The bactericidal efficacy of 16 guanide, biguanide, and bisbiguanide agents was studied in vitro against intact preformed plaques of four oral (plaqueforming) microorganisms: Streptococcus mutans, S. sanguis, Actinomyces viscosus, and A. naeslundii. The activities of these agents were examined in relation to their molecular configurations. These studies indicated that the bisand biguanide configurations are important for efficacy, as is the length of the alkyl side chain. No structural moiety determined efficacy by itself. Furthermore, the activities of these agents were studied to determine the minimal conditions (concentration, duration, and frequency) of treatment required for likely clinical efficacy. At least six agents were judged to have equal or greater efficacy than the reference agent, chlorhexidine digluconate. A plaque bactericidal index was derived for the most potent agents, and comparison to the bactericidal properties of chlorhexidine was expressed as a chlorhexidine coefficient.

The antibacterial activity of three iodine-containing compounds was determined for strains of four dental plaque-forming microorganisms, using an in vitro preclinical plaque model system. Solutions of inorganic iodine, povidone-iodine, and Wescodyne were tested for antiplaque activity against preformed plaques of a number of strains of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus , and Actinomyces naeslundii . Solutions of inorganic iodine were more effective as antiplaque agents, with respect to minimal bactericidal concentration and time and frequency of treatments, than solutions of Wescodyne and povidone-iodine. Inorganic iodine appeared to be particularly effective against the most cariogenic ( S. mutans ) and periodontopathic ( A. viscosus ) organisms while allowing survival of the least orally pathogenic plaque-forming microorganism ( S. sanguis ). It is suggested that topical application of solutions of inorganic iodine may be useful in controlling dental caries and actinomyces-associated periodontal disease.

The bactericidal efficacy of seven cationic detergents was studied in vitro against intact preformed plaques of representative strains of four oral dental plaque-forming microorganisms: Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, and Actinomyces naeslundii. Both absolute (plaque bactericidal index) and relative (chlorhexidine coefficient) indexes of antiplaque activity were established. Only cetyltrimethylammonium bromide was more efficacious than the reference agent, the bisbiguanide chlorhexidine, for the apparently more potent tooth-adherent cariogenic and periodontopathic elements, respectively, of the in vivo plaque microflora, S. mutans and A. viscosus.Control Qf dental plaque, which is associated with gingivitis and dental caries, may be achieved by topical applications of antimicrobial agents (11,18,19). Topical rather than systemic administration of such agents to supragingival plaque is indicated because of its dense, toothadherent nature and, importantly, because plaque is not bathed in blood or interstitial fluids but is exposed to the environment of the oral cavity.Cationic detergents have been known for a number of years to possess bactericidal and fungicidal properties (17). Cationic agents are also of interest because of potential reversible binding (substantivity) to anionic groups on oral mucous membranes (2,21,22,25,26), which could permit possible prolonged intraoral retention and sustained release of such cationic antiseptics. Recent studies have demonstrated modest in vivo and in vitro antiplaque activities of three quaternary ammonium detergents, namely, cetylpyridinium chloride, domiphen bromide, and benzylalkonium chloride (1,6,12,27,35). In those studies, however, the optimal conditions required for in vivo efficacy were not evaluated.In the work reported herein an examination of seven cationic detergents was undertaken with a view to establishing the optimal conditions likely to achieve maximal efficacy in vivo. These agents were assessed for their antiplaque activities against strains of four oral plaqueforming microorgansms by using an in vitro preformed-plaque model system (30, 31), and their potencies were compared on both absolute t Present address:

Three 8-hydroxyquinoline derivatives, assessed using an in vitro preformed dental plaque model system, were differentially inhibitory for four plaque-forming microorganisms.