Erich arch bars vs intermaxillary fixation screws for mandibular fracture reduction during ORIF: a randomized clinical trial

This randomized clinical trial aimed to compare the efficacy of Erich arch bars (EAB) and intermaxillary fixation (IMF) screws in reducing mandibular fractures during open reduction and internal fixation (ORIF). A total of 28 patients with mandibular fractures were randomly allocated to either the EAB group or the IMF screws group. The study evaluated various parameters including occlusal stability, complications, duration of application, oral hygiene status, quality of life, and patient characteristics. The study found no significant differences in occlusal stability between the EAB and IMF screw groups. However, the application and removal times were longer for EAB compared to IMF screws. The EAB group showed a higher presence of biofilm on teeth, indicating poorer oral hygiene status compared to the IMF screws group. In terms of quality of life, patients in the EAB group reported worse results in the “handicap” domain at the 15th postoperative day. No significant differences were observed in other quality-of-life parameters. Patient characteristics were well distributed between the two groups, enhancing the reliability of the results. Both EAB and IMF screws demonstrated comparable occlusal stability for minimally displaced mandibular fractures. However, IMF screws offered advantages such as shorter application and removal times, better oral hygiene maintenance, and potentially improved quality of life in the “handicap” domain. Further studies with larger sample sizes are necessary to validate these findings and explore the stability of IMF methods in cases requiring postoperative malocclusion correction or prolonged IMF.


Introduction
Mandibular fractures are a common type of facial injury that requires prompt and effective treatment to restore dental occlusion and promote proper healing.Intermaxillary fixation (IMF) is a widely used technique to achieve occlusal stability in the management of mandibular fractures.Two common methods of IMF are Erich's arch bars (EAB) and intermaxillary fixation screws.However, there is a lack of randomized clinical trials directly comparing the effectiveness of these two approaches in the treatment of mandibular fractures.
Erich's arch bars have long been considered a standard method for IMF.They involve the placement of stainlesssteel wires and splints on the maxillary and mandibular arches, providing stable fixation and facilitating the alignment of fractured segments.While EAB has been widely used, it is associated with certain disadvantages.These include the need for extensive intraoral manipulation, patient discomfort, difficulties in maintaining oral hygiene, and prolonged treatment duration [1].
Intermaxillary fixation screws have emerged as an alternative technique for achieving occlusal stability in mandibular fractures.These screws offer advantages such as simplified application, improved patient comfort, reduced treatment time, and potentially better oral hygiene maintenance [2].However, the existing literature comparing the outcomes of intermaxillary fixation screws with those of EAB is limited, and previous studies have predominantly been underpowered with low-quality biases.
Several systematic reviews and meta-analyses have attempted to evaluate the efficacy of EAB and intermaxillary fixation screws in the treatment of mandibular fractures [3][4][5].However, the findings from these reviews have been inconsistent.Some systematic reviews have reported no significant differences between the two techniques in terms of occlusal stability, complications, or patient-reported outcomes [3,4].Other reviews have suggested that intermaxillary fixation screws may offer advantages such as shorter treatment duration and improved patient satisfaction.
Despite the existing evidence, the lack of well-designed randomized clinical trials remains a significant gap in the literature.Randomized clinical trials are considered the gold standard for assessing treatment effectiveness as they minimize biases and provide higher-quality evidence.The rationale for conducting this study is to address this research gap and provide more robust and reliable evidence to guide clinical decision-making in the treatment of mandibular fractures.Moreover, there is no any previous published randomized controlled clinical trial that compared the Erich arch bars to the intermaxilary fixation screws with respect of quality of life.
The objective of this randomized clinical trial is to directly compare the efficacy, safety, and patient-reported outcomes of EAB and intermaxillary fixation screws in the treatment of mandibular fractures.By employing rigorous methodology, including appropriate sample size calculation, randomization, and blinding, this trial aims to overcome the limitations of previous studies and provide high-quality evidence to guide clinicians in selecting the optimal IMF technique for mandibular fracture management.

