Local Analgesia

Question 1

What topical preparations of lidocaine are available ?

Answer 1

2% gel
10% spray
5% ointment

Question 2

What topical preparations of benzocaine are available ?

Answer 2

20% gel

Question 3

How does topical lidocaine impact total LA dose ?

Answer 3

Lidocaine is well absorbed so must be included in total dosage

Question 4

What does topical anaesthetise ?

Answer 4

Non keratinised mucosa

2-3 mm into soft tissues

Question 5

What doesn’t topical anaesthetise ?

Answer 5

Limited use on palatial mucosa or attached gingivae

Pain produced by rapid injection

Question 6

What is the difference between analgesia and anaesthesia ?

Answer 6

Analgesia is absence of pain sensation

Anaesthesia is absence of all sensation

Question 7

What skin preparations are available ?

Answer 7

Amitop and EMLA
Amitop takes 60 mins to work
EMLA takes 45 mins to work

Question 8

Lidocaine …

Answer 8

2% and adrenaline 1:80000
2-3 mins to effect
45-60 min duration
Max dose is 4.4 mg/kg up to 300mg max

Question 9

Prilocaine …

Answer 9

4% and felypressin 0.03IU/ml 
Less effective than lidocaine 
Used when adrenaline contraindicated 
Max dose is 6mg/kg up to 400 mg 
Latex free

Question 10

What is the association between felypressin and scheming heart disease ?

Answer 10

Causes coronary arteries to constrict

Limit of 3 cartridges for those with ischemic heart disease

Question 11

Mepivocaine …

Answer 11

2 or 3% with 1:100000 adrenaline 
Least vasodilation so can be used plain 
30 min duration 
Max dose is 4.4mg/kg up to 300 mg 
More effective for block than infiltration

Question 12

Articaine vs lignocaine

Answer 12

Articaine more effective for buccal infiltration next to molars and upper lateral incisors
Safer
But causes more post injection pain

Question 13

What anaesthetic agents can be used as topical anaesthetics ?

Answer 13

Lidocaine

Benzocaine

Question 14

Where is infiltration anaesthesia deposited ?

Answer 14

Around nerve terminals

Question 15

Which sized needles are used for infiltration and nerve block anaesthesia ?

Answer 15

Infiltration is 25mm

Nerve block is 35mm

Question 16

Where is the needle placed for mental block ?

Answer 16

Between the apices of premolars

Question 17

Where is the needle placed for palatial anaesthesia ?

Answer 17

Distal to the tooth being treated
Except for incisors and premolars and third molars
Use chasing technique

Question 18

What is the target for the long buccal block ?

Answer 18

Supra periosteal distal and buccal to the last standing molar
2-4 mm depth
Can also inject in cuscus distal to tooth being treated

Question 19

What are the anatomical landmarks for the inferior alveolar nerve block injection ?

Answer 19

Thumb placed at anterior notch
Needle entry is junction of buccal pad of fat and pterygomandibular raphe
advance to bony contact there should be 1 cm needle showing
If no bony contact move the needle distally
If contact too early move mesially
For lingual anaesthesia withdraw while injecting final 1/3 of solution

Question 20

What are the contraindications to LA?

Answer 20

Bleeding diasthesis
Incomplete root formation
Susceptibility to endocarditis 
Pademaker
Epilepsy
Trismus
Cerebrovascular disease

Question 21

What are the local complications with LA?

Answer 21

Pain on injection 
Pain after injection 
Vascular problems
Failed anaesthesia 
Localised neurological problems 
Infection 
Interference with wound healing 
Self inflicted trauma 
Trismus

Question 22

What causes pain on injection ?

Answer 22

Subperiosteal injection 
Intraepithelial injection 
Too rapid injection 
Direct contact with nerve trunk 
Solution factors ph and temperature

Question 23

What causes post injection pain ?

Answer 23

Sub periosteal injection
Forceful intraligamentary injection
Muscle damage

Question 24

What causes neurological effects in relation to LA?

Answer 24

Prolonged anaesthesia due to nerve trunk damage, repeat injections, solution concentration
Facial paralysis due to injection into parotid gland
Auditory and visual disturbances

Question 25

What vascular problems can be caused by LA?

Answer 25

Intravenous injection - haematoma

Intra arterial injection - localised blanching

Question 26

What effects can LA have on would healing ?

Answer 26

LA decreases cell motility
Adrenaline reduces oxygen tension
Increased risk of dry socket with LA with adrenaline

Question 27

What systemic effects unrelated to LA agent can occur ?

Answer 27

Psychogenic effects eg fainting

Infection eg hiv, hepatitis

Question 28

What systemic effects related to LA agent can occur ?

Answer 28

Toxicity
Methemoglobinaemia
Drug interactions
Allergy

Question 29

What is methaemogloninaemia ?

Answer 29

Prilocaine, benzocaine and articaine metabolites convert iron in Hb to ferric state
Decreases oxygen carrying capacity

Question 30

Which drugs can interact with LA?

Answer 30

Procaine and prilocaine and sulphonamides can produce metheamoglonilinaemia
Lidocaine prolongs suxamethonium
Lidocaine and membrane stabilising agents
La and beta blockers

Question 31

Which drugs can the adrenaline in some LA s react with ?

Answer 31

MAOIs, TCAs, phenothiazine, beta blockers, non potassium sparing diuretics, drugs of abuse

Question 32

What measures should be takes if a patient is having repeated system is post treatment effects ?

Answer 32

Check weight and dosage
Check blood pressure
Check anxiety

Question 33

What are the signs of LA overdose ?

Answer 33

Tonic clonic seizure activity then generalised CNS depression, depressed blood pressure, heart rate and respiratory rate