Several reports described various mosaic chromosomal syndromes characterized by alterations originated by either an excess or deficit in the number of chromosomes. A case of mosaic trisomy 8 and monosomy 18 with significant involvement of the oral cavity is described, both in terms of general medicine and from a dental-oral perspective, and the treatment plan was planned and discussed.Regular follow-up visits enabled to verify significant improvement in all parameters of the patient's oral health, which urged us to press on with our quest to protect the right to health of patients affected by disabilities.