How could I change my face shape to an oval one by using Botox treatments? (Photo)

Botox can be injected into the masseter muscles, large muscles on the jaw on the lower sides of the face, to reduce the squared appearance that results from enlarged masseters.  You may also benefit from the use of hyaluronic acid fillers such as Juvederm to soften the contours of the face.  I would recommend you consult with physician experienced with Botox and fillers to see what would be best for you.

Square shaped face can be addressed by relaxing and reducing the size of chewing muscles .Masseter hypertrophy or overgrown chewing muscles cause teeth grinding and produce a squareness shape to the face .
Botox injections are very quick , placed in 2- 4 spots on each side of the jaw and take 2 weeks to start to see effect
Full effect is apparent at 6 weeks at which point it can be topped up if wish to achieve more contouring or less teeth grinding. Once adequate jaw slimming is achieved , maintenance treatments are required every 6- 9 months
Dermal fillers can be used to contour the face by making the chin more full in the midline and having more projection downward producing an oval shaped face rather than square
If your chin is "frowning" by which I take to mean is dimpling when you speak or eat , then botox can be used to relax it