16 Pain Management of the Dental Patient

Transduction (at nociceptors in the mouth), transmission (electrical), AND projection (to the brainstem)

Where do local blocks act to modulate pain?

Maxillary and mandibular nerve

What are the primary nerves we need to consider for pain of dental procedures?

Transduction (in skin, muscles, etc), electrical transmission, modulation (in spinothalamic tract), projection (to brainstem), perception (in cortex)

note: the word "transduce" means to turn to an electrical form, so the body is receiving stimuli thru touch and it is being converted to electrical impulses so it can be electrically transmitted in the second step

What is the pathway of pain to the brain?

1. increases sensitivity (lowers threshold)

2. buds new receptive terminals

3. receptive field expands (small area of pain may spread if not treated)

4. recruitment of silent (quiescent) nociceptors

How does pain change with repeated stimulation to the CNS?

Chronic pain

This type of pain comes from repeated or amplified stimulation, like those that come with axonal changes, spinal cord changes (windup), and brainstem, thalamic, and cortical changes (these 3 cause central sensitization)

Chronic/Maladaptive pain

Anxiety/depression/fear, more severe degree of CNS injury, and secondary healing problems from initial injury can contribute to what type of pain?

Opioids

What is the first line of pain treatment for dental procedures?

Only a few days post op, NOT LONGTERM

How long should you use opioids for dental pain management?

Opioids

This medication works centrally and peripherally to decrease the magnitude of the acute pain signal

NSAIDs

This medication is an EXTREMELY effective analgesic ESPECIALLY for dental disease, but also works as an antiinflammatory

Few real contraindications for short term use (remember long term more causes GI irritation and renal problems)

NSAID has fewer contraindications for *long term or short term* use?

NSAIDs

What medication is commonly used in combination with opioids?

1. patients who AREN'T stable (essential to stabilize patient first)

2. hypotensive, cold patients

3. renal, GI toxicity with poor perfusion

What are some contraindications for using NSAIDs

Oral nerve blocks

This medication is good for regional anesthesia in oral surgery, reducing the amount of inhalant anesthetic needed, AND provides continued post op analgesia by preventing wind up

1. rostral maxillary (infraorbital)

2. caudal maxillary

3. rostral mandibular (mental)

4. caudal mandibular (inferior alveolar)

Name the 4 dental nerve blocks

Rostral maxillary (infraorbital)

Which dental nerve block blocks:

bone, teeth, intraoral soft tissue from *maxillary 3rd premolar rostral* to the midline

Caudal maxillary block

Which dental nerve block blocks:

bone, teeth, and intraoral soft tissue from *last molar rostral* to the midline, including ipsilateral soft and hard palatal mucosa and bone

Rostral mandibular (mental) block

Which dental nerve block blocks:

bone, teeth, and intraoral soft tissue from the *mandibular 2nd-3rd premolar rostral* to the midline

Caudal mandibular (inferior alveolar) block

Which dental nerve block blocks: bone, teeth, and intraoral soft tissue from the *mandibular 3rd molar rostral* to the midline

MAXILLA: rostral maxillary (infraorbital)

MANDIBLE: caudal mandibular (inferior alveolar)

Which block is the easiest to access on the maxilla? How about the mandible?

Mandibular foramen (caudal mandibular) = inferior alveolar nerve block

What is this? And what block goes here?

Infraorbital foramen (rostral maxillary) = infraorbital nerve block

What is 1? And what block goes here?

Middle mental foramen (rostral mandibular) = mental nerve block

What is 2? And what block goes here?

Maxillary

What is 2? What nerve, if you block it, will approximately block this location?

Middle mental

What is 3? What nerve, if you block it, will approximately block this location?

Inferior Alveolar (the mandibular foramen is the site of the inferior alveolar nerve block)

What is 4? What nerve, if you block it, will approximately block this location?

Bupivacaine

What are the best drugs to use for oral nerve blocks?

2 mg/kg of animal is NOT TO BE EXCEEDED

What is the MAX total dose for bupivacaine for dental blocks?

Bupivacaine and ropivacaine

What drugs (oral blocks) can you NOT combine with lidocaine?

0.2-0.3 mL/site

What volume of local blocks is typically injected for cats and small dogs with dental blocks?

0.5 mL/site

What volume of local blocks is typically injected for medium dogs (15-25 kgs) with dental blocks?

1.0 mL/site

What volume of local blocks is typically injected for large dogs (26-40 kgs) with dental blocks?

1.5 mL/site

What volume of local blocks is typically injected for giant dogs (over 40 kgs) with dental blocks?

25 ga, 5/8 inch for patients under 15 kg, 22 ga, 1/2 inch for patients over 15 kg

What is the most common needle and syringe for performing oral nerve blocks?

ASPIRATE

What is CRUCIAL to do before injecting oral nerve blocks?

Walk needle dorsal to 4th premolar, or the distal root of 3rd maxillary premolar to find foramen

Where do you find the foramen to inject infraorbital block?

Caudal maxillary block

What block is this?

Caudal maxillary block

This block is done by inserting the needle in a ventral to dorsal direction into the soft palatal mucosa where it meets the bone, just caudal to the second mandibular molar to block the maxillary nerve before it reaches the infraorbital foramen

Top image: feline maxilla with a much shorter infraorbital canal

Bottom image: dog maxilla with a longer canal

If you inject the orbit and go too far into the foramen with cats, you may see strabismus and temporary blindness

What is the difference between these two images? What is it showing you?

Caudal maxillary block

Small to medium sized brachycephalic patients do not require WHICH KIND of mental block?

Infraorbital foramen

What is circled in green in this cat?

Rostral maxillary block (infraorbital)

What nerve block is this?

Rostral mandibular/mental block

Which block is this?

Rostral mandibular/mental block

Which block is this?

ECG arrhythmia and heart may stop beating --> do lipid emulsion therapy and CPR to treat

What happens if you inject an artery or vein because you didn't aspirate for a dental nerve block?

Caudal mandibular/inferior alveolar block

Which block is this, approached extraorally and directed thru the skin

Helps to lower the dose you need of opioids and is synergistic bc it works at different receptors

Why would you add ketamine (NMDA) and gabapentin to opioids?

Ketamine = injectable NMDA antagonist

Amantadine/Memantine = oral NMDA antagonist

What is the difference between Ketamine and Amantadine/Memantine?

Ketamine, Amantadine, memantine

These medications attenuate (reduce) excitatory neurotransmission in the brain and spinal cord to prevent/treat CNS sensitization and prevent/reverse opioid tolerance/hyperalgesia

Gabapentin and Pregablin

These medications have activity at the alpha 2 delta subunit of Ca channels to decrease CNS excitation and transmission of nociceptive impulses

Anti-hyperalgesic (because they prevent overall sensitization and helps other forms of pain management work better)

Gabapentin and Pregablin are *anti-hyperalgesic* OR *analgesic*

Mild sedative and anxiolytic effect for SHORT TERM

What is Gabapentin and Pregablin excellent for?

Ketamine and Gabapentin

What medications can be used to decrease wind up mental pain?