Table 1.
Flavored reference e-liquids.
Fig 1.
Quantification of e-cigarette aerosol droplets.
(A) Aerosols were delivered using a simulated human vaping topology (50 mL puff volume in 4 s puff duration every 18 s). Aerosol droplets were imaged by a stereoptical light microscope on a non-reflective vinyl surface (bar = 100 μm). (B) ImageJ was used to quantify the aerosol droplets. The number of particles for control, after 10 puffs, and 150 puffs were (5.7 ± 5.0, 175.5 ± 12.7 and 1051.2 ± 59.4) particles per mm2, respectively (mean ± S.D.). Student t-tests were performed control vs. individual puffing regime (*** = p<0.0001).
Fig 2.
Adhesive force between S. mutans and enamel surface.
The adhesive forces were calculated by averaging 30 measurements on three individual surfaces. The forces for control, after 10 puffs and 150 puffs were (1.2 ± 0.4, 2.2 ± 0.5, and 4.5 ± 2.6) nN, respectively (mean ± S.D.). Student t-tests were performed control vs. individual puffing regime (*** = p<0.0001).
Fig 3.
Biofilm quantification after flavored e-liquid aerosol exposures.
The absorbance for control, sucralose, ethyl butyrate, triacetin, hexyl acetate and ethyl maltol were (0.23 ± 0.03, 0.48 ± 0.05, and 0.42 ± 0.07, 0.42 ± 0.06, 0.36 ± 0.02, and 0.14 ± 0.03) AU, respectively (mean ± S.D.). Student t-tests were performed control vs. individual flavored e-liquid and statistical differences were indicated as: * = p<0.05 or ** = p<0.005.
Fig 4.
Complex interaction among S. mutans, enamel surface and e-cigarette aerosol.
(A) Control: smooth enamel surface, unexposed. (B) Smooth enamel surface, exposed with 10 puff e-cigarette aerosol. (C) Fissure, exposed with 10 puff e-cigarette aerosol. (D) Central pit, exposed with 10 puff e-cigarette aerosol (SEM parameters: X10,000, 10.0 kV, and bar = 1 μm).
Fig 5.
E-liquid aerosol pools into pits and fissures.
(A) Top: a cross section of a human tooth (E = enamel, outer layer, D = dentin, middle layer, and P = pulp, cellular component with nervous and vascular tissues), Bottom: control, unexposed enamel fissure. (B) Top: a tooth after e-cigarette aerosol exposure (A = aerosol, E = enamel, D = dentin, and P = pulp), Bottom: aerosol exposed enamel fissure. (C) Top: a tooth after e-cigarette aerosol exposure and subsequent S. mutans attachment (Spheres = S. mutans), Bottom: S. mutans colonizing fissure and secreting EPS (SEM parameters: X50, 10.0 kV, and bar = 100 μm).
Fig 6.
Enamel hardness loss after flavored e-liquid aerosol exposures.
The hardness loss for control, sucralose, ethyl butyrate, triacetin, hexyl acetate and ethyl maltol were (0.01 ± 6.41, 8.67 ± 5.84, and 15.45 ± 4.02, 27.45 ± 7.19, 21.57 ± 5.76, and 7.80 ± 2.00) %, respectively (mean ± S.D.). Student t-tests were performed control vs. individual flavored e-liquid and statistical differences were indicated as: * = p<0.05 or ** = p<0.005.
Table 2.
GS-MS analyses of e-cigarette aerosols.
Table 3.
Metals in e-cigarette aerosol.