Is the Use of Intermaxillary Fixation Screws an Alternative to Erich Arch Bars for Maxillomandibular Fixation During Management of Maxillofacial Fractures? A Systematic Review and Meta-Analysis

Abstract

Study Design: Systematic review and meta-analysis. Objective: Maxillomandibular fixation (MMF) is a step of paramount importance during the management of maxillofacial trauma. Erich arch bars are being used for this purpose for decades but with advances in maxillofacial trauma management, intermaxillary fixation screws came into existence and are being used routinely. The present study was designed to identify if the intermaxillary fixation screws are really an alternative to Erich arch bars for management of maxillofacial trauma. Methodology: An exhaustive literature search was conducted in May 2020 on various electronic databases and studies comparing Erich arch bars and intermaxillary fixation screws were recruited for the analysis. Random-effects model with Mantel Haenszel statistics was used to analyze oral hygiene and duration of achieving MMF. Results: A total of 96 studies were identified, out of which 8 studies were included in the meta-analysis. There was no statistically significant difference in oral hygiene status of the patients in both the groups. Intermaxillary fixations screws required statistically significantly less time in achieving MMF. Needle stick injury was prominently seen with the use of Erich arch bar whereas other complications like mucosal coverage, root injury, screw loosening and screw fracture makes the use of intermaxillary fixation screws questionable. Conclusions: The present meta-analysis suggests that there is not enough evidence to recommend the use of intermaxillary fixation screws as an alternative to Erich arch bars. Further research with large sample size, high quality evidence and better methodology is recommended in this direction.

1. Introduction

Maxillofacial skeleton is susceptible to trauma and subsequently fractures, due to Road Traffic Accidents (RTA), falls, sports and assaults. With the increasing use of motor vehicles, there has been an escalation in the amount of Road Traffic Accidents (RTA) and a corresponding upsurge in maxillofacial fractures. Also, the rise in the number of sports activities worldwide has contributed significantly to the increased frequency of facial injuries. These fractures must be treated with a goal of restoring the premorbid dental occlusion, appropriate healing of bony fractures and adequate mouth opening along with minimal morbidity and reduced cost of treatment.

Successful treatment of maxillofacial fractures depends on proper reduction either by open or closed technique. However, with technological advancements, the principles of management of maxillofacial fractures have shifted toward a more aggressive as well as stable form of management modality [1]. Currently, open reduction and internal fixation (ORIF) has become the standard procedure for treating simple as well as complex fractures [2,3]. Irrespective of the fixation modality, establishment of stable maxillomandibular fixation (MMF) is essential. MMF is of paramount importance as it secures the occlusal relationship and aids in proper reduction of the fracture.

A plethora of techniques used for achieving MMF have been reported in the literature. Traditionally, Ivy eyelets wiring, Risdon wiring, metal splints, acrylic splints and Erich arch bars are used [4]. Progressively, new techniques such as Intermaxillary Fixation (IMF) screws [5], wiring around single tooth with tight contacts [6], use of 2 miniplates [7], use of zip ties [8], use of bondable buttons [9], 2 looped wires [10] have been developed to expedite securement of MMF.

In spite of the numerous techniques, Erich arch bars remain the standard for securing MMF given their rigidity and versatility [11]. However, they are associated with the risk of needle stick injury and trauma to the surrounding soft tissues. Some authors suggest that the use of IMF screws is less time consuming, provides better oral hygiene and reduces the risk of needle stick injury [12,13]. Conversely, use of IMF screws is associated with teeth root damage and screw loosening leading to instability of MMF. Despite these disadvantages, IMF screws are suggested as an alternative to arch bar for achieving IMF in the management of maxillofacial trauma [14]. Hence, we have designed and conducted this meta-analysis to identify if the use of IMF screws is truly an alternative to Erich Arch Bars for the aforementioned purpose.

2. Methodology

The present meta-analysis was designed and conducted based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) standards elaborated in the Cochrane Handbook for Systematic Reviews of Interventions. The present study has been registered with PROSPERO (International prospective register of systematic reviews) with the registration number CRD42020184615.

The research question for the present study was formulated with the help of PICO (Population, Intervention, Control, Outcome) guidelines. The focus question for the present meta-analysis was: Are Intermaxillary fixation screws (I) an alternative for maxillomandibular fixation when compared with conventional Erich arch bar (C) in terms of stability, duration, oral hygiene and complications (O) during the management of jaw fractures in overall healthy patients (P) (

Table 1. Research Question According to PICO Guidelines.

