We had with these brush heads had never problems, but for some time the heads nachgekauften a disaster. When translating the vibrations from the handpiece into the brush head seems a bit not to vote. It constantly arise dropouts during the cleaning movements. It is definitely on the brush heads, because this problem occurs with all handpieces that we have at home. The fit of the heads has deteriorated. The attachment to the handpiece is now much more difficult. And we also have the impression that the heads wear out recently very quickly. For this price, this is a joke.