Dietary Beverages Create Surfaces Conducive to Microbial Biofilm Development

Exposure of teeth to acidic beverages increases risk of enamel erosion. However, the ability of the eroded surface to support microbial adherence and biofilm development is unknown.

Objective: Our objective was to determine if enamel surfaces, eroded by pretreatment in dietary beverages, are more readily colonized by microorganisms (S. mutans) than enamel surfaces exposed to control solutions.

Methods: Enamel windows were created on extracted molars using an acid resistant varnish. Windows were exposed to beverages (i.e., Coke®, orange juice) or water (negative control) for 10 hours or phosphoric acid (positive control) for 15 seconds. Following beverage treatment, the varnish was removed from Coke® and orange juice molars to create Coke® and orange juice controls. The eroded and control surfaces were incubated in human saliva for 30 minutes then in S. mutans and trypticase soy broth with yeast extract for 3 hours at 37 C. Following incubation, bacteria biofilms were fixed and teeth were viewed by scanning electron microscopy and confocal microscopy. Micrographs and confocal images were analyzed using ImageJ (NIH).

Results: Enamel exposed to Coke® facilitated colonization when compared to unexposed enamel (98±6 vs. 68±6 mean pixels; p=0.025). Colonization following orange juice exposure did not differ from colonization on unexposed enamel (121±28 vs. 98±6 mean pixels; p=0.494). Phosphoric acid exposure facilitated colonization when compared to water exposure (131±15 vs. 85±16 mean pixels; p=0.022). Colonization rates did not differ between exposures to Coke®, orange juice or phosphoric acid (p=0.168), nor did colonization rates differ between Coke® controls, orange juice controls or water controls (p=0.348).

Conclusion: This pilot study found that the surface morphology of enamel is changed during exposure to acidic beverages. Furthermore, the altered morphology has the potential to affect biofilm development. Supported by NIH/NIDCR T32 DE014678 and R01 DE014390.