Stability testing of a two miniplate fixation technique for mandibular angle fractures. An in vitro study

Biomechanical assessment of mandibular fracture fixation using finite element analysis validated by polymeric mandible mechanical testing

The clinical finite element analysis (FEA) application in maxillofacial surgery for mandibular fracture is limited due to the lack of a validated FEA model. Therefore, this study aims to develop a validated FEA model for mandibular fracture treatment, by assessing non-comminuted mandibular fracture fixation. FEA models were created for mandibles with single simple symphysis, parasymphysis, and angle fractures; fixated with 2.0 mm 4-hole titanium miniplates located at three different configurations with clinically known differences in stability, namely: superior border, inferior border, and two plate combinations. The FEA models were validated with series of Synbone polymeric mandible mechanical testing (PMMT) using a mechanical test bench with an identical test set-up. The first outcome was that the current understanding of stable simple mandibular fracture fixation was reproducible in both the FEA and PMMT. Optimal fracture stability was achieved with the two plate combination, followed by superior border, and then inferior border plating. Second, the FEA and the PMMT findings were consistent and comparable (a total displacement difference of 1.13 mm). In conclusion, the FEA and the PMMT outcomes were similar, and hence suitable for simple mandibular fracture treatment analyses. The FEA model can possibly be applied for non-routine complex mandibular fracture management.

Update on ladder plates for mandibular angle fractures

PURPOSE OF REVIEW

Fractures of the mandibular angle are surgically challenging with high rates of postoperative complications. Among established fixation techniques for these injuries, Champy's tension band approach with miniplate fixation has held prominence. Rigid fixation, using two plates, also remains commonly used. More recently, geometric ladder plates, which confer greater three-dimensional stability have been developed to overcome the shortcomings of conventional fixation approaches. Herein, we aim to summarize the recent evidence surrounding the use of ladder plates and offer our own opinion for optimal treatment of these fractures.

RECENT FINDINGS

In high-powered studies, the rates of hardware failure, malocclusion, and malunion are lower among cohorts managed with ladder plates relative to miniplate groups. Rates of infection and paresthesia remain similar. Ladder plates have also been shown to decrease operative time in preliminary study.

SUMMARY

Ladder plates show superiority to miniplate approaches across several outcomes. However, the relatively larger strut plate constructs may not be necessary for minor, uncomplicated fractures. It is our belief that reasonable outcomes may be achieved with either approach depending on surgeon experience and comfort with the given fixation technique.

One miniplate versus two miniplates in the fixation of mandibular angle fractures. An updated systematic review and meta-analysis

PURPOSE

The aim of this study is to compare the outcomes after using one miniplate fixation in the external oblique ridge versus two miniplate fixation for mandibular angle fractures.

METHODS

A systematic review of MEDLINE (via PubMed), Scopus and Cochrane Library database was performed (last search date: 04 February 2022) according to the PRISMA guidelines. The research question was addressed using the PICO criteria. Only comparative studies between the two techniques were included. Random-effects model meta-analyses were performed.

RESULTS

Seventeen studies, comprising a total of 1667 patients, 846 undergoing one miniplate fixation and 854 undergoing two miniplate fixation for mandibular angle fractures were identified. No statistically significant differences were observed regarding surgical site infection (odds ratio [OR]= 0.94, 95% confidence interval [CI]: [0.69] - [1.28], p = 0.68, I²=0.00%), post-operative malocclusion (OR= 0.97, 95% CI: [0.53] - [1.18], p = 0.25, I²=0.00%), post-operative neurosensory dysfunction (OR= 0.67, 95% CI: [0.37] - [1.22], p = 0.19, I²=73.93%), pseudoarthrosis formation (OR=0.90, 95% CI: [0.58] - [(1.39], p = 0.63, I²=0.00%). Wound dehiscence was marginally less common in the one miniplate group (OR=0.52, 95% CI: [0.28] - [0.98], p = 0.04, I²=54.34%). The probability of scarring formation (OR=0.13, 95% CI: [0.05] - [0.32], p = 0.00, I²=0.00%) and hardware failure (OR=0.36, 95% CI [0.21] - [0.62], p = 0.00, I²=29.33%) were statistically significantly higher in the two miniplates arm.

CONCLUSION

One miniplate fixation and two miniplates fixation of mandibular angle fractures have similar results regarding post operative infection, malocclusion, neurosensory dysfunction and pseudoarthrosis formation while wound dehiscence, hardware failure and scarring seem to be more common when two miniplates are used as a fixation technique.

