There are some places in the mouth where floss just won’t get the job done. Not all surfaces between the teeth are smooth and convex and it is easy to miss the dental plaque and other build up that may hide. Special attention needs to be paid between certain teeth to keep them healthy. This is the case between your Canines & First Bicuspids in your Upper Teeth, between your upper and Lower First molars and any teeth next to them as well as you Lower Incisors. In order to keep those areas clean you will need to use an inter-dental brush in addition to flossing in those spots.