To keep scum from building up in your Sonicare toothbrush you can change the replacement brush assemblies every 1-2 months, but the replacement brushes are expensive and there is an easier and much cheaper way to seal up your Sonicare toothbrush and keep scum and black mold at bay. All you need are:

1) A Latex glove
2) Two rubber bands

First take one latex glove (the larger sized gloves work best) and prick a small hole in the end of the thumb. Then, take your Sonicare toothbrush and insert it into the latex glove -- brush first -- and poke the brush end out of the small hole in the glove. Carefully work the latex glove down around the brush assembly so that it covers up the two main places where liquid and scum seep in (see photo above). Next, take the rubber bands and wrap them around the brush assembly (see photo) to keep the seal of the latex glove tight. Finally, cut off the extra fingers from the latex glove and you are done.This will do the trick nicely, and you can buy a bag of latex gloves for cheap at most stores! The thumb of the glove fits the Sonicare toothbrush better than the other fingers, and this will keep your Sonicare toothbrush free from scum build up for several months.

It may look funky, but the latex glove technique works and it will not hamper the effectiveness of the brush. Try it with your Sonicare toothbrush!

A Sonicare Elite toothbrush sealed with the thumb from a latex glove