Join me for a summary looking at the use of botox for deep bite management and bruxism. This was an interesting lecture by Dr Nan Hatch from Seattle, which was presented at this year’s AAO 2023. She explored the use of Botox for masseter hypertrophy and the evidence around it.
Masseter hypertrophy when combined with bruxism can result in:
o Long term changes in
function
o Fixation breakages
o Orofacial pain, tmd,
mobility
How does it work?
· Injection of neurotoxin
into muscle
· Temporary partial paralysis
through chemical denervation
· Most common Botulinum toxin
or Botox
· Mechanism of action
o Block acetylcholine (neuromuscular
transmission) release.
o Also inhibit pain sensory
neuron
How to inject
· Extra oral – use of facial
landmarks
· Intra-oral Use MRI / EMG
guided injection
What are the effects
· Anticipate change facial
aesthetics
· Greater facial contouring
achieved with higher dosage Review Wu 2023
· Last up to 180 days
· Greater complications with
greater dosage
Anticipated change from botox
· Treatment for masseteric
hypertrophy
o 35 units to masseter , two
injections
o 91% reported improvement
headaches
o Duration 25 months
Decrease bite force Ahn 2007
· 25 units to each massenteric
muscle
· Mean bite force 51kg /cm
using bite block attached to a transducer
o Reduced to 30-36kg/cm for 8
weeks (29%-41% reduction)
o After 41kg after 12 weeks ,
no longer statistically significant
· Significantly reduced bite
force up to 8 weeks
Potential adverse effects
· Chewing weakness
· Sunken cheeks – high volume
· Headaches
· Sagging skin
· Asymmetry
· Paradoxical Bulging – miss
masseter and affect other muscles
· Distant spread of toxin
· Speech disturbance
· Muscle fiber atrophy 4-6
weeks, remover 4-6 weeks
Chemical denervation protocol
· 25 units per muscle, both
masetter and temporalis
· Interval 4-5 months and
patient response
· 3-5 serial injections
o Some patients changes can
be permanent
