10 1  Principles of Surgery

Figure 1.6 Clinic room with defined administrative, operative, and hygiene areas.

Prior to sterilisation, instruments should be wiped clear of obvious blood and debris, then cleaned in an ultrasonic (a machine that uses ultrasonic sound waves to vibrate instruments in order to remove small debris). The instruments should be wrapped or bagged, and chemical indicators that will change when sterilisation conditions are met placed on the equipment. Any practice that provides outpatient surgical procedures must ensure that staff are appropriately trained in sterilisation procedures and understand the basic minimum requirements.

Sterilisation of surgical equipment will fall into one of three categories: dry heat, moist heat, or sterilisation with gas. The sterilisation equipment must undergo regular and annual checks to ensure it is adequately maintained.

1.7 The Surgeon’s Preoperative Checklist

When preparing for a procedure, the surgeon should run through a checklist to ensure that everything is in order. This includes:

●A signed consent (to be reviewed with the patient on the day of surgery).

●Confirmation of any allergies.

●A current radiograph, displayed in the surgical room (to be visible to the surgeon during the procedure).

●Confirmation of the correct side and site of the procedure.

●Use of personal protective equipment.

●Surgical handwash, gowning, and gloving.

The surgeon and trained staff should ensure that all equipment has been sterilised, is in suitable condition, and is handled in accordance with aseptic non-touch techniques. All equipment that is anticipated to be used or which may be required in the event of a complication should be ready. In some cases, it may be useful to have a ‘scout’ nurse to collect additional equipment as required.

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1.7 ­Th e Surgen’ s Preoperaiv Checklis 11

Figure 1.7  WHO surgical handrubbing technique. Source: From Surgical Handrubbing Technique, https://www.who.int/gpsc/5may/hh-surgicalA3.pdf, WHO. © WHO.

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12 1  Principles of Surgery

Figure 1.8 Dentist with sufficient sterile and personal protective attire for dentoalveolar surgery.

All surgical procedures require adequate lighting in order to visualise the operative field. This is particularly important when working in a small area such as the mouth. An overhead light should be used to ensure that both the surgeon and the assistant have adequate visual access to the field. The surgeon may also use a personal headlamp.

The surgeon should perform a surgical handwash prior to the procedure, as per the World Health Organization (WHO) surgical handrubbing technique, to ensure disinfection of contaminated skin of the hands, arms, and elbows (Figure 1.7). Typically, this will involve the use of a chlorhexidineor iodine-based surgical handwash.

After the handwash, the surgeon must apply a sterile gown and gloves, so that they may enter the sterile field without contamination (Figure 1.8).

1.8 Operative Note

Following a surgical procedure, detailed clinical notes should be completed as soon as possible, listing all medications or anaesthetics administered and steps taken, the difficulty of the procedure, any intraoperative complications that arose, and any postoperative discussions with or instructions given to the patient. At a minimum, the operative note should include:

●Indications for the procedure and a summary of intraoperative findings.

●Type of anaesthesia used (relative anaesthesia, oral or IV sedation, general anaesthesia):

–specifically, the type of local anaesthesia, dose administered, concentration, and use of vasoconstrictors.

●A detailed procedural note, including:

–methods used for extraction (‘simple’ versus ‘surgical’), with a detailed description of each step;

–any complications encountered;

–difficulty of the procedure;

–haemostatic agents used;

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1.8  ­Operativ Not 13

––suture type;

––ease in obtaining haemostasis.

––Additional notes on any medications prescribed, including type, dose, and duration.

●●Any postoperative orders that were given to the patient, and how they were transmitted (written, verbal, or both).

●●The date and time of the follow-up appointment.

The operative note must reflect a legal memorandum outlining the specific intraoperative details

of every case; a good clinical note enables continuity of care, provides a basis for informative evidence­ for any future complaints or complications, and enhances communication between healthcare professionals.

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16 2  Local Anaesthesia

2.1  Principles­ of Anaesthesia

1)Patient Safety. Patient safety is always the key priority in anaesthetic administration. This involves ensuring that the correct anaesthetic agent is utilised, there are no contraindications, the agent has not expired and has been stored correctly, and appropriate sterilisation and preparation have been carried out. Whenever injecting local anaesthesia, the clinician must ensure that they are up to date with cardiopulmonary resuscitation and are trained in the management of medical emergencies; local anaesthetic solutions may result in systemic side effects, and the patient should be monitored for such complications after administration.

2)Informed Consent. Local anaesthesia is not always well tolerated by patients, and this is largely due to patient expectations. For example, numbing of tongue sensation – a normal outcome of lingual nerve anaesthesia – may result in an anxious patient who feels unable to manage oral secretions. It is critical that patients are adequately informed of the expected effects of local anaesthesia; this is a key component of the informed consent process. The local and systemic risks must also be explained in detail as part of the overall procedural consent.