Macaca mulatta is a good model for human mandibular fixation research

Biomechanical and clinical studies have yet to converge on the optimal fixation technique for angle fractures, one of the most common and controversial fractures in terms of fixation approach. Prior pre-clinical studies have used a variety of animal models and shown abnormal strain environments exacerbated by less rigid (single-plate) Champy fixation and chewing on the side opposite the fracture (contralateral chewing). However, morphological differences between species warrant further investigation to ensure that these findings are translational. Here we present the first study to use realistically loaded finite-element models to compare the biomechanical behaviour of human and macaque mandibles pre- and post-fracture and fixation. Our results reveal only small differences in deformation and strain regimes between human and macaque mandibles. In the human model, more rigid biplanar fixation better approximated physiologically healthy global bone strains and moments around the mandible, and also resulted in less interfragmentary strain than less rigid Champy fixation. Contralateral chewing exacerbated deviations in strain, moments and interfragmentary strain, especially under Champy fixation. Our pre- and post-fracture fixation findings are congruent with those from macaques, confirming that rhesus macaques are excellent animal models for biomedical research into mandibular fixation. Furthermore, these findings strengthen the case for rigid biplanar fixation over less rigid one-plate fixation in the treatment of isolated mandibular angle fractures.

Medial Epicanthoplasty With the Classic and Modified Skin Redraping Method: A Retrospective Case Control Study

ABSTRACT

The skin redraping method for medial epicanthoplasty is characterized by some shortcomings which warrants modification. In this study, clinical data of 193 patients who underwent medial epichanthoplasty by the modified skin redraping technique or the classic skin redraping technique were reviewed retrospectively. The patients underwent operation between May 2018 and June 2020 and were followed up for not less than 6 months. Interepicanthal distance , interpupillary distance, patient satisfaction, and postoperative complications were evaluated. In terms of interepicanthal distance/interpupillary distance ratio (P > 0.05) and satisfaction score (P = 0.759), the modified skin redraping technique and the classic skin redraping technique were similar. In the classic skin redraping group, there were 3 cases of visible scarring in the lower eyelid, corresponding to significantly more cases than in the modified skin redraping group (n = 0, P < 0.001). There were more out-fold cases in the modified skin redraping group (76/90) than in the classic skin redraping group (17/88) (P < 0.001). Utilizing the modified skin redraping medial epicanthoplasty can prevent medial hooding of the upper eyelid, reduce the probability of visible scarring, and produce more out-fold with concurrent double eyelidplasty compared with classic skin redraping epicanthoplasty.Level of evidence: IV.

Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair

Lower jaw (mandible) fractures significantly impact patient health and well‐being due to pain and difficulty eating, but the best technique for repairing the most common subtype—angle fractures—and rehabilitating mastication is unknown. Our study is the first to use realistic in silico simulation of chewing to quantify the effects of Champy and biplanar techniques of angle fracture fixation. We show that more rigid, biplanar fixation results in lower strain magnitudes in the miniplates, the bone around the screws, and in the fracture zone, and that the mandibular strain regime approximates the unfractured condition. Importantly, the strain regime in the fracture zone is affected by chewing laterality, suggesting that both fixation type and the patient's post‐fixation masticatory pattern—ipsi‐ or contralateral to the fracture— impact the bone healing environment. Our study calls for further investigation of the impact of fixation technique on chewing behavior. Research that combines in vivo and in silico approaches can link jaw mechanics to bone healing and yield more definitive recommendations for fixation, hardware, and postoperative rehabilitation to improve outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The effect of the mandibular plane angle on fracture line stability: An ex vivo experimental study

BACKGROUND/AIMS

Mandibular angle fractures fixated with plate osteosynthesis techniques have to withstand the effects of muscle attachments. Individual variations in the craniofacial morphology may alter the biomechanical resistance of the bone-plate construct. The aim of the present study was to determine the influence of variations in the mandibular plane angle (MPa) on the biomechanical stability of sheep mandibular angle fractures (MAFs).

MATERIALS AND METHODS

Sixty sheep hemi-mandibles were used. The mandibles were positioned on a test jig that simulated low (15°, group L), normal (25°, group N), and high (35°, group H) MPa. Unfavorable MAFs were created with thin diamond cutting disks. One four-hole, 9.0-mm-spacing, standard titanium miniplate of 2.0 mm thickness and 5.0-mm-long screws were inserted at the superior border of the alveolar bone in monoplanar orientation. Specimens were then subjected to vertical loads between 10 N and 150 N in a universal testing machine. The displacement values at each 10 N force increment and the load magnitude at which 3.0 mm displacement limit was reached were recorded.

RESULTS

Starting from 40 N, the displacement values at each 10 N increment in the H group were significantly higher than those of the L and N groups until 150 N (P < 0.05). The force magnitude required to reach 3.0 mm of displacement in the H group was significantly lower than that for the L and N groups (P < 0.05 for each).

CONCLUSIONS

The one-miniplate monoplanar fixation technique used in sheep MAF with high MPa is more likely to offer lower biomechanical resistance to the vertical forces applied over the molar region than do the normal and low MPa.

