Context: Primary hyperparathyroidism (HPT) is a systemic disease causing bone loss. Periodontal disease is a local inflammatory disease characterized by alveolar bone loss. The older literature records that HPT is associated with loss of radicular lamina dura and brown tumors of the bone, but contemporary studies are lacking.Objective: The objective of the study was to determine the effects of HPT on oral bony structures and periodontal disease in a contemporary population.Design: This was a cross-sectional, case-controlled study.Setting: The study was conducted at the clinics of endocrine surgery and hospital dentistry.Patients and Other Participants: Fifty-nine patients, 39 with HPT and 20 thyroid controls, were included in the study.Main Outcome Measures: Periodontal clinical measures and dental radiographic analyses were used in this study.Results: HPT patients were more likely to have tori and reductions in radicular lamina dura on dental radiographs. Widening of the periodontal ligament space surrounding teeth correlated with serum PTH levels. Panoramic radiographs demonstrated reduced cortical bone thickness at the angle of the mandible in HPT patients but no evidence of brown tumors or other overt pathologies.Conclusions: Changes in the oral cavity observed in patients with HPT suggested both decreased cortical density and increased likelihood of oral tori. The contemporary oral manifestations of primary HPT are different from those previously reported, and health care providers should be aware of newer, more subtle findings that may be present when treating patients with HPT.