(12) Clinical Success in Coronectomy: A 10 -Year Systematic Review

Abstract: The purpose of the present study was to evaluate the incidence of damage to the inferior alveolar (IAN) after coronectomy, and compare the results within coronectomies that failed, as well as long-term success rates following this procedure. A literature review was made including studies from the years 2010 to 2021 in the PubMed, SCOPUS and Scielo databases, of which fourteen (14) met the selection criteria for this review. This systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) statement. A specific protocol for conducting the study was initially described and documented. Background was defined, a clinical question was asked, specific eligibility criteria for individual studies were included, search for replicable methodologies was done, and statistical analysis techniques (meta-analysis) of the data was obtained.
The development of this project allows us to understand the necessary fundamentals for the correct selection of cases when this procedure is indicated, as well as the associated intra-operative and post-operative complications. Studies have shown that the occurrence of permanent damage to the IAN after the extraction of mandibular third molars goes from 0.35% to 8.4%, which can present with paresthesia, dysesthesia and / or hyposthesia.1 Based on the above information, different surgical techniques have emerged in the oral and maxillofacial surgery field, whose main purpose is to reduce the complications after extraction of mandibular third molars as much as possible. Coronectomy was first described by Knutsson. The technique was developed as an alternative for the traditional complete extraction of the tooth. Coronectomy consist in sectioning the tooth crown below of the cementoenamel junction (CEJ), leaving the root segments in the alveolar socket that are in intimate contact with the IAN.2
In this systematic review, the articles included had a minimum of 1 year follow-up and the following variables were evaluated: complications (infection, dry socket, damage to the IAN), adverse effects (root migration, failed coronectomy, root exposure to the oral cavity), and the need for a second surgical intervention. In addition, the relevant variables that could have affected the success rate were reviewed.

This study shows details of the 2039, coronectomies done with a 3.04% failure rate (n=62). The criteria used to evaluate the failure of the therapy were clearly defined in eleven studies. The incidence of permanent injury to the IAN was reported in 0.73%, (n= 15), which is lower than after the extraction of mandibular third molars. Infection was present in 1.76% (n= 36), mostly seen during the 1st postoperative week . Dry socket was documented in 0.58% (n=12). of the cases. Coronal root migration was a common finding in these studies indicating up to 2 and 3 mm of upward root movement from the original site at 6 and 12 months respectively. Coronectomy with complementary Guided Bone Regeneration (GBR) should be less likely to show long-term root exposure due to roots covering by regenerated bone, preventing a second surgical procedure. Coronectomy is a safe treatment option as an alternative to the extraction of the third molars. It should be planned before surgery and the correct protocol should be used to reduce the likelihood of intraoperative and postoperative complications.

REFERENCES
1. Pedersen MH, Bak J, Matzen L., et al. Coronectomy of mandibular third molars: a clinical and radiological study of 231 cases with a mean follow-up period of 5.7years. Int J Oral Maxillofac Surg 47: 1596–1603, 2018
2. Knutsson K, Lysell L. & Rohlin M. Postoperative status after partial removal of the mandibular third molar. Swedish dental journal, 13(1-2), 15–22, 1989.