A Comparison of Torque Forces Used to Apply Intermaxillary Fixation Screws.

PURPOSE: When establishing intermaxillary fixation (IMF) using bone screws, fracture of a screw is a potential complication. This study was conducted to investigate the forces that arise at bone screw insertion and to determine safety margins between torque for manually tightened insertion and torque until breakage for 3 different IMF screw systems, which could ultimately favor the use of 1 IMF screw system based on decreased risk of complications. MATERIALS AND METHODS: IMF screws were placed into porcine mandibles by 3 oral and maxillofacial surgeons. The porcine mandibles were evaluated for cortical thickness and suitable insertion sites by cone-beam computed tomography. Measurements of torque until failure were performed on predrilled aluminum plates by the primary author. A digital torque screwdriver measured 180 data points per second as continuous data and recorded the measurements. RESULTS: Measurements indicated clear differences in torsion forces between manually tightened insertions and torque until breakage for all 3 IMF screw systems. No statistical difference in safety margins was found among the IMF screw systems. CONCLUSIONS: Because no statistical differences in safety margins were found among the IMF screw systems, this study indicates that IMF screw selection should be based on other clinical factors, such as ease of use or economic factors. Future prospective studies are necessary to fully determine evidence-based criteria for IMF screw selection.

Is There Enough Evidence to Regularly Apply Bone Screws for Intermaxillary Fixation in Mandibular Fractures?

PURPOSE: Intermaxillary fixation (IMF) is traditionally achieved with arch bars; however, this method has several well-known disadvantages and other techniques, such as bone screws, are available. This study evaluated current evidence regarding these IMF screws (IMFSs) for mandibular trauma and to assess whether this allows a change of treatment protocol for IMF. MATERIALS AND METHODS: A systematic electronic literature search was conducted in the PubMed, Embase, and Cochrane databases. Titles and abstracts retrieved from the search were screened and evaluated for inclusion and exclusion criteria. The full text of all relevant articles was read and citation lists were checked for any missing references. All randomized controlled trials (RCTs) were subjected to a quality assessment. Included articles were checked for outcome measurements concerning occlusion, operative time, oral hygiene, root trauma, wire-stick injuries, and mucosa overgrowth. RESULTS: Twenty-two articles (17 case series, 4 RCTs, and 1 cohort study) were included. None of the RCTs scored high methodologic results in the quality assessment. The results suggest IMFSs have similar malocclusion rates as arch bars, fewer wire-stick injuries, improved oral hygiene, and shorter operative time. Root damage is less likely to occur with self-drilling screws and seldom requires treatment. CONCLUSIONS: Although the methodologic quality of the included studies is poor, self-drilling IMFSs are recommended for temporary per-operative IMF of noncomminuted mandibular fractures. More high-quality studies are required to allow an evidence-based change of protocol.