Bruxism is a condition where your patient will unconsciously grind or clench the teeth. Temporomandibular joint disorder is a condition where your patient experiences pain and improper function of the TMJ.  Bruxism can be caused by TMJD, and vice versa. Botox was first used in a patient with bruxism in 1990.  In 2002, Freund documented good outcomes of TMJD patients who received Botox.

People that suffer from bruxism grind their teeth. TMJ disorder is a condition that involves pain and improper functioning of the muscles and joints that attach the lower jaw to the skull. Bruxism can be caused by TMD, but bruxism can in turn also cause or worsen TMD.  Botox can break off this cycle by relaxing the muscle contraction of the masseter and temporalis muscle.

Landmark:

First, ask your patient to clench her teeth.  The masseter and temporalis muscle will become more prominent and easier to inject.  With repeat contraction, identify the outline of both muscle groups and draw the shape with a white pencil.
To inject the masseter muscle, draw a line from the corner of the mouth to the tip of the earlobe (superior margin).  Then, draw a line from the corner of the mouth to the angle of the mandible (inferior margin).  The two vertical lines (anterior and posterior margin) that shape the outline of the masseter muscle (which you will draw as the patient clenches her teeth) will cross-hatch these two lines.  Inject into the most prominent portion of the muscle, in 3 – 4 separate areas 0.5 – 1 cm apart, and at least 1.5cm above the margin of the mandible.  All injections should be done to the lower third of the masseter muscle.
The temporalis muscle is typically 4.5cm from the patient’s zygomatic arch.  The muscle can be divided into anterior, middle and posterior regions.  There is great anatomical variety among patients and the injector must feel this her fingers to identify the outline of the muscle.  Typically, the deep temporal nerve runs through the anterior fibers of the temporalis muscle.  The injection site should be palpated for the superficial temporal artery and its branches.

Amount:

Based on clinical experience, the following doses were used.
Masseter muscle: 20 – 30 units per one side
Temporalis muscle: 10 – 20 unis per one side
It is recommended to inject low concentrations in multiple areas to avoid incomplete effects and diffusion into undesirable areas.

Precaution:

Aside from the typical side effects of Botox (bruising, hematoma and pain), other side effects are possible.  In the masseter muscle, side effects include chewing weakness, The facial nerve is located near the masseter muscle.  To minimize the risk of side effects, asymmetry, sagging, paradoxical hypertrophy, loss of smile, sunken cheeks, difficulty opening the mouth, sunken temporal fossa, dry mouth (if injected into the parotid gland), neuropraxia, and others. Therefore, we recommend that you inject into the center of the landmark.
In injecting the temporalis, you must aspirate before injecting large amounts to avoid intravascular injection into the superficial temporal artery and its branches.  You also want to avoid injecting near the lateral canthus to avoid the paralysis of the lateral rectus muscle.

A hyperactive lip elevator muscles will create what some people call a gummy smile.  This causes the patients to show excessive gingival exposure when smiling.  Previously corrected surgically, now we are able to treat this with Botox.

Yonsei University is in South Korea.  It also shares the name with a Botox injection landmark called “Yonsei point.”  Dr. Hwang is a professor at the College of Dentistry who recommended injection 3 units of Botox for the treatment of the gummy smile.  Yonsei point is the center of a triangular region where the three muscles Levator labii superioris, Levator labii superioris alaeque nasi and Zygomaticus minor passes on the area lateral to the ala.  The location of the insertion mark was found to be 1 cm horizontal to the ala and 3 cm vertically from the lip line.  While some advocate injecting 3 units, some others recommend a lower dose of 2 units.

Aside from the typical side effects of Botox (bruising, hematoma and pain), other side effects are possible.  Side effects include asymmetry, sagging, difficulty opening the mouth, neuropraxia, and others. Therefore, we recommend that you inject into the center of the landmark.

The first off-label report of using Botox for masseter hypertrophy was published in 1994.  Since then, the request for patients to achieve the oval facial shape or a V-shaped jawline has increased.  The good news about treating this is that it is the same as the treatment for TMJ disorder without the temporalis muscle injection.  All the landmarks, units, and precautions are the same except that you do not have to inject the temporalis muscle.  To have the hands-on experience, please sign up for our Botox certification training course for dentists.