Comparison of single versus two non-compression miniplates in the management of unfavourable angle fracture of the mandible: a prospective randomized clinical study

PURPOSE

The purpose of this study was to compare the efficacy of single versus two non-compression miniplates in the management of unfavourable angle fracture of mandible.

MATERIALS AND METHODS

A total of 28 patients who required open reduction of mandibular angle fracture were included in the study. The patients were randomly divided into two groups. Group I comprised of patients treated with two miniplates and those in group II were treated with single non-compression miniplate. The parameters of assessment were malocclusion, surgical site infection, need for implant removal, duration of surgery, inter-incisal mouth opening and cost of implants used, in both the groups. Statistical analysis was carried out to compare all the parameters.

RESULTS

Out of 14 patients in group II, inadequate reduction was noticed in three patients, whereas screw loosening had occurred in two cases. Screw loosening was always associated with chronic infection. In these cases, hardware removal was deemed necessary. Plate bending was observed in two cases resulting in malocclusion and difficulty in eating. Non-union of fracture occurred in one patient treated in group II. In group I, no plate bending, screw loosening, surgical site infection, non-union or malocclusion was observed. No patient had to undergo implant removal in group I.

CONCLUSION

In the management of unfavourable mandibular angle fracture, two miniplates must be preferred over the use of single miniplate as using two miniplates results in better results with minimal complications.

Comparative Evaluation between Single Noncompression Miniplate and Two Noncompression Miniplates in the Treatment of Mandibular Angle Fractures

This study was conducted to compare the outcome of single noncompression miniplate versus two noncompression miniplates in the treatment of mandibular angle fracture. A total of 40 patients were divided into two groups: Group I ( n  = 20), patients were treated by single miniplate at superior border of mandible by intraoral approach; Group II ( n  = 20), patients were treated by one miniplate at superior border of mandible, intraorally, and another at the lateral aspect of angle, transbuccally by trocar and cannula. Comparative evaluation was done at 1, 2, 4, 6, and 12 weeks and 6 months. The findings of this study suggest that there was no significant difference in postoperative complications (malocclusion, pain, swelling, infection, facial nerve injury, wound dehiscence, plate exposure) and bite force between the two groups.

The 3-dimensional miniplate is more effective than the standard miniplate for the management of mandibular fractures: a meta-analysis

PURPOSE

The study aimed to determine the superiority between 3-dimensional (3D) miniplate and standard miniplate for mandibular fractures (MFs) treatment.

BACKGROUND

Controversial results on the use of standard miniplate and 3D miniplate have remained for management of MFs.

METHODS

Several electronic databases were retrieved up to September 2014 to identify eligible studies. The quality of studies was assessed, and the relative risk (RR) with its corresponding 95% confidence interval (CI) was assessed to measure the effect size. Subgroup analyses by different fracture regions and different 3D miniplate sizes were performed. Publication bias was measured by a funnel plot.

RESULTS

There were 13 studies included for the meta-analysis, consisting of 593 participants. The 3D miniplate achieved significant lower incidences of malocclusion (RR 0.43, 95% CI 0.24-0.77, P = 0.004) and hardware failure (RR 0.31, 95% CI 0.13-0.74, P = 0.008) than the standard miniplate. There were no significant differences between the two miniplates on the incidence of the remaining outcomes: wound dehiscence, infection, paresthesia, and nonunion/malunion. Subgroup analyses indicated that 3D miniplate caused a lower hardware failure than standard with the size of 8 or 10 holes (RR 0.23, 95% CI 0.08-0.66, P = 0.006). Besides, publication bias was not detected.

CONCLUSION

The 3D miniplate is superior to the standard miniplate on the reduction of postoperative complication rates for the management of MFs. More holes in the 3D miniplate might contribute to a successful treatment.

Evaluation of in vitro resistance of different 2.0-mm titanium plates on the mandibular angle sectioning

OBJECTIVE

The purpose of this study was to compare, by mechanical in vitro testing, a regular 5-hole plate and a long 4-hole plate with a regular 4-hole plate, applied to stabilize a simulated mandibular angle fracture.

STUDY DESIGN

The plates from the 2.0-mm titanium-based system were adapted and stabilized passively in the same site in both groups using four screws, 6 mm long. During the resistance-to-load test, the force was applied perpendicular to the occlusal plane at three different points: first molar at the plated side, first molar at the contralateral side, and between the central incisors.

RESULTS

The regular 5-hole plates and longer 4-hole plates were superior to the regular 4-hole plates. Furthermore, no statistically significant difference was found between the regular 5-hole plates and long 4-hole plate.

CONCLUSIONS

The length and shape of plates did not interfere with the effectiveness to stabilize the fragments.

