We report the case of a 39-year-old male patient who presented an increase in the bilateral masseteric region of several years of evolution, with a larger size of the masseter muscle on the left side, which motivated the consultation.
In his clinical history, the patient reported being asymptomatic, without aggregated pathologies, with poor dietary habits and daytime and nighttime bruxism.
A simple and contrasted computerized axial tomography (CAT) was performed in March 2008 to rule out pathology of hard and soft tissues such as neoplasia, chronic infectious process or bone growth.
It was finally diagnosed as bilateral masseter muscle hypertrophy, greater on the left side.
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We took measurements of the masseter muscles in the sections more than 53 in anterior and posterior lobes of both masseter and transverse diameter with the following results: 1.40 cm, 1.83 cm and 0.95 cm.
We started treatment based on nocturnal occlusal guard and application of botulinum toxin in November 2009, according to the selected protocol.
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Botulinum toxin application was proposed.
The first application at a dose of 50 U, 25 of which were applied in the zone of greatest hypertrophy (zone IV described by Da-Hye Kim), 15 U in the direction of the lower jaw border and 10 U in the previous application.
With this application distribution in the points proposed by Nam-Ho Kim that improve mandibular contour, marking was performed on the skin at the level of both masseter muscles (5).
A large needle (18G) was used to prepare the product in order to avoid the formation of turbulence.
Alcohol, used either on the vial stopper or on the patient’ s skin, must be completely evaporated before applying the toxin as it may also inactivate the toxin.
Although the vial can be reconstituted at a dilution of 8 cc/100 U, dilution in 4 cc is preferred in order to obtain a dosage of 2.5 U/0.1 cc.
Obtaining a smaller volume in this way will limit the possibility of the toxin spreading into adjacent areas.
It is important to remember that after reconstitution, the product should be used within 4 hours to avoid loss of efficacy, although some authors point out that it can be used without decreasing its efficacy within 3 to 7 days.
To reduce discomfort and to ensure the safe use of a needle (30G).
It is important not to mention that the patient should not take medications that interfere with coagulation 10 to 14 days before the injection to avoid ecchymosis.
We also asked the patient for permission to perform the procedure with a specific informed consent, as we usually do with any invasive procedure.
For subsequent applications we cite the patient every 12 weeks (3 months), using the same technique and completing up to a total of 4 applications.
It is known that when botulinum toxin is used, it is caused by infiltration of muscle groups, which leads to clinical improvement.
It was also indicated to continue the use of nocturnal occlusal guard to control bruxism.
