Treatment Outcomes With the Use of Maxillomandibular Fixation Screws in the Management of Mandible Fractures

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1 CRANIOMAXILLOFACIAL TRAUMA Treatment Outcomes With the Use of Maxillomandibular Fixation Screws in the Management of Mandible Fractures Griffin Harold West, DMD,* Jason Alan Griggs, PhD,y Ravi Chandran, DMD, PhD,z Harry Vincent Precheur, DMD,x William Buchanan, DDS, MMdSc,k and Ron Caloss, DDS, MD{ Purpose: The purpose of this prospective randomized study was to assess whether uncomplicated mandible fractures could be treated successfully in an open or closed fashion using maxillomandibular fixation (MMF) screws. Materials and Methods: This was a prospective institutional review board approved study involving 20 adult patients who presented to the university emergency department or oral and maxillofacial surgical clinic with uncomplicated mandible fractures. Patients who met the exclusion criteria consented to enter the study in the open reduction internal fixation (ORIF) or the closed (MMF) study group. Six to 8 MMF screws were used to obtain intermaxillary fixation (IMF) in the 2 groups. Screw failure was documented. All screws were removed at 5 to 6 weeks postoperatively. Insertional torque (IT) was measured at time of screw placement to assess primary stability. Clinical and photographic documentation was performed to assess fracture healing, occlusion, and gingival health. Ten-centimeter visual analog scales were used to assess patient-centered outcomes. Cone-beam computed tomography was performed to assess the longterm effects on the periodontium and roots. A cost comparison was performed to determine whether the use of screws was cost effective compared with arch bars. Results: Fifteen men and 5 women (mean age, 25.2 yr) entered the study. All patients displayed adequate fracture healing based on clinical examination. All patients had acceptable occlusion at 5 to 6 weeks postoperatively. Total screw failure was 27 of 106 screws (25.5%). Forty percent of screws placed in the MMF group failed compared with only 6% in the ORIF group. Gingival health scores were favorable. Factors that had a significant effect on screw failure included a lower IT (P =.002), use in closed (MMF) treatment (P <.001), and use in the posterior jaw (P =.012). Minimal pain was associated with the MMF screws and pre-existing occlusion was re-established based on patients subjective responses. The MMF group reported a statistically significant lower quality of life (P <.001) compared with the ORIF group. There was only 1 screw site that had a facial cortical bone defect noted at 6-month follow-up CBCT examination. There were no discernible long-term root defects. Cost analysis showed that the use of MMF screws saved around $600 per patient in operating room usage cost alone compared with the estimated use of arch bars. Conclusions: Uncomplicated mandible fractures were successfully treated using MMF screws in open and closed treatments. However, the utility in closed treatment was decreased because of significant screw failure and patient noncompliance. The screws were well tolerated by the patients. There was minimal long-term damage to the periodontium and dental roots. The cost of screws was more than offset by time savings. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72: , 2014 Received from the University of Mississippi Medical Center, Jackson, MS. *Resident, Department of Oral-Maxillofacial Surgery and Pathology. yprofessor, Department of Biomedical Materials Science. zassistant Professor, Department of Oral-Maxillofacial Surgery and Pathology. xprofessor Emeritus, Department of Oral-Maxillofacial Surgery and Pathology. kprofessor, Department of Periodontics and Preventive Sciences. {Associate Professor, Interim Chairman and Program Director, Department of Oral-Maxillofacial Surgery and Pathology. This study was funded by a grant from Stryker Craniomaxillofacial. Address correspondence and reprint requests to Dr Caloss: Oral and Maxillofacial Surgery and Pathology, University of Mississippi Medical Center, 2500 N State St, Jackson, MS 39216; rcaloss@umc.edu Received May Accepted August Ó 2014 American Association of Oral and Maxillofacial Surgeons /13/ $36.00/