OBJECTIVE

The purpose of this study was to compare, by mechanical in vitro testing, a regular 5-hole plate and a long 4-hole plate with a regular 4-hole plate, applied to stabilize a simulated mandibular angle fracture.Study design The plates from the 2.0-mm titanium-based system were adapted and stabilized passively in the same site in both groups using four screws, 6 mm long. During the resistance-to-load test, the force was applied perpendicular to the occlusal plane at three different points: first molar at the plated side, first molar at the contralateral side, and between the central incisors.

RESULTS

The regular 5-hole plates and longer 4-hole plates were superior to the regular 4-hole plates. Furthermore, no statistically significant difference was found between the regular 5-hole plates and long 4-hole plate.Conclusions The length and shape of plates did not interfere with the effectiveness to stabilize the fragments.

Effect of interfragmentary gap on the mechanical behavior of mandibular angle fracture with three fixation designs: A finite element analysis

BACKGROUND

The aim of this study was to simulate stress and strain distribution numerically on a normal mandible under physiological occlusal loadings. The results were compared with those of mandibles that had an angle fracture stabilized with different fixation designs under the same loadings. The amount of displacement at two interfragmentary gaps was also studied.

MATERIALS AND METHODS

A three-dimensional (3D) virtual mandible was reconstructed with an angle fracture that had a fracture gap of either 0.1 or 1 mm. Three types of plate fixation designs were used: Type I, a miniplate was placed across the fracture line following the Champy technique; Type II, two miniplates were used; and Type III, a reconstruction plate was used on the inferior border of the mandible. Loads of 100 and 500 N were applied to the models. The maximum von Mises stress, strain, and displacement were computed using finite element analysis. The results from the control and experimental groups were analyzed and compared.

RESULTS

The results demonstrated that high stresses and strains were distributed to the condylar and angular areas regardless of the loading position. The ratio of the plate/bone average stress ranged from 215% (Type II design) to 848% (Type I design) irrespective of the interfragmentary gap size. With a 1-mm fracture gap, the ratio of the plate/bone stress ranged from 204% (Type II design) to 1130% (Type I design). All strains were well below critical bone strain thresholds. Displacement on the cross-sectional mapping at fracture interface indicated that uneven movement occurred in x, y, and z directions.

CONCLUSIONS

Interfragmentary gaps between 0.1 and 1 mm did not have a substantial effect on the average stress distribution to the fractured bony segments; however, they had a greater effect on the stress distribution to the plates and screws. Type II fixation was the best mechanical design under bite loads. Type I design was the least stable system and had the highest stress distribution and the largest displacement at the fracture site.

Management of Mandibular Angle Fractures by Two Conventional 2.0-mm Miniplates: A Retrospective Study of 389 Patients

Fractures of the mandibular angle account for 23 to 42% of all facial fractures with a high complication rate (0-32%). Although the ideal treatment remains debatable, two main procedures are commonly used to manage the majority of mandibular angle fractures that are open reduction and internal fixation by a noncompression miniplate placed on the external oblique ridge with or without a second miniplate on the outer cortex. The purpose of this study was to describe our management of mandibular angle fractures by two noncompression miniplates placed on the outer cortex via a transbuccal approach. Medical records and radiographic examination of 389 patients (258 males [66.3%] and 131 females [33.7%]) operated from January 2000 to December 2012 were retrospectively reviewed. Postoperative complications including malocclusion, infection, wound dehiscence, nonunion, and reoperative surgery were recorded and analyzed. Fifty-three patients developed postoperative complications (overall complication rate: 13.6%). No significant difference was found in the complication rate by age and gender variables and regarding the interval between the trauma and the operation and the presence of the teeth in the line of fracture. A higher rate of complications was found among patients with alcohol/drug addiction and in patients with multiple-site involvement. The findings of this study suggest that the use of two transbuccal miniplates placed on the outer cortex for the internal fixation of mandibular angle fracture provided a low rate of complications. The global incidence of screw loosening, wound dehiscence, plate exposure, infection, reoperation, and plate removal were similar with the data reported in the literature with improved health outcomes, lower postoperative morbidity, and a faster return to normal life.

Management of Mandibular Angle Fractures: Single Stainless Steel Linear Miniplate Versus Rectangular Grid Plate-A Prospective Randomised Study

PURPOSE

This prospective study was conducted to evaluate the efficacy of stainless steel single linear miniplate with rectangular grid plate in the treatment of mandibular angle fractures.

METHODS

This study included 30 patients who were allocated randomly into two groups of each. Group 1 patients were treated with single 2 mm × 4 hole linear stainless steel miniplate and group 2 patients with 2 mm × 4 hole rectangular grid plate. Patients were evaluated for fracture stability, occlusion, mouth opening, and complications at 1st week, 1 and 3 months post operatively.

