EFFECT OF CHLORHEXIDINE VARNISH ON ACTINOMYCES-NAESLUNDII GENOSPECIESIN PLAQUE FROM DENTAL FISSURES

This study describes the effects of varnish containing 40% chlorhexidi ne diacetate on Actinomyces naeslundii populations in plaque from huma n molar fissures. In each of 15 subjects two dental fissures with high levels of mutans streptococci were selected. The experimental treatme nt consisted of the single application of a small amount of chlorhexid ine varnish onto the selected fissures. The varnish was removed 15 min after application. One month after varnish application a significant increase was observed in A. naeslundii counts while the number of muta ns streptococci had decreased significantly compared with preexperimen tal levels. From 85 randomly selected Actinomyces isolates taken from blood agar plates before varnish application, 44% belonged to A. naesl undii genospecies 1 and 56% to A. naeslundii genospecies 2. From 106 i solates taken 1 month after chlorhexidine varnish application, 42% bel onged to A. naeslundii genospecies 1 and 58% to A. naeslundii genospec ies 2. At baseline 28% of A. naeslundii genospecies 1 strains were cat alase-positive, but 1 month after varnish application 4% of the strain s were catalase-positive (p<0.05). It is concluded that chlorhexidine varnish application caused an increase of A. naeslundii in dental plaq ue, but induced no significant changes in the distribution of the two A. naeslundii genospecies.