Local Anaesthetic* Flashcards
Topical Anaesthetics - chemical needs for function? absorption rate? effective where (depth)? types of TopLA? Other LA not suitable for topical? benzocaine adverse reaction? other formulations and application? Advantages and disadvantages to topical?
Chem:
- higher conc needed to diffuse through mucous mem
Absorption:
- no vasoconstrictor therefore rapid vasc absorption (IV only)
Effective:
- surface tissue 2-3mm
Types:
- lidocaine and benzocaine (other types such as articaine and mepivacaine conc to anaesthetise potential overdose or tox)
Benzocaine:
- ester based allergic reaction at site of application
Other:
- spray or gel (xylocaine)
- sterility problems
- gel applied for 2-3 mins via cotton bud
Adv:
- desensitisation to localised area
- ease of needle penetration for infiltration
Dis:
- absorption rate equal to IV, and so should be used sparingly
Topical - pastes/solutions indications for use? application for use?
Indications: - analgesic prior to injection Application: - according to consistency - sol via cotton wool - paste applied to dried area
Topical - drugs for use? enzymatic addition? factors for onset and depth of analgesic?
Drugs:
- benzocaine, amethocaine and lignocaine (2 or more combined)
Enzyme:
- hyaluronidase allows access of the analgesic to the tissues
- by dissolving cell junctions
Factors:
- permeability of the tissue related to degree of keratinisation
Topical - Oraqix - combination? concentration? appearance? same as? eutectic definition? indications? cartridge size? onset and duration? max dose? using Oraqix? Advantages of oraqix?
Combo: - lidocaine and prilocaine Conc: - 2.5% lido and 2.5% prilo Appearance: - clear liquid Similar to: - EMLA Eutectic: - liquid which sets as a gel at body temp Indications: - non-injectable dental LA periodontal pockets - for probing, scaling or RSI Cartridge: - 1.7g Onset and duration - 30s set and 20m duration Max: - 5 cartridges Using: - must be liquid, cool if in gel form - air bubble is no problem Adv: - no injection (phobia) - no lingering numbness - quick onset - constant numbing - gel state for stability - anaesthesia confined to desired area
Definitions of local infiltration? field block? nerve block?
Local infiltration:
- small terminal nerve endings are anaesthetised with LA
Field block: (infiltration)
- LA deposited near larger terminal nerve branches (apex for pulpal anaesthesia)
Nerve block:
- LA deposited close to main nerve trunk
Infiltration technique (supraperiosteal injection) - indication?
Indication:
- pulpal anaesthesia in all max upper teeth
- multiple teeth require multiple injections
Before administration Infiltration - what to think about? armamentarium (tools)?
What: - hope to achieve? - best technique? - medical history? - consent? Armamentarium: - appropriate anaesthetic sol - syringe system - short needle 27-30 gauge - sharps
Technique for administration - patient position? emergencies? tissues? target? useful landmarks? needle orientation? needle insertion? LA deposition?
Patient: - semi recumbent or fully back Emergencies: - over 50% of emergencies occur after LA admin (due to vaso-vagal syncope) Tissues: - pull them taut Target: - apex of tooth to be anaesthetised Useful: - mucobuccal fold - crown of tooth - root contour Orientation: - bevel faces bone Insertion: - into height of mucobuccal fold over target tooth at 45 deg - advance until bevel above the apex - stabilise with finger stop - don't advance until bone is hit - don't inject into frenum Deposition: - deposit a few drops - aspirate - continue if -ve 1/2 cart over 30s (no tissue ballooning) - wait 3-5mins to kick in
Anaesthesia of the maxilla - why infiltration works?
Why:
- as the outer bone covering the maxillary teeth is thin
Anaesthesia of maxillary incisors and canines - innervation of teeth? buccal gingiva and palatal gingiva? injection area?
Teeth and buccal gingiva: - sup alveolar nerve (ant) Palatal gingiva: - nasopalatine Area: - given near or into the buccal fold near bone towards apex of tooth - target and adj teeth
Maxillary premolar anaesthesia - innervation? injection area (2 areas)?
Innervation:
- by the superior plexus (mostly middle sup alveolar nerve and some of the post sup alveolar nerve)
Area:
- at the apex of the target tooth buccally
- palatally injection near the target tooth (anaesthesia of the greater palatine and nasopalatine)
Maxillary Molar anaesthesia - difficulty why? solution? innervation - of teeth? buccal gingiva? periosteum? pulp?
