Can I get full custody of my son

My sons mom wont take my son to the dentist and she wont give me the insurnse card and i just found out that he has none of his shots and he is ten years old come on really i think this is really messed up plus i have Joint custody she needs to tell me these things if i ask but she wont she is not doing a very good job with my son so what do you ladies think i know am not a mom but i am a very good dad