Any actual community service volunteering that doesn't involve healthcare or tutoring? What did you do with your hospital volunteering?
Fine manual dexterity would help. I'm not a fan that your GPA will be helpful to get you considered for Columbia, so what other holistic value do you bring as a Columbia dental student as opposed to NYU? Also given their curriculum, I would want to know about research... oh, you don't have any. Nothing in what you have disclosed really wows me to say you would be Columbia/Penn/Harvard material.
Are you living in the city? I don't think living with your parents is a good long-term solution in going to dental school. If you are doing it just to save money, you need to look into HPSP and NHSC.