Study design
A randomized controlled clinical trial was conducted to compare two different techniques of intermaxillary fixation (IMF) in the treatment of mandibular fractures: Erich arch bars (EAB) and intermaxillary fixation screws.Due to the obvious visual differences between the two methods, it was not feasible to blind the participants [6].The study protocol received approval from the Research Ethics Committee of the authors' university (approval number 1702907) and was conducted in accordance with the principles outlined in the Declaration of Helsinki and the CONSORT (Consolidated Standards of Reporting Trials) guidelines [7].This trial has been registered with the Brazilian Clinical Trials Registry under the ID number RBR-2rx6k6p.Prior to their inclusion in the study, all enrolled patients provided informed consent after receiving appropriate instructions.

Sample size
The sample size was determined using parameters of a pilot study conducted by the same research team, comparing the EAB and IMF screws, with three patients for each group.The following formula was used (Lwanga and Lemeshow, 1991 Zα was the type I error (1.96); Zβ related to type II error (0.84); dp, the standard deviation of the outcome with the largest sample needed; d, the difference to be detected (25%).The variable presenting the largest sample, and then chosen for the calculation, was the visible plaque index (VPI) 30 days after surgery.A significance level of 5%, 80% power, standard deviation of 40.49, and difference to be detected of 25% were considered.The result determined 12 patients for each group.Assuming a possible 10% sample loss, 14 patients for each group were required.A total of 28 patients were then included in the trial.

Inclusion criteria
Patients who were admitted to the referenced hospital and diagnosed with mild to moderate mandibular fractures (e.g., without overlapping bone fractures) requiring intermaxillary fixation (IMF), and were older than 18 years of age, were considered eligible for inclusion.Additionally, patients needed to be in good health based on their medical history and physical examination.Exclusion criteria included a diagnosis of complex and/or comminuted mandibular or maxillary fractures, including condylar and alveolar fractures that would require postoperative IMF with elastics, presence of metabolic disorders including metabolic bone diseases, previous history of maxillofacial fractures, absence of five or more posterior teeth [8] or being edentulous, and a history of radiotherapy.Intraoperative achievement of dental occlusion without mechanical impairment was also essential.

Randomization
Randomization was conducted using a lottery method employing opaque envelopes.Each envelope contained 28 cards, with 14 cards designated for each group.Just before each surgery, while the patients were under general anesthesia, an assistant who was not involved in the study drew a card from the envelope to determine the assigned IMF method.

Surgery and allocation
All surgeries were performed under general anesthesia following antiseptic procedures.A sterilized surgical field was prepared, and the allocated intermaxillary fixation (IMF) method was applied.Subsequently, incision, tissue dissection, fracture reduction, and fixation were carried out according to the recommended methods of the AO Foundation [9].The mandibular fractures were fixed using two miniplates from the 2.0-mm system.To ensure consistency, all procedures were performed by a single experienced maxillofacial surgeon (SGMF), assisted by the same individual (IAF), thereby eliminating inter-operator variability.Patients were assigned to one of the following groups: Group 1: EAB-Erich arch bars (ENGIMPLAN Ltda.®) were attached to the buccal surface of the upper and lower teeth using flexible stainless-steel wires, connecting tooth to tooth.IMF was achieved by securing the superior and inferior bars together using elastics.
Group 2: IMF screws-four self-drilling and self-threading screws (Locking Screw NEOORTHO Ltda.® 2.0 × 9 mm and 2.0 × 7 mm) were inserted into the alveolar process, with two in the maxilla and two in the mandible (one on each side).
The specific insertion sites were determined based on preoperative imaging exams, preferably between the canine and first premolar or between the premolars in each region [10].Care was taken to ensure proper placement that provided adequate strength vectors for restoring occlusion and remained at a safe distance from adjacent tooth roots.IMF was achieved by connecting the two screws on each side using flexible stainless-steel wires.
Postoperative follow-up visits were scheduled at the 1st, 7th, 15th, and 30th postoperative days.At the 30th-day follow-up, the EAB and IMF screws were removed.An additional appointment was scheduled after the removal of the IMF method to serve as a "baseline" evaluation since it was not possible to assess patients before they were affected by the trauma.
In all study groups, after suturing, the IMF was removed, and the IMF appliance (EAB or IMF screws) remained in position in the patients' dental arches for 30 days postoperatively.This was done to promptly address any postoperative occlusion issues or the development of malocclusion during this period.If necessary, the IMF could be re-established immediately, and elastics would be used to guide the occlusion.None of the patients were required to remain in postoperative IMF.