2 WEST ET AL 113 Intermaxillary fixation (IMF) is germane to mandibular fracture reduction and the re-establishment of occlusion. Various techniques can be used. 1-4 Erich arch bars traditionally have been the standard. 4,5 Although arch bars provide reliable fixation, they have several disadvantages, including the time required to place them, risk for needle or sharps stick, patient discomfort, and trauma to the periodontium. 6 Transmucosal maxillomandibular fixation (MMF) bone screws were first described in a 4-point fixation pattern. 7,8 Bone screws have offered several advantages over arch bars, including relatively simple application and removal, time savings, decreased risk of needle or sharps stick, and improved oral hygiene and periodontal health. 1,4,9 More recent studies have reported the outcomes of MMF screws in the management of trauma However, few of these studies have evaluated MMF screw performance in a prospective and systematic manner. The purpose of this prospective study was to assess whether uncomplicated mandible fractures could be treated successfully using MMF screws to provide IMF. The main treatment outcomes evaluated were fracture union and occlusion. Several other outcomes that could have a direct or indirect effect on treatment also were evaluated, including screw failure in the perioperative period and factors contributing to screw failure, long-term effects of screws on the periodontium and roots, patient-centered outcomes, and cost effectiveness of MMF screws. Materials and Methods This was a prospective institutional review board approved pilot study that assessed the use of MMF screws to manage 20 adult patients presenting with uncomplicated mandible fractures, as defined by strict exclusion criteria (Table 1). These exclusion criteria were established to eliminate confounding factors, such as compromised occlusion and unstable fracture patterns. Eligible patients presented to the University of Mississippi Medical Center emergency department or oral and maxillofacial surgery clinic. Patient age and gender, cause of injury, and fracture pattern were recorded. Four fracture patterns, including symphysis, angle or body, symphysis and angle or body, and double angle or body, were treated in the study. Men and women consented separately to enter into the open reduction internal fixation (ORIF) or closed (MMF) treatment group in an alternating fashion. This was to ensure an even number of male and female patients in each treatment group. TREATMENT PROTOCOL AND INSERTIONAL TORQUE RECORDING Six to mm Food and Drug Administration approved MMF screws (Stryker Craniomaxillofacial, Kalamazoo, MI) were placed at the mucogingival junction to obtain IMF in the 2 groups. Screws were placed between the 2 central incisors and between the second premolars and first molars in most patients. Alternatively, screws were placed between the lateral incisors and canines and between the second premolars and first molars. The principal investigator (R.C.) placed all screws. Screws were driven into bone at least three-fourths of the way with a normal driver. The time to perform this was recorded as the insertion time. The remainder of the screw insertion was performed using an insertional torque (IT) screwdriver (Stanley Proto Industrial Tools, Covington, GA) recording in ounce inches. The measurements were subsequently converted to Newton centimeters. Mean ITs for the ORIF versus MMF group and successful versus failed screws were calculated later. Mean ITs for male versus female patients and jaw location were analyzed to determine whether certain factors might affect IT and predict screw failure. All patients were placed into IMF initially. In the ORIF group, IMF was released after fixation hardware was placed. MMF screws were maintained postoperatively for guiding elastics, if needed. In the MMF group, patients were left in IMF for 5 to 6 weeks, unless screw failure prohibited the maintenance of IMF. Screws were removed at 5 to 6 weeks postoperatively or when determined to have failed. Screw failure was defined as loss of screws before 5 to 6 weeks. This was due to having loose nonfunctional screws that the authors removed or screws that the patients removed on their own for whatever reason. If a screw was loose but still functional or there was mucosal overgrowth that prevented placement of guiding elastics, the screw was noted as failing. CLINICAL DOCUMENTATION OF FRACTURE HEALING, OCCLUSION, AND GINGIVAL HEALTH Clinical documentation of fracture healing and screw failure was performed at 1-, 3-, and 5- to 6-week postoperative visits. Standardized photographs of centric occlusion (frontal and lateral views) were performed with a Canon D50 digital camera (Canon USA, Inc, Melville, NY) with ring flash at preoperative, intraoperative, and 5- to 6-week postoperative time points. The photographic series for each patient were placed side by side in a PowerPoint (Microsoft, Redmond, WA) slide presentation for examiners to assess occlusion and gingival health (Fig 1). Two board-certified oral and maxillofacial surgeons ranked each patient s 5- to 6-week postoperative occlusion as acceptable or unacceptable compared with the centric occlusion established when the patient was in IMF intraoperatively. A board-certified periodontist compared preoperative with 5- to

