Resorbable screw fixation for cortical onlay bone grafting: a pilot study with preliminary results.

PURPOSE: The current "gold standard" in alveolar ridge augmentation is autogenous bone grafting. Autologous cortical onlay grafts provide predictable increases in bone volume when used for alveolar ridge augmentation; however, rigid fixation of the graft to the recipient site is essential. Titanium screws are commonly used to provide rigid fixation for onlay grafting but have potential drawbacks including the need for a second surgery for removal before implant placement and screw fracture during removal. The present study investigated the efficacy of resorbable fixation screws to secure autologous cortical onlay grafts to the maxilla or mandible to augment alveolar bone height and/or width before implant placement. PATIENTS AND METHODS: Eleven patients requiring alveolar ridge augmentation were enrolled in this study. All patients received autologous cortical onlay grafts. Patients were randomly assigned to receive grafts fixated with 2.0-mm resorbable (experimental) or 1.5-mm titanium (control) screws. Integration and survivability of the graft was assessed using cone-beam computed tomography. Graft resorption was calculated at 4 to 7 months postoperatively and used as a quantitative outcome measurement. Statistical analysis was performed using NCSS/PASS (Dawson edition; Kaysville, UT) for Windows XP. Data are presented as mean ± standard error of the mean. Intergroup differences were assessed using Student's t test. RESULTS: Nine of the 11 patients initially enrolled completed the study. In these patients, 12 bone grafts were placed, 4 fixated with 2.0-mm resorbable screws and 8 fixated with 1.5-mm titanium screws. Integration and survivability of the grafts was 100% regardless of fixation type. Cone-beam computed tomographic data indicated that all grafts integrated regardless of fixation type. At 5 to 7 months postoperatively, cone-beam computed tomographic analysis indicated there were 28.07 ± 3.15% and 40.03 ± 3.67% bone resorption in grafts fixated with 2.0-mm resorbable and 1.5-mm titanium screws, respectively (P > .05). CONCLUSION: These data suggest that cortical onlay graft integration and survivability are similar using 2.0-mm resorbable or 1.5-mm titanium screw fixation. Therefore, use of resorbable fixation devices in alveolar ridge augmentation will obviate screw removal, which may result in screw breakage and may be difficult if bony overgrowth occurs. Further studies need to be performed with a larger sample to confirm these data.

Retrograde and submental intubation.

Direct laryngoscopy remains the technique of choice for placing an endotracheal tube (ETT). However, alternative techniques are needed for the difficult airway or unsuccessful intubation. Retrograde intubation may be used in adult or pediatric patients, whether awake, sedated, or obtunded. Contraindications include nonpalpable neck landmarks, pretracheal mass, severe flexion deformities of the neck, tracheal stenosis, coagulopathies, and infections. Submental intubation allows simultaneous access to the dental occlusion and nasal pyramid without the morbidity associated with tracheostomy. Contraindications include patients who require long periods of assisted ventilation and a severe traumatic wound on the floor of mouth. Complications include localized infection and sepsis, poor wound healing or scarring, and postoperative salivary fistula.

Activation of intrinsic and extrinsic finger muscles in relation to the fingertip force vector.

Surface EMG was recorded from two intrinsic and two extrinsic muscles of the index finger during a two-dimensional isometric force task in the plane of flexion and extension. Subjects applied force isometrically at the fingertip in eight equally spaced directions, encompassing 360 degrees. Target forces spanned the range from 20% to 50% of maximum for each direction. The effect of varying the metacarpophalangeal (MCP) and interphalangeal (IP) joint angles was investigated. We found that when applying isometric force with the fingertip, the intrinsic muscles of the index finger behaved as a single unit whose region of activation overlapped that of the extrinsic flexor and extensor muscles. The activation region of the intrinsic muscles also spanned a range of force directions for which the extrinsic muscles were virtually inactive. The activation of all muscles, with the exception of the extrinsic extensor, was modified by changing the MCP and IP joint angles. Both IP flexion and MCP extension produced rotation of the resultant activity vector in the direction of MCP flexion. However, the relative rotation was much greater with IP flexion than MCP extension. The effect of IP flexion is linked to rotation of the force direction where joint torque switches from extension to flexion, while the effect of MCP extension is more likely related to changes in muscle length and MCP moment arm. Our results suggest that the primary role of intrinsic finger muscles is to precisely control the direction of fingertip force, while extrinsic muscles provide stability of the joints.