Variation in adhesion of and in saliva-derived biofilms on raw materials of orthodontic brackets.

Objective: To evaluate differences in the adhesion levels of the most common oral pathogens, and , in human saliva-derived microcosm biofilms with respect to time and raw materials of orthodontic brackets.

Methods: The samples were classified into three groups of bracket materials: 1) monocrystalline alumina ceramic (CR), 2) stainless steel metal (SS), and 3) polycarbonate plastic (PL), and a hydroxyapatite (HA) group was used to mimic the enamel surface. Saliva was collected from a healthy donor, and saliva-derived biofilms were grown on each sample. A real-time polymerase chain reaction was performed to quantitatively evaluate differences in the attachment levels of total bacteria, and at days 1 and 4.

Results: Adhesion of and to CR and HA was higher than the other bracket materials (SS = PL < CR = HA). Total bacteria demonstrated higher adhesion to HA than to bracket materials, but no significant differences in adhesion were observed among the bracket materials (CR = SS = PL < HA). From days 1 to 4, the adhesion of decreased, while that of and total bacteria increased, regardless of material type.

Conclusions: The higher adhesion of oral pathogens, such as and to CR suggests that the use of CR brackets possibly facilitates gingival inflammation and enamel decalcification during orthodontic treatment.