3 114 FIXATION SCREWS FOR MANDIBULAR FRACTURE Table 1. EXCLUSION CRITERIA 1 Fracture(s) of the mandible involving the condylar head or neck 2 Presence of comminution or severe displacement (defined as >1-cm displacement of segments in any direction) 3 Presence of mixed dentition or unerupted permanent teeth (excluding third molars) 4 <18 years old (facial growth incomplete) 5 Concomitant maxillary or Le Fort fractures (other facial fractures are allowed) 6 Alveolar process fracture in the maxilla and mandible 7 Partial edentulism resulting in unstable posterior centric occlusion that will compromise adequate fracture reduction and stabilization 8 Overjet #5 mm 9 Mandibular fracture pattern that could prohibit adequate reduction and stabilization with the authors MMF screw scheme (ie, fracture extending through planned MMF screw sites, bilateral midbody fractures, unilateral double fractures) 10 Lack of primary stability of sufficient number of MMF screws necessary to obtain MMF; adequate primary stability is a judgment by a clinician when a screw does not freely spin when fully inserted into bone 11 General contraindications to MMF, including psychological disorder, seizure disorder, airway compromise, immunocompromise, and other conditions considered unfavorable for MMF treatment 12 Pregnant or breast-feeding woman 13 Non English-speaking patients: in this pilot study the authors needed to be assured that they had the best communication with patients; a communication barrier may adversely affect outcome assessment; the authors do not have routine access to a Spanish translator in the dental school Abbreviation: MMF, maxillomandibular fixation. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg week postoperative gingival inflammation using a 3-point Likert scale (no or mild, moderate, or severe increase in gingival inflammation). The periodontist also graded the inflammation just around the MMF screws at 5 to 6 weeks using a 3-point Likert scale (no or minimal, moderate, or severe inflammation). CONE-BEAM COMPUTED TOMOGRAPHIC ASSESSMENT OF SCREW EFFECT ON ROOTS AND PERIODONTIUM Cone-beam computed tomographic (CBCT) examinations were performed at 1 week and 6 months postoperatively using an ILUMA (IMTEC, Ardmore, OK) or i-cat (Imaging Sciences International, LLC, Hatfield, PA) machine with a slice thickness of 0.1 to 0.4 mm. Digital Imaging and Communications in Medicine (DICOM) data for each scan were transferred into Dolphin Imaging 7.5 (Dolphin Imaging and Management Solutions, Chatsworth, CA) for viewing axial images because of the metal artifactreduction feature of this program. The same 2 board-certified oral and maxillofacial surgeons assessed screw proximity to roots using the 1-week postoperative CBCT image. They noted screws as penetrating the roots, approximating the root surface, or having a discernible space between the screw and the root. The 6-month follow-up CBCT image was used to assess the long-term effects on the interradicular bone and roots. Axial images were used for all assessments. PATIENT-CENTERED OUTCOMES A 10-cm visual analog scale (VAS) was administered to assess patient-centered outcomes at the 5- to 6-week postoperative visit. These included quality of life (QOL; ability to carry out daily activities, such as talking, chewing, and swallowing) after surgery, pain associated with the MMF screws, and subjective occlusal and bite changes. COST COMPARISON A cost comparison of screws and arch bar use was performed to determine whether the time savings with the use of screws would offset their increased cost. The arch bar cost was estimated from the assumption that 1 hour of operating room (OR) time would be used (45 minutes to place and 15 minutes to remove). STATISTICAL ANALYSIS Multiple logistic regression analysis was performed to assess factors that had a significant effect on screw failure. Factors assessed included treatment type (MMF or ORIF) jaw location (maxilla vs mandible and anterior vs posterior), male gender, female gender, IT, and time of entry into the study. A forward stepwise regression model of patient-centered VAS data was performed. Results Twenty patients (15 male, 5 female; mean age, 25 yr) entered the study and contributed some form of data.

