The stability of orthognathic surgery has been the subject of numerous publications over the last 20 years. It is now apparent that studies must pay attention to the homogeneity of the patients investigated and in particular, surgical techniques. In Part 2 of our study of 45 patients who had a uniform one-piece maxillary advancement with rigid fixation to advance the maxilla, we found that uncontrollable variables, including patients age, sex, the degree of advancement, and simultaneous mandibular advancement, had no effect on post-operative skeletal stability.