Stability of bimaxillary osteotomy following surgical correction of class II skeletal deformities: a two-centre study.

This study compares the stability following bimaxillary osteotomy for correction of class II skeletal deformities between two groups of patients. One group (15 patients) were treated at Canniesburn Hospital, West of Scotland Regional Plastic and Maxillofacial Unit, UK. The other group (15 patients) were treated at Ann Arbor Michigan University Hospital, USA. All cases were treated by Le Fort I maxillary advancement/impaction and bilateral sagittal split advancement osteotomy. In all cases Le Fort I maxillary osteotomy was more stable than sagittal split advancement osteotomy. The maxilla stayed within 1 mm of its immediate postoperative position. The average mandibular advancement in Canniesburn cases was 6 mm and about 4 mm in Michigan cases. During surgery the condyles were displaced about 2 mm posteriorly in Canniesburn cases, but remain in their anatomic position in Michigan cases. At 6 months following surgery, Canniesburn patients showed a clockwise mandibular relapse. This increased both the mandibular plane angle and ramus angle by 2.7 degrees and 2.9 degrees respectively. The mandible settled posteriorly 1.7 mm and inferiorly 1.5 mm. In Michigan cases the mandible stayed within 1 mm of its immediate postoperative position. The difference in mandibular relapse between the two groups was statistically significant (P < 0.05). The differences in the stability between the two groups are investigated and the theories of mandibular relapse following sagittal split osteotomy are discussed.

Frequency of radiopaque turbinate bones on lateral cephalometric radiographs.

The lateral cephalometric radiograph of an orthodontic patient demonstrated a large round radiopaque mass resembling an osteoma in the posterior maxillary sinus. Determination that this mass was simply a prominent inferior turbinate bone prompted this study to determine the frequency of visible turbinates on cephalometric radiographs. After calibration, one observer evaluated 479 pretreatment lateral cephalometric radiographs from an orthodontic/orthognathic surgery patient pool for radiopaque inferior turbinates. Ten percent of the films were reevaluated to assess intraexaminer reliability. The sample had a mean age of 23 years, range of 5 to 69 years, with a male/female ratio of 1:15. Visible inferior turbinates were observed on 76.8% of the radiographs. The frequency of visible turbinates was independent of gender, age, and film density. Clinicians should be aware of the frequency of this anatomic finding, so that patients are not subjected to unnecessary diagnostic tests.

Arch dimensional changes in children with idiopathic short stature treated with recombinant growth hormone: a five-year study.

Recombinant human growth hormone (rhGH) increases stature when administered to non-GH-deficient idiopathic short statured children. The aims of this investigation were to determine pretreatment arch dimensions of short statured children (height > or = 2 S.D. below mean for age) and to evaluate their response to rhGH administration by measuring arch-dimensional changes over 5 years of rhGH treatment. Dental casts of 28 short subjects (22 male, 6 female) and of age/gender-matched controls of normal stature were analyzed using a digital imaging system. Four measures of arch width and one of arch depth were calculated for each maxillary and mandibular cast. Subjects receiving orthodontic care were eliminated from the study at the initiation of treatment. Z-scores were calculated to allow for pooling of data. Prior to rhGH treatment, all arch dimensions of the short statured subjects were smaller than the controls, with the exception of mandibular arch depth. Arch dimensions of the rhGH subjects did increase with the continued administration of rhGH. The control group also showed a significant trend for the arch dimensions to increase over time. The influence of rhGH treatment on arch dimensional changes over time remains equivocal based on the results of this investigation.

Autoradiographic study of the effects of pulsed electromagnetic fields on bone and cartilage growth in juvenile rats.

Application of pulsed electromagnetic fields (PEMF) has been used in growth and repair of non-union bone fractures. The similarities between the fibrocartilage callus in non-union bone fractures and the secondary cartilage in the mandibular condyle, both histologically and functionally, lead naturally to study the effects of PEMFs on growth in the condyle. The purposes of this study were: (1) to describe the effects of PEMFs on the growth of the condyle using autoradiography, [3H]-proline and [3H]-thymidine, and (2) to differentiate between the effects of the magnetic and electrical components of the field. Male pre-adolescent Sprague-Dawley rats (28 days old) were divided into three experimental groups of five animals each: (1) PEMF-magnetic (M), (2) PEMF-electrical (E) and (3) control, and were examined at three different times-3, 7 and 14 days of exposure. Each animal was exposed to the field for 8 h per day. Histological coronal sections were processed for quantitative autoradiography to determine the mitotic activity of the condylar cartilage and the amount of bone deposition. The PEMF (magnetic or electrical) had statistically significant effects only on the thickness of the articular zone, with the thickness in the PEMF-M group being the most reduced. Length of treatment was associated with predictable significant changes in the thickness of the condylar cartilage zones and the amount of bone deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Associations between severity of dentofacial deformity and motivation for orthodontic-orthognathic surgery treatment.

The successful outcome of orthognathic surgery is related to patient satisfaction and motivation. The aim of this retrospective study was to analyze the association between 1) severity of dentofacial deformity derived from cephalometric measures and 2) patient motivation for treatment. The initial cephalograms of 142 patients aged 16 years or older from the Dentofacial Program of the University of Michigan were traced and digitized. Inclusion criteria were established by assigning ANB 4 degrees to 15 degrees to define severe skeletal Class II (n = 65) and ANB - 15 degrees to -4 degrees to define severe skeletal Class III (n = 20). Motivation for orthodontics and surgery was derived from clinician administered forms scaled 1-10 with Low (1-5) and High (8-10). The cephalometric measure ANB was significant (p = 0.02) for high/low motivation for orthodontic treatment using Student's t test. No other cephalometric measures were significant for high/low motivation for orthodontics or surgery using Student's t test. Class II patients were significantly (p = 0.014) more motivated than Class III patients for orthodontic treatment. No significant difference was found for motivation for surgery between skeletal Class II and skeletal Class III patients. Patients with severe sagittal Class II deformities had higher motivation for orthodontics than surgery. The cephalometric measure, ANB, defining severe skeletal Class II and Class III patients did predict motivation level for orthodontics. None of the other 18 cephalometric measures were predictive of patient motivation for either orthodontics or surgery.

The Dentofacial Deformity Program of the University of Michigan: organization, analysis of data, and benefits of program.

The Dentofacial Deformity Program of the University of Michigan was established in 1984 to provide a consulting service for the diagnosis, treatment recommendations, and management of patients with dentofacial deformities. This program was designed as a service commitment for the patient, referring doctors, and the medical and dental communities. Educational and research aspects of the program provide benefits for orthodontic and oral and maxillofacial surgery graduate students, and the dental school faculty. The organization, data analysis, and education, research, and service benefits of this program are discussed.