4 WEST ET AL 115 FIGURE 1. Occlusion. INTRAOP, intraoperative; POW 5-6, postoperative week 5 to 6; PREOP, preoperative. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg Eleven patients were in the ORIF group and 9 were in the MMF group. Seventeen patients returned for 5- to 6-week follow-up examination to assess fracture healing, occlusion, and screw failure. Only 7 patients returned for a follow-up 6-month postoperative CBCT examination. The main cause of fracture was assault (n = 16) followed by motor vehicle collision (n = 4). Fracture patterns included symphysis (n = 2), angle or body (n = 9), symphysis and angle or body (n = 5), and double angle or body (n = 4). Noncompliance was an issue for some patients. Three patients in the MMF group removed the MMF wires on their own by 3 weeks. They were maintained on a soft diet and healed without complication. Two patients were completely lost to follow-up 1 immediately after surgery and 1 after the 1-week postoperative visit. One patient did not appear at the 5- to 6-week visit, but came in 4 months after his surgery. Thirteen patients did not return for the 6-month evaluation. FRACTURE HEALING AND OCCLUSION There was successful fracture treatment noted in all 18 patients who had appropriate follow-up. Sixteen of 17 patients who returned at 5 to 6 weeks were noted to have adequate fracture union. One patient, who smoked and had poorly controlled diabetes, was noted to have failed hardware, osteomyelitis, and delayed union of his angle fracture at this time. He underwent hardware removal and wound debridement and was maintained on antibiotics and a soft diet. He subsequently showed clinical and radiographic fracture union. Sixteen patients had 5- to 6-week photographs available and all were noted to have acceptable occlusion by the 2 examiners. Postoperative guiding elastics were rarely required in the ORIF group. SCREW FAILURE AND ASSESSMENT OF CONTRIBUTING FACTORS The overall screw failure rate was 25 of 106 screws (24%). Most screw failures did not occur until 5 to 6 weeks and most of these screws were noted to be failing (loose) at 3 weeks (Fig 2). Most screws failed owing to mobility. However, 2 patients in the MMF group removed a total of 7 screws on their own. Twenty-two of 52 screws (42%) placed in the MMF group failed compared with only 3 of 54 screws (6%) placed in the ORIF group. Six of 8 patients (75%) in the MMF group had at least 1 screw fail compared with only 2 of 9 (22%) in the ORIF group. Of note, 50% of screw failures in the MMF group occurred in 2 patients. These patients were noncompliant with care and removed the IMF wires on their own.

5 116 FIXATION SCREWS FOR MANDIBULAR FRACTURE Screw failures by study group, gender, and jaw locations are shown in Figure 3. As noted earlier, 42% of screws placed in the MMF group failed compared with only 6% placed in the ORIF group. Being in the MMF group was a significant factor contributing to failure (P <.001). Twenty-nine percent of screws placed in the posterior jaw location failed compared with only 14% placed in the anterior jaw. Posterior jaw location was a significant factor contributing to failure (P =.012). Twenty-eight percent of screws placed in the maxilla failed compared with 19% in the mandible; however, there was no significant difference (P >.10). The mean IT was 20 N-cm for the 124 screws placed. Figure 4 shows the mean IT for failed versus successful screws. A lower IT contributed to screw failure (P =.002). Mean IT by treatment type, male vs female gender, and jaw location is shown in Figure 5. EFFECTS OF SCREWS ON THE GINGIVA, BONE, AND ROOTS Gingival health scores were favorable. All 16 patients were noted to have no or minimal increase in gingival inflammation during the treatment period. Some screws were noted to have significant plaque buildup. However, only 9 screws exhibited unfavorable mucosal changes. These included mucosal overgrowth (n = 7), hyperkeratosis (n = 1), and marginal gingival recession (n = 1). Most (n = 5) screws with mucosal overgrowth were in the mandibular midline position. Nineteen patients had 1-week postoperative CBCT evaluation performed for analysis of 118 screws. Root proximity scores of the 2 examiners were averaged. Seventy-two percent of screws were approximating the root surfaces, 14% were penetrating the roots, and 14% had a discernible space between the screw and roots. Only 7 patients returned for the 6-month follow-up CBCT evaluation. Forty-two screw sites were evaluated on these scans. There was only 1 screw site that had a facial cortical bone defect noted by the two oral and maxillofacial examiners. There were no discernible root defects noted. PATIENT-CENTERED QOL Fifteen patients completed the VAS assessment of QOL, pain related to MMF screws, and occlusal and bite changes. Minimal pain was associated with the MMF