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ePaper created 2016-04-19, 10:56:04 | version 1.38.0
Dental Tribune United Kingdom Edition | 5/201518 TRENDS&APPLICATIONS The last two decades have seen significant advances in restorative techniques and materials for den- tistry. The latter, along with com- munity-based preventive measures that aim to reduce the incidence of caries, have resulted in many pa- tients living with functional teeth foralongerperiod.Yet,extractionof teeth forms the considerable bulk of the workload in oral surgeries owing to several factors, including the late presentation of patients with advanced dental disease, the presence of symptomatic impacted teeth, such as third molars, and the need to extract teeth for orthodon- tic or orthognathic treatment. The extraction of teeth varies greatly based on the type of patient who is undergoing the procedure. For example, elderly patients with significant co-morbidities and on a complex combination of medica- tions as compared with young healthy individuals render the pro- cedure complicated and require muchmorepreparationwithmodi- fications during and after patient management. Additionally, extrac- tions can range from a single, fully eruptedtoothwithfavourablemor- phology to multiple misaligned, impacted teeth or teeth with chal- lenging morphology. Local ana- tomy, such as tooth proximity to the nerve, maxillary sinus and tu- berosity,alsoplaysasignificantrole. These variations usually dictate who is to perform the extraction, as many general practitioners deal with less complicated cases of den- tal extraction in individuals re- garded as healthy patients and may not feel comfortable operating on medicallycomplexpatients. Complex extraction cases have beenlinkedtoahigherrateofpost- operative complications; there- fore, a cautious and systematic approach should be adopted that includes a detailed preoperative assessmenttopredictthepotential difficulties that might arise during extraction. The documentation of all complicating risk factors along with their potential postoperative morbidities is crucial and should be included in the informed con- sent. In the following article, other usefultipswillbeprovidedthatare not usually included in traditional textbooks or lecture notes to help general practitioners to perform safer extractions. During clinical examination, it has been proven useful to observe thepatient’sbuild.Tallandmuscu- lar individuals tend to have a long ramus with a higher mandibular foramen, and this increases the possibility of failure of the inferior dental nerve block procedure if the former is not taken into account when determining the height of the injection site. This can be aided by tracing the inferior dental canal (IDC) to the mandibular foramen in the preoperative panoramic radiograph. The teeth of such in- dividualsmayalsohavelongerand more curved roots and be embed- ded in highly dense, compact alve- olar bone, and thus sectioning of the teeth may be required to ease the resistance. Racial differences should also be taken into account, as extractions of teeth from indi- viduals of Afro-Caribbean descent tend to be more challenging owing to the hardness of their bone and divergenceofrootsintheirmolars. The resistance of hard tissue should be expected, particularly if maxillary second and third molars are being extracted, as the poten- tial for fracture of both the buccal plate and the tuberosity is rela- tively common when excessive forceisappliedwithdentalforceps. Fractureofthetuberositymaypro- duce irregular sharp bony bound- aries, significant soft-tissue lacer- ation and potentially an oroantral fistula. If such risk factors are iden- tified, tooth sectioning should be followed by elevation of roots with dental luxatomes instead of tradi- tional elevators or forceps, which are known to deliver much higher force to the alveolar bone. The indications for the extrac- tion of impacted lower third mo- lars (LM3) have been the subject of long-standing debate. Surgical procedures for the extraction of unerupted LM3 are associated with significant morbidity. This includespain,swellingandthepos- sibilityoftemporaryorpermanent nerve damage, resulting in altered sensation of the lip, chin, gingiva or tongue. Damage to the inferior dental nerve (IDN) is a well-known complication of surgical extrac- tion of deeply impacted LM3. It shouldbeacknowledgedthatthisis not simply a loss of sensation; the damaged nerve can be responsible for a number of abnormal sensa- tions, including sharp pain and abnormalresponsetostimuli,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. InjurytotheIDNmayoccurfrom compression of the nerve, either indirectly by forces transmitted by the root and surrounding bone during elevation or directly by sur- gical instruments, such as eleva- tors. The nerve may also become transected by rotary instruments or during extraction of a tooth whose roots are notched or per- forated by the IDN. The risk factors for IDN injury during extraction of LM3 are shown in Table I. Preoperative radiographic in- vestigations may include intra- oral images, such as occlusal radi- ographs; panoramic views of the jaws; and conventional CT or CBCT scans. It should be noted that risk- predicting signs in radiographs only indicate that there is an in- creased risk of nerve damage asso- ciated with the extraction of the corresponding third molar. How- ever, they cannot actually prevent thenerveinjuryifthetoothistobe extracted. The effective strategies that may avoid or minimise the risk of injury to the IDN can be col- lectivelycategorisedintotwomain sets. The first is the preoperative workup, which should include critical assessment of the need to extract the third molar, clinical examination and radiographic in- vestigation,andthesecondisintra- operativemeasures,includingproper selectionoflocalanaestheticagent, the injection technique, modifica- tion 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 evidence 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 fascicular 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 re- portsofnerveinjuryaftertheuseof articaine and prilocaine. Although the reason for this remains un- known, it has been suggested that this may be because they are 4 % solutions, whereas the other com- monlyusedlocalanaestheticshave lower concentrations. Others asso- ciate the damage with the neuro- toxicity potential of 4 % articaine and 3–4 % prilocaine. Hence, it is recommended that the use of such anaesthetics be limited to local in- filtration. It has been claimed that needle contact with a nerve felt by the patient as an electric shock is related to injection injury. An ob- vious explanation is that the pos- sibility of mechanical injury to the nerve is more likely in the case of multiple repeated attempts at the inferior dental nerve block pro- cedure. 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 according to the information ob- tained from the preoperative as- sessment 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 wholetoothmaycarryanunavoid- able risk of injury to the nerve, therefore intentional retention of partsofthetoothwasproposedvia a planned procedure introduced around 20 years ago called coro- nectomy. This is the removal of the crown of a tooth, leaving the root insitu.Itismerelyadoptedtoavoid or minimise damage to the IDN. The rate of complications after coronectomyiscomparabletothat observed after surgical extraction, except with a significantly low in- cidence of injury to the IDN. It should be noted that both sec- tioning and coronectomy can be performed with a shorter incision, Avoiding common problems in tooth extractions By Dr Kamis Gaballah, UAE Overall risk factors for IDN injury Radiographic signs of increased risk of IDN injury Full bony impactions Apices of the LM3 located inferior to the lower border of the IDC Horizontal impactions Darkening of the root Use of burs for extraction Abrupt narrowing of the root Radiographic risk markers Interruption and loss of the white line representing the IDC Clinical observation of the bundle during surgery Displacement of the IDC by the roots Excessive bleeding into the socket during surgery Abrupt narrowing of one or both of the white lines Patient’s age representing the IDC most of dentists and surgeons Table I: Risk factors for IDN injury during LM3 extraction. DTUK0515_18-19_Gaballah 15.10.15 12:06 Seite 1 DTUK0515_18-19_Gaballah 15.10.1512:06 Seite 1