SITE-RELATED STREPTOCOCCAL ATTACHMENT TO BUCCOCERVICAL TOOTH SURFACES- A CORRELATIVE MICROMORPHOLOGICAL AND MICROBIOLOGIC STUDY

Scanning electron (SEM) microscopy of epoxy replicas made from dental impressions has shown that in buccal gingival recession the root surfa ces are devoid of cementum, leaving the dentin exposed. In this study replication techniques were applied to correlate the micromorphology o f the buccocervical region with early streptococcal attachment. The su bjects were 27 healthy young adults. The buccocervical surfaces of all the premolars were meticulously cleaned. The subjects fasted for 2 h before impression-taking. Replicas were made from impressions in hydro philic A-silicone, and streptococcal attachment was visualized by ligh t microscopy of mitis-salivarius agar replicas incubated anaerobically for 48 h. The surface micromorphology was documented by SEM of corres ponding epoxy replicas. Colonization only 2 h after cleaning was very sparse. Sites with healthy or inflamed gingivae had markedly different colonization patterns in the sulcular region. In 4 subjects with a to tal of 12 sites where gingival recession, undetected clinically, was d isclosed by SEM, representative colonies were retrieved and identified microbiologically to species level. Two healthy sites per subject wer e also sampled. Streptococcus mutans and S. sobrinus were identified f rom eight sites with exposed root dentin. S. oralis predominated on th e enamel surfaces. The method offers a valuable complement to in situ and in vitro microbiologic studies of exposed dentin and a novel techn ique for sampling clinical isolates of streptococci.