screws. The mean score was 1.87 (0 = no pain, 10 = intolerable pain). Pre-existing occlusion was subjectively re-established. The mean score was 2.6 (0 = same bite, 10 = totally different bite). Overall selfreported QOL was good as defined by the ability to carry on daily functions of talking, chewing, and swallowing. The mean score was 2.2 (0 = good function, 10 = poor function). The MMF group reported a statistically significant decrease in QOL compared with the ORIF group (P <.001). The respective scores were 5.1 and 0.3. COST COMPARISON A cost comparison showed that MMF screws saved $661 per patient compared with the arch bar estimate. This was due to the decrease in OR time required to place the screws. The average time per patient to place screws was 4 minutes exactly. The authors estimated it would take 1 hour of OR time to place and remove arch bars. At the authors university hospital, the OR usage cost is $1,274 per hour. The cost per screw is $88. This cost savings estimate does not consider the work time saved for surgeons (Table 2). Discussion FIGURE 2. Failed and failing screws. POW 1, postoperative week 1; POW 3, postoperative week 3; POW 5-6, postoperative week 5 to 6. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg This study enrolled patients over a 22-month period. The oral and maxillofacial surgical service treats on average 100 mandible fractures per year. It was difficult to enroll patients into the study. Prisoners were automatically excluded, which is a sizable portion of the authors patient population. Relatively few patients met the strict exclusion criteria that were in place (Table 1). The authors excluded patients with subcondylar and alveolar process fractures, comminuted or severely displaced fractures, and unstable occlusion. The present patient population included only those with relatively straightforward angle, body, or symphysis fractures and relatively good dentition. The authors did not want to introduce confounding variables that might negatively affect treatment. That being said, the authors routinely use MMF screws in patients who met the exclusion criteria that were in place.

6 WEST ET AL 117 FIGURE 3. Screw failures. MMF, maxillomandibular fixation; ORIF, open reduction and internal fixation; Tx, treatment. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg For instance, if a patient has a subcondylar fracture with fallback, MMF screws will be offset to allow for a Class II elastic pattern postoperatively to control the occlusion. The authors still prefer arch bars in compromised situations, such as severely comminuted or alveolar process fractures. Arch bars are not necessarily a prerequisite to acceptable outcomes. Bell and Wilson 14 found no difference in treatment outcomes or complications in their cohort of 162 patients with mandible fracture treated by 2 methods of intraoperative IMF (Erich arch bars and interdental stout wires) or manual reduction with placement of ORIF. Dimitroulis 15 found no difference in fracture reduction or occlusion in ORIF of isolated angle fractures of the mandible treated with versus without IMF using arch bars. All 18 patients with appropriate follow-up were noted to have acceptable fracture healing and occlusion. Guiding elastics were rarely required in the postoperative period to control occlusion in the ORIF group. This may be due to exclusion of patients with FIGURE 4. Mean insertional torque failure versus success. Error bars signify 95% confidence interval. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg factors, such as unstable occlusion, and complicated fracture patterns. These factors should be considered if MMF screws are used because they do not provide as much control of occlusion postoperatively. Although there was no final ill effect on fracture healing or occlusion, the utility of MMF screws for closed treatment was limited because of the high failure rate and lack of patient compliance. There would likely be complications in a noncontrolled setting where patients are not screened and meet the exclusion criteria the authors had in place. The small sample limits the authors ability to draw conclusions. MMF screws did not reliably provide 5 to 6 weeks of IMF for closed treatment. Screw failure was significantly higher in the MMF group compared with the ORIF group. Most screws failed because of significant mobility after 3 weeks. Continued force placed across the screw heads during the postoperative period played a role in failure. There was no time for screw integration into bone before functioning. The fact that screws were composed of stainless steel and not a titanium alloy may have been detrimental for integration. Other studies have reported screw loosening as a common complication Noncompliance with care also was a factor in failure in the closed treatment (MMF) group. Seven of the 22 screws