# Biphasic Injection for Masseter Muscle Reduction with Botulinum Toxin
## 3 Results
In fact, sunken cheeks appearance after BoNTA injection was considered by our patient as a sign of thinness or physical wellness. On the contrary, in Asians it is usually considered as a sign of fatigue or malnourishment and thus interpreted as complication. Therefore, in those patients the superior and anterior area of the masseter should be avoided when performing BoNTA injection, as the atrophy of this region will cause a sunken cheek shape. Comparing our results with findings in Asian ethnicities, injection over the lower part of the masseter is recommended to prevent sunken lateral cheeks. An upper margin far from zygomatic arch should be set for an injection safety zone. In fact, patients should be carefully selected to achieve optimal cosmetic outcome with BoNTA injection procedure. Therefore, patients with large zygoma should be counselled appropriately before injection that can sometimes make the middle third appear more pronounced in relation to the atrophied masseters. In this situation, adjunctive remodeling options, such as lipoinjection or zygomatic bone recontouring is described [61]. This situation is reported in Asian population rather than our Italian study group where did not occur this evidence. Thus, no further remodeling approaches were required after BoNTA injection. Regardless of sex, a female aspect is reputed to be nice-looking in facial features, thus also males seek aesthetic lower facial recontouring [64]. Furthermore, male ideals of attractiveness are more in agreement with a squared jawline [64,65]. Moreover, women find this feature more masculine and attractive, even if authors contradict the dichotomous standards of beauty between the sexes [66]. Although in the literature it is reported a much lower rate of the male patients seeking for procedure (7%) [8], in our experience males requested lower face reshaping slightly more than females. Nowadays, BoNTA masseteric hypertrophy treatment is a reliable technique because it has been performed for a long time and several protocols for an elective and safe procedure have been proposed [38, 39, 40, 41, 42, 43, 44, 45]. Nevertheless, in the literature, several reports still describe how patients continue to experience troublesome and bothersome side effects [44, 45, 46, 50]. Even if BoNTA injection in lower face recontouring is considered to be a safe and effective technique, the risk of side effect still remains [51,67], thus surgeons performing this procedure should be able to identify different complications and especially their prevention. According to our approach, no serious or worrisome side effects was reported to be caused by the treatment. As described by several studies, the most common side effect observed was indeed the temporary decrease in chewing power [8, 9, 10]. In all our patients, a mild temporary massation force was claimed even if no one reported discomfort in mastication. It resulted from the weakened contraction of masseter muscle as an effect of decreased masseteric strength. Decreased chewing power is reported to occur 2-4 weeks after the injection, peaks at 3 weeks, and may persist for 1-2 months [8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45]. This side effect is expected because this approach is based on the toxin effect to paralyze the muscle, causing degenerating atrophy of the masseter. In our experience, it continued for 3 weeks, differently from what described in the literature. Reported complications with a nonmuscular etiology including bruises and hematomas did not occur in our experience. Self-limited bruising was the second most common side effect described in the literature at a rate of 2.5% [50], even if it was not experienced in none of our cases. Moreover, dizziness and headache are unusual side effects. As described by [PERSON] [61], patients who report headaches are likely to experience headaches again after future injections, indicating an individual susceptibility.