Objectives: To assess occurrence and its variation over time of serious accidental perforations during endodontic treatment and the fate of perforated teeth by tooth type and characteristics of patients and dentists.
Materials and methods: Data, based on patient documents on healthcare malpractice claims, comprised all endodontic injuries (n = 970) verified by the Patient Insurance Centre in Finland in 2002-2006 and 2011-2013. Two specialists in endodontics scrutinized the documents. Accidental perforations were recorded by location (tooth type, chamber/canals) and dichotomized as avoidable (could have been avoided by following good clinical practice) or unavoidable (normal treatment-related risks). Fate of perforation cases was recorded as treatment discontinued, root canal(s) filled, or tooth extracted. Background information included patients' and dentists' sex and age and the service sector. Statistical evaluation used Chi-square tests.
Results: Serious accidental perforations comprised 29% of all verified injuries. Most perforations were judged as avoidable: 93% in patients aged below 35 years, 87% when located in the pulp chamber or in molars (84%); 70% of all perforations and 75% of those in molars resulted in tooth extraction. The overall rate of serious accidental perforations was 17.6 cases per 100,000 endodontic patients per year.
Conclusions: The rate of serious accidental perforations increased over time. The majority was in molars and resulted in tooth extraction.
Clinical relevance: Accidental perforations comprise almost a third of serious injuries during root canal treatment. However, four of five perforations could be avoided by following good clinical practice. Therefore, training is needed before adopting new working equipment and methods.
Keywords: Accidental perforation; Endodontics; Injury; Pulp chamber; Root canal treatment.