Adult cancer patients (35-55 years) with primary cervical carious lesions will be recruited from the outpatient clinics of the Faculty of Dentistry, Cairo University. Eligible teeth must be vital by pulp sensitivity testing with controlled periodontal conditions; teeth with previous restorations, irreversible pulpitis signs, mobility, resorption, or cuspal loss will be excluded, as will patients with material allergies, fixed orthodontic appliances, pregnancy, or frequent analgesic use that could mask pain. After signing informed consent, participants will be randomized 1:1 using a computer-generated sequence (random.org) with allocation concealed via sequentially numbered, opaque, sealed envelopes. The study is double-blinded (participants and outcome assessors blinded; the treating operator is not blinded). Baseline data collection includes medical/dental history and pre-operative radiographs. Interventions will be applied by a single trained operator following standardized protocols for SDF/GIC placement (SMART arms) or conventional cavity preparation and GIC placement (control arms). Data will be collected on paper/Excel and analyzed using MedCalc software (v22) with Chi-square, Cochran's Q, one-way ANOVA/Tukey post-hoc, and repeated-measures ANOVA/Bonferroni-corrected comparisons, with significance set at p≤0.05 and 80% power. Sample size (29 teeth/group) was calculated using G*Power based on prior HVGIC retention data. The trial is self-funded, with independent auditing conducted by the co-supervisor.