Surgical risk management when placing dental implants in the mandible – Professor Cemal Ucer
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Professor Cemal Ucer shares some of his expertise regarding nerve damage and surgical risk management in dental implantology, following his ADI Study Club on the topic in February.
Dental implants are becoming a common choice for replacing missing teeth due to the emergence of high quality evidence demonstrating their long-term success and survival. Unfortunately, this increase in popularity is also leading to an increase in short- and long-term problems.
These complications can be mechanical(screw loosening or fractures), technical(fracture of prosthetic components/inappropriate design) and biological(progressive marginal bone loss, soft tissue complications and sensory disturbance). The root-causes of early and late failures in implant dentistry are linked to poor patient assessment and treatment planning, which predispose errors in the delivery of both the surgical and restorative phases of care.
There are many factors that affect the success of dental implant treatment. Mechanical and technical failures occur due to excessive biomechanical loading, which often relates to inappropriate prosthesis design or dental implant position, size and angulation with specific reference to the available bone quantity and density.
Risk of surgical damage
Imprecise insertion of dental implants within inadequately available bone leads to biomechanical complications, including unfavourable hard and soft tissue remodelling, which in turn could predispose to peri-implant bone loss and infection. Insufficient bone density and quantity increase the risk of much more significant complications such as collateral damage to vital structures (e.g. the nerve or blood vessels) occurring during surgery. Complications involving nerve or blood vessel damage can be very serious – even life threatening – and often result in medico-legal complaints.
There are concerns that the incidence of iatrogenic trigeminal nerve injuries (TGI) may be on the rise as the popularity of dental implant treatment increases and more surgeries are undertaken by clinicians with varying levels of experience and training. The neurosensory disturbances related to iatrogenic nerve damage are characterised by altered sensation or numbness affecting the area that is innervated by the branches of the trigeminal nerve. More significantly, iatrogenic TGIs commonly cause chronic neuropathic pain, resulting in constant interference with speaking, eating, kissing, shaving, applying makeup, tooth brushing and drinking. These injuries have a significant negative impact on the patient’s self-image and quality of life with profound psychological effects (Renton and Yilmaz, 2011; Yilmaz et al, 2016).
Iatrogenic nerve damage can occur if adequate clearance is not allowed when placing a dental implant near the mandibular branches of the trigeminal nerve. It can also happen when the surgeon diverges from the pre-determined dental implant position, either inadvertently or deliberately: for example, if unexpected anatomical variations are encountered during surgery. Without accurate 3D imaging, the risks increase significantly.
My colleagues and I published a series of research papers over the past few years on this topic. The evidence shows that inaccurate radiological identification of the inferior alveolar nerve (IAN) or mental nerve (MN) and their anatomical variations are the most frequent cause of nerve damage during dental implant surgery. Nerve damage can also arise from inadequate or poor surgical technique, divergence from the surgical plan and inappropriate postoperative management. Interestingly, dental implant surgeons do not seem to have specific training in diagnosis and management of nerve damage and they don’t seem to be aware that iatrogenic nerve damage is a serious surgical complication that is reportable to the CQC in the UK (Yilmaz et al, 2016; 2017).
Training and best practice guidelines
Our research has shown that specific training in the prevention and management of iatrogenic nerve damage related to dental implants might be lacking during dental implant training. Given the devastating nature of this type of complication, the deficiency should be addressed urgently by course providers. It appears that the incidence of TGI can be reduced when dental implant surgery is performed by experienced and well-trained surgeons, who use a standardised technique and certain preventive measures (Yilmaz et al, 2016; Devine et al, 2014).
It is crucial that surgeons should develop evidence-based skills in assessment and planning of dental implant surgery, use appropriate diagnostic imaging and employ evidence-based strategies to minimise the collateral surgical damage when placing dental implants in the mandible. Surgeons should also equip themselves with skills to allow them to diagnose and manage iatrogenic nerve damage effectively.
In addition, it would be advisable for surgeons to follow the evidence-based protocols set out by organisations such as the ITI, AO, EAO and ICOI. The evidence currently shows that the risk assessment, treatment planning
and consent processes performed by dentists may be short of best practice guidelines in implant dentistry – particularly when placing dental implants in the mandible. We published an evidence-based protocol for placement of dental implants in the mandible, which is designed to prevent devastating iatrogenic injuries occurring to vital structures such as nerves and blood vessels. This research was supported and funded by the ADI, for which I am extremely grateful.
Technological aids
In this respect, given the favourable risk:benefits ratio, the use of small field of view (sFOV) CBCT scanning could be the first choice of diagnostic imaging in the mandible, subject to fulfilling national justification criteria such as those published by the FGDP. Better imaging accuracy, identification of the nerves, bone quality and density assessment, as well as use of guided surgery are all part of the justification criteria for prescribing 3D imaging in dental implant surgery.
Cone beam computer tomography (CBCT) now plays an important role in reducing the risk of TGI or blood vessel damage and any associated morbidity, as it helps to accurately assess the quality and quantity of bone and helps to plan the insertion of the dental implant more precisely in 3D. It is interesting to note that in the AAOMR’s revised evidence-based position statement on the selection criteria for radiology in implant dentistry, it recommends that CBCT be used for the assessment of all dental implant sites (Tyndall et al 2012).
However, it must be remembered that CBCT scanning is still regarded as a supplementary imaging technique in implant dentistry and its routine use in every case has not been recommended by national and international organisations such as the EAO, FGDP, AO and ADI. Nevertheless, the justification for prescribing a CBCT can be strengthened significantly if the scan could also be used for the purpose of guided surgery.
Maximising success
Ultimately, meticulous digital 3D patient assessment, diagnosis and planning, as well as precise surgical placement of dental implants, are all essential prerequisites for a successful treatment outcome. The practitioner’s level of experience and skill can also play a part so sufficient training is essential. The consequences of TGI can be devastating both for the patient and the professional – taking care to avoid such complications is a must in modern implant dentistry.
Cemal is one of various renowned clinicians presenting ADI Study Clubs this year. The full list of dates and topics is available on the website.
For information on upcoming ADI Study Clubs, or to book, please visit www.adi.org.uk/studyclubs
ADI Study Clubs are free to members. Join online today.
The views expressed in this article are those of the author, and not necessarily those of the ADI.
Author bio:
Prof Cemal Ucer, BDS, MSc, PhD, FDTFEd, ITI Fellow,
Specialist Oral Surgeon and Professor of Dental Implantology, School of Health & Society, University of Salford
Director of Postgraduate Institute of Clinical Excellence (ICE) Salford, UK,
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