Obliteration of the pulp canal caused by mandibular distraction: a case report Publication date: Available online 30 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): Olivia Johnson King, Sonia Afzal, Valmiki Sharma Abstract We present a 16-year-old boy with a history of ankylosis of the temporomandibular joint (TMJ) who had been treated with a costochondral graft and mandibular distraction. The distraction seems to have caused pulp canal obliteration of the lower right second premolar and lower right first molar on radiographic examination. To our knowledge this is the only reported instance of such damage related to mandibular distraction. We aim to highlight the risks of this complication and the importance of discussing it with patients as part of the process of informed consent.

Pneumatic tourniquets in maxillofacial surgery: do we need to change practice? A national study Publication date: Available online 27 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): S.D. Khandavilli, S. Mawji, N. Uppal, S. Parmar, P. Praveen, T. Martin Abstract The use of pneumatic tourniquets during the harvest of free flaps is an established practice in oral and maxillofacial surgery. Their use can be associated with severe but preventable complications, for which operating surgeons are ultimately responsible. The aim of this study was to find any pitfalls concerning the safe use of tourniquets by maxillofacial surgeons. An electronic questionnaire based on the Association of Perioperative Registered Nurses (AORN) guidelines was distributed to maxillofacial surgeons nationally. A total of 37 questionnaires were completed and analysed. The mean (range) score for the knowledge-based questions for all respondents was 72.8% (47.3%–94.7%). The number of clinicians who answered correctly on topics relating to cuff position, reperfusion time and contraindications for the use of tourniquets were 15, 10 and 6, respectively. A total of 35 clinicians had had no formal training on the application of a tourniquet. Our study shows that knowledge about their use by maxillofacial surgeons is poor, and it highlights the importance of formal education during basic and higher surgical training.

Development of a new V-shaped implant with locking plates and screws for mandibular fracture fixation: an in vitro study using finite element analysis Publication date: Available online 27 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): James Antony Bhagat, Velmurugan Naganathan, Leela Krishnan, Durai Raj, Raj Prakash

Primary orbital reconstruction with selective laser melted core patient-specific implants: overview of 100 patients Publication date: Available online 27 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): M. Rana, H. Holtmann, M. Rana, A.N. Kanatas, D.D. Singh, C.K. Sproll, N.R. Kübler, R. Ipaktchi, K. Hufendiek, N.-C. Gellrich Abstract Contemporary advances in technology have enabled the transfer of industrial laser melting technology to surgery, and its use can improve the accuracy of orbital restoration. The aim of this study therefore was to evaluate the accuracy of primary orbital reconstruction with the use of selective laser melted, patient-specific implants and navigation. A total of 100 patients with complex orbital fractures were included. Planned orbital volumes were compared with those achieved, and angles were compared with the unaffected side. Analysis included the overlay of postoperative on planned images (iPlan® 3.0.5, Brainlab). The mean (SD) orbital volume of the unaffected side was 27.2 (2.8) ml in men and 25.0 (2.6) ml in women. Fractures that involved the posterior third of the orbital floor and comminuted fractures showed significant orbital enlargement (p = 0.026). The mean (SD) reconstructed orbital volume was 26.9 (2.7) ml in men and 24.26 (2.5) ml in women. Three-dimensional analysis of the colour mapping showed minor deviations when compared with the unaffected side. The results suggest that a high degree of accuracy can be routinely achieved in these complex cases.

Validating a risk stratification tool for audit of early outcome after operations for squamous cell carcinoma of the head and neck Publication date: Available online 26 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): D. Tighe, A.J. Thomas, A. Hills, R. Quadros Abstract The aim of this study was to validate a case-mix adjustment tool (neural network) for the audit of postoperative outcomes. We tested its calibration and discrimination on two unseen groups of patients being treated for squamous cell carcinoma (SCC) of the head and neck and compared observed complication rates with predicted rates. A total of 196 patients who were treated at two UK NHS institutions between 2016 and 2018 were audited. Preoperative data pertaining to risk (T classification, complexity of operation, and “high-risk” status) were collected, together with data on postoperative complications. Diagnostic test statistics and receiver operating curves (ROC) were used to test the performance of the tool. The score was well calibrated (predicted and observed complication rates both 43%), but discrimination suggested only fair accuracy (ROC 0.66 - 0.68). Adjustment of case mix for the audit of postoperative complications is difficult, although our model suggests that departmental audit is possible, and its accuracy is equivalent to that of other national audits. Further work may elucidate key variables that have not yet been assessed.

