Digital technologies are increasingly used to support oral health care, but their clinical effectiveness remains uncertain. This systematic review evaluated the impact of teledentistry and mobile health (mHealth) applications on objective and patient-reported oral health outcomes. Electronic databases were searched up to November 2025 for human studies assessin teledentistry or mobile app–based interventions targeting oral health behaviours, diagnostic accuracy, or treatment outcomes. Ten original studies (mostly randomized controlled trials) and ten systematic reviews or meta-analyses were included. Mobile app interventions in orthodontic patients and older adults consistently improved plaque and gingival indices, tooth-brushing frequency and duration, and oral health knowledge compared with usual education alone. Several trials reported moderate to large short-term improvements in gingival inflammation and self reported behaviours. Teledentistry models using smartphone photography and store-and-forward platforms demonstrated high diagnostic sensitivity and specificity for dental caries screening, and cluster randomized data suggested comparable preventive outcomes to traditional care with better access for underserved groups. However, some app-based trials showed no additional benefit over standard verbal instructions, and follow-up was usually short. Overall, teledentistry and mHealth applications appear to be effective adjuncts—rather than replacements—for conventional oral care. Heterogeneity of interventions and methodological limitations highlight the need for robust, long-term multicentre trials.