Khat chewing is widely practiced in Eastern Africa and the Middle East. Khat is genotoxic to cells within the oral mucosa, and several studies have suggested an association between khat use and oral lesions like hyperkeratosis and oral cancer. This study investigated the mechanism of khat-induced cytotoxicity using primary normal human oral keratinocytes (NOK) and fibroblasts (NOF). Khat induced rounding up of cells, plasma membrane blebbing, and condensation of nuclear chromatin within 3-6 h of exposure. The cells also showed externalization of phosphatidylserine and fragmentation of DNA. Morphological and biochemical features were compatible with cell death by apoptosis. Khat also induced an increase in cytosolic reactive oxygen species (ROS) and a depletion of intracellular glutathione (GSH) within 1 h of exposure. Antioxidants reduced ROS generation, GSH depletion and delayed the onset of cytotoxicity in both cell types. Generally, NOF cells were more sensitive to khat-induced cytotoxicity than NOK cells. These effects were elicited at concentrations of khat expected to occur in the oral cavity during khat chewing. In summary, khat induced apoptotic cell death in primary normal oral keratinocytes and fibroblasts by an early effect on mechanisms that regulate oxidative stress.

Khat-chewing has been associated with oral lesions including oral cancer, but the mechanisms leading to their development are not known. We hypothesized that khat interferes with the physiological processes of the oral mucosa, such as cell proliferation and differentiation, and aimed at investigating the effects of khat exposure on in vitro-reconstructed human normal buccal mucosa. Khat decreased cell proliferation, epithelial thickness, and cytokeratin 13 expression, while inducing premature expression of p21(Waf1/Cip1), transglutaminases, involucrin, and filaggrin. This suggests that khat is able to induce abnormal differentiation of the buccal epithelium. Khat-induced alterations were accompanied by increased levels of p38 and were reversed by p38 inhibition, pointing to p38 as the key player in this process. The morphological changes described herein mirror the in vivo changes previously described in khat users, and demonstrate for the first time that khat induces pathological alterations in human buccal mucosa, providing evidence that raises concerns about the effects of khat use on oral health.

Khat is a psychostimulant plant used by over 10 million people daily, mainly in eastern Africa and the Middle East. Previous studies have suggested an association between khat use and oral lesions such as hyperkeratosis and oral cancer. This study investigated the effects of an extract of khat on primary normal human oral keratinocytes (NOK) and normal human oral fibroblasts (NOF). Low (sublethal) concentrations of khat inhibited the proliferation of both cell types in a dose-dependent and time-dependent manner. Both NOK and NOF treated with khat accumulated in the G1-phase of the cell cycle and showed increased expression of the stress-sensitive p53 protein after 24 h. Normal human oral keratinocytes showed a profound increase in p16(INK4A) (p16) after 24 h and showed morphological changes suggesting cell differentiation. Normal human oral fibroblasts showed growth inhibition and increased expression of p21(WAF1/CIP1) (p21) within 24 h. The concentrations of khat tested in this study were within the range of those found in the oral cavity of khat chewers. The results show that stress induced by khat modulates the cell cycle in oral keratinocytes and fibroblasts. It is further speculated whether khat could have similar effects in vivo, especially in keratinocytes.

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Objectives. The habit of khat chewing is prevalent in many Middle Eastern and African cultures and has been associated with various adverse conditions in humans. This study aimed to describe histological changes induced by chronic khat chewing on the buccal mucosa. Methods. Biopsies of the buccal mucosa from 14 chronic khat chewers, 20 chronic khat chewers who also smoked tobacco, and 8 nonchewers were compared for epithelial thickness, degree and type of keratinization, and connective tissue changes. Results. Tissues from khat chewers depicted abnormal keratinization of the superficial cell layer and showed increased epithelial thickness affecting all layers. Epithelial thickness in control samples was 205 ± 26 μm whereas thickness in khat chewers and khat chewers who smoked tobacco was significantly higher measuring 330 ± 35 μm and 335 ± 19 μm, respectively. Tissues from khat chewers also showed increased intracellular edema, increased melanin pigment deposits, and increased number of rete pegs most of which were thin and deep. Conclusions. These results show that oral lesions induced by chronic chewing of khat in the buccal mucosa present with white and brown discoloration due to increased epithelial thickness, increased keratinization, and melanin deposition.

This study indicates a potential for toombak, higher than for Swedish snuff, to damage human oral epithelium. Dysplastic oral keratinocytes were less sensitive than their normal counterparts, suggesting that they might have acquired a partially resistant phenotype to toombak-induced cytotoxic effects while still being prone to DNA damage that could lead to further malignant progression.

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A number of factors have been cited as determinants for choosing a career in dentistry around the globe. The purpose of this study was to determine motivations for a career in dentistry among dental students and dental interns in Kenya. This was a cross-sectional study where 293 individuals participated by filling and returning self-administered questionnaires. The mean age of all respondents was 22.3 years. Overall, 59.5% of the respondents had selected dentistry as their preferred career at the end of high school. Majority (76.1%) of the respondents agreed that personal interest in dentistry was an important motivating factor for them. This was followed closely by a desire to help or serve people (74%), a desire for a flexible work schedule (63%), and an aspiration to be self-employed (61.8%). There was no difference between males and females regarding these as motivating factors. On the other hand, among factors that the respondents felt had the lowest influence on their choice of dentistry was parental influence, where only 22% of the respondents indicated that this was a motivating factor for them. Other potential motivating factors such as influence by friends and siblings (30.3%) as well as career talk and guidance (41.3%) were also ranked low. In general, the respondents indicated that they were motivated much more by personal and humanitarian factors, when compared to financial and societal factors.