).

2.1. Search Strategy

An exhaustive literature search for inclusion of eligible studies was conducted on electronic databases like PubMed, Medline, Google Scholar, Science direct and the Cochrane database in May 2020 without any restriction for the publication year. Keywords like Intermaxillary fixation, maxillomandibular fixation, Erich arch bar, IMF Screw, intermaxillary fixation screws, bone screws, cortical screws, closed reduction were used for the search purpose. Boolean operators “AND” and “OR” were used for advanced search.

2.2. Study Selection

Following the initial search, the titles and abstracts of all the obtained articles after removal of duplicates were screened for possible inclusion. The articles that dealt with the use of Erich Arch Bar and/or IMF screw for the management of maxillofacial fractures were selected for detailed evaluation. The reference lists was also hand searched and reviewed for relevant articles for inclusion in the full text pool and assessed for eligibility for inclusion in our meta-analysis.

On the basis of title, keyword and abstracts, full texts of all the potentially eligible studies were critically reviewed by 2 trained reviewers for possible inclusion. Full texts that required more information or ones with unclear data were accessed through e-mail or Research Gate communication. Any disagreement regarding study selection was solved by discussion. After evaluating the studies they were recruited in the meta-analysis according to the following inclusion and exclusion criteria.

2.3. Inclusion and Exclusion Criteria

Randomized comparative studies that compared the use of IMF screws (Intervention) and Erich Arch Bar (Comparison) for the management of maxillofacial fractures were included in the meta-analysis. Studies involving other techniques of MMF were excluded. Retrospective studies, nonrandomized studies, case reports, literature reviews and duplicate studies were also excluded. Studies in any language other than English and those with incomplete data were also excluded. Studies that assessed different outcomes were not selected for the meta-analysis.

2.4. Data Extraction

Two reviewers independently conducted data extraction for the included studies. Data such as study characteristics, patients’ characteristics, treatment group characteristics and details of the outcomes were extracted and recorded. Study characteristics included the publication details like the author, year of publication and the location. Patient characteristics included the age range and gender ratio. Treatment group characteristics included the number of patients in each group. Details of the outcomes included the results of primary and secondary outcomes.

The primary outcomes that were assessed were oral hygiene following MMF and the duration of achieving MMF. Secondary outcomes included intraoperative and postopreative complications unique to the chosen MMF technique.

2.5. Quality Assessment

All the studies that were included in the meta-analysis went through a quality assessment using Cochrane Collaboration’s tools of risk of bias assessment for Randomized Controlled Trials which included 7 risk of bias domains, viz. 1. Randomization methods, 2. Allocation concealment, 3. Blinding of participants and personnel, 4. Blinding of outcome assessment, 5. Incomplete outcome data, 6. Selective reporting and 7. Other bias [15]. Each domain was evaluated for each study and a response of “Low”, “Unclear” or “High” was assigned to it. A study was designated as either “Low” risk if all the domains had “Low” response; “unclear” risk if at least 1 domain was judged to have an “unclear” response; or “High” risk of bias if at least 1 domain had “high” response or multiple domains were assessed to have an “unclear” response.

2.6. Data Analysis

Meta-analysis was performed to analyze the result of the included studies for both the IMF techniques and the outcomes of interest using Review Manager, Version 5.3, Cochrane Collaboration. (RevMan, Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) Random-effects model with Mantel Haenszel statistics was used considering the probability of substantial heterogeneity. I square tests and Chi square tests were used in assessing the heterogeneity which was categorized as considerable (75-100%) heterogeneity, substantial (50–90%), moderate (30-60%) and not important (0-40%) heterogeneity [16]. In case of considerable heterogeneity, a sub group analysis was conducted. Standard Mean Difference, 95% confidence intervals, estimate effect size of individual studies and forest plots were used to visualize and calculate the summary of the analysis. Funnel plots were used to identify systematic bias and heterogeneity.

2.7. Grading

GRADE (Grading of Recommendations Assessment, Development, and Evaluation) system was used for quality assessment of evidence of the analysis for all the outcomes independently [17]. Criteria for this system were the study design, inconsistency, risk of bias, indirectness, publication bias, imprecision and other criteria such as dose response, effect magnitude and probable confounders. On the basis of above-mentioned criteria, the quality of evidence of the study was designated to be either high, moderate, low or very low.

