Does the nature of the definitive impression material influence the outcome of (mandibular) complete dentures?

The effects of impression materials on the outcome of complete dentures are poorly understood. This double-blind cross-over randomized controlled trial investigated eleven adult edentulous patients. Each received a maxillary denture and three mandibular dentures (which differed only in the three materials used to record the definitive impressions). The three mandibular dentures were given in a random order. Patients' opinions of each denture were recorded using a Linear Analogue Scale. There was a statistically-significant difference between the outcome of the dentures constructed when zinc-oxide eugenol was used, this material being least favoured (p < 0.001). It would therefore appear that care should be exercised when selecting impression materials when constructing mandibular complete dentures.

An antifungal coating for dental silicones composed of chlorhexidine nanoparticles.

OBJECTIVES: The aims of this study were to synthesise a range of chlorhexidine-containing nanoparticles (CHX-NPs), and investigate the feasibility of using these as an antifungal coating for dental silicones. METHODS: CHX-NPs were precipitated in aqueous reaction by mixing solutions of CHX digluconate with solutions of sodium triphosphate (TP), trimetaphosphate (TMP) or hexametaphosphate (HMP). CHX-NPs were deposited on commercial dental silicones by immersion coating, and these were characterised for hydrophilicity (contact angle) and water uptake (mass change). Soluble CHX elution into artificial saliva was measured using ultraviolet spectrophotometry. Antifungal efficacy against Candida albicans was investigated using a cell proliferation assay. RESULTS: Coating silicones with CHX-NPs did not significantly affect hydrophilicity, as assessed using water contact angle, or water uptake as assessed by mass change following 16 weeks' immersion in artificial saliva. CHX-NP-coated silicone specimens released soluble CHX into artificial saliva. The salt of CHX and the immersion time affected the rate, concentration and duration of CHX release, with CHX-HMP exhibiting a slow, sustained release and CHX-TP and CHX-TMP exhibiting a faster, more concentrated release. C. albicans metabolic activity was inhibited by presence of CHX-HMP-NPs in suspension. CONCLUSIONS: CHX-NPs provided a localised, controlled dose of soluble CHX at the surface of dental silicones without adversely affecting hydrophilicity or water uptake. CHX-HMP NPs provided effective antifungal control of C. albicans in a cell proliferation assay. Coating materials with these nanoparticles could be an effective way of delivering low, but clinically relevant, concentrations of chlorhexidine in the oral environment. CLINICAL SIGNIFICANCE: Denture stomatitis is a common oral infection and is associated with fungal infestation of denture soft lining and obturator materials, which are often silicones such as those used here. Our study suggests that CHX-NPs may be a useful strategy in design of antifungal coatings for these materials.