failed because patients removed the screws. Three patients in the MMF group cut their wires by 3 weeks. All fractures in these patients healed with no other treatment, most likely because they had single nondisplaced or minimally displaced angle or symphysis fractures. IMF is easier to release when MMF screws are used compared with arch bars and this should be considered when treating noncompliant patients. IT is a parameter used to evaluate the biomechanical performance of screws placed into bone. 16,17 IT is the result of frictional resistance between screw threads and bone and determines primary stability. To the authors knowledge, there are no clinical studies that have documented the IT of MMF screws in this setting. MMF screws placed in alveolar bone should have less primary stability compared with the basal

7 118 FIXATION SCREWS FOR MANDIBULAR FRACTURE FIGURE 5. Mean insertional torque. MMF, maxillomandibular fixation; ORIF, open reduction and internal fixation; Tx, treatment. Error bars signify 95% confidence interval. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg bone of the jaws owing to less cortical bone thickness. IT showed a statistically significant effect on screw failure. Those with a lower IT were more likely to fail. The present study was too small to determine whether factors such as jaw location or patient gender affect IT and screw stability. The effect of screw dimension (length and diameter) was not tested in this study. Posterior jaw location also was a significant factor in failure. This is most likely due to greater forces being generated in the posterior jaw regions from the Class III lever effect of the maxillomandibular complex. The authors did not see a significant increase in IT in the posterior jaw regions that might overcome this effect. This suggests that the inter-radicular alveolar bone is not of better quality in the posterior jaw regions. Although more screws failed in the maxilla than in the mandible, it was not statistically significant in the multiple logistic regression analysis. Coletti et al 11 and Rai et al 13 found that failure rates were similar in the maxilla and mandible. This may be due to the alveolar inter-radicular bone quality not being significantly different in the 2 jaws. This study was too small to fully Table 2. ANALYSIS OF TIME AND COST SAVINGS ASSOCIATED WITH MMF SCREWS Treatment Type OR Time OR Cost ($1,274/hr) MMF screws (placement 4 minutes $85 only) Arch bars (placement + 1 hour $1,274 removal) OR savings 56 minutes $1,189 MMF screw cost: 6 screws $528 at $88/screw Total cost savings $661 Abbreviations: MMF, maxillomandibular fixation; OR, operating room. West et al. Fixation Screws for Mandibular Fracture. J Oral Maxillofac Surg appreciate the effect of all factors that may be relevant to predict screw failure. A larger sample is needed to analyze all possible combinations of factors that may have an effect on screw failure. Gingival health was not an issue with MMF screws for the most part in this study. Although they did not compare MMF screws with arch bars, the authors experience indicates that the short-term gingival health associated with MMF screws is better than with arch bars. Rai et al 13 found that oral hygiene as measured by the plaque index was better in patients with MMF screws than with arch bars in their comparison study. The only major short-term negative effect in the present study was mucosal overgrowth, mostly in the mandibular midline, owing to frenum pull. Consideration should be given to place screws off the midline if they are left postoperatively to avoid this problem. There was significant variation between the two examiners reading of screw proximity to the roots. This was likely, in part, due to the quality of the scans and metal scatter that occurred from the stainless steel screws. The initial 8 patients had scans with 0.1mm slice thickness using the ILUMA machine. The rendering of these scans caused significant metal scatter. On all subsequent patients the scan thickness was increased to 0.4 mm (for the ILUMA) and 0.25 mm (for the i-cat). This reduced the metal scatter significantly and made it easier to assess the screw-root interface. Another factor that may account for variation in readings is that the examiners where not calibrated. There were no long-term complications noted with the dental roots approximating screws at the 6-month follow-up CBCT evaluation. On average, 72% of the screws were approximating the roots and 14% were penetrating the roots on CBCT images. Because the screws were self-drilling and no rotary instruments were used, the screws likely deflected off the roots most of the time instead of penetrating the surface. The inter-radicular bone seemed to heal well once the screws were removed. There was only 1 site that had a facial bone defect noted by the two examiners.

