Revision jaw surgery: how many mm and what dimensional movements would be needed for the best result?

There is no need to repeat the previous jaw surgery. A sliding genioplasty will give you more chin projection. In men, I typically advance the chin a minimum of 5 mm and usually 7-9 mm. A 3 mm advancement is generally insignificant. The chin can simultaneously be lengthened.

A genioplasty of a significant magnitude can be beneficial given the position of the lower teeth,lip and chin bone contour. It will also 'flatten' the area under the chin