RESULTS

There were no significant differences between the two groups with respective variables statistically. In group 1 20 % (n = 3) had mild occlussal derangement 6.66 % (n = 1) patient had deranged occlusion at 1 week post operatively and 13.3 % (n = 2) had mild derangement at 1 month post operatively. In group 2 6.66 % (n = 1) had mild derangement at 1 week postoperatively. 20 % (n = 3) had limited mouth opening at 1 week in group 1 and 13.3 % (n = 2) in group 2. All patients in both groups achieved adequate mouth opening by the end of 3 month. None of the patients in both groups had plate fracture, screw loosening, non union or mal-union.

CONCLUSION

Within the limits of the study, use of rectangular grid plates for fixation of mandibular angle fractures was reliable with low complication rates, easy adaptation and an effective alternative to conventional miniplates. Further clinical studies with larger sample size can derive a more comprehensive conclusion.

Finite-Element Analysis of a New Designed Miniplate which is Used via Intraoral Approach to the Mandible Angle Fracture: Comparison of the Different Fixation Techniques

The mandible is the largest facial bone as well as the most commonly fractured bone in the maxillofacial region. Despite numerous studies conducted to identify optimal treatment modalities and plates configurations for intraoral and transoral approaches, no definitive conclusion has been reached. This study used finite element analysis (FEA) to assess 4 scenarios for treatment of an angle fracture (6-hole noncompression miniplate; 6-hole single plate/Champy's technique, 3D strut plate; 2 parallel 4-hole noncompression miniplates). Analysis included segmental displacement and Von Mises Stress evaluations of a 3D reconstruction of a human mandible. Von Mises Stress values for plates did not vary significantly among treatment groups. Moreover, no significant differences were observed in cumulative displacement of segments subjected to vertical and horizontal loads, with all treatment configurations demonstrating clinical acceptability.

A comparison of three treatment methods for fractures of the mandibular angle

The purpose of this study was to determine a practical and cost-effective treatment method for fixing mandibular angle fractures using miniplates. Patients were divided into three groups for comparison, based on the intraoperative plates and maxillomandibular fixation (MMF) used: group A, single miniplate fixation with MMF (n=37); group B, double miniplate fixation with MMF (n=59); group C, double miniplate fixation without MMF (n=38). Details of the characteristics of the fractures and the treatments and outcomes were collected retrospectively and analyzed statistically. This study was based on 134 cases of isolated mandibular angle fracture. Of the surgically treated patients, 78.4% (n=105) were completely free of complications. A detailed complication correlation matrix is given in the text. Besides screw loosening and malocclusion, no statistically significant difference was observed between the groups. The results of this study suggest that treatment with single miniplate fixation and MMF has a low incidence rate of complications, and this method of treatment is considered to be simple.

Miniplate osteosynthesis for mandibular angle fractures--A retrospective comparative study of 3 concepts in a temporal cohort

PURPOSE

Purpose of this retrospective study was to compare fixation of mandibular angle fractures by three different miniplating-concepts (single miniplate, double miniplate, TriLock mandibular angle plate) regarding osteosynthesis failure and hardware removal.

METHODS

In this retrospective study a temporal cohort of 184 patients with 194 simple mandibular angle fractures, which had been treated by open reduction and internal fixation via miniplates at the University Clinic of Cranio-, Maxillofacial and Oral Surgery (General Hospital Vienna) in the period of 2005-2011, were included. Patients with pathologic fractures (e.g. tumour or osteonecrosis related) or comminuted fractures were not considered.

RESULTS

9 of 194 (4.6%) fractures showed osteosynthesis failures. The osteosynthesis failure rates were 2.9% in the single miniplate group, 3.4% in the TriLock plate group, and 11.1% in the double miniplate group. In the double miniplate group 33.3% of the patients had undergone hardware removal, 21.4% in the single miniplate group, and 11.4% in the TriLock plate group.

CONCLUSION

A single 4-hole locking plate with a thickness of 1.25-1.3 mm guarantees for low osteosynthesis failure rates without postoperative maxillo-mandibular fixation and requires less hardware removal in simple mandibular angle fractures. Two miniplates, longer plates with more holes and thicker plates are prone to hardware removal.

Biomechanical study in polyurethane mandibles of different metal plates and internal fixation techniques, employed in mandibular angle fractures

The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P.

In Vitro Mechanical Analysis of Different Techniques of Internal Fixation of Combined Mandibular Angle and Body Fractures

PURPOSE

To evaluate in vitro resistance of 5 techniques of internal fixation of bilateral fractures involving the mandibular angle and body.

