Maxillary Anaesthesia

Question 1

What are the 3 things the LA technique used depend on?

Answer 1

1. Patient (bespoke technique - specific to patient)
2. nature, location and duration of planned procedure
3. LA drug; some drugs work better with specific techniques

Question 2

label the the trigeminal nerve and its two devisions shown in the diagram.

Answer 2

Question 3

label the branches of the maxillary devision of the trigeminal nerve. Explain how these branches arise

Answer 3

• The maxillary nerve gives rise to three branches within the skull:

1. posterior superior alveolar nerve
2. middle superior alveolar nerve
3. anterior superior alveolar nerve

• The maxillary nerve exits the skull through infraorbital Forman as infraorbital nerve

Question 4

What teeth do each posterior superior alveolar nerves, middle superior alveolar nerve and anterior superior alveolar nerve innervate?

Answer 4

Anterior superior alveolar nerve

• 1 2 and 3 (all anterior teeth)

Middle superior alveolar nerve

• 4, 5 and bucco-mesial root of 6

Posterior superior alveolar nerve

• Tooth 6, 7 and 8

Question 5

Which three nerves innervate the palate, which part of the palate do they each innervate and where do they originate form?

Answer 5

1. Incisive nerve: Nasopalatine nerve is a branch arising from the pterygopalatine ganglion, exits through nasopalatine foramen and supplies tissues on the palatal side of anterior teeth.
2. Greater palatine nerve: a nerve that arises from the pterygopalatine ganglion (bilateral) and innervate the hard palate
3. lesser palatine nerve: a nerve that arises from the greater palatine nerve and travel posteriorly to supply the soft palate.

Background:

• Pterygopalatine ganglion is a ganglion found within the pterygopalatine fossa, it comes from the maxillary branch of the trigeminal nerve. it is connected to the maxillary nerve via pterygopalatine nerve.
• The pterygopalatine ganglion has 3 relevant branches to know: greater palatine nerve, pterygopalatine nerve and nasopalatine nerve.

Question 6

Mucosal innervation: label the diagram showing the nerves innervating the mucosa within the oral cavity. Explain where each nerve innervates.

Answer 6

• infraorbital nerve supplies the mucosa within the sulcus
• Anterior superior alveolar nerve supplies labial mucosa adjacent to anterior teeth
• Middle superior alveolar nerve supplies buccal mucosa adjacent to teeth 4, 5 and Mesio-buccal root of 6
• posterior superior alveolar nerve supplies mucosa adjacent to teeth 6, 7 and 8
• Incisive branch of nasopalatine nerve supplies the palatal mucosa adjacent to anterior teeth.
• Greater palatine nerve supplies the hard palate and mucosa adjacent to all posterior teeth (4-8)
• lesser palatine nerve supplies the soft palate including tonsil and uvula.

Question 7

What are all the LA techniques used?

Answer 7

1. topical anaesthesia
2. infiltration anaesthesia
3. regional/ block anaesthesia
4. supplementary techniques: intraosseous, intraligamentary, intrapapillary, intra-pocket and computer controlled anaesthesia.

Question 8

Give a brief explanation of how supplementary techniques are carried out: intraosseous, intraligamentary, intrapapillary, intra-pocket and computer controlled anaesthesia.

Answer 8

1. Intraosseous: force needle into cortical bone/ create a proliferation in cortical bone using drill and inject needle to dispense LA.
2. intraligamentary: inject directly into PDL space using ultrashort needle.
3. Intrapapillary: inject LA into medial and distal papilla of tooth without injecting PDL.
4. intra-pocket: inject in the pocket of tooth
5. computer controlled: method used to reduce pain during LA, a device that slowly injects LA and uses computer system to control injection speed.

Question 9

What are some uses of topical anaesthesia?

Answer 9

1. aids painless injection
2. very minor surgical procedures
3. abscess incision
4. rubber dam clamps
5. impressions (can be risky because patient won’t feel that they swallowed any material)

Question 10

what are some ways of delivering topical anaesthesia?

Answer 10

1. solutions
2. sprays
3. gels/pastes
4. refrigeration: ethyl chloride - not LA, it freezes the tissues

Question 11

compare the two main LA techniques: infiltration and block

Answer 11

Infiltration

• Easy to do
• safe
• low risk of IV administration
• low risk of nerve damage
• local homeostasis: no blood flow due to vasoconstrictor in LA.
• local diffusion required so drug must be able to diffuse to required area - thick bone can make this hard.
• acts on nerve endings rather than trunk
• risk of cross infection if you inject multiple areas

Regional /Block

• can be difficult
• less safe
• higher risk of IV administration
• higher risk of nerve injury by putting needle into the nerve itself
• acts on nerve trunk
• widespread effect form single injection so useful if need multiple teeth anaesthetised but bad if only one tooth required.
• Reduces risk of transmitting infection from one place to another as you use the needle in one area only so no cross infection risk.

Question 12

what does infiltration anaesthesia rely on to work? what is its efficacy dependent on?

Answer 12

• diffusion of anaesthetic to target tissue by injecting near the area
• for tooth, target is tooth apex
• efficacy depends on the ability of solution to reach target, thicker bone makes it harder for solution to reach

Question 13

what needle do we use for infiltration anaesthesia?

Answer 13

• short needle (25 mm) - has a blue cap

Question 14

which areas do infiltration anaesthesia work best and why?

