摘要：Dental plaque is the biofilm found naturally on teeth and it is the etiologic agent in dental caries and periodontal diseases. A better understanding of bacterial communities found in biofilms provides opportunities for new methods to control biofilm formation. Therefore, control of the dental plaque biofilm is a major objective of dental professionals and critical to the maintenance of optimal oral health. The aim of this study was to isolate and identify aerobic bacteria from dental plaque biofilm on the external surface of the teeth and gums and to determine their role in the etiology of gingivitis and dental caries. Fifty nine samples of dental plaque from gingiva and teeth were collected randomly from patients attending Sebha dental clinic, Libya, males and females of different age groups. All samples were cultured on different media, conventional methods used for isolation and identification. Results revealed that 52 samples (88%) were positive for culture, and they were polymicrobial. Bacteria isolated were 110 species, 93 (84.5%) were gram positive composed of Streptococcus species 43 (39%), Lactobacillus 27 (24.5%), Staphylococcus 23 (21%) and 17 were gram negative (15.5%), they were E.coli 7 (6.4%), Enterobacter 6 (5.5%), Proteus 4 (3.6%). Isolates from males were 66 (60%) and females were 44 (40%), 61 (55.5%) of the isolates were from children (5-15) years old (44% were Streptococcus species and 25% were lactobacilli, Staphylococcus 18%) and 49 (44.5%) were from the age group (16-68) years old (28% were Streptococci and 21% were Lactobacilli). Most of the isolated bacteria (58%) was from patients who do not clean their teeth by daily brushing with toothpaste.
