Sir, cone beam computed tomography (CBCT) is an established radiographic investigation for accurate delineation of the inferior dental nerve (IDN) in high-risk mandibular third molars (M3M). In recent times, it is commonly used as part of the preoperative work up and risk assessment for coronectomy procedures.

Coronectomy is 'deliberate surgical removal of the dental crown and vital tooth retention to prevent iatrogenic damage to associated vital structure(s)'. In the case of M3M teeth, the proximity of the IDN can be radiologically assessed using a simplified risk assessment tool based on various criteria proposed in the past (Table 1).1,2

Table 1 Radiological risk assessment of M3M (any one)
Full size table

Cross-sectional imaging such as CBCT and medical CT may be required to further delineate the intimate structures and assist in surgical planning.

Occasionally, teeth found to be intimate to IDN on plain radiographs may appear well separated on the CBCT. We feel that doing a coronectomy in these cases is not justified as there is no higher risk to the nerve in the first place. Coronectomy is to be considered only if benefits outweigh its risks in management of high-risk M3M.

A retrospective study of 80 patients booked for coronectomy procedure was conducted in our unit. All patients had an orthopantomogram (OPT) radiograph, following which 73% (58/80) patients had further CBCT assessment.

Based on the risk assessment tool, the imaging was evaluated to assess whether surgeons are using CBCT correctly while planning coronectomy.

This small cohort study demonstrated that only two thirds (66%) of the booked patients satisfied the criteria for the coronectomy procedure.

Slightly more than a quarter of these patients (n = 22) had only OPT imaging as part of radiological assessment. More than two thirds of these patients (68.2%) were booked to have a coronectomy in spite of well separated M3M and IDN.

Furthermore, in patients who had CBCT assessment, 21% (n = 12) were not adequately risk assessed in spite of availability of cross sectional imaging. This could have been due to a lack of general consensus in the use of CBCT for assessment of impacted M3M and understanding of the indications for coronectomy.

Hence, we recommend a standardised coronectomy criteria to assist clinicians in making correct and informed decisions.

The authors wish to highlight the importance of justifying investigations/procedures to prevent harm and improve surgical outcomes. Additionally, coronectomy should only be performed in select cases where complete extractions may cause more harm than benefit to the patient.