Award Date

5-1-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Dental Medicine

First Committee Member

John Colombo

Second Committee Member

Charles Hill

Third Committee Member

Jessica Immonen

Fourth Committee Member

Maxim Gakh

Number of Pages

32

Abstract

Background: In 2024, the Center of Disease Control (CDC) reported that 1.63 million middle and high school students (5.9%) were using e-cigarettes, with 87.6% opting for flavored varieties. Flavored electronic liquids (e-liquids), particularly those with fruity or sweet additives, release harmful substances when heated. Studies have shown that the vapor contains heavy metals, toxic chemicals, various carbonyls and other byproducts that pose significant health risks. These byproducts have been linked to oral cancer, periodontal disease, inflammation, and cardiovascular disease, yet their specific effects on the oral epithelium remain poorly understood. While the dental community strongly discourages smoking due to its association with inflammation and increased risk of periodontal disease, the precise impact of vaping on the cells and tissues of the oral cavity is not well defined.Objectives: This study aimed to investigate the cytotoxic effects of flavored electronic cigarette (e-cigarette) vapor on oral epithelial cells. A custom-designed vaping chamber was developed to expose cell growth media to vape byproducts. Vaporized components of mint and fruit-flavored e-liquids were analyzed in collaboration with the Desert Research Institute (DRI). The infused media was then used to assess its impact on the vitality and proliferation of OKF-4 cells, a human-derived oral epithelial cell line. Additionally, we examined the expression of a cellular marker associated with apoptosis and DNA damage to explore the potential mechanisms of toxicity. Methods: Oral keratinocyte cells, OKF-4s, were cultured in triplicate using media infused with vaporized e-liquid byproducts. Two flavored e-liquids, Frozen Fruit Monster Strawberry Kiwi and Mints Wintergreen, were tested at two different concentration levels: 1x, 5x ‘puffs.’ Since the vape device had an automatic shut-off at 8 seconds, 1 ‘puff’ was equivalent to 8 seconds of vapor exposure. Cell counts were recorded using a Countess™ II automated cell counter, and cell viability was assessed via trypan blue dye exclusion. Statistical analyses were conducted with a repeated measures ANOVA for vitality and population doubling over time. To further investigate cellular responses, the expression of DNA damage by analyzing a γH2AX marker was evaluated in cells exposed to vaporized byproducts. Additionally, carbonyl composition of unvaporized and vaporized e-liquids was conducted in collaboration with DRI. Results: Cells cultured in media not exposed to vaporized e-liquid exhibited minimal changes in cell count. In contrast, media infused with 5x vaporized mint and fruit e-liquids demonstrated a dose-dependent cytotoxic effect, with significantly reduced cell counts compared to the 1x exposure. By day 7, cells exposed to 5x vaporized media showed a marked decline in vitality, with very few viable cells remaining. Notably, mint-flavored vape byproducts exhibited greater cytotoxic effects with a more rapid onset than compared to the fruit-flavored byproducts. Conclusion: Exposure to vaporized e-liquid byproducts had a dose-dependent negative impact on OKF-4 cell viability and proliferation. Mint-flavored vape byproducts demonstrated a more pronounced toxic effect compared to fruit-flavored vape byproducts. These findings highlight the potential harmful effects of vaping on oral epithelial health and provide a foundation for further research into the mechanisms of vaping-induced cytotoxicity in the oral cavity.

Controlled Subject

Electronic cigarettes; Antineoplastic agents; Epithelial cells

Disciplines

Dentistry | Medicine and Health Sciences

File Format

pdf

File Size

3800 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

Download

Available for download on Monday, May 15, 2028


Included in

Dentistry Commons

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