What is the difference between a local infiltration and a regional nerve block?
A local infiltration is where the LA diffuses through the thin outer cortical bone and pools around the nerves entering at the root apex.
A regional nerve block is where the anaesthetic pools around the nerve supplying a specific area.
What teeth can local infiltration be used on?
Potentially all maxillary teeth, and anterior mandibular teeth where the bone is thin enough.
What type of needle is used for local infiltrations?
27G short (25mm) needle
What are the 2 types of local infiltration?
- Buccal infiltration (needle placed superior to apex)
- Palatal infiltration (painful, needle placed midway between tooth and median palatine raphe, inject slowly)
What are the 3 maxillary nerve block techniques?
- Nasopalatine nerve block
- Infraorbital nerve block
- Posterior superior alveolar nerve block (PSAN)
Describe the nasopalatine nerve block.
- 25G short needle
- Nasopalatine nerve is a branch of the maxillary nerve
- Enters the oral cavity through the incisive foramen in the hard palate
- Insert needle 1cm into nasopalatine canal
- Used for profound anaesthesia of the palate
Describe the infraorbital nerve block.
- 25G long (35mm) needle
- Branches off the maxillary nerve
- Profound anaesthesia of face, lip, gingivae and teeth
- Insert needle 1cm from alveolar ridge of maxillary canine, 2cm deep, deposit
- Rarely used, mostly for oral surgery on anterior teeth
Describe the posterior superior alveolar nerve block.
- PSAN block
- Rarely used, indicated for profound anaesthesia of maxillary molars
- 25/27G short needle
- Needle placed into mucobuccal fold distal to second molar
- Insert 2cm
- Deposit 1-2ml
What are the 5 mandibular nerve block techniques?
- Inferior dental/alveolar/lingual nerve block
- Long buccal nerve block
- Mental nerve block
- Sublingual nerve block
- Gow-Gates technique
Describe the inferior alveolar nerve block and lingual nerve block.
- Main technique used, anaesthetises all lower teeth
- Deposition of LA around the IAN as it enters the mandibular foramen beneath the lingula
- Pt opens as wide as possible
- 25G long needle
- Place thumb on cornoid notch
- Point needle at the pterygomandibular space (triangle), inject lateral to the pterygomandibular raphe into the pterygomandibular depression
- For lingual nerve sink to 5mm depth
- Deposit 0.5ml solution
- Handle of needle angled between the premolars
Describe the long buccal nerve block.
- Generally used in conjunction with ID block
- Anaesthetises gingivae buccal to mandibular molars
- 25G long needle
- Place needle posterior and buccal to last standing molar
- Inject 1ml
Describe the mental nerve block.
- Indicated for lower lip surgery, biopsies and surgery of anterior portion of denture bearing area
- Does NOT anaesthetise teeth
- 25G short needle
- Needle inserted between the lower premolars in the mucobuccal fold
- 1ml deposited
Describe the sublingual nerve block.
- Anaesthetises anterior portion of lingual nerve
- 25G short needle
- Needle inserted lingually to the premolars
- Inject 0.5ml
Describe the Gow-Gates technique.
- Pt opens as wide as possible
- Anaesthetises entire mandibular nerve
- Use thumb to located coronoid process, insert needle mesial to this
- Depth of approx. 25mm until condyle is contacted
- Inject 2ml
What is the difference in length between a short and long needle?
Short: 25mm
Long: 35mm
What should always be done prior to injecting anaesthetic and why?
Aspirate. Ensures that you don’t inject into a blood vessel.
What is intraligamentry anaesthesia?
- Uses specialist intraligamentary syringe and ultrafine needle, teeth must be plaque free
- Anaesthetises individual teeth
- Solution deposited along PDL under high pressure
- Risk of temporary extrusion, discomfort
- Potentially increased risk of dry socket when this technique is used for extractions
What is intraosseus anaesthesia?
- Anaesthetises individual teeth
- Motor-driven perforator used to penetrate buccal gingiva and outer cortical plate
- Injected directly into porous cancellous bone, easily diffuses to root apex
Which topical anaesthetics are used in the dental hospital?
- Lidocaine ointment 5% (applied to dry mucosa, wait for 2-5 minutes)
- Benzocaine 20% w/v (only under staff supervision)
What are the usual LA doses for an infiltration and nerve block?
Local infiltration = 1ml
Nerve block = 1.5-2ml
What adjustments should be made if your patient has taken cannabis, cocaine, inhalants or performance enhancing drugs in the past 24 hours?
Avoid using LA containing epinephrine.
When would you decrease the number of maximum cartridges to 2 cartridges containing epinephrine, or 3 cartridges containing felypressin?
For elderly or medically compromised patients: e.g. hypertension myocardial infarction in the past 6 months, stable angina, taking calcium channel blockers, taking beta blockers, taking non-potassium sparing diuretics.
For which patients should LA containing epinephrine never be used, and felypressin with caution?
Patients with unstable angina, uncontrolled arrhythmias or phaechromocytoma.
Which LA is recommended for pregnant or breastfeeding patients?
- Lidocaine 2% with adrenaline (1:80000) can be used with caution in early pregnancy and nursing mothers
- Prilocaine with felypressin (citanest 3% with octapressin) should not be used in early pregnancy, and not recommended as the best choice for any pregnant patients
