So, considering Le Fort 1 and posterior impaction, I wonder what does the value they give you in mm for your impaction mean relative to the face shortening effect. This study
http://www.ncbi.nlm.nih.gov/pubmed/18213459 found that "the results of the first evaluation step revealed that the chin had advanced on average by 79%, while the lower face was shortened by as much as 70% in the pogonion point.". All right now, 70% of what? Then a little bit below it says " ....in relation to the distance covered during impaction.". I am hoping to get my hands on the full-text article, but in the meantime, does anyone know what "distance covered during impaction" means? It's not the actual impaction value, is it? For example, even with parallel impaction it doesn't make sense that 3 mm of impaction would result in 0.7*3 = 2.1mm shortening of the face at the pogonion. Does it? Because whenever I try to visualize an impaction
https://www.youtube.com/watch?v=gEQLb7aYTWo, it looks like the actual shortening exceeds by far in length the vertical length of the impaction. I would think a 3mm of impaction would shorten the face more than 3 mm at the pogonion (4, 5mm perhaps more?) because of the mechanics of the movement. The lower posterior teeth may move up by the same amount maybe, but the lower anterior would move up more because of the angle. So what do they mean by "distance covered"? Any guesses?
