Mandibular Relapse Research Articles

The stability of double jaw surgery: A comparison of rigid versus wire fixation

The subjects of this study were 35 patients who underwent simultaneous surgery for superior repositioning of the maxilla and advancement of the mandible. They were studied cephalometrically for a comparison of the postsurgical stability of two commonly used fixation techniques: (1) rigid fixation with bone plates and (2) skeletal-wire fixation. One surgeon performed the operations on all 35 patients, and both groups were studied for an average of 15 months after surgery. Results showed that, although the maxilla remained relatively stable after surgery with both fixation techniques, rigid fixation tended to improve stability, primarily by eliminating relapse in excess of 2 mm. Mandibular stability was much greater with rigid fixation: the amount of relapse of the horizontal projection of B point with this method was 6%, while in the skeletal-wire sample it was 26%. Increased rotational stability between the proximal and distal segments of the mandible appeared to be a major factor in the improved overall stability of the rigid-fixation sample. The amount of mandibular relapse was found to be correlated to the amount of advancement in the wire-fixation sample, but not in the rigid-fixation sample.

Mandibular Advancement Using the Bilateral Sagittal Osteotomy Past, Present, and Future

SUMMARY Although the group of articles studying the sagittal split osteotomy is large and varied, it is possible to draw several conclusions regarding the present state of knowledge. First, several variables have been shown not to cause relapse within the limits of the patients studied. These variables include age, preoperative orthodontics, and mandibular plane angle. Likewise, several factors decidedly do have an influence on relapse. As various investigators have shown,26'30'56 the magnitude of advancement is positively correlated with relapse, presumably secondary to stretch of muscles and other paramandibular soft tissues. Condylar displacement has also been shown by many authors15,17, 25, 28-30, 34, 39, 45, 59 to lead to relapse, along with a more general variable of proximal fragment position. In addition, as Schendel and Epker45 reported (and the variability of relapse figures demonstrates), “different surgeons had predictably good or unacceptable results”— i.e., some unspecified technical variables are apparently at work. Although identifying some of the factors responsible for relapse is an important step, it is only a first step. The next step is to find ways of preventing relapse by manipulating these factors. Skeletal fixation has been conclusively shown to reduce the amount of horizontal relapse and anterior facial height increase after sagittal osteotomies.11,35 It is less clear what effect the devices used intraoperatively to position the proximal segment might have on relapse. Several investigators reported on such devices15,22,31,41 and recommended their use, but only Raveh and coworkers41 had data to support such a recommendation. Rigid internal fixation was regarded as a panacea for the relapse problem for several years, but recent studies have shown that the role of this technique in the stability of the advanced mandible is not so clearcut. The present understanding is that when the amount of advancement exceeds 6 to 7 mm, there is a significant decrease in stability. It should be realized that with the different screws (self-tapping, nonself-tapping) and the different configurations of screws and plates used, rigid fixation cannot be considered a single technique. Finally, some potential influences on stability have not yet been ruled in or out. The suprahyoid myotomy is a prime example. Indeed, clinicians and researchers have postulated for 20 years that “muscle pull” is one of the primary causes of mandibular relapse.16,20,21,36,38, 49 The extent of the contribution of muscle pull to instability, and the specific role played by the suprahyoid muscle group and its myotomy, is one of the prime questions left for the future. Another factor whose role is as yet unclear is the articular cartilage and its response, both short and long term, to increased loading such as is found after mandibular advancement. Huang and Ross23 examined the amount of advancement and its influence on mandibular relapse in growing individuals. They found in all patients that growth ceased for 1 year, during which time neuromuscular adaptation presumably occurred. However, growth then resumed in 6 of the 11 patients having less than 10 mm of advancement. Those patients with greater than 10 mm of advancement showed no growth, with three of ten patients even showing continued decrease in mandibular length. This suggests that the articular cartilage was loaded with concomitant remodeling changes, and in the group with larger advancements, the loading was above the level that permitted mandibular growth. Copray and colleagues6 also investigated the influence of compressive forces on condylar cartilage, using rat embryonic cartilage in culture. They found that although continuous and intermittent compressive forces up to 3 g and 8 g, respectively, not only allowed but stimulated growth, forces above these levels caused deformation and necrotic shrinkage of the condyles. What does the future hold for the bilateral sagittal osteotomy? It seems clear that the procedure will continue to be the main technique for surgical mandibular advancement. The principal advances that need to be made lie in the areas of determining the role of muscle stretch and adaptation and the response of the articular cartilage. Once these two factors are well understood, the bilateral sagittal osteotomy will be much more predictable.

