Your question is about one year old but it might still be actual. I understand that you are looking for a donation of used but functional dental units. In fact, this kind of equipment some times is left over when new units are purchased. Unfortunately is transportation quite expensive. In some cases shipping companies can give you a free ride for a donation especially if it is for educational- och non-profit oragnizations. Do you have any arrangement concerning transportation between Europe and your country?
Right now I do not have any units. I will keep you in mind if something shows up in the future.
Anyways, I recommend that you sort out how a transportation can be arranged and what kind of customs regulation would apply for this. May be transportation & customs are more expensive than buying used units in your country.