Why Is Mandibular Third Molar Coronectomy Successful Without Concurrent Root Canal Treatment?

J Oral Maxillofac Surg. 2020 Nov;78(11):1886-1891. doi: 10.1016/j.joms.2020.05.046. Epub 2020 Jun 11.


Purpose: Coronectomy is performed to avoid injury to the inferior alveolar nerve when mandibular third molars (M3s) in close proximity to the inferior alveolar nerve are indicated for extraction. Concern has been raised regarding the fate of submerged roots with exposed pulp tissue and whether this will serve as a nidus for infection. The study purpose was to answer the following clinical question: Among patients undergoing coronectomy, do those treated with concurrent root canal treatment (RCT), when compared with those not treated with RCT, have a decreased frequency of postoperative infections? The specific aims of this study were to 1) perform a comprehensive review to compare postoperative infection rates in M3 coronectomies with and without concurrent RCT and 2) review relevant animal and human studies pertaining to pulpal physiology as it relates to coronectomy.

Materials and methods: The study was designed as a comprehensive review to identify controlled studies that compared outcomes of M3 coronectomies with and without concurrent RCT published through January 2020. Studies included in the sample needed to meet the following criteria: 1) studies published in English, 2) human studies, and 3) studies that reported the postoperative infection outcomes. The predictor variable was concurrent RCT at the time of coronectomy. The outcome variable was postoperative infection.

Results: The database search identified 107 publications for initial review. After application of the inclusion and exclusion criteria, the final sample included only 1 publication. The frequencies of postoperative infection with and without concurrent RCT were 87.5% and 12.5%, respectively.

Conclusions: The one study identified for detailed review showed that RCT at the time of coronectomy does not decrease the frequency of postoperative infections. This result supports the recommendation that it is unnecessary to perform concurrent RCT on M3 roots that are retained. The finding that intentional submersion of roots does not require RCT also is supported by multiple animal and human studies.

Publication types

  • Review

MeSH terms

  • Dental Pulp Cavity
  • Humans
  • Mandible / surgery
  • Mandibular Nerve
  • Molar, Third / diagnostic imaging
  • Molar, Third / surgery
  • Tooth Crown / surgery
  • Tooth Extraction
  • Tooth Root / surgery
  • Tooth, Impacted* / surgery
  • Trigeminal Nerve Injuries*