Salivary levels of mutans streptococci associated with restorations: A case-control study

Our aim was to estimate whether restorative therapy with amalgam and compos ite resin could decrease salivary mutans streptococcal level, thus also dec reasing the risk for other caries development. We selected a case group of 93 children with detectable salivary mutans levels (i.e., at least 1x10(4) cfu/ml), and a control group (n=93 subjects) with undetectable levels. Chil dren had the same age (12 years), no extracted teeth, crowns, temporary fil lings, and restorations other than amalgam and composite resin, and the two groups had similar gender distribution. We clinically examined children an d recorded active caries, restorations and oral hygiene level by means of g ingival bleeding on probing; we also investigated sucrose intake at breakfa st. The case group had statistically significant higher prevalence of resto rations (36.6% vs. 18.3%), active caries (44.1% vs. 12.9%), and bad oral hy giene (84.9% vs. 68.8%) than the control group. However, the logistic regre ssion analysis showed that presence of active caries was the only significa nt variable associated with mutans streptococci (OR=4.0; p=0.0002), while t he effects of sucrose intake and of restorations were marginally significan t. This apparent contrast between statistical analyses was due to the conco mitant presence, in children with detectable mutans streptococci level, of restorations and decayed teeth at the same time, and, on the basis of the m ultivariate analysis, presence of mutans streptococci in these children was explained by the presence of active caries, more than restorations.