Page 144 - BSAVA Guide to Pain Management in Small Animal Practice

7 | Dental pain

VetBooks.ir for general anaesthetic drugs during surgery. vasoconstrictors (adrenaline, -noradrenaline)
In human dentistry and oral surgery,
When given at the end of a procedure, prior to
are routinely used in combination with the local
recovery from anaesthesia, they will provide
post operative analgesia. anaesthetic. The main reason is to delay
Useful techniques in the oral cavity include systemic absorption of the local anaesthetic,
in ltration anaesthesia and regional nerve blocks. thus reducing the toxicity and increasing the
In ltration anaesthesia is where a small amount of margin of safety. Local anaesthetics produce
anaesthetic agent is deposited locally to di use analgesia when given in small doses
into the tissue and exert its e ect. Regional intravenously, but are potent proconvulsants
anaesthesia is where the anaesthetic agent is and can induce marked myocardial depression
deposited as close to the nerve as possible and and cardiac dysrythmias when administered
its e ect is thus to block all sensation distally. systemically. The addition of vasoconstrictors,
In ltration techni ues are easier to perform by reducing systemic absorption of the local
and safer to use than regional blocks, yet they anaesthetic, will also increase intensity and
are often not described in veterinary textbooks. prolong anaesthetic activity. owever, they may
The main risk with regional blocks is damage to increase the risk of cardiac arrhythmias and
the nerve as the anaesthetic agent is placed. ventricular brillation. In veterinary dentistry
Iatrogenic nerve damage (when the needle and oral surgery, local anaesthetics are
scratches or perforates the nerve) causes pain generally used without the addition of
and it can take weeks to months before the vasoconstrictors. The author uses local
tissue regenerates and the patient is pain free. anaesthetics with added vasoconstrictor to
In rare instances, there is permanent nerve ensure that the anaesthetic agent remains
damage. In veterinary dentistry, the described locally active for a prolonged period. As already
techniques for regional blocks involve placing a mentioned, it also reduces bleeding and thus
needle well into a foramen/canal. Moreover, allows for better visualization and facilitates
this is performed on an anaesthetized animal many techniques, especially extraction.
where there will be no sensory feedback to The use of a dental local anaesthetic
alert the veterinary surgeon (veterinarian) that syringe and needle igure 7.9 is strongly
the nerve is being damaged. In the author’s recommended. Safe maximum doses are
opinion, regional blocks should be performed 4 mg kg lidocaine and 1 mg kg bupivacaine.
with great caution and only be used in areas This is calculated for each animal. In general,
where in ltration anaesthesia is not possible, i.e. . 1 ml of local anaesthetic agent is
mandibular premolars and molars. deposited per site. Always aspirate for blood
All clinically used local anaesthetics stop or before injecting.
slow conduction of impulses. Sensation
disappears in the following order: pain, cold,
warmth, touch, joint, and deep pressure. anaesthesia
For local anaesthesia in the oral cavity, The technique involves depositing a small
lidocaine, mepivacaine, bupivacaine and amount of local anaesthetic (bleb technique)
ropivacaine are all suitable. The local into the gingiva and alveolar periosteum in the
anaesthetic drug chosen for postoperative pain region of the apex of the tooth that needs to
relief should ideally have a long duration of be desensiti ed igure 7.1 . he anaesthetic
action, and therefore bupivacaine onset 1 agent di uses into the tissue to have local
minutes, duration 4 6 hours is the drug of e ect on the nerve. he in ltrates are
choice. Lidocaine can be used during surgery deposited buccally and palatally/lingually as
for more immediate e ect. In in amed or required. This technique can be used to
infected tissue, local anaesthetic may be provide desensitization of all teeth in the upper
virtually ine ective due to the acidic p jaw. In fact, regional blocks are not necessary
interfering with dissociation of anaesthetic base. in the upper aw. In ltration can also be used

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