materials were investigated, and the performance of the therapeutic-agents release profile, evaluated. The gels used in this study demonstrated excellent capacity in leading to high internal surface areas with low diffusional resistance. An increase in bond strength of the dentin treated with the BIOF-IPNs compared to the bond strength of the conventionally bonded teeth was indicated, and a significant increase in the modulus of elasticity observed. BIOF-INPs showed high adhesive force promotes binding to the negative surface of skin or dentin structure. It was found that chitosan alone increased the cell survival rate remarkably (113%) and its presence with naproxen and ibuprofen increased the cell survival rate [naproxen (93%), chitosan/naproxen (96.6%), ibuprofen (76.6%), and chitosan/ibuprofen (89.1%). The use of BIOF-IPNs has increased the time of the release of therapeutic agents, and protected the active ingredient from any type of free radical damage produced in and around the active site. Present results demonstrate the capability of the BIOF-IPNs to play an important role in the defense mechanism, and in the functional multidimensional restorative repair materials. The findings suggest that the new material would definitely find applications in functional dental composites and regenerative dentistry.

Evaluation of Nystatin Containing Chitosan Hydrogels as Potential Dual Action Bio-Active Restorative Materials: in Vitro Approach

Healing is a specific biological process related to the general phenomenon of growth and tissue regeneration and is a process generally affected by several systemic conditions or as detrimental side-effects of chemotherapy- and radiotherapy-induced inflammation of the oral mucosa. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems, which can be successfully incorporated into “dual action bioactive restorative materials”, capable of inducing in vitro improved wound healing prototype and containing an antibiotic, such as nystatin, krill oil as an antioxidant and hydroxyapatite as a molecular bone scaffold, which is naturally present in bone and is reported to be successfully used in promoting bone integration when implanted as well as promoting healing. The hydrogels were prepared using a protocol as previously reported by us. The physico-chemical features, including surface morphology (SEM), release behaviors, stability of the therapeutic agent-antioxidant-chitosan, were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel are reported. Release of nystatin was investigated for all newly prepared hydrogels. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defense capacity of the biomaterials was evaluated using established in vitro model. The bio-adhesive capacity of the materials in the in vitro system was tested and quantified. It was found that the favorable synergistic effect of free radical built-in defense mechanism of the new functional materials increased sustainable bio-adhesion and therefore acted as a functional multi-dimensional restorative material with potential application in wound healing in vitro.

Bioactive-functionalized interpenetrating network hydrogel (BIOF-IPN)

The implication of oxidative stress in the etiology of many chronic and degenerative diseases, the body’s protective antioxidant mechanisms and the role dietary antioxidants play, suggests that an antioxidant therapy represents a promising avenue for treatment. In this chapter, we focus on the advantages of a novel functional biomaterial, the Bioactive-Functionalized Interpenetrating Network Hydrogel (BIOF-IPN). BIOF-IPN is a chitosan based and chitosan-containing biomaterial, designed for several uses in the dental field through amalgamation of structural features and build in therapeutic free radical defence capacity and desired dental properties. In addition, the use of antioxidants together with conventional therapeutic agents as a platform for development of novel prototypes of functional chitosan based hydrogels as drug-delivery systems, and the in vitro evaluation of their performance using conventional chemistry.