If you’ve got an Arm & Hammer or Crest SpinBrush, get rid of it, especially if it belongs to your kids.
…while turned on, the brush head has either “popped off” or broken off in the user’s mouth or near the face, causing cuts to the mouth and gums, chipped or broken teeth, swallowing and choking on the broken pieces, and injuries to the face and eyes. When the unexpected release of any part of the powered toothbrush occurs, there is a potential for serious injury. This risk is higher for unattended children or adults who may need assistance while using this device.
The report goes on to give tips for safe usage if you are interested but I say, go ahead and toss the thing. Get another toothbrush. I’ve chipped a tooth on a toothbrush before and it’s no fun.