Outcome variable assessment
All postoperative evaluations and procedures were performed by only one previously trained evaluator (IAF).The predictor variable was the use of EAB versus IMF screws for achieving IMF.The outcome variables were the following: 1 Intraoperative IMF and occlusal stability: During the surgical procedure, the occlusal stability was tested by the surgeon and the assistant.The teeth position according to the canine guidance key and the molar inter-arch key, with the patient in the maximal habitual intercuspation position, was considered.These same parameters were evaluated using forced movements to open the patient's occlusion.Evaluators assigned a value from 1 to 5 according to the IMF stability: 1, very poor; 2, poor; 3, moderate (fair); 4, good; and 5, very good stability.The values were given blinded and independently by the evaluators.These parameters were evaluated shortly after achieving the IMF, after fracture reduction, and after fracture fixation.2 Postoperative occlusal stability and quality: After fracture fixation and IMF removal, in the operating room, occlusal stability was checked through opening and closing the patient's occlusion, without applying force, by the surgeon and the assistants were the evaluators, with the patient in the same position, and according to the same occlusal keys, as the previous variable.Also, this variable was evaluated by the own patients' opinions at the 1st, 7th, and 30th postoperative days.They were asked to assign a value, also from 1 to 5, for their perspective on their dental occlusion compared to how it was before the mandibular fracture.3 Time for IMF's method appliance application and removal: Time taken to achieve the IMF trans-operatively and to remove all IMF devices postoperatively.4 Amount of anesthetic used to remove the IMF appliance: The number of lidocaine HCl 2% and epinephrine 1:100.000cartridges was recorded.5 Adverse events and complications related to each IMF method: Occurrences of adverse events during the IMF application, manipulation of the appliance, and postoperative effects on the patients were documented.6 Oral hygiene: A trained evaluator (IAF) assessed the periodontal indexes on the 7th and 15th postoperative days, shortly after the removal of the IMF appliance (30th postoperative day), and 1 week after its removal.The visible plaque index (VPI) developed by Ainamo and Bay [11] was used, which involves a binary assessment of the presence or absence of visible biofilm to the naked eye.The gingival bleeding index (GBI), also developed by Ainamo and Bay, was measured by assessing marginal bleeding after gently inserting a millimeter Williams periodontal probe into the gingival sulcus, from one proximal interface to the other, on both buccal and lingual surfaces.Gingival bleeding was considered present if it persisted for at least 20 s after probing.VPI measurements were conducted on all four surfaces (buccal, mesial, distal, and lingual) of each tooth, from the right first molar to the left first molar in both dental arches.A score of "0" indicated the absence of biofilm deposits, while "1" indicated the presence of biofilm.For the GBI, "0" indicated the absence of bleeding, and "1" indicated the presence of bleeding.7 Quality of life: The patients' quality of life was assessed on the 1st, 7th, 15th, and 30th postoperative days using a modified version of the Oral Health Impact Profile (OHIP-14) [12] questionnaire.The questionnaire covered domains such as functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap.The patients rated the impact of the IMF methods on their life using Likert-type rating categories, with scores ranging from 0 (never) to 4 (always).

Statistical analysis
The SPSS Statistical package version 22 (IBM, Chicago, IL, USA) was utilized for statistical analyses.Descriptive statistics, including frequencies, arithmetic means, and standard deviations, were conducted.The normality of the outcomes was assessed using the Shapiro-Wilk test.The significance of the relationships between the IMF methods groups and all variables was examined using suitable statistical methods: the independent student t-test and Mann-Whitney test were employed for continuous variables based on their distribution (parametric or non-parametric), while the chi-squared test was employed for categorical variables.

