Mini-plate removal in maxillofacial trauma patients during a five-year retrospective study

Titanium vs PEO Surface-Modified Magnesium Plate Fixation in a Mandible Bone Healing Model in Sheep

Titanium plates are the current gold standard for fracture fixation of the mandible. Magnesium alloys such as WE43 are suitable biodegradable alternatives due to their high biocompatibility and elasticity modulus close to those of cortical bone. By surface modification, the reagibility of magnesium and thus hydrogen gas accumulation per time are further reduced, bringing plate fixation with magnesium closer to clinical application. This study aimed to compare bone healing in a monocortical mandibular fracture model in sheep with a human-standard size, magnesium-based, plasma electrolytic-oxidation (PEO) surface modified miniplate fixation system following 4 and 12 weeks. Bone healing was analyzed using micro-computed tomography and histological analysis with Movat's pentachrome and Giemsa staining. For evaluation of the tissue's osteogenic activity, polychrome fluorescent labeling was performed, and vascularization was analyzed using immunohistochemical staining for alpha-smooth muscle actin. Bone density and bone mineralization did not differ significantly between titanium and magnesium (BV/TV: T1: 8.74 ± 2.30%, M1: 6.83 ± 2.89%, p = 0.589 and T2: 71.99 ± 3.13%, M2: 68.58 ± 3.74%, p = 0.394; MinB: T1: 26.16 ± 9.21%, M1: 22.15 ± 7.99%, p = 0.818 and T2: 77.56 ± 3.61%, M2: 79.06 ± 4.46%, p = 0.699). After 12 weeks, minor differences were observed regarding bone microstructure, osteogenic activity, and vascularization. There was significance with regard to bone microstructure (TrTh: T2: 0.08 ± 0.01 mm, M2: 0.06 ± 0.01 mm; p = 0.041). Nevertheless, these differences did not interfere with bone healing. In this study, adequate bone healing was observed in both groups. Only after 12 weeks were some differences detected with larger trabecular spacing and more vessel density in magnesium vs titanium plates. However, a longer observational time with full resorption of the implants should be targeted in future investigations.

Compositional and surface changes of retrieved stainless-steel hardware and its effects on surrounding soft tissues: A prospective study

Purpose

To evaluate the surface, compositional, and histological changes in the overlying soft tissues of retrieved stainless-steel mini-plates and screws used for rigid internal fixation in the maxillofacial skeleton.

Materials and Method

A prospective study was conducted comprising 60 patients who sustained maxillofacial trauma and underwent ORIF in our unit previously and who required hardware retrieval in the post-operative phase. The retrieved hardware was evaluated for surface and compositional changes with the help of a scanning electron microscope for surface roughness and corrosion changes. Energy-dispersive X-ray study was done to know the composition and metal release from the hardware. The data obtained from these results were compared with a control unused and a sterile stainless-steel mini-plate and screw. The effects of the corrosion changes of this hardware on the adjacent soft tissues were evaluated histologically to assess the cellular changes of the soft tissue cover overlying the stainless-steel mini-plates and screws.

Results

A total of 96 stainless-steel mini-plates and 380 stainless-steel screws were retrieved from 60 patients. The control plate was smooth without any surface and corrosion defects, while the retrieved mini-plates irrespective of the reason for removal have shown surface roughness. Fe and Ni ions were found to be significantly reduced in the retrieved mini-plates. The presence of CrC in the retrieved plates indicates corrosion, which was seen only in hardware retrieved from symptomatic patients. The histological study revealed chronic inflammatory cell infiltrate with hyalinized connective tissue in all the samples irrespective of the reason for the removal of the plate.

Conclusion

Stainless-steel mini-plates and screws act as a potent foreign body material and initiate a localized inflammatory reaction due to its corrosive products with longer duration of stay. Hence, the authors advocate the overall shift in the use of stainless-steel hardware to titanium hardware for ORIF.

Mandibular Titanium Miniplates Change the Biomechanical Behaviour of the Mandible in the Case of Facial Trauma: A Three-Dimensional Finite Element Analysis

Our study aimed to compare the biomechanical behaviour of mandibles with or without titanium miniplates when subjected to an impact after bone healing using a finite element model (FEM) of the human mandible. We simulated mandibular trauma on an FEM of a human mandible carrying or not two parasymphyseal miniplates and applying a concentrated force of 2000 N to four different areas, including the insertion area, the area straddling the edge of the miniplates and the adjacent bone, at a distance from the miniplates on the symphysis, and on the basilar border of the mandible below the miniplates. Then, we compared the Von Mises stress distributions between the two models. In the case of an impact on the miniplates, the maximum Von Mises stress occurred in two specific areas, on the cortical bone at the posterior border of the two miniplates at a distance from the impact, while in the model without miniplates, the Von Mises stresses were homogenously distributed in the impact area. The presence of titanium miniplates in the case of trauma affects the biomechanical behaviour of the mandible and could cause more complex fractures. We recommend informing patients of this potential risk.