MATERIALS AND METHODS

Twenty-five polyurethane mandibles were used as substrates, fixed with a 2-mm fixation system, and divided into 5 groups: I, 1 4-hole plate, without intermediate space, in the neutral zone of the mandibular body and another similar plate in the external oblique ridge of the contralateral mandibular angle; II, 1 6-hole plate, with intermediate space, in the neutral zone of the mandibular body and a similar plate in the external oblique ridge of the left mandibular angle; III, 1 4-hole locking plate, with intermediate space, in the right neutral zone and another similar plate in the left external oblique ridge; IV, 2 4-hole plates, with intermediate space, one in the tension zone and the other in the compression zone of the mandibular body, and 1 4-hole plate, with intermediate space, in the external oblique ridge of the contralateral mandibular angle; V, 2 4-hole plates with intermediate space, one in the tension zone and the other in the compression zone of the mandibular body and similarly in the buccal side of the left mandibular angle. Mandibles were subjected to vertical linear load tests by a mechanical testing machine (Instron 4411, Instron Corp, Norwood, MA) to record peak load and load for displacements of 3, 5, and 7 mm.

RESULTS

Group I had the least mechanical resistance of all groups, regardless of displacement, and group IV had the greatest mechanical resistance. Among groups II, III, and V, there was no statistically meaningful difference.

CONCLUSION

Fixation of bilateral mandibular fractures involving the mandibular angle and body using 2 plates in the region of the body and 1 plate in the tension zone in the region of the mandibular angle was the technique that presented the best mechanical resistance.

Routine removal of the plate after surgical treatment for mandibular angle fracture with a third molar in relation to the fracture line

Purpose:

The purpose was to analyze the clinical course of surgically treated mandibular angle fractures from the viewpoint of routine removal of the plate because these fractures are associated with high rates of complications and plate removal.

Subjects and Methods:

The subjects were 40 patients with unilateral mandibular angle fracture, which was intraorally reduced and principally fixed with a single miniplate on the external oblique ridge. The third molar in relation to the fracture line was extracted in seven patients during the surgery. Clinical course was evaluated in terms of removal of the plate, preservation of the third molar and complications.

Results:

One patient showed a wound infection postoperatively, and two patients developed pericoronitis during the follow-up. These were managed with medication and local irrigation. One patient with a preserved third molar did not make a required visit and was lost from the follow-up. Removal of the plates was performed in 39 patients after confirmation of good fracture healing, mostly within a year. Twenty-four of 32 preserved third molars were simultaneously extracted. These procedures were generally performed under local anesthesia on an outpatient basis, and they did not cause any complications.

Conclusions:

Routine removal of the plate after surgical treatment for mandibular angle fractures, simultaneously with extraction of the third molar if indicated, may be beneficial to avoid complications related to the plate and the third molar later in life.

Biomechanical comparison of four mandibular angle fracture fixation techniques

The aim of this study was to make a comparison of the biomechanical behavior of four different internal fixation systems for mandibular angle fractures. A total of 40 polyurethane mandible replicas were employed with different fixation methods: group 1SP, one 2.0-mm four-hole miniplate; group 2PPL, two 2.0-mm four-hole parallel miniplates; group 3DP, one 3D 2.0-mm four-hole miniplate; and group 3DPP, one 3D 2.0-mm eight-hole miniplate. Each group was subjected to incisal or homolateral molar region loading. The load resistance values were measured at load application causing tip displacement of 1, 3, and 5 mm, and at the time at which the system achieves its maximum strength (MS). Means and standard deviations were compared among groups using analysis of variance and the Tukey test. Group 2PPL showed higher strength for all the displacements. For incisal loading, no statistically significant differences were found between groups 1SP, 3DP, and 3DPP. For molar loading, group 1SP and 3DPP showed statistically significant differences. For MS testing, group 1SP and 2PPL showed statistically significant differences in incisal loading; group 1SP and 3DP showed no statistically significant differences; and group 3DPP showed lower values of strength. Two parallel miniplates provide the most favorable mechanical behavior under the conditions tested.

Biomechanical evaluation of a new design titanium miniplate for the treatment of mandibular angle fractures

The optimal management of mandibular angle fractures remains controversial. The aim of this experimental study was to test the stability and resistance to mechanical force of a new titanium miniplate design. Thirty fresh sheep hemimandibles, sectioned at the angle region, were used to evaluate two plating techniques. One group received fixation via a new design single non-compression titanium miniplate and the second group via a six-hole straight non-compression titanium miniplate. A custom-made biomechanical test model was used for the samples. Each hemimandible was subjected to compressive and tensile forces using an Instron machine. The biomechanical forces (N) that caused 4-mm displacement or fixation loosening were compared. Comparison between the groups showed that fixation with the new design miniplate had more resistance to lateral compression forces than with a six-hole straight miniplate (P<0.009). Moreover, the new design miniplate fixation displayed more resistance to vertical compression and tensile forces (P>0.46 and P>0.61, respectively). The study demonstrated that mandibular fracture fixation with the new design non-compression titanium miniplate offered greater resistance to lateral displacement forces and may also provide increased resistance to vertical compressive and tensile forces than a conventional six-hole straight miniplate.

