title: In vitro evaluation of complex carbohydrate denture adhesive formulations.
abstract: OBJECTIVE
  Acemannan, a complex mannose carbohydrate derived from the aloe vera plant, has an inherent stickiness/viscosity. Prototype Acemannan denture adhesive formulations were evaluated for pH changes, cytotoxicity to human gingival fibroblasts and adhesive strength in both dry and wet conditions.
  
  
  METHODS
  The denture adhesive formulations consisted of five combinations of Acemannan with varying concentrations of preservatives and two other formulations without preservatives. The pH of each formulation was measured over 24 hours. Assessment of cytotoxicity was accomplished using the in vitro, tetrazolium-based colorimetric assay on cultures of human gingival fibroblasts after exposure to the adhesive formulations for up to 24 hours. The adhesive strength was evaluated with a universal testing machine under initial 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 dissolution) 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 fibroblasts over 24 hours. Formulations 4, 20:1, and 150:1 demonstrated minimal cytotoxicity. Formulation 1 exhibited the poorest adhesive strength, while the most viscous formulation (prototype 150:1) was by far the best performer. Generally, adhesive bond strengths for all prototypes were quite high and relatively stable over time in a wet environment.
  
  
  CONCLUSIONS
  To achieve the ideal adhesive in terms of strength, pH, and cytotoxicity, Acemannan formulation 150:1 should be adjusted to contain the preservative concentration of formulation 4 and have an initial pH value of 6.0 or higher.
authors.affiliation: Department of Restorative Dentistry, Baylor College of Dentistry, Dallas, Texas 75266-0677, USA.
authors.forename: C G
authors.initials: CG
authors.lastname: Tello
authors.forename: P
authors.initials: P
authors.lastname: Ford
authors.forename: A M
authors.initials: AM
authors.lastname: Iacopino
mesh_terms: D000268:Adhesiveness; D000269:Adhesives / Q000737:chemistry* / Q000633:toxicity; D000704:Analysis of Variance; D002478:Cells, Cultured; D003781:Denture Retention; D005069:Evaluation Studies as Topic; D005347:Fibroblasts / Q000187:drug effects; D005782:Gels; D005881:Gingiva / Q000166:cytology / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008351:Mannans / Q000633:toxicity; D008422:Materials Testing
chemical_list: D000269:Adhesives; D005782:Gels; D008351:Mannans; C058414:acemannan