All ETDs from UAB

Advisory Committee Chair

Noel K Childers

Advisory Committee Members

Hui Wu

Gary R Cutter

Amjad Javed

Document Type


Date of Award


Degree Name by School

Master of Science (MS) School of Dentistry


Streptococcus mutans (Sm) and Streptococcus sobrinus (Ss) , are considered the major bacterium associated with dental caries. However, recent findings identify Scardovia species (Sc) is associated with early childhood caries, with or without the presence of Sm or Ss. This IRB approved study quantified the presence of Sm and Sc in saliva by real-time quantitative PCR (qPCR) in relation to caries. Saliva samples were collected from 72 preschool children in a high-caries risk community in rural Alabama. SYBR Green-based qPCR using extracted DNA and primers specific for Sm, Ss, Sc and total bacteria determined the copy number (CN/ml). Twenty two subjects (30.6%) were in caries-free group (DMFS/dmfs=0), whereas 50 (69.4%) subjects in caries-experience group (DMFS/dmfs>0). The detection limited for quantification was determined to be 1000 CN/ml. Sc was detected in 72.8% in the caries-free group and 80% of subjects in the caries-experience group. Sm was ubiquitous (approached 100%) in both groups. None of the samples had quantitatable levels of Ss. Generally, the level of Sm was much higher than Sc. Although the caries-experience group had higher mean ratio of Sm/total bacteria and Sc/total bacteria than children in caries-free group, the only significant difference between the two groups was found in the mean ratio of Sc/total bacteria (p=0.022). No statistical difference was found in detection frequency between caries-experience and caries-free group in the three different bacterial combination groups (Sc negative+ Sm negative, Sc negative+ Sm positive, Sc positive+ Sm positive). The overall results indicated that Sc was highly detected in caries-experience group and the ratio of Sc/total bacteria was significantly associated with caries history. Although the presence of Sm, Sc or the combination of both bacteria didn't show correlation to caries, other factors (e.g., diet & dietary practices, ethnicity, oral hygiene factors, socioeconomic influences, host factors and general health conditions, medications) must also be considered since caries is a multifactorial disease.

Included in

Dentistry Commons



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