Use of 3-d plate in displaced angle fracture of mandible

Introduction Mandibular angle fractures can be treated by various methods, but even the most popular methods may not be able to give satisfactory results, as the pterygomasseteric sling and masticatory forces can result in displaced angle fracture. These displaced fragments cannot be satisfactorily retained by single miniplate fixation. The aim of this study is to assess treatment of displaced angle fracture with 3-D miniplate fixation. This study can also be considered as a therapeutic study with level V evidence. Materials and Methods This study was designed to assess the feasibility of 3-D matrix miniplate fixation in displaced angle fractures. Eighteen patients with displaced angle fractures were included in this study. Matrix miniplate fixation was done transorally under general anesthesia. Results All these cases were treated successfully, and common complications like infection (5.5% of patients), wound dehiscence (11%), paresthesia (16.7%), and malocclusion (11%) were observed in our study. Conclusions Three-dimensional miniplate fixation in displaced angle fractures provides better stability and function.

Transoral Miniplate Fixation of Mandibular Angle Fracture with and without 2 Weeks of Maxillomandibular Fixation: A Clinical Trial Study

Background and Objectives The ideal line of osteosynthesis in mandibular angle fractures indicates that a plate might be placed either along or just below the external oblique ridge. Some authors believe that using one miniplate at this line at the mandibular angle region provides sufficient strength to stabilize the fracture but others imply a second plate is required. Such controversies exist in the use of maxillomandibular fixation (MMF). The intention of the present study was to compare efficiency and complications of using one miniplate with and without MMF in mandibular angle fractures. Methods and Materials Forty patients with facial trauma with mandibular angle fractures including displaced and unfavorable fractures were categorized into two groups of 20 persons. In all patients, one miniplate was placed on the external oblique ridge. In the first group, patients had light maxillomandibular elastic bands just after surgery but no rigid MMF. In the second group, patients had rigid MMF for 2 weeks after surgery. Patients were followed to evaluate complications and treatment efficiency. Conclusions Our study showed that use of a single miniplate in the external oblique ridge is a functionally stable treatment for all types of angle fractures (including displaced and unfavorable fractures) except comminuted and long oblique fractures, which were not included in our study. Use of postoperative MMF did not improve the results.

Fixation of mandibular angle fractures: in vitro biomechanical assessments and computer-based studies

PURPOSE

The purpose of this study was to review the literature regarding the evolution of current thoughts on fixation of mandibular angle fractures (MAFs), based on in vitro biomechanical assessments and computer-based studies.

METHODS

An electronic search in PubMed was undertaken in August 2012. The titles and abstracts from these results were read to identify studies within the selection criteria. Eligibility criteria included studies from the last 30 years (from 1983 onwards).

RESULTS

The search strategy initially identified 767 studies. Thirty-one studies were identified without repetition within the selection criteria. Two articles showing significance in the development of treatment techniques was included. Additional hand searching yielded five additional papers. Thus, a total of 38 studies were included.

CONCLUSIONS

The osteosynthesis positions as well as the plating technique play important roles in the stability of MAF repair. The only in vitro study evaluating the use of wire osteosynthesis concluded that wires placed through the lower border approach would provide greater stability than those at the upper border. Many studies indicate that the use of two miniplates avoids (or decreases) lateral displacement of the lower mandibular border and opening of the inferior fracture gap. Some studies even suggest that the use of two miniplates may be considered a more "rigid" fixation technique for MAFs than the use of a reconstruction plate. When using two miniplates, the biplanar plate orientation provides greater biomechanical stability than the monoplanar one. However, despite its greater biomechanical stability, the two-miniplate technique has some disadvantages that should also be taken into account. Studies with biodegradable plates suggest the use of at least two plates for each MAF. There are few studies with compression plates, and they have not yet reached a consensus. The solitary lag screw proved to withstand the functional loading of the mandible; however, only few biomechanical assessments were performed. In vitro studies have shown good biomechanical stability with the use of 3-D grid plates. The use of malleable miniplates alone is not sufficient to withstand the early postoperative bite force. Some studies suggest that the segment of the tension band miniplate located at the distal fragment of the MAF should be fixed with three screws. The studies also showed some limitations. None considered the stabilization of the fracture site afforded by the masseter-pterygoid muscle pouch. Most of the studies did not evaluate plating system strength in the long term and therefore did not observe the effect of resorption on the strength of the different biodegradable plating systems. Another limitation of many studies is the absence of a control group. A confounding factor that could not be tested in in vitro investigations is the additional resistance to displacement of jagged fracture margins present in the human fracture.

Fractures of angle of mandible - A retrospective study

AIMS

This retrospective study was done to evaluate the efficacy of single miniplate osteosynthesis at superior border of angle of mandible.