3)Understanding of Regional Anatomy. Effective local anaesthesia depends on delivery of a local anaesthetic agent to the appropriate nerves, tissues, or anatomic spaces. Similarly, avoidance of complications of local anaesthesia requires active avoidance of surrounding anatomic structures which may be encountered in similar anatomic areas. A sound knowledge of regional anatomy will ensure delivery of anaesthetic to the correct areas, whilst avoiding complications related to anatomic misadventure.

4)Technical Expertise to Utilise Appropriate Techniques. Surgeons who work in the oral cavity are technical experts in navigating the oral tissues, and the application of local anaesthesia is a skill that requires technical proficiency. The appropriate use of finger rests, retraction, and patient positioning can optimise patient comfort and tolerance of the procedure.

5)Ability to Troubleshoot. The surgeon performing anaesthesia must always think critically and determine potential reasons why local anaesthesia may have failed, including where additional techniques may be required to produce profound anaesthesia.

2.2  Mechanism­ of Action

Local anaesthetic agents produce their effect by reversibly blocking voltage-gated sodium ion channels in the axonal membranes of nerve cells, resulting in inhibition of action potential transmission along the axon (Figure 2.1). When local anaesthesia is applied to sensory nerves, painful stimuli are not conducted to the sensory cortex and pain is no longer perceived.

Local anaesthetic preparations are usually combined with a vasoconstrictive agent, commonly adrenaline or a synthetic vasopressin derivative (Figure 2.2). The concentration of local anaesthetic is typically given as a percentage, whilst the concentration of vasoconstrictor is given as a ratio (Table 2.1). The preparation may come in a dental cartridge, or in a vial to be drawn up before use. Before administering local anaesthetic, it is important to confirm the type, concentration, vasoconstrictor, and expiry date. Solutions with adrenaline have a number of advantages: the vasoconstrictive effect results in less haemorrhage in the operative field, allowing better visualisation; the duration of action is increased; and the risk of systemic toxicity is reduced. Whilst extremely rare, ischaemic cardiovascular complications may occur in patients with a prior history of cardiovascular disease, if preparations containing adrenaline are used in excess.

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Sensory

cortex

Trigeminal nerve ganglion

Figure 2.2 Example preparations of local anaesthetic. https://t.me/DentalBooksWorld

182  Local Anaesthesia

Table 2.1  Conversion tables for local anaesthetic and adrenaline in solution.

2.3  Common­ Local Anaesthetic Preparations

Lignocaine is the most common agent used for local anaesthesia in dentistry. It is an amide-type anaesthetic with a rapid onset of action and an excellent safety profile, and when prepared with adrenaline, it has a duration of action of two to three hours, making it suitable for use in dentoalveolar extractions. It is commonly prepared as a 2% solution with 1 : 80 000 adrenaline. This provides 20 mg of lignocaine per millilitre of solution. The standard dental cartridge (2.2 ml) will deliver 44 mg of lignocaine. The maximum safe dose when prepared with adrenaline is 7 mg/kg.

Articaine has been in use for almost 20 years. It is advantageous for use in dental extractions due to its rapid onset of action and great diffusion potential. This is related to its unique molecular structure, which has both amide-like and ester-like bonds and an additional thiophene ring. These structures increase the lipid solubility of the molecule, whilst also making it susceptible to degradation by plasma esterases in the tissues. There is some controversy over its use in regional nerve blocks in dentistry, due to its association with increased neurotoxicity which may result in prolonged paraesthesia. Articaine is available in a 4% solution and is thought to provide a more profound anaesthesia than lignocaine when delivered as an infiltration. When prepared with adrenaline, the maximum dose is 7 mg/kg.

Bupivacaine is a local anaesthetic agent with a slower onset and longer duration of action than either lignocaine or articaine, with an anaesthetic effect of up to eight hours. Whilst this may be a disadvantage for procedures in the dental clinic setting, where rapid anaesthesia is desirable, it has the advantage of reducing the onset of postoperative discomfort. Bupivacaine is commonly prepared as a 0.5% solution with 1 : 200 000 adrenaline. The maximum safe dose is 2 mg/kg. Caution should be taken when administering bupivacaine because the dose leading to cardiotoxicity can precede symptoms associated with neurotoxicity. For most other anaesthetic agents, the reverse is true, and local anaesthetic overdose is more rapidly recognised.

Ropivacaine is a newer anaesthetic agent with similar characteristics to bupivacaine but a number of additional desirable qualities. It has a long duration of action of six hours and a comparably rapid onset. One unique benefit is that the molecule itself is vasoconstrictive, avoiding the need for additional vasoactive agents in its preparation. Additionally, there appears to be a lower risk of cardiotoxicity associated with the use of ropivacaine compared with bupivacaine. However, commercially available preparations are generally more expensive than other common anaesthetic agents used for dentoalveolar extractions.

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