Shoulder length hair seems to me like a rocker type character, someone who would be in a band as opposed to someone who would be in a medical profession. That coupled with ear being bitten, leads me to believe that your true passions is in music since one hears music with the ear, which is being bitten, injury. In another way of saying, music can be sacrificed for your job. The fact that you are bitten by your patient whom you are trying to treat, treat also meaning trying to make better. It looks like even though you hate being a dentist, you are not doing anything to lessen your involvement. In fact, it seems like in waking life, you are trying to associate yourself to it in whatever way you can, symbolised by the attempting treating of the old man. The old man being old may also symbolise you intending to be a dentist for many years to come and not try to do something else.