The aim of this retrospective cohort study was to compare the costs and characteristics between isolated mandible fractures and mandibular nonunions. From October 2015 to December 2016, the National Inpatient Sample (NIS) was searched for patients admitted with a primary diagnosis of a mandible fracture. The sample was divided between those admitted for an initial evaluation of an isolated fracture and a fracture nonunion. Demographic descriptors, injury characteristics, and inpatient factors were recorded. A total of 1432 patients were included in the final sample, of whom 51 (3.6%) were admitted for a nonunion. Nonunion patients were significantly older (P < 0.01), and nonunions were more often localized to the body (24 vs 11%; P = 0.02). Compared to that of isolated fractures, a greater proportion of nonunions required open reduction and internal fixation (86 vs 59%; P < 0.01) and bone grafting (37 vs 1.4%; P < 0.01), and nonunions imparted +32.6% greater hospitals costs (median: $10,680 vs 14,162; P < 0.01). In conclusion, compared to isolated mandible fractures, mandibular nonunions occurred in older patients, had a higher frequency in body of the mandible, and utilized significantly more hospital resources per admission.