Results
A total of 28 patients underwent treatment, with 14 patients in each group (Fig. 1).However, in the EAB group, one patient missed the 7th and 30th follow-up appointments, and four patients missed the 15th day appointment and did not return after IMF removal.In the IMF screws group, one patient did not attend any of the follow-up visits but was evaluated for intraoperative variables and on the first postoperative day before hospital discharge.Additionally, one patient did not attend the 7th and 15th follow-up appointments.Table 1 presents the characteristics of the 28 participants who underwent the surgeries.

Occlusal stability
There were no statistically significant differences in occlusal stability between the groups during any of the evaluations: immediately after IMF (p = 1.00, according to the surgeon's opinion; p = 0.541, according to the assistant's opinion), immediately after fracture reduction (p = 0.513, according to the surgeon's opinion; p = 0.214, according to the assistant's opinion), and immediately after fracture fixation (p = 0.116, according to the surgeon's opinion; p = 0.056, according to the assistant's opinion).Postoperative occlusal stability and quality also did not show any significant differences between the groups: surgeon's opinion at the end of the surgeries (p = 0.430), assistant's opinion at the end of the surgeries (p = 0.541), patients' opinion on the first postoperative day (p = 0.787), seventh day (p = 0.721), and thirtieth day (p = 0.445).

Complications and duration of application
The duration of applying and removing the IMF appliance was significantly longer for the EAB group compared to the IMF screws group (p < 0.01).However, there was no statistically significant difference in the amount of anesthetic used for IMF material removal.When it comes to the occurrence of cut and puncture accidents during manipulation of the EAB, there were no significant statistical differences between the groups (p = 0.053) (Table 2).Other accidents and complications associated with the IMF

Oral hygiene status
Significant differences were observed in the presence of biofilm on teeth, as measured by the visible plaque index (VPI), on the 15th (p = 0.039) and 30th (p = 0.020) follow-up days.
Patients in the EAB group had a higher presence of biofilm compared to those in the IMF screw group.However, no differences were found when evaluating the gingival bleeding index (GBI) (Table 3).

Quality of life
There were no statistically significant differences in the total scores of the oral health impact profile-14 (OHIP-14) when comparing the two groups.However, when analyzing the mean scores of the OHIP-14 subscales, a statistically significant difference was found in the "handicap" domain on  4).Specific questions in the OHIP-14 questionnaire also showed statistically significant differences between the two groups, with patients in the EAB group reporting worse outcomes.This included question 10 ("been a bit embarrassed") on the 7th postoperative day (p = 0.041; U = 54.00),question 13 ("felt life less satisfying") on the 15th postoperative day (p = 0.047; U = 42.00), and question 3 ("had painful aching") on the 30th postoperative day (p = 0.021; U = 48.00).

