In Vitro Analysis of Surface Roughness of Acrylic Resin Exposed to the Combined Hygiene Method of Brushing and Immersion in Ricinus communis and Sodium Hypochlorite

Purpose: To evaluate a solution based on Ricinus communis (Castor oil) for denture cleansing, comparing it to sodium hypochlorite (NaOCl) for the surface roughness of heat-polymerized acrylic resin.

Materials and methods: Forty polished and unpolished resin specimens (90 × 30 × 4 mm) were evaluated before and after their exposure to protocol hygiene: brushing the specimens with a specific denture brush and mild soap for 3 minutes, three times a day, and immersing them in hygiene solutions (0.25% NaOCl-S1 and 0.5% NaOCl-S2; 10% R. communis-S3; saline-S4: control) for 20 minutes. Surface roughness was evaluated by rugosimeter and scanning electron microscopy (SEM) before and after the protocol. For evaluation of surface roughness, polished and unpolished surfaces were used.

Results: The roughness of the polished surface was not affected by time (p = 0.062), but was affected by solutions (p < 0.0001) and the interaction between factors (p = 0.005). For S1 and S4, the period did not influence the roughness. For S2, there was a change after 7 days, remaining stable after 14 days. For S3, there were changes, and stabilization occurred after 14 days. After 7 and 14 days, S2 and S3 promoted major changes, but after 21 days, there were no differences among solutions, except saline. The unpolished surface was not influenced by factors: period (p = 0.115), solution (p = 0.120), and their interaction (p = 0.382). SEM analysis showed similar results on the evaluation of surface roughness.

Conclusions: The polished surface of the prosthesis was more susceptible to changes when exposed to hygiene solutions, and although the 0.5% NaOCl solution promoted an increase in the surface roughness compared with the same solution at 0.25% and R. communis at 10%, the values are clinically acceptable.