During a routine dental appointment at a dental school clinic, a fifteen-year-old black male patient was diagnosed with severe erosion of the dentition together with several carious lesions and a crowded dentition. During treatment of the carious lesions, severe erosion (perimylolysis) of the maxillary and mandibular teeth were observed, which at first alerted the attending clinician to a preliminary diagnosis of anorexia and/or bulimia. Because of the age, gender and social and medical history of the patient, these preliminary diagnoses were discounted, with a hypothesis of gastrointestinal disorder presented to the patient and his parents after consultation with oral medicine and oral pathology faculty. Saliva pH analysis, along with further research concluded that gastrointestinal reflux disease (GERD), surreptitious rumination, or a combination of both were possible diagnoses. Referral to a gastroenterologist for further examination was recommended, while a night-guard was fabricated for the patient to wear at night with fluoride gel. Root canal therapy together with prosthodontic care are often treatment options for patients suffering from gastrointestinal problems. This paper demonstrates how important routine dental examinations are, especially since dentists can often recognize systemic disorders whose symptoms first appear in the oral cavity.