Modified pellicle formation and reduced in vitro bacterial adherence after surface treatment with different siloxane polymers

The formation of a salivary pellicle is a prerequisite of bacterial colonization on the tooth, and the aim of this study has been to further the understanding of the role of surface properties in the formation of the salivary pellicle and subsequent adhesion of oral bacteria. Surface modification as a means of interfering with pellicle and plaque formation has been investigated. Five different silicone-containing compounds were used for the surface treatments: polydimethylsiloxane containing aminoalkyl groups (I), polydimethylsiloxane containing partially neutralized aminoalkyl groups (II), ethyl silicate (III), potassium methyl siliconate (IV) and sodium silicate (V). Studies of water wetting, surface charge, oral bacterial adherence and pellicle formation were performed on glass slides and hydroxyapatite beads coated by the test compounds. No correlation was found between contact angle and surface charge, and evidently hydrophobicity, as expressed by water wetting, is not necessarily an indication of a low surface concentration of polar groups. All compounds reduced bacterial adherence after saliva contact, compound IV by around 90%. Different patterns were seen in the adsorption of pellicle proteins on the different polysiloxanes.