Three Different Fixation Modalities following Mandibular Setback Surgery with Sagittal Split Ramus Osteotomy: A Comparative Study using Three-dimensional Finite Elements Analysis

Background

The provision of sufficient stability after maxillofacial surgery is essential for the reduction of complications and disease recurrence. The stabilization of osteotomized pieces results in rapid restoration of normal masticatory function, reduction of skeletal relapse, and uneventful healing at the osteotomy site. We aimed to compare qualitatively stress distribution patterns over a virtual mandible model after bilateral sagittal split osteotomy (BSSO) bridged with three different intraoral fixation techniques.

Methods

This study was conducted in the Oral and Maxillofacial Surgery Department of Mashhad School of Dentistry, Mashhad, Iran, from March 2021-March 2022. The mandible computed tomography scan of a healthy adult was used to generate a 3D model; thereafter, BSSO with a 3mm setback was simulated. The three following fixation techniques were applied to the model: 1) two bicortical screws, 2) three bicortical screws, and 3) a miniplate. The bilateral second premolars and first molars were placed under mechanical loads of 75, 135, and 600N in order to simulate symmetric occlusal forces. Finite element analysis (FEA) was carried out in Ansys software, and the mechanical strain, stress, and displacement calculations were recorded.

Results

The FEA contours revealed that stress was mainly concentrated in the fixation units. Although bicortical screws presented better rigidity than miniplates, they were associated with higher stress and displacement readings.

Conclusion

Miniplate fixation demonstrated the most favorable biomechanical performance, followed by fixation with two and three bicortical screws, respectively. Intraoral fixation with miniplates in combination with monocortical screws can serve as an appropriate fixation arrangement and treatment option for skeletal stabilization after BSSO setback surgery.

Biomechanical Comparison of WE43-Based Magnesium vs. Titanium Miniplates in a Mandible Fracture Model in Sheep

In fractures of the mandible, osteosynthesis with titanium plates is considered the gold standard. Titanium is an established and reliable material, its main disadvantages being metal artefacts and the need for removal in case of osteosynthesis complications. Magnesium, as a resorbable material with an elastic modulus close to cortical bone, offers a resorbable alternative osteosynthesis material, yet mechanical studies in mandible fracture fixation are still missing. The hypothesis of this study was that magnesium miniplates show no significant difference in the mechanical integrity provided for fracture fixation in mandible fractures under load-sharing indications. In a non-inferiority test, a continuous load was applied to a sheep mandible fracture model with osteosynthesis using either titanium miniplates of 1.0 mm thickness (Ti1.0), magnesium plates of 1.75 mm (Mg1.75), or magnesium plates of 1.5 mm thickness (Mg1.5). No significant difference (p > 0.05) was found in the peak force at failure, stiffness, or force at vertical displacement of 1.0 mm between Mg1.75, Mg1.5, and Ti1.0. This study shows the non-inferiority of WE43 magnesium miniplates compared to the clinical gold standard titanium miniplates.

Do mandibular titanium miniplates affect the biomechanical behaviour of the mandible? A preliminary experimental study

INTRODUCTION

Whether to conserve or remove titanium miniplates after rigid internal fixation of mandibular fractures still remains controversial. Miniplates could affect the biomechanical behaviour of the mandible in case of trauma, and therefore cause more complex fractures.

MATERIALS AND METHODS

An experimental study, consisting in simulating a mandibular trauma, was designed in order to compare the fractures caused by an impact on the mandible in the presence or absence of an internal fixation. We simulated an impact on the right parasymphysis region in 10 post-mortem human subjects, according to the Charpy impact test method at an impact speed of 7.4 m/s, using a 5 kg test impactor.

RESULTS

In the control group, the fracture lines were vertical and straight, without comminution. In the miniplate group, the fractures occurred close to the miniplates (4 cases) and under the miniplates (one case). The fracture lines were more complex, even comminuted in 2 cases. Thus, miniplates impacted the biomechanical behavior of the mandible, resulting in more complex fractures.

