BACTERIAL MORPHOTYPES OF 3-DAY OLD PLAQUE IN CHINESE - A PILOT-STUDY

The aim of the this study was to estimate the % distribution of bacter ial morphotypes of supragingival plaque in Chinese subjects after 3 da ys of no oral hygiene. 36 dental students, hygienists or dental surger y assistants (mean age: 24.3 years) were recruited. Prophylaxis and or al hygiene reinforcement were given 1X a week for 3 weeks to obtain gi ngival health and a 3-day period without any plaque control started af terwards. At the end of the 3-day period, the plaque along the gingiva l margin of the upper right central incisor was removed and direct Gra m stained smears were prepared for light microscopy. Bacteria were cla ssified as gram-positive or gram-negative cocci, rods, filaments, fusi form organisms, spirilla or spirochetes. A differential count of 200 o rganisms from 3-6 microscopic fields was performed and the results exp ressed as a % of the organisms counted. Results from the 36 direct sme ars showed approximately 83% (range: 52%-96%) of the organisms to be g ram-negative while gram-positive bacteria comprised only a minority of about 12% (range: 0.70-43%). This result is remark ably different fro m previous reports from the West where gram-positive bacteria were the predominant bacterial types noted in early supragingival plaque. Furt her longitudinal studies involving both microscopy and bacteriological culture will be necessary to confirm this finding.