Effect of Biofilm on the Mechanical Properties and Repair Strength of Denture Acrylic

Hypothesis: The null hypothesis was that presence and exposure to biofilm from C. albicans would have no effect on the mechanical properties and repair strength of denture acrylics. Objective: To test whether exposure to C. albicans and subsequent biofilm formation would have an effect on the mechanical properties and repair strength of denture acrylic. Methods: 90 samples of Lucitone 199® denture acrylic were fabricated from a standardized jig and processed with conventional flask and process methods. Samples were randomly assigned to 3 groups: control, 3 days (3d), and 12 days (12d) for subsequent C. albicans exposure. Initial and post treatment measurements were taken for microhardness, surface roughness, and flexural strength on repaired and unrepaired samples. Results: Statistically significant differences were observed between control and experimental samples in repair flexural strength and microhardness (p< 0.05). Differences were also observed in surface roughness, but not statistically significant (p> 0.05). Cohesive failures increased as exposure time increased. Conclusions: The null hypothesis was rejected as exposure to C. albicans had a significant effect on the microhardness and repair flexural strength of denture acrylic. Changes in mode of failure and surface roughness were observed, indicating a possible change in surface topography with biofilm formation. These changes are further information the clinician can use in deciding if repair or replacement of a fractured acrylic prosthesis is warranted.