# Protocol for Diagnostic Test Accuracy Study: Evaluation of Cone Beam Computed Tomography (CBCT) in Prediction of Inferior Alveolar Nerve Injury as Compared to Orthopantomography (OPG) Secondary to Surgical Removal of Impacted Mandibular Third Molars

## TL;DR

This study compares the effectiveness of two imaging methods in predicting nerve injury after wisdom tooth surgery.

## Contribution

The study introduces a new protocol to evaluate whether cone beam computed tomography is more accurate than orthopantomography in predicting nerve injury.

## Key findings

- The study will assess if CBCT is more effective than OPG in predicting IAN injuries.
- It will determine if surgeon experience influences the risk of nerve injury.
- Findings could guide the use of CBCT to reduce unnecessary radiation and costs.

## Abstract

Introduction

Impairment of the inferior alveolar/dental nerve (IAN) is a relatively uncommon complication after lower wisdom tooth removal. Studies report varying incidences of IAN injury, with dysesthesia being noted as particularly distressing and 0-0.9% cases extending for a long duration. Neurosensory disruptions can severely impact speech, chewing, swallowing, and social interactions, leading to chronic pain and a lower quality of life. It also poses a risk of inadvertent injuries during meals. Although orthopantomogram (OPG) is primarily used for diagnosis, but when the lower wisdom tooth and nerve are in close approximation, cone beam computed tomography (CBCT) is recommended, despite its higher cost and radiation exposure. A white paper on third molar management necessitates further research on CBCT's role, citing conflicting evidence. Further in a multicentric trial, the difference between the OPG versus CBCT group was not statistically significant due to the low incidence of IAN injuries. They have emphasized the need for more well-designed studies to reach a statistically significant conclusion by meta-analyses. Hence, this study aims to provide additional evidence.

Methods

It is a two-arm, parallel, diagnostic study design involving individuals between the ages of 18 and 50 years, requiring lower wisdom tooth removal that is closely approximated with the nerve. Eligible adults, based on the specified inclusion/exclusion criteria, will be recruited into the study; informed consent will be obtained; then assigned randomly to the OPG or CBCT group using a random computer-generated sequence. Extractions will be done under local anesthesia using a standard surgical protocol with odontectomy. Surgical variables will include the experience of the surgeon, amongst others. The outcome variables will be recorded using patient interviews (subjective) and objective examinations from day one up to six months after surgery. The primary outcome will comprise the number of patients reporting abnormal sensations post-surgery. Secondary outcomes will include objectively confirmed IAN injuries and permanent IAN injuries (>6 months). Results will be analyzed statistically to look for significance and possible risk factors associated with it.

Results

If a statistically significant result is obtained, then we can deliberately reduce CBCT referrals and reserve them only for high-risk cases, wherein the risk of IAN injury cannot be predicted by OPG alone. If the experience of the surgeon proves to be an important risk factor, then it can also help refer high-risk patients to surgeons with more experience.

Conclusion

If CBCT proves to be statistically superior to OPG in the prediction of nerve injury, then we will be able to avoid significant morbidity and improve the quality of life of such patients by either modifying the surgical steps or by choosing other conservative treatment modalities. Further, this may reduce unnecessary CBCT referrals, thus reducing radiation exposure, the cost to patients, and, in turn, national healthcare expenditure. Besides, CBCT is not available at all centers, so a lot of low-risk patients can be managed safely at primary health centers, thus reducing the urban patient load.