Dental Anesthesia: GDC Outcomes & Safety

• The session focuses on local anaesthetics, aiming to deliver safe and effective anaesthesia, identify oral anatomy, safely deliver infiltrations and IDBs, understand the legal framework, and highlight potential complications.
• The expected GDC learning outcomes covers describing dental anatomy, physiology, properties of medicines, and managing patient anxiety and pain.
• Key areas to be covered include nerve supply, patient preparation, infiltrations, and inferior dental block (IDB) techniques.
• Trigeminal nerve has three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3).

Patient Preparation

• Requires obtaining a valid prescription, reviewing the patient's medical history, and checking for contraindications.
• Ensure to ask about past reactions to LA and if the patient has eaten, to prevent vasovagal attacks.
• Explain the procedure and sensations associated with LA to the patient and use distraction techniques to address anxiety especially using calm and appropriate language.

Factors affecting pain threshold

• Anxiety, previous experience, culture and age
• Additionally, psychological makeup, the physical environment, and the patient's emotional state.
• Gate Control Theory involves using hypnosis, distraction, creating a calm atmosphere, and providing alternative stimuli to manage pain.

Infiltration Techniques and Nerves

• Infiltrations are used to anaesthetize the anterior, superior, alveolar and middle superior alveolar nerves.
• Pterygopalatine nerves include the nasopalatine nerve, and the greater and lesser palatine nerves.
• Patient should be supine, comfortable and well supported, at proper height for the operator with light directed into sulcus.
• Dry the mucosa, apply topical anaesthetic on a cotton wool roll for 2-3 minutes before injection

Buccal Filtration Technique

• Estimate the apex of the tooth and pull the surface mucosa taut while maintaining good retraction.
• Insert the needle through the mucosa at 25 degrees to the bone, aiming for the apex.
• Maintain the needle parallel to the long axis of the tooth; glide the needle smoothly through the mucosa.
• Avoid contacting the bone, but if you do, withdraw 1-2mm; the bevel should face the bone.
• Aspirate prior to injection, especially around the upper second/third molars.
• The quantity should be 0.5ml - 1ml per site for perio work, or 2.2ml for restorations; pulpal analgesia should occur within 2-5 minutes.
• Extra care should be taken for labial aspect of upper incisors and labial aspect of lower incisors

Supplementary injections

• Palatal infiltrations, lingual infiltrations and intrapapillary injections
• In a palatal infiltration, apply topical and pressure first, inject at 90 degrees with considerable resistance, and deposit 0.2 ml of solution.
• Palatal Infiltration can be used for deep restorations, subgingival PMPR, and extractions of deciduous maxillary dentition.
• Intrapapillary injections are useful for palatal analgesia in children and nervous patients.
• Direct the needle at right angles to the interdental papilla, insert into the center at the periosteum attachment level, deposit 0.25ml of solution, and check for blanching.

IDB

• IDBs are a method of anaesthetizing the inferior dental / alveolar nerve, mylohyoid nerve and the lingual nerve.
• The basic anatomy of mandible to be aware of includes: condylar process, coronoid process, submandibular fossa, sublingual fossa, alveolar process, mental foramen, mental, protuberance, body and ramus.
• The pterygomandibular space includes the: parotid salivary gland, sphenomandibular ligament, medial pterygoid muscle, facial nerve, inferior alveolar nerve, medial surface of ramus of mandible, coronoid notch of mandible, masseter muscle and pterygomandibular raphe.
• A needle entering deeply and depositing analgesic solution outside the pterygomandibular space into the parotid gland's deep lobe can cause facial nerve paralysis.
• To perform an IDB Patient can be supine or upright, with patient's mouth wide open, topical analgesia should be used, and good lighting.
• One should select a long needle of 35mm, 27 gauge.

IDB technique

• Use a finger or thumb to locate the retromolar fossa and identify the pterygomandibular raphe.
• Position the syringe barrel over contralateral premolars.
• Find the correct mandibular foramen level by bisecting the thumb/fingernail and drawing a 1cm line above the occlusal plane.
• Insert the needle slowly into the pterygomandibular space aiming for the mandibular foramen,.
• Inject to a depth of 2.0-2.5 cm but do not insert the full needle (5mm must always be visible).
• Withdraw 1 mm and aspirate, if mandatedibular bone is contacted.
• If blood is present, withdraw needle 1-2mm and aspirate again; if still present, reposition and repeat.
• Deliver the solution slowly only if the needle tip is verified not to be in a vein, and re sheathe the needle.
• When complete, the patient should be sat up for a rinse.

Anatomical variations

• If bone is struck too soon during an IDB, withdraw, swing the needle round to the midline, advance for 7 mm before swinging back.
• Experiencing an electric shock sensation in the tongue or lip indicates the needle has touched the lingual/mandibular nerve, requiring a 1-2mm withdrawal.
• With incisive and mental blocks, aim for the mental foramen between apices of first and second premolars while remembering to use a lingual infiltration.
• For incisive and mental blocks, ensure the patient is supine with good lighting and apply topical LA
• Place the needle tip in the buccal sulcus reflection between the root apices of LL4 and LL5, aspirate, and slowly inject.
• Do not give Articaine for IDBs or incisive and mental blocks

Legal Framework

• LA is a Prescription Only Medicine (POM)
• A written prescription is required for each agent from a recognised prescriber- a dentist.
• The Human Medicines Regulations 2012, along with Patient Group Directives, provide frameworks allowing registered professionals such as dental hygienists and therapists to administer certain medicines without a prescription.
• Beginning June 26, 2024, dental therapists and hygienists can supply and administer POMs under exemptions, provided they’ve undertaken appropriate training.
• Written prescriptions for LA should include Type of LA, Route of Administration, Dosage and the date is still valid.

Protocols in case of a needle stick injury

• If before patient contact, stop proceedure, double lock the cover on the needle, wash hands with gloves, wash wound with soup, inform tutor and replace needle with a new one.
• After patient contact, cover the needle to prevent further harm, remove gloves, and wash the wound.
• Report the incident to a senior tutor, check the patient’s medical history for blood-borne viruses, contact occupational health for advice and obtain a patient blood sample.

Documentation and Complications

• A signed entry must be made on the patient's record post-injection, detailing: LA type, solution amount, injection site, any uncommon effects, and verbally given post-op instructions (POIV).
• Post injection, do not leave the patient alone, check for reactions: including faininting and anaphylaxis
• Adverse effects may come from injecting inappropriate or excess solution, or wrong injection site.
• Complications can be either Local or General Local complications:
  • Failure to go numb
  • Prolonged impairment of sensation (seek help immediately)
  • Facial paralysis (typically with IDB)
  • Needle breakage
  • Post-anaesthetic herpes simplex virus reactivation.
• General complications:
  • Psychogenic reactions
  • Toxicity of anesthetic agent
  • Overdose
  • Reduced tolerability
  • Intravascular adrenaline
  • Allergic reactions
  • Drug interactions.
• Contraindications due to bleeding risk include ID blocks and lingual infiltrations for patients with genetic bleeding disorders or on anticoagulants
• If anaesthesia fails, the dentist should not overdose and should get advice.
• Never inject into an area of inflammation/infection, inject mesial and distal to the area.
• Possible causes of failure are: delay before commencing, too little solution, intravascular injection, inaccurate placement of needle tip, or incorrect technique choice.
• Further possible causes include: anatomical variations, anxiety/fear/negative experience, poor LA storage.