i would write a letter, i find it easier to write it down than say it face to face or over the phone, that way they cant say you didnt ask that etc, can you email them?
i worked in a simular practice to the one you describe and have been in a simular situation with poor management and lack of communication - luckily my mum was a receptionist there at the same time so i got the low down and got her to be my go between.
it was like this for 7years i had enough and left as i never got interviews with the boss's or time to raise my concerns etc, i asked over and over again for something to be done and nothing was. i even went to the practice owners where i was met by them and their children! they wouldnt even send their children out the room so i could talk in private. they basicaly told me to get on with it thats the way it is! this is not good enough from any management!
i put atopic on here about a unioin, asking if there was a dental union as i feel they would be the best people to help you, but im not sure how to go about it or even if one exsists.
i would suggest putting all your concerns down in writing and put it bluntly you are not happy by the lack of communication etc, they need to know what they are doing is wrong.
goodluck and i hope it sorts its self out, if not maybe do what i did and leave? management will never change hun x