Comparison of Conventional 2.0 mm Non-Locking and Locking Miniplates in Management of Fracture Mandible

Aim: This study aims to compare post-operative evaluation of locking and non-locking miniplates in mandibular fractures. Materials and Methods: The study consisted sample size of 40 patients non-comminuted fractures (40 fracture sites) were divided randomly but equally (single-blind control trial study) into two equal groups. Each group contains 20 patients (20 similar fracture sites in each group). Group 1 was treated with open reduction and internal fixation using 2.0 mm non-locking miniplates. Group 2 was treated using locking 2 mm miniplates. Results: Of 20 patients treated by conventional 2 mm miniplates, no any patients developed occlusal discrepancy, but one had post-operative mobility at fracture site, and one developed plate failure and subsequent infection, which was treated by removal of the plate under antibiotic coverage. One patient treated by three-dimensional plates had tooth damage. Conclusion: Based on the results of this original research concluded that the treatment of various mandibular fractures (parasymphysis, symphysis, and angle) with 2.0 mm locking plates provided three-dimensional stability, more stable configuration with lower meant element stresses and thus showed zero morbidity and was not associated with any major complications. The only probable limitations of locking plates were excessive implant material due to the extra vertical bars incorporated for countering the torque forces.


INTRODUCTION
Monocortical miniplate fixation is a globally accepted and most trusted method for open reduction internal fixation in mandibular fractures. Although placement of a second miniplate may theoretically provide more stability, the clinical importance fixation of the second miniplate a per Champy and Pape [1] line of osteosynthesis still remains controversial.
The mandibular fractures are one of the most commonly fractured shown in the department or clinics of oral and maxillofacial surgery. [1] The frequent involvement of the mandibular fractures can be attributed to changes in the lines of calcification and strength from the horizontal body to the vertical line (from symphysis, parasymphysis angle, and ramus mandible), the thinner cross-sectional area, and due to the presence of impacted or partially erupted third molars. [2] Fractures of the mandibular angle are the most problematic in the facial region because of the high frequency of complications and difficult access to the surgical site. [3] Traditional methods of mandibular fractures are reduction and fixation included wire osteosynthesis and maxillomandibular fixation. These fractures are currently treated by plate/screw osteosynthesis and depending on the case, the bone segments are secured by one miniplate fixation, two miniplate fixation, or by a single rigid plate. [4,5] However, the discussion about the ideal type of fixation for mandibular angle fractures is still going on. Fixation of mandibular angle fractures is biomechanically complex because the major stress bearing area of the mandible are disrupted in this region. [6,7] Finite element analysis (FEA) is a numerical analysis technique that can determine the displacements, stresses, and strains, over an irregular solid body given the complex material behavior and the loading conditions imposed on that body. The stress analysis obtained from FEA modeling of the maxillofacial bony structures can provide information regarding interactions between hardware and bone during normal patient functioning.

MATERIALS AND METHODS
This original research was a prospective study carried out on both equally divided groups of undisplaced as well as displaced mandibular fractures, i.e., Group I and II were operated for open reduction and rigid internal fixation (ORIF). This research was done to compare the efficacy between locking and non-locking titanium miniplates in both groups of mandibular fractures for frequency of wound dehiscence, post-operative pain and swelling, development of infection, malocclusion, malunion, screw breakage, and any other technical difficult. Exclusion criteria for this research were infected, malunited, and comminuted fractures as well as mandibular coronoid and condylar fractures. All patients were within the age group of 18-60 years, excluding medically compromised patients. Strict asepsis was followed during whole procedure. Patients were operated either under general anesthesia or local anesthesia. Detailed history, examination chart, and informed consent were taken by each patient before surgery.
All selected patients underwent Erich's arch bar (maxillomandibular fixation) placement preoperatively. Orthopantogram and posterior-anterior (PA) view of mandible were the standard radiographs for clinical findings before involve in this research. The radiological findings were recorded as fracture site, presence of additional mandibular fracture, and degree of fracture dislocation.
Patients were distributed into two groups and were treated with two of the standard techniques, i.e., one is non-locking miniplate osteosynthesis and other is locking miniplate osteosynthesis. 20 patients were included in each group, Group I (20 patients): Internal fixation was done with non-locking plate Group II (20 patients): Internal fixation was done with locking miniplate.
Open reduction and internal fixation of mandibular fracture segments were done intraorally under GA or LA, except in some inaccessible angle fractures where transbuccal approach was used. In Group I patients, internal fixation of mandibular fracture was done by non-locking plates and in Group II patients locking plate. The surgery was carried out by the same surgical team and the operation technique was the same for most patients.
Depending on the site of fracture, incision was planned and given, and flap was reflected. The fracture site was exposed and fracture ends were manipulated for anatomic reduction. Following reduction of the fragments, temporary maxillomandibular fixation was placed with wires. A suitable plate was selected and bent with a plate bending pliers to confirm the proper adaptation of plates to bone surface on subapical position of teeth, and injury to dental roots was avoided using monocortical screws locking and non-locking plates were placed in equally divided groups according to Champy's line of osteosynthesis.