3. Results

3.1. Literature Search Results

The exhaustive search of databases yielded a total of 96 studies relevant to the present review. After screening of titles, abstracts and keywords, 79 studies were excluded and a total of 17 studies were found to be potentially eligible for inclusion in the review. After a detailed analysis of these 17 full text articles, 9 studies were excluded and 8 studies were included in the meta-analysis.

Table 2. Excluded Studies with Reasons for Exclusion.

highlights all the excluded studies with reasons for exclusion. The study selection process has been summarized in Figure 1 as a PRISMA flow diagram.

Data extraction was done for all the included 8 studies.

Table 3. Characteristics of the Included Studies.

highlights the characteristics of included studies. Meta-analysis was performed for the primary outcomes and the secondary outcome i.e. complications were narratively reviewed.

3.2. Quality Assessment Results

All the included studies were assessed for their quality by 2 independent reviewers using Cochrane’s risk of bias assessment tool. Out of the 8 included studies, 2 studies had low risk of bias in all the 7 domains [29,30] whereas the other 6 studies showed a high risk of bias [12,13,26,27,28,31]. These studies did not provide adequate information on the procedure on randomization, moreover they failed to describe allocation concealment completely. None of the studies mentioned about the blinding of participant and personal, however, this domain was considered to have a low risk of bias as the method of assessment were objective in nature and would hardly be affected if the blinding was not done. A few studies failed to report complete data, hence they were categorized as high in that particular risk of bias domain. In summary, majority of the studies had high risk of bias which might affect the result of the analysis.

3.3. Meta-Analysis Results

The primary outcomes analyzed in the present study were Oral hygiene and the time taken for achieving MMF. The analysis of the outcome data and the pooled estimate of the included studies for evaluating oral hygiene revealed that there was no statistically significant difference between the oral hygiene status of both the groups (Standard Mean Difference [SMD] = —1.94; 95% Confidence Interval [CI] = —4.38 to 0.5; P = 0.66; I [2] = 97%) (Figure 2). Considering the heterogeneity of 97% a subgroup analysis was conducted based on the method of evaluating the oral hygiene. A total 5 studies have evaluated oral hygiene out of which 3 studies used Turesky-Gilmore-Glickman modification of Quigley-Hein Plaque Index [32] and the other 2 studies used varied indices. The subgroup analysis revealed that the oral hygiene was better when IMF screws were used and assessed with Turesky-Gilmore-Glickman modification of Quigley-Hein Plaque Index, this difference was statistically significant, whereas when the oral hygiene was evaluated with other indices the difference was statistically insignificant. Hence, the overall results favor IMF screws but the difference is statistically not significant.

The other outcome which was statistically analyzed is the duration required for achieving MMF. A total of 6 studies were included in this analysis, all of which individually concluded that IMF screws take lesser time for

MMF. The present analysis revealed that achieving MMF using IMF screws takes statistically significantly less time when compared to Erich arch bars (SMD = —7.13; 95% CI = —9.75 to —4.50; P < 0.00001; I² = 93%) (Figure 3). The result showed a considerable heterogeneity but a subgroup analysis was not possible while analyzing this outcome.

3.4. Narrative Review

The various complications evaluated in all the included studies were also analyzed. A total of 6 studies have reported about the various complications in both the groups (

Table 4. Complications Observed in Included Studies.

). Needle stick injury or glove perforation was reported by 5 studies and was seen in Arch Bar group in all the studies, [12,13,27,29,30] whereas only 2 studies had needle stick injuries or glove perforations in IMF screw group [27,30]. This data suggests that there is a high risk of communication of blood borne diseases when arch bar is used for IMF. On the contrary, 4 studies reported mucosal coverage [12,28,29,30] and 5 studies reported tooth mobility with the use of IMF screws [13,27,28,29,30]. These complications were not seen when arch bar was used; only 2 teeth crowns were damaged while using arch bar [30]. Three studies reported IMF screw loosening [12,28,29] and 2 studies reported IMF screw fracture [28,30].

3.5. GRADE Analysis Result

Based on the GRADE assessment, the quality of evidence in the present meta-analysis was found to be high for working time. This suggests that future research is very unlikely to change the estimate of effect concerning this outcome. The quality of evidence for Oral hygiene was found to be moderate when evaluated with Turesky-Gilmore-Glickman modification of Quigley-Hein Plaque Index and low when other indices were used for evaluation. A moderate quality of evidence suggests that further research may change the estimate of effect whereas a low quality of evidence suggests that further research is very likely to change the estimate of effect. Results of GRADE evidence have been provided in the summary of finding

Table 5. Grade Analysis.

