by Dr. Hicham Nuaimi and Dr. Mustafa Kamil
A growing number of dentists, who are offering Botox to treat patients. Previously Botox was administrated by dermatologists and neurologists . Later dentists entered this domain according to their training and knowledge incorporates the head and neck anatomy and physiology.
Firstly, botulinum toxin was created and developed by German physician Dr. Justinus Kerner (1786-1862). He assumed that botulinum toxin proceeded by interrupting signal transmission within the peripheral sympathetic nervous system, leaving sensory transmission intact. In 1870, John Muller, another German physician, devised the name (botulism) from the Latin root botulus .
In 1949, Burgen was the first who discovered the ability of toxin to block neuromuscular transmission . Scott et.al,1981 used type A strain during their study, this strain was approved by the FDA in 1989 under the trade name Botox for treating strabismus (lazy eye), and hemi-facial spasm for younger than 12 years old, more over in 2000, Botox was approved for use in treating cervical dystonia (wry neck) .
What is Botulinum toxin?
It is a deadly poison produced by Ciostridium botulitium, gram-positive anaerobic bacterium. The bacteria produce 7 antigenically different toxins that are lettered A – G. Conversely, Toxin A has been the most extensively toxin used in researches .
What is the Mechanism Action?
The botulinum toxin causes muscle paralysis by inhibiting acetylcholine release at the neuromuscular junction through several steps .
- The toxin binds to the nerve.
- it is internalized into the nerve.
- The toxin is cleaved by internal proteolytic enzymes.
- The degradation by interfere with the normal process of vesicle fusion to the plasma membrane.
- This degradation inhibits acetylcholine, that produces neuromuscular blocking effect.
- This blockade is temporary and its action varies from three months to four months after which new axon terminals sprout and return to their normal neuromuscular function.
In which cases Botox are used to treat in dentistry?
- Hemifacial Spasm
- Tempromandibular Disorder
- Gummy Smile
is abnormal grinding or clenching of the teeth. Bruxism may lead to tooth wear, periodontal disease, headaches and TMJ disorders. The traditional treatment for bruxism has used an intraoral appliances as night guard .
Botox can be injected bilateral into the masseter and temporalis muscles. Another technique is a bilaterally injection of Botox into the masseter muscle immediately superior to the angle of the mandible. These treatments may afford relief for four to six months or may lead to a total resolution of bruxism. In addition, Botox may also work to inhibit periodontal mechanoreceptors, which may provide a solution to problems with jaw closure.3 but soreness at the injection site and mild drooling may occur .
is over production of saliva in which inability to hold it within the mouth. It presents in many neurological disorders, including infant cerebral palsy, Parkinson’s disease and amyotrophic lateral sclerosis. Patients have to use an anticholinergic drug (glycopyrrolate, propantheline and scopolamine) to treat this disorder. Drugs action on reversibly block muscarinic cholinergic receptors, particularly M3 receptors. Unfortunately, these drugs have adverse side effects that include constipation, urinary retention, tiredness, irritability and drowsiness .
The conventional technique for treating sialorrhea have included surgical refashioning of the submandibular gland duct route, irradiation, removable appliances that promote the movement of the lip and tongue, and oral motor or behavioral therapy 
Botox is injected into salivary glands (parotid and submaxillary glands) to inhibit the stimulation of the cholingeric receptors that lead to reduction in saliva production and secretion. Normally, resolution lasts for one to six months. While, xerostomia, dysphagia and chewing difficulties are only the side effects.
3- Hemifacial Spasm
is an involuntary, irregular or chronic contractions of the muscles that innervated by the facial nerve (cranial nerve VII) on the ipsilateral side of the face. Drugs may be used to treat it, but for long term these medications manage to be ineffective.
Botox has offered to relief hemifacial spasms. Botox have to injected in the orbicularis oculi, corrugator, frontalis, zygomaticus major, buccinator and depressor anguli oris muscles. Actually, the orbicularis oris is not injected due to the potential risk of paralysis of the mouth. Treatment looks to be effective over a number of years, while erythema, ecchymosis, dry eyes and facial muscle weakness shows its side effects  .
4- Tempromandibular Disorder
Temporomandibular disorder (TMD), can be divided into two groups according to causes of pain into:
- Pain caused by the muscles themselves
- Pain attributed to TMJ.
Conventionally, anti-inflammatory agents, muscle relaxants and antidepressants drugs have been used for pain management. Other treatments include orthodontic devices and massage. Surgical intervention can be used as management, like arthrocentesis, intra-articular steroid injection, arthroscopy.
Botox can be used as primarily targets the muscles of mastication (temporalis, masseter, and medial and lateral pterygoid muscles). Botox shows progress less painful symptoms may reach up to 90% of patients, while Botox presents a side effect includes muscle weakness in the area of injection  .
5- Gummy Smile
is the display of excessive gingival tissue in the maxilla during smiling. This will interfere patients in both an oral hygiene and cosmetic pattern. Factors involved in the formation of gummy smile can be:
1-Skeletal (vertical maxillary excess)
2-Gingival (passive eruption).
3-Muscular (hyper functional upper lip)
Surgical options for treatment are range from Le fort I osteotomy, crown lengthening, intrusion, myectomy to muscle resection. Excessive gum exposure is due to the over-contraction of the upper lip muscles, particularly the levator labii Superioris alaeque nasi.
Botox should be injected in small, carefully titrated doses to limit muscular over-contraction of upper lip, thus reducing exposure of the upper gums when smiling .
Migraine is of the most common problem confronted by the population nowadays. Conventional treatments by using medications with some side effects as stomach discomfort, drowsiness, even may be some weight gain.
Botox used to treat migraine by injected into pericranial muscles relieves headache by relaxing the over active muscles. For migraines, there is no muscle component involved. Botox blocks the protein that carries the message of pain to the brain and relief normally effective for 2-3 weeks. The longer the treatment duration, the better the pain relief .
Is there Any Side Effect of using Botox?
Yes, the injected muscles may be suffering for pain for a few days after the injections, in addition it may lead to temporary partial weakening of the injected muscles .
Using Botox for a long time, it may cause atrophy of the injected muscles, but this atrophy is reversible. Some cases suffer for (1-2) days from palpitations, tingling sensations, or nausea.
Botox is not indicated during pregnancy or while breast feeding 
Patients who are treated by calcium channel blockers drugs, aminoglycoside antibiotics agents are not indicated to use Botox, because these agents interfere with neuromuscular transmission.
Using of Botox in the dental profession has a great conceivable. It paralyzes or weakens the injected muscle, while the other muscles unaffected.
Botox injections may lead to block the extra muscular but leave enough strength for normal use, while intra muscular injections Botox reconstructs the balance between masticatory closing and opening muscles, so that it is used for relieving muscle pain, reversing masseteric hypotrophy with improvement of facial outlines.
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