Answer 14

Works best:

• Maxillary anterior teeth because it has thin porous bone so anaesthetic solution can diffuse easily

Question 15

which area is more difficult for infiltration anaesthesia to work and why?

Answer 15

Upper molars because:

• thicker bone due to zygomatic process so more difficult for anaesthetic solution to diffuse through
• divergent roots so anaesthetic solution might not reach so could have to inject from the palate.

Question 16

Which area does infiltration anaesthesia not work on and why? what is an alternative way that could allow infiltration anaesthesia to work in that area?

Answer 16

Lower molars

• very dense outer cortical bone, lidocaine will not work
• articaine may work

Question 17

what is the main method used for maxillary anaesthesia? what two things is this method useful for?

Answer 17

• infiltration

useful for:

• pulpal anaesthesia for most upper teeth
• soft tissue anaesthesia wherever its injected - buccal or palatal

Question 18

Which particular upper tooth is difficult to anaesthetise with infiltration and why?

Answer 18

• pulpal anaesthesia for upper 1st molars because of thicker bone due to zygomatic process

Question 19

What is the spread of effect for infiltration anaesthesia?

Answer 19

• effect is on tooth you’re injecting and the mucosa surrounding it on the side you are injecting
• might numb adjacent tooth

Question 20

What is the first step before giving infiltration anaesthesia?

Answer 20

• Medical history

Question 21

what is the equipment you need for infiltration anaesthesia?

Answer 21

• short needle
• appropriate anaesthetic - normally lidocaine in maxilla

Question 22

what is the most commonly used anaesthetic in the maxilla?

Answer 22

• lidocaine

Question 23

what is the patient position when giving infiltration anaesthesia?

Answer 23

• based on operator preference and patient comfort
• most suitable is supine as patient less likely to faint or upright

Question 24

What are the steps for giving topical anaesthesia? e.g. to make injection more comfortable.

Answer 24

1. identify site
2. dry the site with 3 in 1
3. apply gel on cotton wool wool
4. retract soft tissues with mirror
5. place the cotton wool on the site, e.g. in sulcus for anterior upper incisor
6. leave it in to hold effect: normally for 3/5 mins in dental school
7. Remove cotton wool
8. deliver injection or perform procedure

Question 25

Why is it key to be efficient with carrier out procedure after applying topical anaesthesia?

Answer 25

* The effect of topical will not lost long, just a few mins

Question 26

When is it best to give topical anaesthesia when used before injection for efficiency and time management?

Answer 26

* before setting up your LA injection

Question 27

what are the steps for giving infiltration anaesthesia?

Answer 27

1. retract soft tissues 2. identify injection site 3. hold the tissues taught so the needle penetration is easier and clean 4. approach injection site with the syringe at 45 degree angle to bone and bevel facing bone (black sign on syringe hub shows direction of bevel) 5. gently insert needle until bone is contacted: bone will feel hard so you will know when you reach it 6. withdraw needle by 1mm (0.1cm) and aspirate 7. if clear aspiration, slowly inject solution 8. should inject 1ml LA solution in 1 minute - cartridge has 2.2ml so should take 2 mins and half to inject. - Key to inject slowly 9. withdraw needle and make it safe by pulling cap down to single lock ( if reusing) or double lock if not using again. 10. wait … for solution to diffuse through bone 11. should have anaesthesia of the tooth and tissues where you injected (e.g. if injected labially for central incisor - tooth should be numb along with the labial tissues)

Question 28

What are 4 things to consider for pain free injection?

Answer 28

1. topical anesthetic 2. taught tissue for quick and precise needle penetration 3. slow injection - 1ml/minute 4. Two stage injection for upper anterior

Question 29

What is the two stage injection technique for upper anterior teeth? why is it useful?

Answer 29

* Give a small amount of LA solution initially * wait for it to give effect and go numb * then inject again Makes it more comfortable

Question 30

What is vibraject? Why might it be uncomfortable for some patients?

Answer 30

* an instrument used for delivering LA * uses vibrations of needle to reduce discomfort of needle going in * patient might feel anxious if a vibrating needle comes towards them (not used in dental school)

Question 31

For palatal infiltration, why doesn't the needle go in far?

Answer 31

* The palatal tissue is tightly bound to bone underneath * often uncomfortable injection

Question 32

When is buccal/labial infiltration commonly used in the maxilla?

Answer 32

* for simple restorations * can be painless if you become good at it

Question 33

when is palatal infiltration commonly used and why is it uncomfortable/painful?

Answer 33

* For tooth extraction as it requires soft tissue anaesthesia palatally * if buccal/labial infiltration fails e.g. upper 6's and 2's * uncomfortable because we tend to lift the periosteum from bone with the needle so its painful

Question 34

When do we use block anaesthesia in the maxilla? Why is it useful to use sometimes compared to infiltration? what needle is used ?

Answer 34

* mostly palatal block anaesthesia of greater palatine nerve and incisive branch of nasopalatine nerve * useful for surgery involving the palatal soft tissues * reduces dose of multiple palatal infiltrations * more comfortable than multiple infiltrations * short needle

Question 35

Describe where the landmarks are for incisive nerve block and greater palatine nerve block

Answer 35

* incisive nerve block landmark: midline between central incisors, roughly in line with canines * greater palatine nerve block landmark: imaginary line between upper 7 and 8, about 1cm away from gingival margin of 8