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Dental Tribune Middle East & Africa Edition | 2/2017 ORTHO TRIBUNE E3 cient volume. Therefore, it is crucial for the dental practitioner not to compromise the alveolar bone dur- ing extraction of the teeth. Changes in the alveolar bone ridge after an extraction are inevitable. After all dental extractions, bone height and width always undergo dimensional changes. Bone does not regenerate above the level of the alveolar crest, that is, its height will not increase during healing. The buccal plate tends to shrink, shifting the crest of the alveolar ridge lingually, and of- ten forms a concavity. Such changes are proportional to the amount of trauma to the soft- and hard-tissue during the extraction. An additional unfavourable change that may take place is the slow re- modelling of the bone formed to fill up the extraction socket owing to lack of functional stimulation. The presence of poorly remodelled alveolar bone may compromise the stability and function of the future implant. Furthermore, studies show that the stripping and elevation of mucoperiosteal tissue produce a higher number of osteoclasts within the alveolar ridge and hence greater resorption and shrinkage are seen after the classical surgical or the trau- matic extraction of teeth. The preservation of alveolar bone for future implant placement may be achieved by avoiding unnecessary bone removal and stripping of the periosteum during surgery, as well as performing a surgical alveolar bone preservation procedure. Bone removal can be largely avoided or minimised through modification of the traditional extraction technique. walls, thus preventing their collapse and shrinkage. It should be noted that this intervention can only slow down the post-extraction changes to improve the success of the dental implant, but cannot stop them alto- gether. The first such modification is the use of dental periotomes and luxato- mes to gently strip the periodontal ligament fibres and widen the socket without causing cracks or fracture of the cortical plates, as commonly encountered when using dental forceps or the bulky elevators. The use of such gentle instruments also eliminates the need for elevation of mucoperiosteal tissue. However, it should be noted that the safe use of these instruments requires adequate training and should be encouraged during undergraduate clinics. Clot stabilisation through light packing of the socket with collagen sponges may help to minimise clot dislodg- ment, as well as accelerate the heal- ing process and bone regeneration. The second strategy is the alveolar bone preservation procedure. This includes packing the extraction socket with different fillers, such as osteoinductive or osteoconductive materials, like autogenous, natural or synthetic bone grafting materi- als that support the alveolar socket Finally, post-extraction care should include an explanation of the heal- ing process and potential symptoms encountered after such procedures. The prescription of medications should be limited to non-steroidal anti-inflammatory drugs in most cases and imprudent use of antibi- otics or socket dressing should be avoided. Editorial note: The artilce was pub- lished in Ortho Magazine 1/2016 Dr Kamis Gaballah Educated in the UK and Ireland, Dr Kamis Gaballah is currently an associate professor and senior specialist in oral and maxillofacial surgery at the Ajman University of Science and Technology in the United Arab Emir- ates. He can be contacted at kamisomfs@yahoo.co.uk. ◊Page E2 longer and more curved roots and be embedded in highly dense, compact alveolar bone, and thus sectioning of the teeth may be required to ease the resistance. Racial differences should also be taken into account, as extrac- tions of teeth from individuals of Afro-Caribbean descent tend to be more challenging owing to the hard- ness of their bone and divergence of roots in their molars. The resistance of hard tissue should be expected, particularly if maxil- lary second and third molars are being extracted, as the potential for fracture of both the buccal plate and the tuberosity is relatively com- mon when excessive force is applied with dental forceps. Fracture of the tuberosity may produce irregular sharp bony boundaries, significant soft-tissue laceration and potentially an oroantral fistula. If such risk fac- tors are identified, tooth sectioning should be followed by elevation of roots with dental luxatomes instead of traditional elevators or forceps, which are known to deliver much higher force to the alveolar bone. The indications for the extraction of impacted lower third molars (LM3) have been the subject of long- standing debate. Surgical procedures for the extraction of unerupted LM3 are associated with significant mor- bidity. This includes pain, swelling and the possibility of temporary or permanent nerve damage, result- ing in altered sensation of the lip, chin, gingiva or tongue. Damage to the inferior dental nerve (IDN) is a well-known complication of surgical extraction of deeply impacted LM3. It should be acknowledged that this is not simply a loss of sensation; the damaged nerve