Regression analyses of the cumulative chlorhexidine release for 28 days against the water sorption of resins (R1–R5). The cumulative chlorhexidine release represents as mg per g of samples. Equations for 0.2%, 1.0% and 2.0% are Y = 0.0007X + 0.00578 (R2 = 0.6557, p = 0.097), Y = 0.0015X + 0.3734 (R2 = 0.926, p = 0.009) and Y = 0.0019X + 0.4789 (R2 = 0.8243 p = 0.0033), respectively.