My left cheekbone is flat unlike my right. im 19. is it some kind of syndrome or maybe a dental problem.itsnoticable and itmakes my face appear longer?

Facial Asymmetry: It is not unusual that a slight difference exists between the right and left sides of your face. It is most likely genetic in nature. Consult with a local dentist, oral surgeon, or plastic surgeon to discuss your options if the discrepancy is that disfiguring.

Masseter hypertrophy: Masseteric hypertrophy is a relatively uncommon, condition that can occur unilaterally or bilaterally. Non-surgical modalities of treatment include tranquilizers or muscle relaxants, cognitive behavioral therapy and injection of very small doses of Botox A. See an orofacial pain specialist.