CONCLUSION

Our experimental study highlighted the impact of the presence of miniplates on the mandible in case of trauma, and the risk of causing more complex fractures. We therefore recommend further investigations to determine if titanium miniplates should be systematically removed after bone healing, in patients with a higher risk of trauma in relation with previous assault injuries, alcohol or substance abuse, the practice of fighting or contact sport/activities, and soldiers.

Titanium or Biodegradable Osteosynthesis in Maxillofacial Surgery? In Vitro and In Vivo Performances

Osteosynthesis systems are used to fixate bone segments in maxillofacial surgery. Titanium osteosynthesis systems are currently the gold standard. However, the disadvantages result in symptomatic removal in up to 40% of cases. Biodegradable osteosynthesis systems, composed of degradable polymers, could reduce the need for removal of osteosynthesis systems while avoiding the aforementioned disadvantages of titanium osteosyntheses. However, disadvantages of biodegradable systems include decreased mechanical properties and possible foreign body reactions. In this review, the literature that focused on the in vitro and in vivo performances of biodegradable and titanium osteosyntheses is discussed. The focus was on factors underlying the favorable clinical outcome of osteosyntheses, including the degradation characteristics of biodegradable osteosyntheses and the host response they elicit. Furthermore, recommendations for clinical usage and future research are given. Based on the available (clinical) evidence, biodegradable copolymeric osteosyntheses are a viable alternative to titanium osteosyntheses when applied to treat maxillofacial trauma, with similar efficacy and significantly lower symptomatic osteosynthesis removal. For orthognathic surgery, biodegradable copolymeric osteosyntheses are a valid alternative to titanium osteosyntheses, but a longer operation time is needed. An osteosynthesis system composed of an amorphous copolymer, preferably using ultrasound welding with well-contoured shapes and sufficient mechanical properties, has the greatest potential as a biocompatible biodegradable copolymeric osteosynthesis system. Future research should focus on surface modifications (e.g., nanogel coatings) and novel biodegradable materials (e.g., magnesium alloys and silk) to address the disadvantages of current osteosynthesis systems.

Improved in vivo osseointegration and degradation behavior of PEO surface-modified WE43 magnesium plates and screws after 6 and 12 months

Magnesium is a highly promising candidate with respect to its future use as a material for resorbable implants. When magnesium degrades, hydrogen gas is released. High doses of gas emergence are reported to impair osseointegration and may therefore lead to fixation failure. The successful delay and reduction of the degradation rate by applying plasma electrolytic oxidation (PEO) as a post processing surface modification method for magnesium alloy has recently been demonstrated. The aim of this study was thus to compare the degradation behavior of a WE43-based plate system with and without respective PEO surface modification and to further investigate osseointegration, as well as the resulting effects on the surrounding bony tissue of both variants in a miniature pig model. WE43 magnesium screws and plates without (WE43) and with PEO surface modification (WE43-PEO) were implanted in long bones of Göttingen Miniature Pigs. At six and twelve months after surgery, micro-CT and histomorphometric analysis was performed. Residual screw volume (SV/TV; WE43: 28.8 ± 21.1%; WE43-PEO: 62.9 ± 31.0%; p = 0.027) and bone implant contact area (BIC; WE43: 18.1 ± 21.7%; WE43-PEO: 51.6 ± 27.7%; p = 0.015) were increased after six months among the PEO-modified implants. Also, surrounding bone density within the cortical bone was not affected by surface modification (BVTV; WE43: 76.7 ± 13.1%; WE43-PEO: 73.1 ± 16.2%; p = 0.732). Intramedullar (BV/TV; WE43: 33.2 ± 16.7%; WE43-PEO 18.4 ± 9.0%; p = 0.047) and subperiosteal (bone area; WE43: 2.6 ± 3.4 mm²; WE43-PEO: 6,9 ± 5.2 mm²; p = 0.049) new bone formation was found for both, surface-modified and non-surface-modified groups. After twelve months, no significant differences of SV/TV and BV/TV were found between the two groups. PEO surface modification of WE43 plate systems improved osseointegration and significantly reduced the degradation rate within the first six months in vivo. Osteoconductive and osteogenic stimulation by WE43 magnesium implants led to overall increased bone growth, when prior PEO surface modification was conducted.

