Probiotic fermented sheep’s milk containing Lactobacillus casei 01: Effects on enamel mineral loss and Streptococcus counts in a dental biofilm model

Abstract

The effects of probiotic fermented sheep’s milk containing Lactobacillus casei 01 on enamel demineralization and microorganism counts in a mixed biofilm model were investigated. Enamel blocks (N = 50) were fixed in polystyrene plates in which a mixed biofilm (Streptococcus mutans 25175, Streptococcus parasanguinis 903, and Streptococcus salivarius 8618) was formed. The mature biofilm was treated for five days with the following: (1) sheep’s milk (SM); (2) fermented sheep’s milk with starter culture (FSMS); (3) fermented sheep’s milk with probiotic culture (FSMP); and (4) fermented sheep’s milk with starter and probiotic cultures (FSMSP). A growth control group was also included (brain–heart–infusion medium with inoculum). The percentage of surface hardness loss (%SHL) and total microorganism and Streptococcus counts (log10 colony-forming units/mL) were calculated. In addition, mean internal mineral density loss determination (ΔZ) by micro–computed tomography and descriptive topographic analysis via scanning electronic microscopy (SEM) were performed. No group prevented %SHL (p = 0.168), with a similarity in values (p > 0.05) confirmed in SEM images. No differences were found between the tested groups and growth control group in terms of total microorganism or Streptococcus counts (p > 0.05). In relation to total microorganism reduction, FSMS and FSMP were similar (p = 0.153), presenting a reduced number of microorganisms. Both were different from FSMSP (p < 0.05), which presented a higher number of total microorganisms. FSMS presented a lower Streptococcus count versus FSMP (p = 0.04) and FSMSP (p = 0.006). FSMSP was not able to inhibit the growth of Streptococcus spp. in a dental biofilm model; however, FSMP presented a tendency to control enamel internal demineralization, since it presented lower ΔZ values in comparison with the other groups. Overall, both probiotic fermented sheep milk samples (FSMP and FSMPS) presented similar performance at cariogenic challenge.

Keywords

• Oral bacteria
• Dental biofilm
• Tooth
• Probiotic
• Fermented sheep’s milk