Timothy A. Turvey

The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension

A hierarchy of stability exists among the types of surgical movements that are possible with orthognathic surgery. This report updates the hierarchy, focusing on comparison of the stability of procedures when rigid fixation is used. Two procedures not previously placed in the hierarchy now are included: correction of asymmetry is stable with rigid fixation and repositioning of the chin also is very stable. During the first post-surgical year, surgical movements in patients treated for Class II/long face problems tend to be more stable than those treated for Class III problems. Clinically relevant changes (more than 2 mm) occur in a surprisingly large percentage of orthognathic surgery patients from one to five years post-treatment, after surgical healing is complete. During the first post-surgical year, patients treated for Class II/long face problems are more stable than those treated for Class III problems; from one to five years post-treatment, some patients in both groups experience skeletal change, but the Class III patients then are more stable than the Class II/long face patients. Fewer patients exhibit long-term changes in the dental occlusion than skeletal changes, because the dentition usually adapts to the skeletal change.

Early fracture of the mandibular condyles: frequently an unsuspected cause of growth disturbances.

Experience with patients referred to the Dentofacial Clinic at the University of North Carolina indicates that previous fracture of the mandibular condylar process may be involved in 5 to 10 percent of all severe mandibular deficiency or asymmetry problems. Since these fractures often go undiagnosed and since three fourths of the children with fractures have no growth deficits, the incidence of condylar fractures probably is much higher than commonly thought. Management of fracture patients immediately following the accident, during the postinjury stages of mandibular growth, and at completion or near-completion of growth is discussed.

Delayed bone grafting in the cleft maxilla and palate: A retrospective multidisciplinary analysis

The results of delayed bone-grafting procedures in a group of twenty-four cleft patients are reported. All patients benefitted from closure of their fistulas. The need for a prosthesis was eliminated in twelve patients, and eight of the remaining twelve patients required only a three-unit bridge. Residual movement of the premaxilla in two of the nine bilateral cases included in this study was detectable. The esthetic benefits were difficult to assess since sixteen of the patients simultaneously underwent lip and nasal revisions. In seventeen patients, the graft was placed prior to canine eruption, and in sixteen of these patients, the canine erupted passively into the arch. Not every patient with a cleft is a candidate for delayed bone grafting, but the procedure has been found to be beneficial in selected persons.

The nasal airway following maxillary expansion

There have been suggestions that maxillary expansion may be justified on the basis of airway considerations alone. The present study assessed the effects of rapid maxillary expansion and surgical expansion on nasal airway size to determine how useful these techniques are for breathing purposes. The results demonstrate that both procedures generally improve the nasal airway. However, approximately one third of the subjects in both groups did not achieve enough improvement to eliminate the probability of obligatory mouth breathing. These findings suggest that maxillary expansion for airway purposes alone is not justified.

Long-term stability of surgical open-bite correction by Le Fort I osteotomy.

Skeletal changes greater than those observed in untreated adults have been noted beyond 1 year post-surgery in adult patients who had surgical correction of a long face deformity. The stability of skeletal landmarks and dental relationships from 1 to >3 years post-surgery was examined in 28 patients who had undergone surgery of the maxilla only, and in 26 patients who had undergone 2-jaw surgery to correct >2 mm anterior open bite. Although the average changes in almost all landmark positions and skeletal dimensions were less than 1 mm, point B moved down >2 mm and face height increased >2 mm in one-third of the maxilla-only group and in 40% of the 2-jaw group (>4 mm in 10% and 22% respectively). Overbite decreased 2-4 mm in only 7% of the maxilla-only and 12% of the 2 groups, with no changes >4 mm, because in three-fourths of the patients with an increase in anterior face height, further eruption of the incisors maintained the overbite relationship. In the maxilla-only group, mandibular length (Co-Pg) showed >2 mm long-term change in 45% of the patients, two-thirds of whom showed an increase rather than a decrease in length. In the 2-jaw group, no patients showed a decrease in Co-Pg length and one-third had an increase. For both groups, changes in overjet were smaller and less frequent than changes in mandibular length.

Intraoperative complications of sagittal osteotomy of the mandibular ramus: incidence and management.

