Assessment of Cytotoxicity, Genotoxicity

Inclusion Criteria: Underwent routine dental imaging using OPG or CBCT (no additional radiation for research purposes). Age 15-25 years or 40-50 years at the time of enrolment. Able and willing to provide written informed consent (or consent from a legal guardian for minors). Agreed to provide pre-exposure and follow-up buccal epithelial cell samples. Exclusion Criteria: History of systemic diseases, including but not limited to leukemia, lymphoma, rheumatic disorders, or diabetes mellitus. Prior exposure to head-and-neck radiotherapy, immunosuppressive drugs, or cytotoxic medications. Presence of active infectious diseases or acute/chronic inflammatory conditions at the time of enrolment. Clinically visible oral pathological lesions, including mucosal abnormalities, gingivitis, or periodontitis. Use of removable intra-oral prostheses or appliances (e.g., dentures, orthodontic appliances). Engagement in smoking, alcohol consumption, or betel-nut chewing. Diagnostic or therapeutic X-ray exposure within the preceding 3 months. Previous or current oral mucosal diseases, including oral lichen planus, recurrent aphthous stomatitis, oral candidiasis, HSV infection, leukoplakia, oropharyngeal carcinoma, mucous membrane pemphigoid, or pemphigus vulgaris. Presence of persistent local irritants, including ill-fitting dental prostheses, sharp teeth/restorations, chemical irritation (acidic foods, alcohol-based mouthwash), or recurrent thermal injury.