Gum disease has the top priority etiologically. Bad alignment of teeth makes gum disease and decay easier to develop. With the gum disease orthodontic treatment may lead to further bone loss that is extremely difficult to reverse. With too much bone loss teeth dont have a good longevity and gum disease develops faster. Lets put it simply: leaving gum disease untreated, you will have your dental health in a vicious cycle. Go see periodontists first please.