F o l l o w -u p a n d E v a l u a t i o n w e r e d o n e Radiographically as well as Clinically
R a d i o g r a p h i c a l l y b y p a n o r a m i c X-r a y s v i e w (orthopantomogram), patients' follow-up and evaluation were done on every 1 month, 3 months, and 6 months for any malunion, nonunion, and resorption around screws.
Patients were also advised to visit the department on regular interval for clinical follow-up at an interval of 1 week, 3 weeks, 6 weeks, and also if any problems occur after internal fixation.

RESULTS
In 40 patients, 28 (70%) were male and 12 (30%) were female [ Figure 1]. Traffic accident was the etiological factor in 28 (70.00%) patients followed by falls were 4 (10.00%) whereas assault caused fracture were 4 (10.00%) [ Figure 2]. Overall, there were seven patients with fractures of the left angle and 10 patients with a fracture on the right side [ Figure  2]. 14 (82%) cases had a displaced fracture and 3 (18%) cases were undisplaced with the presence of the impacted wisdom tooth in the fracture line, hence, requiring surgery [ Figure 3]. Undisplaced fractures of the angle with no occlusal derangement were treated by simple closed reduction and, hence, not included in the study. After fixation of the miniplate, all fractures appeared to be well reduced and stable. Post-operative occlusion was normal in all, but one patient who showed minor occlusal discrepancies corrected by the use of elastics for 1 week. The PA mandible view was used to assess the patient preoperatively as it best showed the displacement of the fracture. The same view was done postoperatively to assess the reduction and fixation of the fracture. When we analyzed the palpability of the plate after 6 months, it was observed that in 16 (94.12%) cases the plate was palpable only on exerting pressure and 1 (5.88%) case was found to have pain on palpation, with no infection present [ Figure  4]. There was no case of plate exposure, but we encountered three patients with local inflammation due to improper oral hygiene. This was resolved with antibiotics and local oral hygiene methods without any further surgical intervention. There was no case with post-operative paresthesia.
Patients of both groups were evaluated for pain, swelling, hardware failure, malunion, non-union, damage to root by screw, infection at site, neurosensory deficit, occlusal discrepancy, and post-operative mobility at fracture site [ Figure 5].

DISCUSSION
In this study, interpersonal violence accounted for 10.00% of the cases, fall injury accounts for 10.00% of cases of mandible fracture. Road trauma was responsible for majority of patients [ Figure 2] 70% of mandibular fractures. This is in accordance with the study by Atik et al. [7] [ Figure 2]. Of 40 patients in our study 32 (80.00%) were male and 08 (20.00%) were female. This male dominance was also reported by Haug et al. [8] The age group most commonly affected was 21-30 years (40%). Eight patients had bilateral mandible fracture and 12 had unilateral fracture. The most common site of mandible fracture was parasymphysis (35%) and angle (35%), followed by body (20%) and symphysis (10%) According to Arbeitsgemeinschaft für Osteosynthesefragen (AO)/Association for the Study of Internal Fixation (ASIF) principles, [9][10][11] the main aim of ORIF in the reduction of mandibular fractures is to achieve normal occlusion, masticatory functions, undisturbed healing, and immediate restoration of form and function without the adjunctive [12]     use of maxillomandibular fixation. This approach has become increasingly popular during the past 20 years for all types of mandibular fractures, and diverse plating systems have been developed to meet this fundamental requirement. [13][14][15][16] The locking plating system has been developed and popularized by AO/ASIF to obviate the main disadvantage of conventional plate system, which requires the plate to be perfectly adapted to the underlying bone to avoid gaping of the fracture and associated instability. This bone plate system acts as an internal-external fixator, which results in better distribution of the load and prevents load concentration on a single screw, thus decreasing the risk of a screw's loosening and stripping. Moreover, because anatomic adaptation of the plate to the underlying bone contour is not crucial, there are theoretically fewer interferences with the adjacent vascular supply. [17,18] Our study reviews the efficacy of 2.0 mm locking plate/ screw system in 20 patients requiring open reduction and internal fixation without maxillomandibular fixation. The patients were evaluated for the location, type, and number of fractures; the presence of tooth in line, time elapsed between the presentations of the patient after trauma, pre-and postsurgical occlusal relationship, adequacy of reduction on postoperative radiograph, and any post-surgical complications requiring a secondary surgical intervention.
In this study, 32 fractures were observed in the 20 patients selected. Open reduction and internal fixation were carried out in standard operating protocol using either an intraoral or an extraoral approach. The system was found to be reliable and effective treatment modality of mandibular fractures. Our observations do correlate with those of the study conducted by Ayman et al. (2005) [ Figure 6]. [19][20][21] Post-operative complications were noted in two patients. One developed an intraoral wound dehiscence which was treated with antibiotics and local measures. There was one major complication (3.125%) with infection at fracture site requiring incision and drainage and subsequent miniplate removal after 5 weeks of fracture treatment. Primary bone healing was noted in 93.75% of fracture sites with an overall post-operative complication of 6.25% in the study. Our study observations do correlate with those of the study conducted by Edward Ellis III and John Graham (2002).

CONCLUSION
The most common cause of mandibular fracture was found to be road traffic accidents, and males were most commonly affected in both genders. Patients between 16 and 30 years of age were mostly affected by mandibular fracture in which parasymphysis followed by parasymphysis with angle and parasymphysis bilateral with angel fracture was seen. Of 40 patients, few patients were found infected postoperatively