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Preoperative assessment is essential to prevent inferior alveolar nerve (IAN) injury during surgical extraction of the lower third molar (LM3). Here, we aimed to establish an assessment system to predict IAN injury during surgical extraction of the LM3. We conducted a retrospective cohort study on 115 patients diagnosed as 'high-risk' based on our previous risk assessment method involving three anatomical features of the inferior alveolar canal using computed tomographic (CT) images. We evaluated the occurrence of neurosensory impairment in these high-risk patients, and its association with novel anatomic features based on CT images. Neurosensory impairments were observed in 19 patients (16.5%). The inferior alveolar canal major diameter (p < 0.0001) and lingual bone thickness (p = 0.0039) were significantly associated with the occurrence of neurosensory impairment during LM3 extraction. Receiver operating characteristic curves were used to determine cut-off values of these quantitative factors to specifically predict IAN injury. Preoperative risk assessment with quantitative factors based on anatomical features observed on CT images may facilitate more appropriate surgical planning for patients at a high risk of IAN injury., Competing Interests: Conflict of interest We have no conflicts of interest., (Copyright © 2021 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

In recent years, coronectomy of impacted lower third molar teeth has become an increasingly popular alternative to removal. Traditionally, orthopantomograms of mandibular third molars have been used to indicate features that show that the tooth is in close proximity to, or in an intimate relation with, the inferior dental nerve. Some authors advocate coronectomy as opposed to surgical removal to reduce the risk of damage to the nerve. In our Trust during the last two years, there has been a noticeable increase in the prescription of coronectomy for the management of pericoronitis associated with mandibular third molars. The purpose of this study therefore was to examine the differences among clinicians in their assessment of the need for coronectomy using plain-view radiographs. An online survey was completed by 25 clinicians with different levels of experience from six units across the UK and Republic of Ireland. We found a wide variation in the number of coronectomies prescribed (intraclass correlation 2.67), and when prescribed, a lack of agreement about the radiographic feature that had influenced the decision. These judgments are not straightforward. They are, to some extent, subjective, and in certain cases may benefit from a team-led approach., (Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.)

Mandibular angle osteotomy (MAO) and mandibular angle splitting osteotomy (MASO) are the two main surgical approaches used to correct a square mandible for a desirable aesthetic appearance. However, there are concerns about the safety and accuracy of both procedures as they may lead to unsatisfactory results such as injury to the nerve. To achieve symmetry and security we designed and evaluated a 3-dimensional printed surgical template, which indicates the outer cortex splitting line of the MASO, and the curved cutting line of the MAO. We operated on 11 patients who had been diagnosed with broad mandibles using the assisted template. The mean duration of osteotomy, degree of numbness of the inferior alveolar nerve, and reduction in the width of the mandible (Go-Go) were recorded. The mandibular curve before and after operation was fitted to evaluate its accuracy. The results showed that mean duration of osteotomy and numbness of the nerve were reduced, and there was no significant difference between simulation and postoperatively. The mean (SD) reduction in the mandibular width was 15.2 (1.6)mm. The template facilitated accuracy and safety in both procedures., (Copyright © 2018. Published by Elsevier Ltd.)

The current most common technique for repositioning of the mandible, bilateral sagittal split osteotomy (BSSO), was first described by Obwegeser and Dal Pont in the early1960s, and has since been modified several times. However, there is always a risk of damaging the inferior alveolar nerve. We have studied 50 consecutive patients who had high oblique sagittal split osteotomy (HSSO) as an alternative to avoid damage to the nerve. The patients were evaluated for sensory alterations and function of the temporomandibular joint (TMJ). Healing of both wound and bone were complete and uneventful in all 50 patients. Mean (SD) sagittal movement of the mandible was 6.6 (2.9)mm and length of the osteotomy line was 11.0 (3.1)mm. No patient had either temporary or permanent alteration in sensitivity. Pinprick tests showed no significant changes between the preoperative and postoperative readings (p>0.16) or in the chronological results (p>0.23). No disorders of the TMJ developed. Mean (SD) mouth opening 6months postoperatively was 41.6 (8.6)mm. The lateral excursion increased postoperatively by 1.86mm to the left and by 0.76mm to the right. Protrusion increased by 0.66mm. HSSO is therefore a suitable alternative to BSSO as it avoids injury to the inferior alveolar nerve without compromising the TMJ. Ossification was uneventful though bony attachment was less than with the classic BSSO., (Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

We aimed to find out whether improved preoperative assessment and surgical planning with cone beam computed tomography (CT) could reduce damage to the inferior alveolar nerve when high risk impacted mandibular third molars are extracted. We recorded the presence or absence of postoperative neuropathy after extraction of 200 lower third molars in 185 patients (where cone beam CT had shown contact between the nerve and root) after treatment in the oral surgery department of King's College Hospital. All patients had had cone beam CT of the teeth after panoramic radiography had indicated increased risk of injury to the nerve during extraction. Experienced oral surgeons did all the operations and postoperative reviews. Patients reported temporary alteration of sensation after operation in 12% of teeth but it resolved in all cases and no patient reported permanent loss of sensation. Permanent sensory disturbance in the distribution of the inferior alveolar nerve after third molars have been removed can be eliminated in high risk cases if operations are planned carefully (including cone beam CT), and the procedure is done by a skilled surgeon who has an appreciation of the anatomy of the nerve and roots, and an insight into the mechanical effect of their surgical manipulation. The incidence of permanent neurosensory dysfunction in this study was zero even though all teeth were intimately related to the inferior alveolar canal., (Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Coronectomy is a technique that reduces morbidity of the nerve after operation on high-risk mandibular third molars. This two-part paper aims to give an overview of the technique and a description of common problems that can be encountered during and after operation. In this paper we discuss the technique as an overview and then each type of impaction more specifically. We also explore common problems encountered during the procedure and their subsequent management., (Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)