Do mandibular miniplates increase the risk of complex fracture in facial trauma recurrence? Case series

Whether to conserve or remove miniplates, widely used in oral and maxillofacial surgery, has not been agreed on in the literature. Complications such as pain, infection, and screw exposure or loosening have already been largely described. We present the consequences of a trauma recurrence on a mandible with miniplates. The data of 13 patients who had a mandibular fracture previously surgically treated with miniplates (ten mandibular fractures and three mandibular osteotomies) were analysed. All the patients were male; the average age was 32 years (range, 20-64 years). The mechanism of the second trauma was assault in most of the cases. The average time between the first osteosynthesis and the new fracture was 35 months (range, 6-128 months). The fractures occurred at a distance from the miniplates in all the cases except two. No plate fracture was reported. We hypothesised that miniplates reinforced the underlying bone, protecting it from fractures, and transmitted the forces to areas anterior or posterior to the miniplates or to the condyle. Thus, the risk of mandible trauma recurrence should be taken into account in the indication of plate removal, and the biomechanical consequences of the conservation of the miniplates should be studied.

Is Mini-Plate Removal Necessary for Oral and Maxillofacial Surgery Patients? A Five-Year Case-Control Study

Objectives:

The purpose of this study was to determine the mini-plate and screw removal rate and reasons in maxillofacial surgery patients under previous semi-rigid fixation treatment in the past five years at the main trauma center of Mashhad.

Materials and Methods:

This was a census-based retrospective study. All the candidates who admitted to our department for maxillofacial plate removal due to symptomatic or infected mini-plates were included in this study. The patients’ age and gender, plate removal etiologies, and the time between plate insertion and removal were analyzed.

Results:

Mini-plates were inserted for 1026 patients. However, only 94 patients with a mean age of 29.4±11.1 years were candidates for plate removal. The plate removal rate was 9.16%. Infection and exposure were the most common causes of plate removal. The most prevalent removal site was the mandible (angle and body). The interval between mini-plate insertion and removal was an average of 12.9±5.6 months. It is noteworthy that the shortest lasting duration was when plate removal was secondary to pain (6.67 months) and infection (11.45 months).

Conclusion:

This research showed that the routine removal of plates does not appear to be generally indicated in healthy subjects unless there is an obvious and definitive clinical indication.

Miniplate removal in operated cases of maxillofacial region in a dental institute in Rajasthan, India

Background

The long term management of miniplate fixation osteosynthesis remains debatable and controversial with few authors advocating routine removal of the miniplates after 3–6 months of placement, while others recommend retention of the miniplates unless their removal is clinically indicated.

Objective

The aim was to study the incidence, indications, time gap, role of metallic composition and site of removal of miniplates in operated cases of maxillofacial region over a two-year period.

Methods

Patients undergoing removal of miniplates over 2-year period were studied and evaluated regarding the number of miniplates removed, time gap present between fixation and removal of miniplates, indications for removal, metallic composition of miniplates removed, sites of removal and complications. Correlations between indications for miniplate removal based upon time gap, metallic composition, age group and number of miniplates present were determined using Chi-square test. Correlation between metallic composition of miniplate and time gap was also determined using Chi-square test.

Results

The miniplates were removed in 20 patients (16 males and 4 females). Most common indication for removal was infection (45%). Forty-five percent of the patients underwent miniplate removal within 1 year of placement. Thirty-four miniplates and 118 screws were removed. The correlation between indications for miniplate removal and time gap was found to be statistically significant (P = 0.04).

Conclusion

Most of the hardware removal is performed subsequent to complications associated with hardware and local factors play more important role than metallic composition. Routine asymptomatic miniplates do not require removal and is not recommended.

No Need to Routinely Remove Titanium Implants for Maxillofacial Fractures

PURPOSE

Titanium implants are typically used to fix maxillofacial fractures and their routine removal is a controversial topic in maxillofacial surgery. This study aimed to estimate the removal rate and risk factors associated with removal.

MATERIALS AND METHODS

The authors designed and implemented a retrospective study. Adult patients who underwent open reduction and internal fixation with titanium implants for maxillofacial fractures were included and those who returned for implant removal were identified from January 2007 to December 2016. The predictor variables were gender, age, preoperative infection, injury time, trauma cause, and fracture site. The primary outcome variable was removal of titanium implants. Descriptive and bivariate statistics were computed. Kaplan-Meier survival methods were used to estimate rate of removal. Univariate and multivariate Cox proportional hazards models were used to identify risk factors associated with removal.

RESULTS

Of 2,325 patients (1,890 men and 435 women; average age, ∼35.49 yr) registered in this study, 163 (7.01%) had their titanium implants removed and 1-, 2-, and 10-year removal rates were 3, 7, and 8%, respectively. The risk factors most closely associated with removal were preoperative infection, injury by a blow from an object, obsolete fracture, and female gender.