Difficulty:
- achieving close proximity with the root apices
- zygomatic arch arises from maxilla can be obstructive
Solution:
- 2 infiltrations mesially and distally to the first molar
Innervation:
- by the post sup alveolar to the teeth, buccal gingiva and periosteum
- greater palatine for pulp
Palatal anaesthesia - direct approach - molar nerve target? caution for? never do this? injection site? success sign? avoid landmarks? indications? tip?
Target: - greater palatine nerve Caution: - avoid injecting directly around greater palatine foramen Never: - inject post to vibrating line (lesser palatine supplies soft palate Site: - equidistant point between median raphe and gingival margin of target tooth Success: - blanching of tissue Avoid: - rugae and foramen Indications: - after buccal infiltration Tip: - apply Pa to injection site prior to injection
Palatal anaesthesia - indirect approach - access via? needs initially? injection technique?
Access: - via the buccal papilla Needs: - buccal infiltration first Technique: - short needle introduced perpendicular to the surface of the papillae and advanced before the needle pierces the palatal mucosa
Anaesthesia of mandible - infiltration - limited why? solution? new drug advancements?
Why:
- incisors have thin bone covering
- premolars and molars are covered by thick compact lamina preventing diffusion
Solution:
- inferior alveolar block
Advancements:
- 4% articaine with 1:100,000 ADR used at first molar
Anaesthesia of mandibular incisors and canines - innervated by? midline? technique?
Innervated: - incisive nerve - lies within the ID canal Midline: - anastomosis Technique: - tip of needle angled to apex - canine may need mental block
Anaesthesia of lingual nerve - 2 techniques?
Techniques:
- infiltration just under the attached gingiva lingually
- interpapillary injection (into interdental papilla, insert into centre near crest bone, blanching confirms success used following infiltration)
Anaesthesia of mandibular buccal gingiva of post - infiltration - indications?
Indications:
- LR/LL8s and its surrounding gingiva
- post teeth
Anaesthesia onset - time? factors? duration?
TIme: - within 2m Factors: - anaesthetic type - vasoconstrictor Duration: - 1hr pulpal - tissue longer
Nerve block definition?
Placement of LA sol around the main trunk of a sensory nerve or one of its major branches blocking all sensory input from the whole region of tissues supplied by that nerve
inferior alveolar nerve block - course? injection site?
Passage:
- inferior alveolar nerve passes down between lateral and medial pterygoid muscle
- behind the lingual nerve and through the mandibular foramen into the mandibular canal
- nerve runs forward in the canal and gives of ranches to the teeth of the mandible
Injection site:
- at the mandibular foramen found on the medial aspect of the ramus before the nerve enters
- very close to lingual nerve
- achieved by introducing LA into the lateral side of mouth in the fat of the pterygomandibular space
Before administration IDB - what to think about? armamentarium (tools)?
What: - hope to achieve? - best technique? - medical history? - consent? Armamentarium: - appropriate anaesthetic sol - syringe system - long needle 27 gauge - sharps
IDB - direct technique - aim? landmarks? technique (palpate)? entry of needle (location)?
Aim:
- deposit LA close to mandibular foramen
Landmarks:
- external oblique ridge at anterior aspect of ascending ramus
- pterygomandibular raphe (separates the buccinator from the sup constrictor)
- runs from pterygoid hamulus down to mandible in retromolar region
- a V ridge of mucous mem
Technique:
- using thumb palpate the ramus whilst the injection is given
Entry:
- from premolars of opposite side
- barrel of syringe is parallel to lower occlusal plane
- needle neter tissue back of mouth
- lateral to pterygomandibular raphe
- medial to ramus of mandible
- at a level halfway up the thumb palpating the ramus
- advance needle until bone is felt and then withdraw slightly
- aspirate
- then deposit 2ml
Electric shock phenomenon - what occurs? why? solution? help the patient? diagnostic sign of success? reasons for failure of IDB?
What occurs: - jump from sharp pain Why: - Pa on nerve bundle or hit the lingual nerve Solution: - withdraw slightly Help: - reassure and document Sign: - tingling of lower lip Failure: try articaine - anatomical variation - little solution - give it time - wrong placement - additional nerve supply