The intraoperative complications occurring with 256 sagittal osteotomies operated by two different osteotomy designs are presented. Intraoperative complications occurred in 8.2% of the cases. Aside from operator experience and skill, complications appeared to be related to the osteotomy design and attention to detail during the operation.

Use of autogenous cranial bone grafts in maxillofacial surgery: a preliminary report.

In conventional reconstruction of the facial skeleton, bone grafts are usually harvested from distant sites such as the ilium or ribs. Because of the morbidity associated with the use of these sites, the calvarium was studied as an alternate donor site. Twenty-three patients underwent bone grafting using autogenous calvarial bone. Reconstructive procedures included alveolar cleft grafts, Le Fort I osteotomies, midface onlay grafts, and grafting of a mandibular continuity defect. Intraoperative and postoperative morbidity associated with the bone donor site was minimal, and there was good incorporation of all the grafts. Long-term follow up is necessary before definitive conclusions about the response of the grafted bone can be made, but short-term results were promising.

Stability following superior repositioning of the maxilla by LeFort I osteotomy

Cephalometric data from 61 patients who had undergone superior repositioning of the maxilla via LeFort I osteotomy by means of the downfracture technique were analyzed to evaluate stability of skeletal and dental landmarks at various time intervals up to 1 year. None of these patients had concurrent mandibular ramus or body osteotomy except genioplasty and all had at least 2 mm intrusion at the maxillary incisor or molar. In approximately 20% of the patients, there was 2 mm (critical value) or more postsurgical movement of skeletal or dental landmarks. During the first 6 weeks postoperatively, the maxilla showed a strong tendency to move farther upward in the patients in whom it was not stable. The posterior maxilla was vertically stable in 90% of the patients, the anterior maxilla in 80%. Horizontally, skeletal landmarks were stable in 80%, but when changes occurred, there was a tendency for the anterior maxilla to move back when it had been advanced. After the first 6 weeks, the posterior maxilla was stable vertically in all patients, but in 20% anterior maxillary landmarks moved downward, opposite to the direction of movement during fixation. In 11 of the 15 patients who demonstrated vertical changes postsurgery, the movement from fixation release to 1 year follow-up was opposite and approximately equal to the initial change, so that the net movement after 1 year was less than 2 mm. Only 6.5% (four patients) demonstrated 2 mm or greater net vertical movement for any of the variables studied 1 year after surgical treatment. There was no indication that the amount of presurgical orthodontic movement of incisors, the presence of multiple segments at surgery, the age of the patient, the presence or absence of genioplasty, or the presence or absence of suspension wires was a risk factor for instability.

Stability of mandibular advancement after sagittal osteotomy with screw or wire fixation: A comparative study

Stability and clinical results in 70 patients who underwent bilateral sagittal ramus osteotomy for mandibular advancement were studied. The patients were grouped by the method of fixation (screws vs. wire) and matched for the amount of advancement. There were 35 patients in each group, and the age, sex, and presurgical mandibular plane angle distributions were similar for the two groups. Although the pattern of skeletal and dental changes during the first postsurgical year were quite different for the groups, stability, incisal opening, and clinical results were equivalent at 1 year following surgery. In the first 6 weeks postsurgery, the screw fixation group was more stable horizontally and vertically than the wire group, but between 6 weeks and 1 year, the wire group showed recovery, and the mean differences all but disappeared.

The effect of orthognathic surgery on occlusal force

To investigate the effect of orthognathic surgery on occlusal force, such force was measured during maximum effort, chewing, and swallowing in 70 patients who had superior repositioning of the maxilla and/or mandibular advancement or setback. Larger changes in occlusal force than could be accounted for by the altered geometry were observed in all groups. Of 15 patients who had only superior repositioning of the maxilla, ten had greater than 20% increase in occlusal force, three had little change, and two showed a greater than 20% decrease. When the mandible was advanced, 11 of 34 patients had greater than 20% increase in maximum biting force, 11 had little or no change, and 12 had greater than 20% decrease. When the mandible was set back, six of the 21 patients had greater than 20% increase, nine had little or no change, and six had greater than 20% decrease. It appears that considerable change in bit force, which is not primarily related to jaw geometry, occurs after orthognathic surgery.