IN-VITRO EVALUATION OF COMPLEX CARBOHYDRATE DENTURE ADHESIVE FORMULATIONS

Objective: Acemannan, a complex mannose carbohydrate derived from the aloe vera plant, has an inherent stickiness/viscosity. Prototype Acema nnan denture adhesive formulations were evaluated for pH changes, cyto toxicity to human gingival fibroblasts and adhesive strength in both d ry and wet conditions. Method and materials: The denture adhesive form ulations consisted of five combinations of Acemannan with varying conc entrations of preservatives and two other formulations without preserv atives. The pH of each formulation was measured over 24 hours. Assessm ent of cytotoxicity was accomplished using the in vitro, tetrazolium-b ased colorimetric assay on cultures of human gingival fibroblasts afte r exposure to the adhesive formulations for up to 24 hours. The adhesi ve strength was evaluated,vith a universal testing machine under initi al dry conditions and after immersion in a constant-temperature water bath for up to 20 minutes. Results: Formulations 1 and 2 achieved and maintained pH values above 6.0 (the critical pH for hydroxyapatite dis solution) approximately 6 hours into the study. None of the prototypes demonstrated an initial pH above the critical pH. Formulations 1, 2, 3, and 5 exhibited significant cytotoxicity to human gingival fibrobla sts over 24 hours. Formulations 4 20:1, and 150:1 demonstrated minimal cytotoxicity. Formulation I exhibited the poorest adhesive strength, while the mast viscous formulation (prototype 150:1) was by far the be st performer Generally, adhesive bond strengths for all prototypes wer e quite high and relatively stable over time in a wet environment. Con clusion: To achieve the ideal adhesive in terms of strength, pH, and c ytotoxicity, Acemannan formulation 150:1 should be adjusted to contain the preservative concentration of formulation 4 and have art initial pH value of 6.0 or higher.