(17) Histopathological Insight Into the Pulpal Status of Enamel Retained Coronectomy Roots

Abstract: Coronectomy is a commonly performed procedure, primarily for mandibular third molars, aimed at reducing the risk of damage to the inferior alveolar nerve (IAN). In recent years, coronectomy has gained popularity due to emerging evidence suggesting a low risk of late infective complications when performed successfully,1,2 Growing evidence has shown that the pulp post-coronectomy remain vital even when erupting into the oral mucosa.1 However, little is known about the management of ‘failed coronectomies’, where enamel shards are inadvertently retained. Traditionally, root retrieval has been deemed the sole recourse in such cases, due to the belief that retained roots lose vitality.Here, we present three cases of failed coronectomy whereby subsequent root retrieval was performed and provide an ideal opportunity to determine the pulpal status. Patients were retrospectively identified from our departmental database of coronectomy root retrievals. Patients were subdivided into early (within one year) and delayed (beyond one year) root retrieval.1 All retrieved roots were sent for histopathological analysis. Patient information such as date of initial surgery, symptoms and investigations carried out were collected retrospectively from clinical records. A total of 3 failed coronectomy roots were retrieved from three patients. The average age was 36 years old (range 28-43 years old) with a 2:1 female to male ratio. One patient had early retrieval while two had delayed retrieval. In the early retrieval group, the average time to root retrieval was 31 days while for the latter group, it was 6 years and 1.5 years respectively. Overall, there were 6 root canals which were assessed, and all had vital tissue without signs of inflammation. Early retrievalThe case that presented in the short term for root-retrieval had persisting extra-oral swelling. It was initially hypothesized that the retained shard of enamel led to a root infection. Given the short time-lapse to root retrieval, root migration did not occur, and the elevated risk of IAN damage was accepted given the extensive nature of the infection. However, histologically, the roots appeared to be vital, and raises the question of whether a repeat attempt to complete the coronectomy procedure could be an alternative especially in elevated nerve injury risk cases. Delayed retrieval It is expected that in delayed cases that the pulp necrosis would have occurred having being exposed to the oral environment for a sustained period of time. However, in both cases pulpal vitality was maintained. Symptoms reported are likely to have been a mixture of pulpal stimulation from the failed coronectomy root, continued peri-coronal inflammation with the retention of enamel and as evident in figure 1 from the adjacent tooth with irreversible pulpitis. This report is seminal as it demonstrates that even in instances of failed coronectomies, where shards of enamels are retained, the root maintains its vitality. This finding may allow for consideration of repeat coronectomy procedures, particularly in cases where root migration away from the nerve has not occurred, and the risk of inferior alveolar nerve (IAN) damage remains.References 1. Shokouhi B, Thavaraj S, Sproat C, Kwok J, Beneng K, Patel V. Coronectomy root retrievals: a review of 92 cases. Oral Surg Oral Med Oral Pathol Oral Radiol. 2019 Mar;127(3):200-209. doi: 10.1016/j.oooo.2018.09.001. Epub 2018 Sep 10. PMID: 30309828. 2. Patel V, Sproat C, Kwok J, Beneng K, Thavaraj S, McGurk M. Histological evaluation of mandibular third molar roots retrieved after coronectomy. Br J Oral Maxillofac Surg. 2014 May;52(5):415-9. doi: 10.1016/j.bjoms.2014.02.016. Epub 2014 Mar 29. PMID: 24684971.

Figure 1 – Right sectional OPG taken 5 years following the initial coronectomy procedure showing the partially erupted LR8 coronectomy root with a retained shard of mesial enamel adjacent to the lower right 2nd molar tooth.