Discussion
The aim of this RCT was to compare the effectiveness and outcomes of EAB vs IMF screws, in patients with mandibular fractures in respect of intra-and postoperative occlusion, time of application, oral hygiene status, and quality of life.
The main key findings of the study were the following: 1) There were no statistically significant differences in occlusal stability between the EAB and IMF screws groups during various evaluations throughout the treatment process; 2) the application and removal of the IMF appliance took significantly longer in the EAB group compared to the IMF screws group.However, there were no significant differences in the amount of anesthetic used or the occurrence of cut and puncture accidents between the groups.3) Patients in the EAB group exhibited a greater presence of biofilm on teeth compared to the IMF screws group on the 15th and 30th follow-up days.However, there were no differences observed when evaluating gingival bleeding, and finally, there were no significant differences in the overall scores of the oral health impact profile-14 (OHIP-14) between the two groups.However, patients in the EAB group reported worse results in the "handicap" domain on the 15th day follow-up, and specific questions related to embarrassment, life satisfaction, and painful aching showed worse outcomes for patients in the EAB group at different postoperative days.The limitations of both EAB and IMF screws have been extensively discussed in the existing literature.Recently published systematic reviews have recommended conducting new clinical trials with meticulous methodology to compare these IMF methods.
In the current trial, there were no differences in occlusal stability between the two groups.This finding aligns with the study conducted by Rai et al. [13], which also reported no occlusal disturbances in either group.Conversely, three clinical trials [14][15][16] reported better outcomes with EAB, while one trial [5] favored IMF screws.However, a recent systematic review [4] identified uncertain biases in all five studies, rendering them scientifically unreliable.Given that only non-complex mandibular fractures were included in our study, it is suggested that both IMF screws and EAB can achieve appropriate occlusal stability for this fracture pattern.However, it should be noted that different outcomes can be expected when treating mandibular fractures with greater displacement that require postoperative IMF.Shorter surgical time is associated with a shorter duration of general anesthesia, reduced costs, decreased patient trauma, and improved surgeon comfort [17].In our study, the application and removal of IMF methods took longer when using EAB compared to IMF screws.This finding supports the conclusions of the previously mentioned systematic reviews [4,13], all the studies included in those reviews, and a recent retrospective study [18].The extended application time for EAB can be attributed to the use of multiple wires to secure the bars to the teeth [12] and the associated challenges, such as the presence of dental calculus, dental mobility, and dental crowding.The mean duration for applying and removing EAB may vary across studies, primarily due to differences in surgeons' experience [13,19], but it consistently takes longer than applying/removing IMF screws [4].
Regarding oral hygiene, a statistically significant difference was observed in the visible plaque index (VPI) on the 15th and 30th postoperative days.Although there was no statistical difference in the gingival bleeding index (GBI), the results revealed nearly twice as high GBI values in the EAB group compared to the IMF group.The significance of VPI values on the 15th and 30th postoperative days may be attributed to the accumulation of biofilm over time, which becomes more clinically evident due to difficulties in maintaining oral hygiene.These findings align with studies conducted by Balihallimath et al. [20], Jain et al. [1], and Rothe et al. [16], which reported poorer periodontal index values in patients treated with EAB.This parameter highlights the advantages of IMF screws in facilitating easier dental hygiene maintenance, leading to faster and healthier postoperative recovery and reduced rates of wound infection.Statistically significant differences were observed in the visible plaque index (VPI) at the 15th and 30th postoperative days, indicating a significant disparity in oral hygiene.Although no statistical difference was found for the gingival bleeding index (GBI), the results revealed GBI values almost twice as high in the EAB group compared to the IMF group.The significance of VPI values at the 15th and 30th postoperative days may be attributed to the gradual accumulation of biofilm, which becomes more evident due to the challenges in cleaning teeth during this period.These findings support the studies conducted by Balihallimath et al. [20], Jain et al. [1], and Rothe et al. [16], which reported poorer periodontal index values in patients treated with EAB.IMF screws offer an advantage in facilitating easier dental hygiene maintenance, leading to faster and healthier postoperative recovery and reduced rates of wound infection.
It is important to acknowledge the difficulty of accurately measuring periodontal indexes in patients with EAB as a limitation.The tight positioning of the bars on the cervical surface of the teeth restricts adequate probing and visualization of alterations [21,22].Additionally, differences in oral hygiene education and patient guidance between the two groups may also influence periodontal outcomes [15,21].Patients were advised to maintain their regular oral hygiene routine after surgery, which could result in varying patterns of oral hygiene habits between the IMF screws and EAB groups.Temporary periodontal damage was observed in all patients assigned to the EAB group during at least one of the follow-up assessments.This could be attributed to excessive compression of the bar on the gingiva [23], highlighting a disadvantage of EAB compared to IMF screws.However, all of these damages were transient, as no patients exhibited periodontal alterations 1 week after EAB removal.Therefore, this parameter gains importance when considering the discomfort to the patients.
