Enamel staining with e-cigarettes, tobacco heating products and modern oral nicotine products compared with cigarettes and snus: An in vitro study

PURPOSE

To evaluate the effect of cigarette smoke, smokeless tobacco (e.g. snus), tobacco heating products (THP), electronic cigarettes (EC), and modern oral nicotine products on tooth staining.

METHODS

In this in vitro study, staining was assessed for 86 days following exposure of bovine enamel samples to a scientific reference cigarette (1R6F), a THP (glo), an EC (ePen 3), a reference snus product (CRP1.1), and a modern oral product (LYFT). Red wine and coffee were used as positive controls and DMSO and complete artificial saliva as negative controls. Whether brushing could reduce staining levels was also assessed. Changes in staining levels were assessed using the Commission Internationale de L'éclairage L*a*b* method.

RESULTS

Enamel staining increased with incubation time, and cigarette smoke, snus, coffee and wine induced statistically higher staining levels. THP, EC and modern oral exposure induced minimal staining levels that were also comparable to negative control samples. At day 86, ΔE mean and SD values were 28.50 ± 3.14, 19.76 ± 1.26, 17.35 ± 3.44, 16.22 ± 2.07, 18.30 ± 3.82, 4.10 ± 1.99, 11.30 ± 2.60, 49.56 ± 2.44 for cigarette, glo, EC with blended tobacco, EC with rich tobacco, reference snus product, modern oral product, coffee or wine. The control ΔE mean and SD values at day 86 were 18.68 ± 3.89 for DMSO and 2.17± 0.78 for complete artificial saliva. The ΔE values for all DMSO extracted samples and control increased from day 1 to 86, which suggests that the DMSO used to extract the samples contributes to the enamel sample staining levels. Staining levels were reduced by brushing.

CLINICAL SIGNIFICANCE

Cigarette smoke, red wine, snus and coffee stained enamel. Exposure to THP, EC or modern oral product extracts for 86 days resulted in minimal enamel staining. Further studies are required to assess the long-term impact on staining and the oral cavity following consumer exclusive use of EC, THP or modern oral products.

Development of a novel method to measure material surface staining by cigarette, e-cigarette or tobacco heating product aerosols

Tobacco smoke (CS) may visually stain indoor surfaces including ceilings, walls and soft furnishings over time. Potentially reduced risk products (PRRPs) such as e-cigarettes (EC) and tobacco heating products (THP) produce chemically less complex aerosols with significantly reduced levels of toxicants, particles and odour. However, the potential effects of EC and THP aerosols on the staining of indoor surfaces are currently unknown. In this study, an exposure chamber was developed as a model system to enable the accelerated staining of wallpaper and cotton samples by a scientific reference cigarette (3R4F), three THP (glo™, glo™ pro, glo™ sens) and an e-cigarette (iSwitch Maxx).

Exposure to 3R4F reference cigarettes caused the greatest level of staining, which was significantly higher than glo™, glo™ pro, glo™ sens or iSwitch Maxx aerosols, all of which showed relatively little colour change. Exposure to 200–1000 puffs of 3R4F cigarette smoke resulted in a visible dose response effect to wallpaper and cotton samples which was not observed following exposure to glo™, glo™ pro, glo™ sens or iSwitch Maxx aerosols. Aging of the samples for 4 weeks post-exposure resulted in changes to the staining levels, however PRRP staining levels were minimal and significantly lower than 3R4F exposed samples.

For the first time, diverse PRRPs across the tobacco and nicotine products risk continuum have been assessed in vitro for their impact on surface staining. CS exposure significantly increased the level of wallpaper and cotton staining, whereas exposure to glo™, glo™ pro, glo™ sens or iSwitch Maxx aerosols resulted in significantly reduced levels of staining, staining levels were also comparable to untreated control samples.

Assessment of enamel discoloration in vitro following exposure to cigarette smoke and emissions from novel vapor and tobacco heating products

PURPOSE

To evaluate in vitro enamel sample discoloration following exposure to a scientific reference cigarette (3R4F) or emissions from next generation tobacco and nicotine products (NGPs) such as electronic cigarettes (EC) and tobacco heating products (THP).

METHODS

Bovine enamel blocks (6.5 × 6.5 mm) were prepared and pre-incubated with human or artificial saliva, to form a pellicle layer before exposure to either particulate matter (PM) or whole aerosols. PM was prepared by capturing 3R4F cigarette smoke (CS), a commercial THP (THP1.0) or a novel vapor product (NVP)/next generation e-cigarette aerosols on Cambridge filter pads followed by elution with dimethyl sulfoxide (DMSO). Ten enamel samples were exposed to each PM for 14 days. For aerosol exposure, 12 enamel samples were exposed (200 puffs per day, for 5 consecutive days) to 3R4F CS or THP1.0 and NVP aerosols. Control samples were incubated with DMSO (PM study) or phosphate buffered saline (PBS, aerosol study). Individual enamel sample color readings (L*, a*, b*) were measured at baseline and on each exposure day. Mean ΔL*, Δa*, Δb* and ΔE values were calculated for each product or control. A one-way ANOVA was used to assess the differences between the products and controls. The Tukey procedure for pairwise comparisons was also used.

RESULTS

At all timepoints, 3R4F PM and CS induced enamel discoloration that was statistically significant (< 0.0001) when compared to THP1.0 or NVP. After 14-day PM exposure, mean ΔE values were 29.4± 3.6, 10.5 ± 2.3, 10.7 ± 2.6 and 12.6 ± 2.0 for 3R4F, THP1.0, NVP and DMSO control respectively. After 5-day CS or aerosol exposure, mean ΔE values were 26.2 ± 3.2, 3.6 ± 1.9, 3.4 ± 1.3, 5.3 ± 0.8 for 3R4F CS, THP1.0, NVP or PBS control, respectively. Both exposure methods demonstrated that THP1.0 and NVP induced minimal staining, mean ΔL* , Δa* , Δb* and ΔE values were comparable to DMSO or PBS controls.

CLINICAL SIGNIFICANCE

For the first time, diverse NGPs across the risk continuum were assessed in vitro for their impact on enamel staining. CS exposure significantly increased the level of bovine enamel sample discoloration, whereas THP1.0 or NVP exposure resulted in values comparable to the controls.