David E. Frost

Internal screw fixation: Comparison of placement pattern and rigidity

Multiple screw placement patterns and techniques have been described for fixation of the sagittal split ramus osteotomy. This study evaluated transverse strength (rigidity) of six groups of simulated sagittal osteotomies fixed with different screw patterns and placement techniques. Osteotomies fixed with screws placed in an inverted L pattern were significantly more rigid than those fixed with screws placed in a linear pattern or K-wires placed in a triangular pattern (P less than .05). No significant difference in rigidity was noted between compression and bicortical screws placed in identical patterns.

Mandibular interpositional and onlay bone grafting for treatment of mandibular bony deficiency in the edentulous patient

The development of interpositional and onlay bone grafting techniques for atrophic mandibles is reviewed. A further modification of the visor osteotomy is presented along with follow-up evaluation of the conditions of 16 patients. Results of radiographic measurements show the procedure to be stable, vertical resorption of the augmented mandible in the body regions being 11.2% over a mean follow-up of 8.8 months. Neurosensory evaluation showed altered sensation and dysesthesia as a significant problem in these patients. The results are presented and discussed.

Revascularization and healing of onlay particulate allogeneic bone grafts in primates

Particle size of allogeneic bone grafts was investigated to determine its effect on revascularization and healing. Freeze-dried chips of different sizes were placed on the monkey lateral mandibular cortex, and the subsequent healing and revascularization were studied by histologic, autoradiographic, and microangiographic techniques. It appears that allogeneic bone is a reasonable substitute for autologous bone in mandibular ridge augmentation procedures.

Propofol and Fentanyl Compared With Midazolam and Fentanyl During Third Molar Surgery

PURPOSE The purpose of this study was to measure the safety and efficacy of propofol combined with fentanyl as sedative agents during third molar outpatient surgery. PATIENTS AND METHODS A double-blind, prospective, randomized clinical trial involving 57 patients undergoing removal of third molars under intravenous sedation between November 1994 and December 1995 was performed. Patients randomly received either propofol and fentanyl (P + F, th = 24) or midazolam and fentanyl (M + F, M = 33). Patient demographics, Corah anxiety scores, and physiologic parameters were determined preoperatively. All medications were titrated to the same clinical end point for sedation. Intraoperative physiologic parameters, cooperation, alertness, and pain scores were assessed. Postoperative recovery and degree of amnesia also were determined. RESULTS There were no significant differences in either patient demographics or surgical characteristics between groups. The P + F group was significantly less cooperative than the M + F group. Pain during injection of propofol was a significant adverse side effect. Both groups experienced a small percentage of apneic episodes, but mechanical ventilation was never required. There were no differences in recovery between groups as measured by the Treiger dot test and psychomotor recovery scores. The degree of anterograde amnesia was greater for the M + F group, although the difference was not statistically significant. Sedation was rated good to excellent by the patient, surgeon, and observer, and there were no statistically significant differences between groups. CONCLUSION Propofol appears to be a safe and efficacious drug for use during outpatient oral surgical procedures.

Lingual mandibular bone defect: report of three cases.

Two new cases of LMBD are reported here, and the use of CT for diagnosis is described. These two cases bring to 18 the number of anterior LMBDs reported, and to 3 the number of bilateral anterior LMBDs cases

Torque and pullout analysis of six currently available self-tapping and “emergency” screws

Insertional torque (IT), stripping torque (ST), and uniaxial pullout tests were performed to evaluate the effectiveness of six screw systems (Wurzburg, Techmedica, Synthes, Timesh, Steinhouser, Luhr) in thin porcine rib. The Timesh 2.2-mm self-tapping screw produced the largest insertional and stripping torque of all systems tested as well as the largest difference between the insertional and stripping torque. The Timesh emergency screw also had the largest insertional and stripping torque as well as the largest difference between the insertional and stripping torque. In pullout tests, the Timesh screw was found to be the most retentive. The overall data indicated that the ideal self-tapping screw should have the largest difference possible between drill size and external diameter, a channel, and at least three self-tapping threads for maximum retention.

Uniaxial pullout evaluation of internal screw fixation

Multiple techniques of internal screw fixation are being used in clinical oral and maxillofacial surgery. This study evaluated the uniaxial pull-out strength of five commonly used screws and Kirschner pins placed by five different techniques. The pull-out strength of the Kirschner pins was significantly less (P greater than .0001) than that of the screws. The screw techniques did not differ significantly.

Evaluation of metacarpal bone plates in the mandibular fracture

Of 1587 mandibular fractures, 75 (4.7 per cent) were treated by open reduction with metacarpal bone plates. The plated fractures were reviewed and evaluated for failure. Seventeen plates of the 96 placed were removed (17.7 per cent). Infection was the major cause of failure (9.4 per cent). Operator error played a role in the failure of eight out of 17 plates (47.1 per cent). Various aspects were studied in order to find the significant factors present, and these are discussed.

Healing of interpositional allogeneic lyophilized bone grafts following total maxillary osteotomy

Healing of allogeneic lyophilized bone grafted to total maxillary osteotomy sites was studied in Macaca fasciularis monkeys using histologic, microangiographic, and autoradiographic methods. Results of the study indicate that allogeneic lyophilized grafts are slowly replaced by host bone. Revascularization around the margins of the graft becomes evident at two weeks and increases until eight weeks; a hypervascular response is still present at six months. The palatal mucosa and facial gingiva provide an adequate nutrient pedicle for interpositional allogeneic grafts.

The effect of repetitive screw hole use on the retentive strength of pretapped and self-tapped screws☆

Multiple systems for internal screw fixation are presently in use in oral and maxillofacial surgery. These systems differ in screw diameter, material, and design. This study evaluated the uniaxial pullout strength of five screw systems. Two-millimeter, 2.7-mm, and 3.5-mm screws were initially evaluated for pullout strength. Pretapped and self-tapped screws were then inserted into the same hole multiple times before pullout testing. Results of pullout testing revealed no significant difference in pullout strength of pretapped and self-tapped screws of equal diameter (P greater than .05). Increased screw diameter produced increased pullout strength. No significant difference in pullout strength was noted in pretapped or self-tapped screws inserted into the same hole one, two, or three times before pullout testing (P greater than .05).