Machine learning methods applied to audit of surgical outcomes after treatment for cancer of the head and neck Publication date: Available online 26 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): D. Tighe, T. Lewis-Morris, A. Freitas Abstract Most surgical specialties have attempted to address concerns about unfair comparison of outcomes by “risk-adjusting” data to benchmark specialty-specific outcomes that are indicative of the quality of care. We are building on previous work in head and neck surgery to address the current need for a robust validated means of risk adjustment. A dataset of care episodes, which were recorded as a clinical audit of complications after operations for squamous cell carcinoma (SCC) of the head and neck (n = 1254), was analysed with the Waikarto Environment for Knowledge Analysis (WEKA) machine learning tool. This produced 4 classification models that could predict complications using data on the preoperative demographics of the patients, operation, functional status, and tumour stage. Three of them performed acceptably: one that predicted “any complication” within 30 days (area under the receiver operating characteristic curve (AUROC) 0.72), one that predicted severe complications (Clavien-Dindo grade 3 or above) within 30 days (AUROC 0.70), and one that predicted a prolonged duration of hospital stay of more than 15 days, (AUROC 0.81). The final model, which was developed on a subgroup of patients who had free tissue transfer (n = 443), performed poorly (AUROC 0.59). Subspecialty groups within oral and maxillofacial surgery are seeking metrics that will allow a meaningful comparison of the quality of care delivered by surgical units in the UK. For these metrics to be effective they must show variation between units and be amendable to change by service personnel. Published baseline data must also be available. They should be modelled effectively so that meaningful comparison, which takes account of variations in the complexity of the patients’ needs or care, is possible.

Case-mix adjustment in audit of length of hospital stay in patients operated on for cancer of the head and neck Publication date: Available online 25 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): D. Tighe, I. Sassoon, A. Hills, R. Quadros Abstract Patients treated surgically for squamous cell carcinoma (SCC) of the head and neck form a heterogeneous group, and it is difficult to take this variation into account when measuring the quality of care. We have tested the feasibility of mathematical models that allow for the adjustment for case mix when auditing the length of hospital stay as a proxy indicator of the quality of care. We completed a case-note audit of 733 surgical episodes of care for SCC of the head and neck in five cancer networks, and used logistic regression and decision tree analysis to adjust for case mix using pertinent preoperative variables. Risk adjustment models of length of stay included age, alcohol, T classification, performance status, tracheostomy, high-risk status, and complexity of operation. The risk-adjusted length of stay differed significantly between the cancer networks studied (p < 0.001). The models performed acceptably for the purpose of audit when this was under 15 days. Length of stay is a measurable outcome that can be used as a benchmark of surgical care. Audits of this after operations for cancer of the head and neck, if reported in national clinical audits, should take case mix into account.

Anatomical relation of third molars and the retromolar canal Publication date: Available online 24 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): C. Moreno Rabie, M. Vranckx, M.I. Rusque, C. Deambrosi, A. Ockerman, C. Politis, R. Jacobs Abstract The study was designed to assess, by direct anatomical observations and cone-beam computed tomography (CT), the prevalence of a retromolar canal and foramen in relation to the mandibular third molar in dry human mandibles. Dry mandibles from European skeletons (n = 89) were observed directly and after cone-beam CT scanning (Newtom VGI evo). The following variables were assessed: the presence of a retromolar foramen and canal; the presence of a third molar, and orientation of the third molar. From the total of 89 mandibles selected, 73 showed a retromolar foramen (49 of which were bilateral). A retromolar canal was identified in 64 mandibles based on cone-beam CT assessment, with a total of 101 canals, including 74 that were bilateral. A total of 112 hemimandibles contained a third molar. Orientation of the third molar did not seem to indicate the presence of retromolar foramina or canals. A similar prevalence of retromolar canals was found for both vertically (41/79) and mesially (17/33) orientated third molars. A retromolar foramen and canal were present in most mandibles, with more than half being bilateral. We were unable to confirm a potential relation between the retromolar foramen and canal on the one hand, and the orientation of the third molar on the other.

McLaughlin’s legacy in the current treatment of facial palsy Publication date: Available online 23 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): A. Poker, E. Pescarini, C. Nduka, R.Y. Kannan Abstract Charles Redmond McLaughlin was a pioneer in both facial palsy surgery and in facial plastic surgery (East Grinstead, 1946-1969). Thanks to his work, the personalised treatment of facial palsy was begun.

Mandibular reconstruction using the deep circumflex iliac artery free flap: effect of the length of bone harvested on donor site morbidity Publication date: Available online 23 July 2019 Source: British Journal of Oral and Maxillofacial Surgery Author(s): Q. Liu, Z. Shao, Z. Shang Abstract The aim of this study was to assess the amounts of pain and morbidity that is associated with the length of the harvested anterior iliac bone graft (cm), and their effect on the contour of the donor site and activities of daily life. A total of 62 patients who had mandibular reconstruction using an iliac bone graft were enrolled in this study at the Wuhan University Hospital. The same surgical standards were used throughout. We divided the patients into two groups depending to the length of the graft (<9 cm or 9 cm or more). The amount and duration of the pain, the time necessary to walk normally, abnormalities of sensation, contour of the donor site, length of the scar, and the patients’ satisfaction with the donor site were evaluated, and outcomes in the two groups compared. The worst pain after operation (p = 0.001) the length of the scar (p = 0.001), and the time needed before the patients were able to walk (p = 0.001) differed significantly between the two groups. There was no significant difference between the two groups regarding other complications. The anterior iliac crest might still be considered to be an ideal donor site for large mandibular defects.