Chlorhexidine release from orthodontic adhesives after topical chlorhexidine treatment

This study was designed to investigate the ability of orthodontic adhesives to adsorb and release chlorhexidine (CHX) after periodic treatment with 1% CHX solution. Composite and resin-modified glass-ionomer cement (RM-GIC) adhesive disks were incubated with whole saliva or distilled water for 2 h. Release of CHX was measured using high-performance liquid chromatography after 1, 2, and 5 d of incubation, 1 min after exposure to 1% CHX solution. The CHX measurements were performed in a 5-d cycle, which was repeated four consecutive times (n = 7). The amount of CHX adsorbed and the cumulative amounts of CHX released, with respect to type of adhesive and saliva-coating, were analyzed using repeated-measures anova. Chlorhexidine-adsorbed orthodontic adhesives demonstrated a short-term release of CHX, which rapidly returned to near-baseline levels within 3 d. Saliva-coating did not significantly influence CHX release from RM-GIC, but increased the amount of CHX released from the composite. The amount of CHX released from the composite was 20-fold higher than that released from the RM-GIC after saliva-coating. The composite adhesive showed a greater adsorption capacity for CHX than did the RM-GIC, which was more evident after saliva-coating. This study suggests that composite adhesives may be a significantly more effective CHX reservoir than RM-GICs in the oral cavity filled with saliva.