Surface modifications and antifungal efficacy of origanum oil incorporation in denture-based materials : an in vitro study

Abstract

Aim: This study aimed to assess if the addition of origanum oil to denture materials could decrease microorganisms counts and biofilm formation without changing their mechanical/surface properties. Materials and methods: A total of 66 resilient denture liner discs (SoftConfort, Dencril Comércio de Plásticos Ltda, SP, Brazil) were prepared with fixed dimensions of 10 × 3 mm for biofilm assay (n = 36) and 12 × 2 mm for sorption-solubility tests (n = 30) containing three oil concentrations – 0, 2.5 and 5%, thereby n = 12 per each group samples for biofilm assay and n = 10 per each group for sorption-solubility test respectively. While the microcosm biofilms of Streptococcus mutans, Candida species, and total microorganisms formed on denture liner were counted and expressed as colony-forming units per disc surface area, the water sorption (WS) and solubility (SL), was calculated by weighing the samples with an analytical balance at different intervals after storing them in a desiccator and distilled water alternatively. Data was recorded and statistically analyzed. Results: Surface roughness increased in all groups after biofilm formation (p < 0.001), with the most significant change observed in the 2.5% oil group. The tested oil concentrations did not result in sorption changes, but a 5% oil concentration resulted in higher solubility (p < 0.001). A reduction of total microorganisms and S. mutans was seen after 24 hours for all concentrations (p < 0.05). No significant reduction was found for Candida (C.) albicans after 24 hours, whilst 2.5% oil concentration presented lower counts of C. albicans in comparison to the 5% group after 24 hours (p < 0.05). Conclusions: Incorporating 2.5% origanum essential oil into resilient denture liners seems to reduce microorganisms count in a complex biofilm model. These results need to be confirmed in future studies.