Dr Watzke and coworkers are to be congratulated for a thorough clinical investigation which explores in some detail stability of the mandible after advancement using two different postsurgical means of fixation. The topic of this report, stability of the mandible after advancement, has undergone a resurgence of interest in the past several years owing to the emerging use of rigid internal fixation. This study stands as one of the finest comparisons of rigid and nonrigid fixation in the literature. Indeed, most studies on stability of the mandible following advancement do not compare one group with another but instead evaluate stability of one sample from the immediate postoperative radiograph to one at a later time. Therefore, the study by Watzke et al provides three sets of data: an evaluation of the stability of advancement using wire fixation, an evaluation of the stability of advancement using rigid fixation, and a study comparing them to each other. Furthermore, it attempts to evaluate both shortand long-term stability. Like all clinical studies, where the number of variables can be extremely difficult to control, Dr Watzke's study suffers from the necessity of including several uncontrolled variables such as multiple surgeons, differing surgical techniques, radiographic intervals, the presence or absence of splints at the time of radiographs, different orthodontists, duration of orthodontics, etc. To their credit, the authors attempted to control the variables by matching those patients treated with wires or screws by the magnitude of mandibular advancement. If the sample from which to select patients were infinite, further matching on sex, age, type, and duration of presurgical orthodontics, dentofacial morphology, genioplasty, etc, would assist in controlling the variables to a greater extent. However, given the nature of their sample, the two groups were remarkably similar in most respects. Unfortunately, one variable which was not controlled, that of the presence of an interocclusal splint at the time of the 6-week radiograph, makes interpretation of all but the long-term data extremely difficult. The reasons for this are that not alI patients had 6-week radiographs, not alI had their splints in at the time of the radiograph, and we do not know the timing of the radiograph in relation to the time of release of maxillomandibular fixation (MMF) in those patients in the MMF group. When MMF is used for postsurgical fixation, it becomes imperative to standardize the timing of the postoperative radiographs if one wishes to determine the etiology of postsurgical instability. For instance, if one takes the 6-week radiograph before the removal of MMF, any change from the immediate postoperative radiograph will be from the effect of soft-tissue forces moving the mandible orthopedically. On the other hand, if a 6-week radiograph is taken after