can be responsible for a number of abnormal sensa- tions, including sharp pain and ab- normal response to stimuli, such as the perception of a light touch as a sharp stab. This can have a sig- nificant impact on quality of life for many patients. Injury to the IDN may occur from compression of the nerve, either indirectly by forces transmitted by the root and surrounding bone dur- ing elevation or directly by surgical instruments, such as elevators. The nerve may also become transected by rotary instruments or during ex- traction of a tooth whose roots are notched or perforated by the IDN. The risk factors for IDN injury dur- ing extraction of LM3 are shown in Table I. Preoperative radiographic investiga- tions may include intra-oral images, such as occlusal radiographs; pano- ramic views of the jaws; and conven- tional CT or CBCT scans. It should be noted that risk-predicting signs in radiographs only indicate that there is an increased risk of nerve damage associated with the extraction of the corresponding third molar. How- ever, they cannot actually prevent the nerve injury if the tooth is to be extracted. The effective strategies that may avoid or minimise the risk of injury to the IDN can be collec- tively categorised into two main sets. The first is the preoperative workup, which should include critical assess- ment of the need to extract the third molar, clinical examination and radiographic investigation, and the second is intra-operative measures, including proper selection of local anaesthetic agent, the injection tech- nique, modification of the surgical procedure and measures to reduce the degree of potential injury to the nerve. Most literature published in the last decade has given us sufficient evi- dence to suggest a significant risk of damage to both the inferior dental and the lingual nerve owing to the nerve block procedure. This injury may be related to the pharmacological properties of the agent itself or the injection tech- nique. Studies have shown that the lingual nerve is affected approxi- mately twice as often as the IDN, and one reason for this may be the fascic- ular pattern in the region where the injection is given. It also appears that about half of patients feel an electric shock sensation during injection. There is a higher incidence of reports of nerve injury after the use of artic- aine and prilocaine. Although the reason for this remains unknown, it has been suggested that this may be because they are 4 % solutions, whereas the other commonly used local anaesthetics have lower con- centrations. Others associate the damage with the neurotoxicity po- tential of 4 % articaine and 3–4 % pri- locaine. Hence, it is recommended that the use of such anaesthetics be limited to local infiltration. It has been claimed that needle contact with a nerve felt by the patient as an electric shock is related to injection injury. An obvious explanation is that the possibility of mechanical in- jury to the nerve is more likely in the case of multiple repeated attempts at the inferior dental nerve block procedure. Therefore, it is crucial that the operator achieve optimal pain control with minimal episodes of injection with minimal doses of anaesthetic agent. The surgery should be planned ac- cording to the information obtained from the preoperative assessment process. The procedure itself should aim to minimise the manipulation around the IDC. Both should include the carefully planned access, tooth sectioning and elevation techniques. In many scenarios, the extraction of the whole tooth may carry an una- voidable risk of injury to the nerve, therefore intentional retention of parts of the tooth was proposed via a planned procedure introduced around 20 years ago called coro- nectomy. This is the removal of the crown of a tooth, leaving the root in situ. It is merely adopted to avoid or minimise damage to the IDN. The rate of complications after coronec- tomy is comparable to that observed after surgical extraction, except with a significantly low incidence of in- jury to the IDN. It should be noted that both sec- tioning and coronectomy can be performed with a shorter incision, as the amount of bone removal re- quired is minimal, thus minimising the postoperative morbidity. How- ever, it cannot be performed in all cases in which the LM3 is close to the IDC and is certainly contra-indicated when the LM3 is decayed or its roots are associated with a pathology and should be considered with caution in severely inclined mesio-angular and horizontal impaction cases. The author does not recommend distal bone removal or retraction of the lingual flap with the intention of protecting the lingual nerve, as these may increase the risk of damaging the lingual nerve. It should be em- phasised that incision may not ex- tend beyond the distobuccal aspect of the tooth. The other important aspect of the dental extraction procedure is the future replacement of the tooth to be extracted. The current trend of tooth replacement for both functional and aesthetic reasons is the placement of dental implants. The success of this treatment largely depends on the availability of healthy bone in suffi-