One of the services that every dental office should be providing is online bill pay. When asked patients prefer to pay online, they can pay you whenever they want 24/7, no one has to answer the phone and the payments arrive much, actually much much faster than they do if you get paid by check.
There are several companies that offer this service including PayJunction.
Look here for rates. Credit card processing is very competitive and they offer a rate match as well.
Of course in order to offer online payments yo need a web site you are not embarrassed to send people to. For creative web site design check out my friends at TNT Dental.