Dental Anesthesia Techniques

• The session aims to help deliver safe and effective local anesthesia to patients
• Aims to describe and identify oral anatomy and nerve supplies
• Goal is to relate how to safely deliver infiltrations and IDBs (Inferior Dental Blocks)
• Examined will be the legal framework for LA delivery in dentistry
• Potential complications of LA delivery will be highlighted

Nerve Supply

• The trigeminal nerve has ophthalmic, maxillary, and mandibular branches
• V1 ophthalmic area reaches the top of the head down to just above the eyes and nose area
• V2 maxillary area starts below the eyes reaching down to just above the top lip area
• V3 mandibular area starts below the top lip area reaching down to the jawline

Patient Preparation

• Legally, a valid prescription is needed
• Contraindications, medication and previous LA reactions are all important as part of the medical history Consumption of food is a consideration to avoid a vaso-vagal attack
• Explain the procedure and sensation
• The operator should consider dental anxiety/phobias through distraction techniques and a calm atmosphere
• Positioning, visibility and LA equipment are all part of the preparation

Addressing Patient Pain Threshold

• Anxiety, previous relevant experiences, culture and age may each affect a patient's threshold

Methods to Enhance Calm

• Hypnosis
• Distraction
• The Gate Control theory
• A calm atmosphere
• Using alternative stimuli

Infiltration Anesthesia

• Relates to Maxillary nerve
• Targets the anterior superior alveolar, middle superior alveolar, and posterior superior alveolar nerves
• Pterygopalatine nerves: Nasopalatine nerve and Greater palatine artery/nerve (hard palate)

Patient Positioning

• The patient should be lying in a supine position
• Position the patient at the correct height for the operator
• Ensure light is directed into the sulcus area

Topical Anesthetic Application

• Dry the mucosa
• Apply topical on a cotton wool roll
• Leave for duration of 2-3 minutes

Buccal Infiltration Technique

• Estimate the position of apex of the tooth
• Pull surface mucosa taut for a good retraction
• Insert the needle through mucosa at 25 degrees to the bone
• Aim for the apex of the tooth
• Insertion should be parallel to the long axis of the tooth
• Smoothly allow needle to glide through taut mucosa
• One should avoid contacting bone; withdraw 1-2mm if this occurs
• The needle should be bevel to bone
• Aspirate, particularly if injecting around upper second/third molars and then check cartridge
• Deliver solution gently and slowly
• Very little pressure is required on the plunger
• Withdraw needle smoothly
• Make the needle safe
• Use 0.5ml - 1ml of solution per site for infils for perio work and 2.2ml for restorations
• Pulpal analgesia should be established within 2-5 minutes; soft tissue analgesia in 1-2 minutes

Specific Care Required

• The labial aspect of upper incisions is very sensitive, so employ topical anesthetics and inject slowly
• The labial aspect of lower incisors affects attachment of mentalis and depressor labii inferioris muscles

Supplementary Injections

• Can include palatal infiltrations, lingual infiltrations, and intrapapillary injections

Palatal Infiltration

• Topical application/pressure should be applied on area first
• Infiltrate the palatal mucosa of the appropriate tooth
• Inject at 90 degrees to the mucosa at about 1-1.5cm from the gingival margin and halfway between gingival margin and midline of palate
• Expect considerable resistance
• Deposit 0.2 ml of solution
• Used for deep restorations, subgingival PMPR, and extractions of deciduous maxillary dentition

Intrapapillary Injection

• Useful for achieving palatal analgesia in children and nervous patients
• Direct needle at right angles to interdental papilla
• Insert needle into the centre of papilla at the level of attachment to periosteum
• Deposit 0.25ml of solution
• Check that palatal mucosa has blanched

Inferior Dental Block (IDB)

• Targets the innervation of the mandible: inferior dental/alveolar nerve, mylohyoid nerve, lingual nerve and mental nerve
• Reviewing anatomy of mandible is helpful for precision during the procedure
• Must understand the coronoid process, condylar process, mandibular foramen, retromolar fossa and ramus

Pterygomandibular Space

• The facial nerve is impacted if analgesic solution is deposited outside the pterygomandibular space and into deep lobe of parotid gland
• Facial nerve blockage causes paralysis of facial muscles, resulting in temporary facial palsy

IDB Techniques

• Patient can be supine or upright; using an upright if patient has a large tongue or is obese
• Topical analgesia ideally used
• The the mouth should be wide open to allow good visualization of the anatomical landmarks
• Location through using finger/thumb to locate the retromolar fossa, then identify pterygomandibular raphe
• Identify point of entry, external oblique ridge and the crease in the soft tissue
• Position barrel of syringe over contra-lateral premolars
• The correct level for mandibular foramen is bisecting the thumb/fingernail and drawing an imaginary line 1cm above occlusal plane
• Insert needle smoothly and slowly into the pterygomandibular space, aiming for the mandibular foramen
• Inject to a depth of 2.0-2.5 cm
• Avoid inserting the full needle, at least 5mm should always be visible
• If mandibular bone is contacted, withdraw needle 1 mm and aspirate
• Once certain the needle is not in a vein, slowly deliver the anaesthetic solution
• Smoothly and quickly withdraw needle and re-sheath needle to make it safe
• Sit patient up for a rinse