Clinically isolated mandibular relapse in childhood acute leukemia

With improved methods for preventing extramedullary relapse in the leptomeninges and gonads, the problem of clinically isolated relapse at other sites has become more significant. The authors report here two children with acute leukemia who developed mandibular relapse while in complete hematologic remission. One had been off chemotherapy for acute lymphoid leukemia for 2.5 years. The other child is apparently the first patient with promyeloid morphologic features to experience relapse at this site. Both children are in second complete remission and off treatment after local radiation therapy and second courses of chemotherapy. Review of these two and five previously reported isolated mandibular relapses in childhood leukemia indicate that they are usually delayed until after cessation of therapy. Treatment with radiation and combination chemotherapy can result in long remission and possibly cure.

Radiographic changes of the temporomandibular joint after oblique sliding osteotomy of the mandibular rami

64 patients with mandibular prognathism were operated upon with oblique sliding osteotomies of the mandibular rami. The patients were followed with cephalometric and temporomandibular joint (TMJ) radiographs for 3 years. 60% of the TMJs showed skeletal remodelling 3 years postoperatively. The condylar remodelling was significantly correlated to the degree of postoperative displacement of the condyle. The average condyle displacement postoperatively was about 3 mm inferiorly and anteriorly, but the position was almost completely back to normal during the control period, due to a combination of reverse movement of the condyle and remodelling. Mandibular relapse was not correlated to postoperative displacement of the condyle or condylar remodelling. The range of condylar movement was unchanged at follow-up.

Position of anterior teeth following surgical correction of prognathism

20 patients who had all undergone surgical correction of progenia by sagittal split operation in the ascending ramus were chosen for a follow-up investigation 5 years after the operation. The patients could be divided into two groups showing either horizontal or vertical facial growth pattern. A cephalometric analysis was made of all the patients and the results of both groups were compared with one another. In particular the changes in the position of the anterior teeth and the amount of sagittal and vertical relapse were noted. It was noticed, that the type of measurable postoperative relapse was different in the two groups. Postoperative mandibular relapse is partially compensated by the position of the anterior teeth. Therefore the postoperative changes in the position of the anterior teeth are different in the two groups.

Rejoinder to "comments on a method to predict and prevent mandibular incisor relapse".

Rejoinder to "comments on a method to predict and prevent mandibular incisor relapse".

Hormonal effects on orthodontic tooth movement in cats—A pilot study

s of papers presented before the Research Section of the American Association of Orthodontists, Ne’w Orleans, La., May 3, 1971 Changes in Tongue Position and Activity Following Mandibular Osteotomy N. A. Wickwire and W. R. Proffit University of Kentucky, College of Dentistry, Lexington, Ky. This study of tongue response and activity was developed from serial cephalometric films and lingual pressure recordings. Preoperative and postoperative cephalograme were analyzed to determine the extent and direction of changes of the odontoid process, the body of the hyoid, and the mandible following surgical treatment. The postoperative response of the mandibular setback in nineteen of twenty-two patients was a posterior deflection of the hyoid body. The hyoid was elevated or depressed in negative correlation with mandibular vertical positioning. In the absence of mandibular vertical change, the vertical changes of the hyoid related to the direction and extent of the hinging of the odontoid process, These movements of the hyoid served to preclude change in the pharyngeal space. This constancy enforces the concept of reflex maintenance of airway patency. Analyses made 1 year postoperatively showed stable mandibular positioning in ten patients. Five patients showed mandibular anterior repositioning, with a mean of -0.6 mm. In three of these patients with mandibular relapse the hyoid was seen to be assuming a more anterior position. Lingual pressure changes, as measured by pressure transducers mounted in a palate-covering device, also indicate that the tongue repositions after the surgical procedure, then returns somewhat toward its original position in the postoperative period. Tongue-tip pressure in most patients decreases after surgery, then returns to approximately the original level. If tongue-tip pressure increases after the operation, the incisor position is likely to be unstable, and a