8 WEST ET AL 119 The principle investigator noted 3 additional sites having incomplete bone fill or a facial cortical defect. They were minimal and did not seem to have any ill-effect on the overall periodontal support of the teeth. Again, scan quality and lack of examiner calibration may have played a role in this variation. Three of the seven 6-month follow-up scans were done with the ILUMA machine using a slice thickness of 0.4 mm. The clarity of these scans were not as good as the others done using the i-cat machine with a smaller slice thickness of 0.25 mm. These findings are consistent with other studies. Borah and Ashmead 18 found no long-term adverse outcome when tooth root impingement occurred with MMF screws in managing facial fractures in their case series. Kadioglu et al 19 evaluated root damage when temporary anchorage devices (TADS) impinged on roots and found favorable repair and healing within a few weeks after screw removal. However, others have reported that root or tooth damage occurs in 4 to 6% of patients Poor operating technique can contribute to this complication. There were no screw fractures in the present study. Several have reported this as a problem in 2 to 3% of their treated patients. 10,11,13 Two studies used stainless steel screws, which should be less likely to break than titanium alloy. Poor operating technique can contribute to screw fracture. The authors found that the alveolar bone simply did not provide significant resistance. Screw fracture was not a concern in this study. MMF screws were originally described for 4-point fixation with placement farther from the teeth in the basal bone in the anterior jaw only. 7,8 In this study, MMF screws were placed in inter-radicular locations similar to TADS placed for orthodontic anchorage There was less chance of mucosal overgrowth when placed away from the depth of the vestibule. There may have been a greater favorable biomechanical advantage owing to the closer proximity to the occlusal contact points. In addition, a more widespread pattern of placement was used across the arches. One to 2 screws were placed in each anterior jaw and 1 screw was placed in the posterior jaw region of each arch (total, 6 to 8 MMF screws). Compared with 4-point fixation, this pattern provides more occlusal control, especially in the posterior region, when using open treatment for a posterior body or angle fracture. However, it may be appropriate to use fewer screws for anterior fractures or minimally displaced fractures with stable occlusion. Patient-centered outcomes are important for assessment of treatment outcome. Pain associated with the MMF screws was reported to be minimal. QOL was good overall and expectedly better in the ORIF group. This study did not compare outcomes with Erich arch bars, so the authors are limited in making direct comparisons with this technique. However, it is reasonable that patient acceptance of MMF screws should be as good as or better than patient acceptance of arch bars. The cost comparison with arch bars was favorable for the use of MMF screws. This comparison is limited because there was no arch bar control group. The costs for MMF screws and OR cost were based on the authors university hospital and may not represent national averages. Time estimates for placing arch bars were reasonable for lower-level residents who are typically assigned this task. The cost analysis was based on the assumption that arch bars would be removed in the OR. This is routinely performed by other services at the authors hospital that treat maxillofacial trauma. However, in their clinic, the authors remove arch bars under local anesthesia with or without intravenous sedation. This lowers the estimated cost for the use of arch bars. MMF screw placement for closed treatment was relatively simple. It was performed under intravenous sedation in a few study patients in the OR and oral and maxillofacial surgical outpatient clinic. If screws are placed in the clinic setting, the overall cost of care is lowered but the surgeon absorbs the supply costs. Uncomplicated mandible fractures were successfully managed using open and closed methods and MMF screws in this small cohort of patients. All patients exhibited adequate fracture union with acceptable occlusion. However, the utility of MMF screws for closed treatment was decreased because of significant screw failure and patient noncompliance. In a noncontrolled setting, this likely would lead to complications. Lower IT and posterior jaw location were factors contributing to screw failure. A study with a larger sample is needed to better assess all factors that contribute to screw failure and negatively affect outcomes. The MMF screws caused minimal ill effects in the short term on the gingival or mucosal tissues or in the long term on periodontal bone and dental roots. Patient-centered outcomes related to QOL, occlusion, and pain were favorable. There was additional cost incurred with the use of MMF screws compared with traditional Erich arch bars. However, time savings in the OR outweighed their cost. A future study directly comparing outcomes and costs of MMF screws with arch bars is warranted to draw more comprehensive conclusions. References 1. Ayoub AF, Rowson J: Comparative assessment of two methods used for interdental immobilization. J Craniomaxillofac Surg 31:159, Busch RF, Prunes F: Intermaxillary fixation with intraoral cortical bone screws. Laryngoscope 101:1336, Dal Pont G: A new method of intermaxillary bone fixation. Trans Int Conf Oral Surg 325, Foneseca RJ, Walker RV, Betts NJ, et al: Oral and Maxillofacial Trauma. ed 3. Philadelphia, PA: WB Saunders, 2004

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