Botulinum toxin

  • Botulinum toxin also called “miracle poison” is one of the most poisonous biological substances known. It is a neurotoxin produced by bacterium Clostridium botulinum.
  • Cl. botulinum elaborates eight antigenically distinguishable exotoxins (A,B,C1,C2,D,EF&G). Type A is the most potent toxin followed by types B and F.

How does Botox work?

Intramuscular administration of botulinum toxin acts at neuromuscular junction to cause muscle paralysis by inhibiting the release of acetylcholine from presynaptic motor neurons. Botulinum toxin acts at four different sites in the body : The neuromuscular junction, autonomic ganglia, postganglionic parasympathetic nerve endings and postganglionic sympathetic nerve endings that release acetylcholine.

Applications of botulinum toxin in maxillofacial region :

Cosmetic applications :

  • Facial wrinkles : forehead rhitids are managed by injecting 10-20 U of BTA injected at least 1cm above the orbital rim
  • Lateral canthal lines known as “crow’s feet” are generally managed by superficial injections of 8-16 U of BTA into lateral orbicularis oculi.
  • Eyebrow lift can be managed by BTA injections.

Temporalis and masseter muscle hypertrophy : This hypertrophy is generally associated with clenching or other parafunctional use of the jaws. The results of BT use in such cases appears to be effective in treating chronic facial pain associated with masticatory hyperactivity.

Lip flip : fast and easy procedure that takes just 30 minutes, leaving lips looking full and soft. Botox injections around the lips relax those muscles, allowing the lip to roll slightly outward. This reveals more of the lip surface, making them look larger

Gummy smile : Botox is injected in the area between upper lip and nose to temporarily freeze the muscles that contract or elevate smile which allows to smile without showing gums.

Dropping corners of the mouth : Hyperactivity of depressor anguli oris can lead to dropping of the corner of the mouth. The site of injection is on the trajectory of nasolabial fold to the jaw line.

Therapeutic applications :

  • Temporomandibular disorders (TMD) : TMDs may be myofascial (those related to muscles themselves) or arthrogenic (those related to TMJ). BTA has been found to be effective in resolving pain and tenderness in TMDs. The diverse group of TMDs those likely to be benefited by injection of BT includes : bruxism and clenching, OMDs, myofascial pain, trismus, headaches, hypermobility
  • Sialorrhea and salivary secretory disorders : injection of BTA into the parotid and submandibular glands is effective in controlling drooling. BTA injections have also been shown to be effective in managing gustatory sweating (Frey’s syndrome)
  • Implantology – BT has been postulated to be therapeutically beneficial by allowing unimpeded osseointegration of implants. Stress due to any excessive functional force or any parafunctional habit may cause implant failure. Thus injecting BTA relaxes the masticatory muscles, sparing the implant leading to unimpeded osseointegration.
  • Denture wearers : BTA is usedin patients struggling in getting used to a new set of dentures due to irregular and uncoordinated muscle activity, especially who have been edentulous for a long period of time by providing muscle relaxation.
  • Adjunct to orthodontic treatment and to prevent relapse : in some cases, relapse following an orthodontic correction may occur in patients with strong muscle activity such as that of mentalis muscle. BTA can be used during treatment to reduce the intensity of muscle contractions and muscles can be slowly & gradually trained post treatment to a more physiologic movement.

Source : ncbi.nlm.nih.gov

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