SCANNING ELECTRON-MICROSCOPIC OBSERVATIONS OF EARLY PLAQUE-FORMATION INVIVO ON ENAMEL SPECIMENS TREATED WITH DELMOPINOL

The aim of this double blind, cross-over, scanning electron microscopi c (SEM) study was to compare the effect of topical application of 0.5% delmopinol HCl (aqueous solution) with placebo on early supragingival plaque formation on enamel specimens attached to a maxillary premolar . 3 subjects underwent 2 x (placebo and delmopinol treatment, respecti vely) 7 treatment periods (1/2, 1, 2, 8, 24 hours; 3, 7 days) of undis turbed dental plaque accumulation, during which 2 ml of placebo and de lmopinol HCl 0.5%, respectively, were applied topically to all teeth 2 x daily. At the end of each period, the specimen was retrieved and pr ocessed for SEM. For the specimens obtained after 24 h or less, the nu mber of visible micro-organisms was estimated. For the 3- and 7-day sp ecimens, the area covered by plaque was calculated planimetrically. La rge inter-individual differences were observed in the number of bacter ia attaching during the first 24 h, with apparently no major differenc es between delmopinol and placebo. 1 subject showed a bacterial coloni zation predominated by curved rods throughout the first 8 h. Compared to placebo, the area of the specimens covered by plaque was reduced af ter 3 and 7 days of delmopinol use, with coccoid cells as the predomin ant morphotype. Plaque maturity, characterized by the appearance of co rncob formations and high numbers of different morphotypes, was not ob served on the delmopinol specimens, in contrast to the placebo specime ns. The study shows that topical application of 0.5% delmopinol HCl de lays and interferes with dental plaque maturation.