In many people suffering from bruxism, one of the most visible — and sometimes aesthetically troubling — side effects is hypertrophy of the masseter muscles, which are responsible for chewing. This increase in muscle volume, resulting from chronic overuse, gives the jaw a more angular, square shape, sometimes perceived as masculine or disproportionate.
While this morphology is purely genetic in some individuals, in bruxism patients it develops gradually, directly linked to the repeated and involuntary contractions of the masticatory muscles, particularly during sleep. Hence the question arises : is it possible to refine this jawline, without surgery, and in a lasting way ?
The answer is yes, provided that both the functional cause (bruxism) and its anatomical consequence (muscular hypertrophy) are addressed. An appropriate approach, combining medical treatment and aesthetic care, makes it possible to achieve a natural, harmonious, and lasting result.
Bruxism, whether diurnal or nocturnal, causes intense and repeated muscle contractions. These prolonged contractions of the masseters — muscles located on each side of the mandible — lead to a phenomenon of functional hypertrophy. Like an overworked athlete’s muscle, the masseter increases in volume to meet the excessive demand.
This muscle hypertrophy does not affect only men. In many women, the unconscious clenching of the teeth gradually leads to a widening of the jaw. This changes the shape of the face : the oval becomes less soft, the jaw more angular. This imbalance can give a tense or tired appearance.
Contrary to what is often believed, the increase in muscle volume caused by bruxism is not permanent. Like all muscles, the masseter can become thinner again if it is less solicited. To achieve this, involuntary contractions must be reduced.
Botox® is therefore particularly suitable. Injected directly into the masseter muscle, it temporarily reduces its strength without preventing normal chewing. The muscle relaxes, which relieves bruxism-related pain and allows the jaw to gradually regain a slimmer appearance.
The injection of botulinum toxin into the masseter muscles is a well-established, safe technique, widely validated by medical literature. It offers a dual benefit : functional and aesthetic.
Functionally, it reduces the contraction strength of the masseter, thereby relieving jaw pain, tension headaches, and morning muscle fatigue. It also helps reduce dental wear related to nocturnal bruxism.
Aesthetically, the reduction of muscle activity causes, within a few weeks, a moderate but visible atrophy of the muscle. The jaw becomes less prominent, and the face regains more harmonious features, often associated with a more feminine and rejuvenated appearance.
Results generally appear between 4 and 8 weeks after the first injection, with a gradual and natural evolution, without any abrupt change in facial appearance.
The relaxing effect of botulinum toxin lasts about 4 to 6 months. However, when used with the goal of muscle reduction, the aesthetic results extend well beyond the simple pharmacological duration, due to the functional atrophy induced by muscle inactivity.
Thus, after 2 to 3 sessions spaced 4 to 6 months apart, stabilization of muscle volume is often observed, allowing for a significant reduction in injection frequency. Some patients require only annual maintenance once the facial shape has been optimized.
The result is reversible : if injections are stopped, the masseter muscle gradually regains its initial volume under the influence of contraction habits and a possible return of bruxism.
In certain cases, particularly when the facial contour is weighed down by excess fatty tissue or skin laxity, the injection of botulinum toxin into the masseters can be combined with other complementary medical techniques.
These treatments should be proposed on a case-by-case basis, following a thorough assessment of facial morphology and the patient’s expectations.
The injection of botulinum toxin into the masseter is mainly indicated for patients suffering from bruxism associated with visible hypertrophy of the masseters. It is suitable for both women and men, provided that masticatory function is properly evaluated.
This technique should not be considered in patients whose wide jaw is due to bone reasons (prognathism, mandibular hypertrophy of genetic origin). In such cases, only orthodontic or surgical treatment would be appropriate.
Furthermore, very thin patients or those who already have a hollow face may not be good candidates, as additional muscle atrophy could compromise the harmony of the face.
After several well-performed sessions, most patients achieve a clear slimming of the jawline, without any loss of functionality (chewing) and without a frozen appearance. The face gains lightness and softness, often accompanied by a notable psychological improvement, especially in individuals who feel self-conscious about their profile or jawline.
After several properly conducted sessions, the majority of patients observe a marked refinement of the jaw. Function remains intact, and the face retains full mobility without stiffness. The features become lighter and softer, often with a significant psychological benefit, particularly for those who are self-conscious about their profile or jawline.
The aesthetic effect can last several years, with simple maintenance — sometimes even unnecessary if bruxism disappears. When properly planned, this treatment offers an alternative to surgery, with progressive, natural, and reversible results.
When botulinum toxin treatment is chosen to slim a jaw hypertrophied by bruxism, it is important to establish a standardized photographic follow-up, taken from consistent angles and under identical lighting conditions. This follow-up allows for an objective documentation of muscle volume changes, which can sometimes be difficult to assess in the short term, especially when the modifications are gradual and natural. It serves as both a clinical and educational tool, helping the patient to become aware of the treatment’s benefits and to adjust, if necessary, the technique during maintenance sessions.
The treatment of the masseters in the context of bruxism requires higher doses than those used for expression lines. In practice, the injected dose is generally between one and two vials of botulinum toxin per side, depending on muscle strength, muscle volume, and the patient’s sex (men typically have stronger muscles). It is essential to respect safe injection points to limit the risk of diffusion to adjacent muscles (pterygoids, buccinators) and to ensure a homogeneous effect without asymmetry. Technical precision is therefore a key factor for success.
Before undertaking a mandibular slimming treatment in a bruxism patient, it is essential to evaluate the overall masticatory function, both subjectively (eating habits, pain, fatigue) and objectively (symmetry, bite strength, temporomandibular joint disorders). This assessment ensures that the patient does not present any major occlusal imbalance or pre-existing muscle weakness that could be worsened by the injection. In the absence of functional disorders, relaxation of the masseter has no adverse effect on chewing — the temporalis and other masticatory muscles naturally compensate.
The management of the lower third of the face (jaw, chin, jawline) is a key component of facial rejuvenation. In bruxism patients, hypertrophy of the masseters often distorts the perception of facial structure by creating a disproportion between the lower face and the rest of the face. Treatment of bruxism with botulinum toxin therefore aims not only to reduce pain or protect the teeth but also to restore the fundamental aesthetic balance of the face, by refining and feminizing the jawline without surgery.
In the context of a purely aesthetic treatment aimed at slimming the jawline, botulinum toxin injections are not covered by health insurance, even if they indirectly act on a functional symptom. However, if the patient presents with a disabling, diagnosed, and documented bruxism, some complementary health insurances may partially reimburse the procedure when performed by a physician and justified by a medical indication. It is therefore important to distinguish between the therapeutic and the aesthetic purpose, even though in this particular case, the two objectives are closely interconnected.
Article written by Dr Romano Valeria
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