Child Support is already a binding agreement as such. It doesn’t cover things like braces. You can get a financial agreement drawn up on top of this to set the scene for bigger things like braces. But it also depends on whether he see them as necessity or not, my ex did not.
I think you don’t really understand the difference between discretionary expenses (like braces) and binding child support. “Medical, dental, schooling ect” is incredibly vague but I will assume that it refers to indescretinary items not covered by CS. He’s actually not entitled to pay it unless you stipulated explicitly that orthodontics will be covered equally by both parties. If you don’t understand your court ordered agreement, I reccomend you seek legal council. He doesn’t not have to pay a cent for braces and you have no legal recourse in enforcing him to do so, unless you take him to court again and he agrees to do so. It is so important to understand to understand the legal agreements you enter into.