To determine the number and diagnoses of caries-related complaints presenting at Canada's largest children's hospital emergency department (ED) and the costs associated with treatment over 5 years. We carried out a retrospective review of the health records of all children who presented to The Hospital for Sick Children, Toronto, with caries-related emergency complaints from 1 January 2008 to 31 December 2012. A caries-related complaint was defined as a chief complaint of pain or swelling resulting from the sequelae of dental decay (reversible pulpitis, irreversible pulpitis, abscess or cellulitis), as recorded in the chart by the treating physician or dentist. Visit information included chief complaint, final diagnosis, treatment rendered and patient disposition at discharge. Decision Support Services, a hospital department that analyzes resource use and associated costs, calculated the institutional costs for the episodes of emergency care. There were 1081 visits over the 5-year period, with a 19% increase in visits over that time. The most common presenting complaint was pain (50.8%) and the most common diagnosis abscess (35.6%). A dentist was consulted for 60.0% of the children and dental treatment in the ED was provided for 25.9%. The mean cost of treatment per patient was Can$575.17 (95% confidence interval $501.91-$648.43). Over the 5-year study period, dental visits to this tertiary care pediatric hospital increased. The most common complaint was pain, and the diagnosis for about a third of these cases was abscess. Dental consultation was often included in the management of these patients and the resultant cost of these visits was about Can$600/patient.