Cut and puncture accidents were the most prevalent adverse events associated with the IMF methods, and statistical analysis supported this finding.The surgeon experienced more accidents when handling the EAB compared to IMF screws, although no statistically significant differences were observed.This aligns with existing literature, which indicates a higher risk ratio of 3.81 for cut and puncture accidents during the application of bars compared to IMF screws [4].The manipulation of wires during bar application may contribute to this difference, as the risk of perforation is low when handling IMF screws.This presents a disadvantage for EAB due to the increased occupational transmission risk of blood-borne pathogens [22].
Two patients exhibited loosening of screws, which is consistent with findings reported in other studies [1,5,16,20,24].This phenomenon may be attributed to the muscle forces exerted on the screws during mandibular movements or inadequate adaptation of the screws to the bone.Consequently, IMF screws may not be recommended in cases requiring prolonged periods of IMF.However, the duration of IMF has decreased over time with the introduction of open reduction and internal fixation [2].Mucosal coverage of IMF screws was observed in two patients, although at lower rates compared to other studies [13,16,24].This can be attributed to careful screw placement, ensuring they are not positioned too close to the mucosa and are located occlusally at the boundary between attached gingiva and mucosa.This approach prevents trauma that could lead to mucosal growth over the screw.
One patient in the EAB group experienced tooth extrusion, which was associated with postoperative malocclusion.The underlying causes could be pre-existing periodontal diseases or the absence of an opposing tooth.Unfortunately, no data pertaining to this parameter were found in the literature.
In the "handicap" domain, the EAB group exhibited a lower quality of life compared to the IMF screws group on the 15th postoperative day.The use of EAB can be associated with several factors that influence overall quality of life.In this study, the most commonly reported complaint was the discomfort caused by the bars hurting the mucosa.Patients also mentioned difficulty in toothbrushing.Only one study in the literature compared quality of life between EAB and IMF screws, specifically in the treatment of condylar fractures, and it found worse results for the EAB group in terms of social isolation during the 6-week follow-up period [25].However, the evaluation on the 1st postoperative day in this study has limitations.Patients were experiencing significant postoperative swelling, making it difficult for them to notice the presence of the IMF methods.Additionally, they had not yet resumed their daily activities, so the effects of the IMF methods on their lives could not be fully assessed.
When examining the characteristics of the patients, no significant differences were observed between the two groups in this study.The mean age, sex distribution, trauma etiology, and time elapsed between trauma and treatment were well balanced, which enhances the reliability of the results.A systematic review comparing IMF methods highlighted the absence of a control group and lack of blinding in the included clinical trials as a limitation [3].In this study, utmost importance was given to developing a methodology of the highest possible quality.However, including a control group would have violated ethical principles by leaving patients without treatment.Blinding the evaluator responsible for assessing the outcomes, as well as all other participants, was not feasible in this clinical trial design since the IMF methods were easily identifiable during a simple clinical examination.
The limitations of this study include the following: 1) Lack of evaluation of IMF method stability in the postoperative period for cases requiring correction of postoperative malocclusion or prolonged IMF; 2) small sample size, which may limit the generalizability of the findings and reduce the statistical power of the study; 3) the study focused on patients with minimally displaced mandibular fractures, limiting the applicability of the results to more complex fracture patterns; 4) the study relied on self-reported measures for assessing quality of life, which may be subjective and influenced by individual perceptions; 5) the study did not blind the evaluator responsible for assessing the outcomes, which may introduce bias; 6) the study did not evaluate long-term outcomes or the impact of IMF methods on factors such as bone healing or functional outcomes; 7) the study did not consider variations in oral hygiene education and patient compliance, which could have influenced the results.
In conclusion, patients treated with IMF screws demonstrated better outcomes in terms of IMF method application and removal times, VPI, and quality of life at specific followup periods.There were no statistically significant differences between the two groups in terms of IMF stability and the quality and stability of dental occlusion during intra-and postoperative stages.However, it is important to interpret the results of this study with caution, particularly considering that the included mandibular fractures were minimally displaced.

Table 3
Periodontal indexes outcomes and the comparison groups * p < 0.05, t-test

Table 4
Mean OHIP-14 total and subscale scores and standard deviations for each follow-up moment Erich arch bars IMF screws Erich arch bars IMF screws Erich arch bars IMF screws Erich arch bars IMF screws * p < 0.05 (t-test = 2.462); NSE, not statistically estimable