Botox for Deep Bites and Bruxism. Nan Hatch

orthodontics In summary

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