.

4. Discussion

Management of maxillofacial fractures is incomplete without IMF. Closed reduction is achieved by IMF whereas open reduction and internal fixation also requires IMF for control over dental occlusion. Introduction of bone plating has obviously omitted the need of prolonged IMF, but a temporary intraoperative IMF is definitely needed to secure the correct occlusal position of teeth for proper postoperative functioning.

Since, world war I, arch bar has been the mainstay for management of maxillofacial trauma. Initially, an ordinary round bar flattened on one side was used for this purpose by Sauer in Germany and Gilmer in United States. This bar was ligated to the teeth with the help of brass ligature wires. Blair and Ivy modified it such that the flattened side was 2 mm in width so that the adaptation is better on the teeth and hence better stability [33]. Erich arch bars are presently the most common methods for achieving IMF considering the stability that it provides. On the contrary there are various disadvantages that are associated with its use such as prolonged duration of surgery, higher risk of needle stick injury and injury to surrounding soft tissues. To overcome these complications various other techniques of IMF have been introduced.

One such technique is use of IMF screws, which were first introduced by Arthur and Berardo [5] in 1989, which was later modified by Carl Jones [34]. Jones modified the screw head design into a capstan shape, this facilitated in keeping the wires and elastics away from the soft tissue. Use of IMF screw was advocated to have fewer complications and shorter application time. It was also concluded in many studies that it facilitates in maintenance of good oral hygiene and hence, it can be used as an alternative to Erich arch bars. Hence, the current meta-analysis was conducted specifically to compare these 2 techniques in management of maxillofacial fractures.

In our meta-analysis we found that while IMF screws trended toward improved oral hygiene the results did not achieve significance. When the operating time was compared, MMF using IMF screws was definitely faster and hence reduces the duration of the procedure significantly. We also found that the frequency of needle stick injury is significantly higher in the cases were arch bars were used. This increases the risk for operators and assistant toward the blood borne diseases. But this data is not sufficient to declare IMF screws as an effective alternative to arch bar as its use is associated with various other complications such as screw loosening and screw fracture. These complications puts a direct question on the stability that IMF screws can provide during the period of MMF. Other than these complications, use of IMF screws is also associated with root damage and mucosal coverage of the screws.

We found a considerable heterogeneity in the present analysis. This is because of the different methodologies of assessment of oral hygiene status. Also, many studies in the analysis suffered from lack of power due to small sample size and hence heterogeneity on a higher side [35]. Another aspect is that most of the studies included in the analysis had high risk of bias. A considerable heterogeneity and high risk of bias affect the result of the analysis, hence it cannot be definitively concluded that IMF screws are superior to Erich arch bars.

The result of the present meta-analysis is associated with significant confounding variables within the included studies. As mentioned earlier, small sample size and difference in methodologies are some of the confounding factors. Another confounding factor is the number of IMF screws used, some studies used 4 screws while some used 6, this directly affects the time required for achieving IMF. The most preferred site for insertion of screws is between canine and premolars [36]. Another confounding factor is the degree and severity of fractures, some included studies fail to emphasize upon the severity of fractures which definitely affect the results. Comminuted fractures require more stability with MMF hence it is important to know if IMF screws can provide the adequate stability with such fractures before shifting to IMF screws from Erich arch bars.

Majority of the studies included in the analysis recommend the use of IMF screws for MMF. A systematic review conducted by Bins et al [37] suggested that IMF screws can be used for temporary MMF for uncomminuted fractures. Considering the result of present meta-analysis, high risk of bias, confounding factors and the considerable heterogeneity we confirm that there not enough evidence to conclude that IMF screws are alternative to Erich arch bars. Further prospective studies with better methodologies, standardized protocols, large sample size, low risk of bias and high quality of evidence are recommended for changing protocol of using Erich arch bars for MMF.

5. Conclusions

It can be concluded from the present meta-analysis that despite being a less time consuming procedure, facilitating oral hygiene and comfort, IMF screws cannot act as an alternative to arch bars. Erich arch bars should be kept as a modality of choice when MMF is required for management of maxillofacial fractures.