Local Anaesthesia: Theory and Application

Local Anaesthetics Theory - Part 2

• The module is FCSP, Year 1
• The tutor is Lucy Harrison
• Learning outcomes include: describing relevant dental, oral, craniofacial anatomy and its application to patient management
• Describing relevant physiology and its application to patient management
• Describing the properties of relevant medicines and therapeutic agents and their application to patient management
• Managing patient anxiety and pain effectively through communication, reassurance, and behavioural techniques
• Managing patient pain through the appropriate use of analgesia

Aims and Objectives

• Delivering safe and effective local anaesthesia to patients
• Describing and identifying related oral anatomy and nerve supplies
• Relating safe delivery of infiltrations and IDBs
• Investigating the legal framework for LA delivery in dentistry
• Highlighting potential complications of LA delivery

Nerve Supply

• Trigeminal nerve: ophthalmic (V1), maxillary (V2), mandibular (V3) branches
• Branches include: superior alveolar nerve, lingual nerve, inferior alveolar nerve

Patient Preparation

• Essential elements for LA administration include:
  • Valid prescription
  • Medical history (medications, allergies, eating habits)
  • Previous reactions to LA
  • Food (recent intake)
  • Explaining the procedure and sensation
  • Patient anxiety/phobia management
  • Distraction techniques
  • Calm atmosphere
  • Appropriate language
  • Positioning (patient supine and well supported)
  • Lighting directed into the sulcus area
  • Operator visibility
  • LA equipment

Patient Pain Threshold Factors

• Anxiety
• Psychological makeup
• Previous experience
• Culture
• Age
• Physical environment
• Emotional state

Pain Management Theories

• Gate Control Theory
• Distraction
• Calm atmosphere
• Hypnosis

Infiltrations

• Technique for infiltrations describes:
  • Estimating tooth apex position
  • Taut surface mucosa
  • Needle insertion at 25 degrees to the bone, aiming for the tooth apex, staying parallel to the long axis of the tooth
  • Guiding needle through taut mucosa, avoiding bone contact (withdrawing if contacted)
  • Aspiration (especially around upper second/third molars)
  • Gentle and low-pressure solution delivery
  • Smooth needle withdrawal
  • Needle safety
  • Solution volumes (0.5ml - 1ml for perio work; 2.2ml for restorations).
  • Timing for analgesia (2-5 minutes for pulpal; 1-2 minutes for soft tissue)

Particular Care Required for Infiltrations

• Labial aspect of upper incisors: extremely sensitive
• Labial aspect of lower incisors: delicate tissue attachments (avoid mentalis and depressor labii inferioris muscles)

Supplementary Injections

• Palatal infiltrations
• Lingual infiltrations
• Intrapapillary Injections: use for children/nervous patients, needle directed at right angles to interdental papilla, injecting at level of attachment, depositing 0.25ml of solution, checking for palatal blanching

Inferior Dental Block (IDB)

• Procedure for delivering IDBs involves:
  • Locating the retromolar fossa and pterygomandibular raphe
  • Bisecting the thumb/fingernail and drawing a line 1cm above the occlusal plane (aimed at mandibular foramen).
  • Smooth and slow needle insertion into the space
  • Injecting to a depth of 2.0-2.5cm (with at least 5mm of needle visible)
  • Aspirating before injection (withdraw if bone contact occurs, repositioning if needed)
  • Slow solution delivery, and needle re-sheathing.

IDB Technique- Positive Aspiration

• If blood appears during aspiration, withdraw, re-aspirate, and reposition if needed
• If no blood, continue injection
• Thoroughly wash and dry the area after injection

IDB Technique- Additional Steps

• Positioning the patient correctly
• Ensuring good lighting
• Use of topical analgesia
• Positioning the barrel of the syringe over the contra-lateral premolars
• Use of finger or thumb to locate the retromolar fossa
• Using 35mm, 27-gauge needle
• Ensuring enough solution is applied for anaesthesia

Incisive and Mental Block

• This procedure provides anaesthesia to multiple anterior teeth. The procedure involves: checking mental foramen on radiograph (if available), positioning the patient (ideally supine with good lighting),applying topical LA, instructing the patient to open wide, unsheathing a 30-gauge needle,placing the needle tip into the reflected buccal sulcus between the roots of the lower premolars, aspirating (if not positive), and injecting at least 1 ml of solution, withdrawing the needle and re-sheathing it safely. Avoid Articaine for this procedure.

Post-Operative Precautions

• Never leave the patient alone after injection
• Monitor for reactions (e.g., faint, anaphylaxis)

Post-Operative Instructions

• Typical duration of anaesthesia is a few hours
• Avoid hot food/drinks, biting lips/cheeks, poking/prodding the area, smoking

Documentation of Local Anaesthesia

• Records of every administration must include:
• Type of LA agent and vasoconstrictor
• Amount of solution used
• Injection site
• Post-operative instructions (verbally)
• Unusual reactions.

Complications of Local Anaesthesia

• Unwanted effects: inappropriate solution, too much solution, incorrect site
• Local complications: failure to go numb, prolonged sensations (possible injury), facial paralysis (IDB), needle breakage, herpes reactivation
• General complications: psychogenic reactions, drug toxicity, overdose, reduced tolerance, intravascular adrenaline, allergy, drug interactions.
• Bleeding risk: considerations for ID blocks and lingual infiltrations (patient factors: genetic bleeding disorders, anticoagulant or antiplatelet use, reduced liver function, liver disease)
• Potential for failure of anaesthesia: long treatment delay, insufficient solution, intravascular injection, needle placement error, technical mistakes, patient anxiety, poor LA storage

Summary

• This presentation covers oral anatomy, nerve supplies, safe delivery of infiltrations and IDBs
• Details of the legal frameworks for LA delivery
• Potential complications are outlined: local and general
• Critical notes on procedures like IDBs and Incisive blocks for achieving effective patient management, while addressing the possibilities of complications

Explore the safe and effective delivery of local anesthesia, covering oral anatomy, nerve supplies, and legal frameworks. Understand how to relate infiltrations and IDBs, and identify potential complications. This lesson provides a comprehensive overview of local anesthesia in dentistry.