CONCLUSIONS

Routinely removing titanium implants in patients with maxillofacial fracture is not necessary. When the risk factors listed earlier are present in these patients, follow-up should be scheduled more frequently.

Mini titanium plates; hearkening the end of non-rigid cranial bone flap fixation

BACKGROUND AND OBJECTIVE

Craniotomy bone flaps should be replaced for both cosmetic and protective purposes. Different methods are available commercially. The aim of this study was to assess outcome of bone flap fixation using mini titanium plates and screws.

METHODS

Between March, 2011 and March, 2014, 71 patients underwent cranial bone flap fixation with mini titanium plates and screws after craniotomy and excision of supratentorial lesions at Combined Military Hospital, Peshawar. There were 42 males and 30 females with a mean age of 40.07. All patients had supratentorial lesions. Intracranial lesion size ranged from 3 cm by 2 cm to 7 cm by 5 cm. The changes of local incision and general condition were observed.

RESULTS

Subcutaneous effusion occurred in two patients. One patient developed a mild postoperative wound infection. CT scan showed good repositioning of the flap and edge to edge apposition at two weeks after operation. All the patients were followed up for 12 months post operatively. Skull had good appearance without any discharge and, local deformity or effusion. Repeat CT/MRI showed no subsidence or displacement of cranial flap or artifacts.

CONCLUSION

Mini titanium plate and screw fixation of cranial flaps is a simple, cost effective and safe option for repositioning and immediate stability as compared to traditional sutures.

The correlation between periodontal health status and suspectibility to infections associated with craniomaxillofacial osteosynthesis plates

AIM

The aim of the present study was to demonstrate the possible relation between periodontal health status and infections associated with osteosynthesis materials (OMs) used in the oral and maxillofacial reconstruction.

MATERIAL AND METHODS

The study group consisted of 32 individuals which were subdivided into two groups regarding their PSI scores. After the removal of the osteosynthesis plates, microbial colonization was assessed via microbiological cultivation, fluorescence microscopy and scanning electron microscopy. In addition, samples obtained from gingival crevicular fluids were investigated by fluorescence microscopy.

RESULTS

A total of 118 osteosynthesis plates were examined. 8.5% (n = 10) of the plates were associated at least one of the clinical signs of infection. There was a positive correlation between periodontal disease and clinical signs of infection (p = 0.022). Patients with infection signs also had a higher number of smoking history (pack years, p = 0.010). Intraorally placed osteosynthesis plates showed wide range of bacterial colonizations compared to extraorally inserted osteosynthesis materials (p = 0.004).

CONCLUSION

Patients with poor periodontal health might be potential candidates for OM related infections. Early removal of OMs in patients with poor periodontal health status and/or heavy smokers would have clinical benefits. In addition, preferation of extraoral access to the fracture line might decrease the possibility of plate related infections.

Effects of degradable osteosynthesis plates of MgYREZr alloy on cell function of human osteoblasts, fibroblasts and osteosarcoma cells

The aim was to evaluate the biocompatibility of osteosynthesis plates of the MgYREZr/WE43 alloy by using human cells in vitro. Eluates of degradable magnesium osteosynthesis plates as well as halved plates were used for incubation with human osteoblasts, fibroblasts and osteosarcoma cells. The cell viability was evaluated by using FDA/PI-Staining and LDH analysis. Cell proliferation was assessed by MTT, WST-Test and BrdU-ELISA. Scanning electron microscope was used for investigation of the cell adhesion. The number of devitalized cells in all treatment groups did not significantly deviate from the control group. According to MTT results, the number of metabolically active cells was not significantly affected by the addition of the eluates. The number of metabolically active cells was reduced by 24 to 38% compared to the control on incubation in direct contact with the osteosynthesis plates. The proliferation of the cells was inhibited by the addition of the eluates. While the eluate of the half-hour elution has only a very small effect, the 24 h eluate significantly inhibits proliferation by 23-25% compared to the control. The roughened surface of the magnesium osteosynthesis plate after incubation showed adherent cells. However, some areas of the plates were also free of adherent cells. WE43 based magnesium alloys showed favorable biocompatibility considering the viability of the cells evaluated; however, proliferation rates were reduced in a time dependent manner, especially in fibroblast group. This might be a potential clinical benefit of magnesium osteosynthesis plates and their superiority to titanium, thus the fibroblastic ingrowth might negatively influence the bone-plate contact.