Botulinum Toxin Injection


General assessment

I would like to introduce our next patient, Hanna, who is currently 30 years old. When I asked her what she would ideally be looking to improve, she mentioned that she had 3 primary concerns. Her first concern was her chin – she described this as a ‘witch’s chin,’ by which she meant that she had a little bit of excessive anterior projection, and she felt that the chin was dominant. Her next indication was the under eye hollows, and finally, she was seeking to improve the size and shape of her lips.


Let’s have a look at her face shape – when we look at her from the front, we can see that she‘s young and attractive, and in line with that, she has a very nice dominant cheekbone that we can see leading down. However, she also has a very dominant jaw, accordingly, this gives off a little bit of a square shape to the face. We do know that the ideal face shape for a female is a heart, formed by the cheekbones coming down into a delicate chin, or an oval, but in Hanna’s case, the angle of the jaw gives a bit of squaring. We can see that if we were able to contour the jawline, we would potentially make her more attractive and give her a more delicate face shape.

Lower third assessment

Let’s now look at Hanna’s lower third, from the subnasale to the pogonion. We notice that she has well defined philtral columns and a well defined Cupid’s bow. When we look at the lip, we notice again, it has a good shape and definition, but both the upper and the lower lip appear a bit thin for her face. This is compounded by the fact that she appears to have an excessively long and dominant chin: we can see that the chin has a lot of anterior projection, and the mentalis muscle can move this up, creating this labiomental crease. We can see however that we can remove the labiomental crease to give a better shape to the chin. If I evert the upper lip, and then evert both the upper and lower lip, we can see that it takes away the dominance of the chin and gives her a more attractive perioral region. If I now ask Hanna to smile, we can see that if I evert the lower lip, that she has relatively good occlusion of her teeth, and there is not an excessive overbite or underbite.


Moving Hanna to the side and asking her to smile again, we can see something very interesting: on smile she has these vertical cheek lines, and in her case this is most likely due to the fact that she does have some degree of masseter hypertrophy as pointed out before. Accordingly, the line is formed by the oral commissure pushing against the hypertrophic masseter, creating the vertical creases in the side of her cheek. When I get her to frown, we see minimal DAO activity, but we see a lot of mentalis activity, causing cobblestoning of the chin. This makes her a candidate for treatment in this region with botulinum toxin.


If I turn Hanna’s face to the side, we notice that she has a very smooth jawline with a very good shape and definition from chin to the angle of the jaw. If I get her to contract her neck muscles, we see some platysmal banding, and with minimal contraction, the jawline is preserved. When she contracts heavily, we can see that there is a little bit of blunting on the jawline, so in time she may be a candidate for treatment in this region with botulinum toxin to the cervical portion of her platysma. In summary, Hanna, although young, does have treatment indication in the upper third, middle third, lower third, and in the future possibly the neck.

Lower face anatomy markings

Let’s have a look at the surface anatomy for masseter injections. This is often done to contour the jawline, but in Hanna’s case we’re also doing it for the fact that she does suffer from tension headaches due to excessive clenching of the jaw. We can see now some surface markings, which I will describe. The temporalis is the main muscle implicated in chewing, or mastication, and the masseter is actually three layers, which all originate from the underside of the zygoma and insert into the mandible. You will notice here that I have drawn a line from the tragus to the oral commissure, and ideally we should inject below this line. If we inject above this line, we can get complications and there is no aesthetic advantage. You can also see that behind the masseter, there is some parotid gland, and in front of the masseter there is a risorius muscle, which arises from the fascia overlying the masseter and inserts into the modiolus. Because the risorius is used during smiling, if we do get diffusion of toxin onto this muscle, it can give us a smile asymmetry. The masseter is thick and accordingly, we should use a deep needle to reach it.

Injection site markings and treatments

When I inject the patient for jawline contouring, the first thing I get the patient to do is clench the masseter. I can then see the shape of the muscle and also palpate it. I will palpate the anterior border and draw a line down, then do exactly the same thing for the posterior border of the muscle, which delineates the anterior and posterior limits of the muscle. Next, I will take a line from the tragus all the way to the oral commissure, which will form my vertical limit for injecting. I have now created a zone in which I will have my injection points. Because Hanna is small and petite, her muscle bulk is not too big. Accordingly, I am happy to treat her with two injection points, one lower down and one more superior. The masseter itself is a thick, bulky muscle, and it’s important to look at the needle depth. A lot of the standard Botox needles are 13mm, however, I will choose to use a 20mm needle here so I can ensure I get to the posterior and deepest fibres of the masseter muscle. I will ask Hanna to clench, and then insert the needle deep and inject the first 10 units slowly. I withdraw, ask her to clench again, insert the needle, and then inject another 10 units into the superior injection point.

Treatment outcomes at 6 weeks

We have our patient Hanna here, at 6 weeks following some botulinum toxin treatment and some dermal filler treatment. The first thing to notice is a significantly improved facial shape – we can see, due to the masseter Botox treatment, that she now has a more feminine, oval, or heart-shaped face. This is due to a diminution in the projection and angle of the jaw when we treated the masseter. We can see that when she frowns, she has practically no activity of the procerus or corrugator, and that when she raises her brow, there is some movement, but lines are diminished. This is the perfect ideal for frontalis treatment because we have preserved movement while reducing the lines. If you look at her brow shape, you will also notice that the tails of the brow have lifted, and are more aesthetically pleasing.


When we look at the chin, we notice that it is now soft and there is no longer the cobblestone appearance that she had pre-treatment. If we turn Hanna to the side, we will notice that the chin is still slightly projected anteriorly, but considerably less so than previously. If we turn her to the side and get her to smile, we will notice that the little lines she had in her cheek have also reduced substantially following the treatment to her masseter. Also notice the significant improvement of the under eye area after treatment.