Positive Aspiration During IDB Injection

• If blood is present upon aspiration, withdraw needle 1 or 2 mm and aspirate again

• Continue with injection if no blood

• Reposition and repeat aspiration if again positive

• The IDB injection result makes the area with lingual soft tissue and bone, tongue, alveolar mucous membrane and extraoral soft tissue numb

• Bone struck too soon, withdraw, swing needle round to midline, advance for 7 mm, swing back to original position and proceed

• Electric shock sensation in tongue or lip means lingual nerve or mandibular nerve being impacted

• For sensation, withdraw 1-2mm from mandibular nerve

Incisive and Mental Block

• Useful if you want anesthesia of several anterior teeth including incisors, canine and first premolar

• Aim for mental foramen which lies between apices of first and second premolar

• This may provide unreliable anesthesia requiring lingual infiltration

• Check position of mental foramen on radiograph

• The patient is ideally supine with good lighting

• Apply topical LA

• Ask patient to open wide

• Unsheathe needle (30 gauge short)

• Place tip of needle in reflection of buccal sulcus between root apices of LL4 and LL5

• Aspirate, and if not positive, slowly inject at least 1ml solution

• Withdraw needle and re-sheath safely

• Articaine should not be administered for IDBs or Incisive and Mental blocks

Needle Stick Injury Procedure

• Double lock cover on needle, remove gloves and wash with soap to dress wound if needed
• Inform senior tutor on clinic
• Use new syringe/needle/cartridge and holder; and new gloves
• After contact with patient, check medical history to confirm known risk, and contact Occupational Health or A&E
• Obtain patient blood sample
• Record the incident in notes/Datix incident report
• A legal framework is provided under a Patient Group Directive (PGD) to allow registered health professionals to administer specified medicines without prescription

Who Can Change the LA Agent?

• LA is a Prescription Only Medicine (POM)
• A written prescription is needed for each specific agent from a dentist
• The Human Medicines Regulations 2012 provides framework to allow registered health professionals to administer certain medicines without needing a prescription

Elements of Prescription

• Type of LA

• Route of Administration

• Dosage

• Date verification

• As of June 26 2024 amendments to the Human Medicines Regulations made it possible for dental hygienists and therapists to supply and administer certain POMs without a prescription from a dentist or patient group direction

• While specified medicines can be administered, dental hygienists and therapists must undertake training to ensure competency

• There is no obligation for dental hygienists and therapists to administer these medicines

• These changes do not give any prescribing powers or amend the POM status of listed medicines

Post-Operative

• Post-injection precaution: Never leave your patient alone after an injection
• Reactions, including faint or anaphylaxis, may occur at any time
• Provide duration of the effect
• Avoid hot food/drinks and biting lips/cheeks
• Avoid poking or prodding area
• Avoid smoking
• A dated signed entry must be made on the patient's record every time LA is given with post-operative instructions

Documentation of Administered LA

• Type of LA agent including the vasoconstrictor
• Amount of solution administered and site of injection
• Any unusual effects
• Provide verbal post operative instructions; for example, LA - 2ml lidocaine 2% with epinephrine 1: 80,000, buccal infiltration UL7, UL4, UL2. POIGV

Adverse Effects/Complications of LA Delivery

• May occur as a result of injecting either an inappropriate solution, too much solution, and at the wrong site
• Complications can be divided into Local or General
• Local: Failure to go numb, prolonged impairment of sensation, facial paralysis, and needle breakage
• General: Psychogenic, toxicity of LA agent, allergy, and drug interactions
• ID blocks and lingual infiltrations may be contraindicated or used with caution depending on bleeding risk
• Bleeding risk relates to the act of injection, not the LA agent; examples include patients with genetic bleeding disorders, patients on anticoagulants, alcoholics or those with liver issues
• The most common local complication is failure of injection to numb
• Other local complications include: pain during injection, haematoma or trauma
• General complications: Systemic toxic effects, infection, lip/soft tissue trauma, skin blanching due to artery spasms
• Severe complications: nerve damage, facial nerve paralysis
• Other failure risks: delay treatment, little administered medicine, or inaccurate needle placement

Anesthetic Failure

• Too long a delay before commencing treatment or insufficient solution administered cause anesthetic failure
• Intravascular injection, inaccurate needle placement or anatomical variations can also cause failure
• Incorrect choice of technique or anxiety all contribute to failure
• Poor storage of LA (too hot/in sunlight) may cause it also

Presence of Infection Considerations

• Never inject into an area of inflammation/infection

• Inject mesial and distal to desired area to avoid infected tissue

• If LA fails, do not overdose and seek further qualified advice and assistance