I think I should explain the mechanics behind changing maxillary shape. As you know the Stage 1 Biobloc is almost unique in sharing the load between the teeth and the palatal tissue. This also re-contours the vault.
Obviously the initial shape is very different from the final one and during expansion there will be greater pressure on some points than others. One can anticipate these to start with (as shown) but during treatment as the shape changes more pressure will fall on certain points and these will develop sores.
These must be eased promptly or they will turn into ulcers and ultimately can erode the underlying bone. This is best done by grinding the acrylic at the spot I usually do this twice at any spot and the appliance is designed with additional thickness in the areas lingual to the cribbed molars where sores are most common. After two easings it is best to lift the whole appliance.
I do this by roughening the collets where they touch the teeth and covering them with a thin layer of ‘runny’ acrylic and quickly dipping it in hot water before inserting it. This will lift the appliance by about 1 millimetre and allow the ulcer to heal and the vault to recontour. The advantage of this procedure is that at the end of expansion you have widened the dental arch by 10 to 15mm and have a perfectly contoured palate with four or six straight anteriors and a space behind the canines so no further dental alignment is required see picture. Many expansion appliances subsequently require fixed appliances to align the teeth which inevitably undoes much of the facial improvement. I am sure that this natural change in shape is why Biobloc faces are often judged the best.