Ill-fitting Dental Crowns? One of the crowns is rubbing against the inside of my mouth and I still speak with a lisp 3 weeks on.

A crown on a front tooth will cause a lisp if the upper and lower front teeth are prevented from coming together the way they did previously.  This is often the case if the crown is too thick on the inside surface of an upper crown or the outside surface of a lower crown.  Your dentist should be able to make the necessary adjustment and repolish the crown and have you speaking normally again. 

Problems such as a crown rubbing the inside of your cheek or speaking with a lisp require the attention of your dentist. This is a classic example of the fact that your dental crowns are generally made on a stone model in a dental laboratory (we also have CAD/CAM computer generated impressions and crown fabrication) that are unable to replicate the mouth environment completely with your lips, cheeks, tongue etc.. Therefore a cusp rubbing on your cheek or a lisp from to much air passing between your teeth may be a simple adjustment such as re-contouring and adjusting your bite, or sending the crown back to the laboratory for re-baking and/or addition of porcelain. Hopefully, they are not permanently cemented which can make adjustments more difficult.