An In Vitro Microbial-Caries Model Used to Study the Efficacy of Antibodies toStreptococcus mutansSurface Proteins in Preventing Dental Caries

Abstract

The first step for a pathogenic bacterium to initiate infection is via attachment (i.e., through surface determinants) to a suitable receptor. An in vitro microbial artificial-mouth model was used to test the efficacy of polyclonal antibodies to Streptococcus mutans cell surface proteins (CsAb) and a cell surface 59-kDa protein (59Ab) in preventing S. mutans colonization and carious lesion formation. In study 1, groups of 12 human teeth specimens were inoculated with S. mutans, which were incubated with different concentrations of CsAb (A1 [positive control], sterile saline, no antibody; A2, 0.007 mg of antibody protein/ml; and A3, 0.7 mg of antibody protein/ml) for 1 h at 37°C. The negative control group (B1) was not infected and was incubated with Trypticase soy broth (TSB) without dextrose supplemented with 5% sucrose (TSBS). In study 2, the same study design was used except that 59Ab was used instead of CsAb, normal rabbit serum was used in the positive control group (A1), and TSB supplemented with 1% glucose was used as the nutrient to control for sucrose-dependent colonization. All groups were exposed for 4 days to circulating cycles of TSBS and TSB (study 1 and study 2, respectively; 30 min each, three times per day) and a mineral washing solution (21 h per day). Prior to each nutrient cycle, 1 ml of the appropriate CsAb or 59Ab solution was administered to each group and allowed to mix for 30 min before cycling was resumed. Data obtained by confocal laser scanning microscopy demonstrated the presence of a significantly smaller (P < 0.05) lesion area and a smaller total lesion fluorescence in group A3 than in group A1 for both studies. In study 1, group A2 had significantly smaller values than A1 for lesion depth and area. There were no significant differences between groups A2 and A3 for lesion area or between groups A1 and A2 for total lesion fluorescence. In study 2, there were no significant differences among groups A1 and A2 for lesion depth or between groups A2 and A3 for all of the parameters studied. In both studies, there were no significant differences between S. mutans plaque CFU numbers among any of the groups. These studies demonstrated the efficacy of CsAb and 59Ab in reducing primary caries development in this model, although the underlying mechanism remains unclear.

A Novel in vitro Microbial-Based Model for Studying Caries Formation – Development and Initial Testing

“…However, the possibility for manipulation of the test specimens during operation or their number per turn has been considered to be very limited for most devices described in the literature or they do not allow for the use of whole tooth specimens [Fontana et al, 2000;Noorda et al, 1985;Tang et al, 2003;Deng and ten Cate, 2004]. According to our knowledge, no reports regarding caries development at marginal gaps of fissure sealants in artificial mouth models are available in the literature written in English.…”

Caries lesion development and biofilm composition responses to varying demineralization times and sucrose exposures

“…Although in vitro chemical caries systems allow strict control of the experimental environment and are relatively simple and inexpensive, they do not simulate the in vivo situation as accurately as a bacterial system does. Many other variables, such as different nutrients, dental materials (Fontana et al, 1999a), bacterial strains (Yang et al, 1998;Fontana et al, 1999b), and anticariogenic agents such as dentifrices , varnishes (Fontana et al, 2002) and antibodies (Fontana et al, 2000) have been studied in this model. Selection of the type of model and combination of bacteria to be used depends greatly on the purpose of the study.…”

Correlation among mutans streptococci counts, dental caries, and IgA to Streptococcus mutans in saliva

“…Salivary IgA seems to be directly involved in the immunity to dental caries. This immunoglobulin presumably prevents the adherence of cariogenic microorganisms to hard surfaces 7 , and may also inhibit the activity of glucosyltransferases 10 .…”