2017-18 HSC Section 3 Green Book

Volume 137, Number 1 • Hybrid Maxillomandibular Fixation System

Table 2. Medical Comorbidities Comorbidity

Table 6. Complications

No. of Patients (%)

No. of Patients (%)

No. of Screws (%)

Complication

No medical condition

5 (22) 15 (65) 4 (17) 3 (13)

Mucosal overgrowth Screw loosening

9 (38) 4 (17) 4 (17) 3 (13) 1 (4) 1 (4) 1 (4) 1 (4) 1 (4) 1 (4) 0 (0) 0 (0) 0 (0)

6 (1.9) 10 (3.1)

Smoking

Psychiatric disease Diabetes mellitus type 2

Lip irritation Malocclusion

N/A N/A N/A N/A N/A N/A N/A 0 (0) N/A

Hypertension

1 (4)

Nonunion/fibrous union Wound dehiscence

Screw loss

1 (0.31) 1 (0.31)

Table 3. Fracture Classification Type of Fracture

Tooth devitalization

Loose plate Plate fracture

No. of Patients

Wire or screw stick

Mandibular Le Fort II Le Fort III

35

Tooth loss Infection

1 2

N/A, not applicable.

Table 4. Location of Mandibular Fractures Location Right

healed uneventfully. There was one patient that had a loose plate requiring removal and healed uneventfully. There were no surgeon exposures to sharp instruments or wires. None of the patients developed infection and none of the patients in the study sample required extraction of teeth. These results are listed in Table 6. All patients had postoperative cone-beam com- puted tomographic imaging of the maxilla and mandible to evaluate whether there was damage to tooth roots from screw placement (Table 7). Each screw was evaluated to determine the degree of tooth involvement as follows: (1) no damage to tooth, (2) screw in periodontal ligament, (3) screw in dentin, (4) screw in pulp, or (5) root frac- ture. Two hundred ninety-five of the 319 screws (92.5 percent) that were placed and evaluated on cone-beam computed tomography did not dam- age teeth (no damage versus periodontal liga- ment involvement). Twenty-four of the 319 screws (7.5 percent) that were placed were damaging to tooth structure. Of the 24 teeth that were dam- aged, 21 (87.5 percent) had dentin involvement, one (4.2 percent) had pulp involvement, and two (8.3 percent) had root fractures. Only one of the damaged teeth (0.3 percent) required treatment Table 7. Evaluation of Screw Placement on Cone- Beam Computed Tomography* No. (%) No damage to tooth 295 (92.5)  No tooth involvement 142 (44.5)  Periodontal ligament involvement 153 (48.0) Damage to tooth 24 (7.5)  Dentin involvement 21 (6.6)  Pulp involvement 1 (0.3)  Root fracture 2 (0.6) No. of screws causing tooth damage and requiring treatment 1 (0.3) *Total no. of screws, 319.

Left

Symphysis

2 3 4 3 3 1

7 4 1 2 4 1

Body Angle Ramus

Subcondylar Condylar

Table 5. Placement and Removal of Hybrid Maxillomandibular Fixation System

Value

Total no. of screws placed Average no. of screws per patient Placement time per patient, min Placement time per screw, sec Removal time per patient, min Removal time per screw, sec

319 13.9 14.4 61.8 10.5

47

the hybrid maxillomandibular fixation system was 10.5 minutes (range, 4.6 to 17 minutes) and the average time to remove each screw was 47 seconds. The complications associated with the SMARTLock system were reviewed (Table 6). Nine patients had mucosal overgrowth of 16 total screws. There were four patients with 10 loose screws on removal. There was one patient with one screw lost. Four patients had lip irritation treated with orthodontic wax. Three patients reported malocclusion, and one of these required a future mandibular osteotomy because of noncompliance with maxillomandibular fixation. One patient had dehiscence of an intraoral surgical wound. One tooth was devitalized (tooth 8) and required endodontic therapy. One patient had nonunions requiring plate removal and placement of recon- struction plates. There was one plate fracture of a superior border plate placed at the left angle seen at the 6-week follow-up, and the patient had

10