MATERIAL AND METHODS

In this study 50 patients were treated by single miniplate osteosynthesis according to Champy's principle. Bite force generated was used as a parameter for judging the efficacy of internal fixation. In this article we present our experience over the years in the management of the fractures of angle of mandible based on this model.

RESULTS

Most patients were of 21-30 yrs of age with unilateral angle fracture of mandible except one patient who had isolated bilateral angle fracture. The patients were treated successfully according to Champy's principle of osteosynthesis. There was a progressive improvement in the bite force generated after osteosynthesis.

CONCLUSIONS

The angle of the mandible is an anatomically weak and an area susceptible to fracture. The presence of an impacted or partially erupted third molar tooth further weakens it. Angle of mandible is the most common site for fracture however, bilateral angle fracture is very rare and uncommon. Osteosynthesis according to Champy's model led to an early functional improvement as demonstrated by the bite force generated.

A new biomechanical model for evaluation of fixation systems of maxillofacial fractures

The aim of this study was to develop a new type of biomechanical model for biomechanical researches of maxillofacial fractures and then evaluate it. Twenty synthetic polyurethane maxillary and mandibular models were used to simulate the mandible and maxilla. Springs were used to represent the forces of masseter, medial pterygoid, temporalis, and lateral pterygoid muscles acting on the models. Four masticatory conditions, namely clenching in the intercuspal position (ICP), incisal clenching (INC), left unilateral molar clenching (L-MOL, contralateral side of fracture) and right unilateral molar clenching (R-MOL, fracture side) were simulated. The strain on a miniplates placed across a simulated fracture was measured using strain gauges attached to the plate surface. During INC and L-MOL, the strain on the miniplates confirmed the findings of Champy. The upper miniplate was subjected to tension force and the lower miniplate to compression. When the bite point moved to the fracture, the tension-compression zone reversed, with the upper miniplate relatively compressed and the lower miniplate tension. During ICP, the tension-compression zone changed again, with both miniplates tension. In conclusion, we have successfully developed a model which is much closer to physiological conditions than models used previously. It is reliable and useful for biomechanical tests of mandibular fractures. Models including soft tissue need developing to further understand fracture healing biomechanics.

Is a single miniplate at the inferior border adequate in the management of an angle fracture of the mandible?

OBJECTIVE

This prospective study evaluates the efficacy of using a single miniplate at the inferior border in the management of a displaced angle fracture.

STUDY DESIGN

Case series with chart review.

SETTING

Pt. B.D. Sharma University of Health Sciences.

SUBJECTS AND METHODS

Fifty-two patients with angle fracture of the mandible were evaluated. All fractures were displaced. The displacement of fracture was assessed on panoramic radiography by measuring the displacement of the inferior alveolar canal. Fractures with displacement greater than 2 mm were included in the study. Fixation with a 4-hole noncompression miniplate along the inferior border and 2 bicortical screws on each side of the fracture was done.

RESULTS

Among these 52 patients, 20 sustained isolated angle fracture, 2 sustained bilateral angle fracture, and 30 sustained angle fracture associated with contralateral parasymphysis or body fracture. Five patients (9.5%) experienced complications. All were considered minor and did not require hospitalization. Two had a slight occlusal discrepancy requiring selective occlusal grinding, and 2 minor infections were managed by incision and drainage. One patient suffered from paresis of the facial nerve that resolved itself after 3 months.

CONCLUSION

Based on this single study, at a single institution, we can conclude that outcomes are acceptable in our patients, but there is very limited ability to generalize the results to different practice settings. Because of these limitations, a multicenter study with an appropriate comparison group is required to substantiate a more generalizable conclusion of efficacy of this single miniplate at inferior border.

A comparative study between transbuccal and extra-oral approaches in treatment of mandibular fractures

BACKGROUND AND OBJECTIVES

Mandibular angle fractures continue to be a common type of facial injury. The objectives in treatment are to effect rapid healing by anatomic reduction and fixation and to restore function and appearance with minimal disability and complications. Traditionally, when open techniques are utilised, the extra-oral approach is performed through a skin incision concealed in the submandibular crease. However, patients develop unsightly scars and there is a risk of injury to the marginal mandibular nerve. In comparison, the trans-oral approach, performed through an oral mucosal incision, results in minimal external scarring or injury to the marginal mandibular nerve and allows direct visualisation and confirmation of the desired occlusion during the placement of the miniplates. The basic aim of the study was to provide a treatment for the mandibular fractures which results in minimal scarring and fulfills all the functional needs of the patient.

STUDY DESIGN

Patients coming to KLES PK Hospital and MRC with mandibular angle fractures requiring open reduction and internal fixation admitted under OMFS were taken for the study. The sample size of the study was 15. In one group, the patients were treated by extra-oral approach and the other group by transbuccal approach. In patients treated by transbuccal approach, special armamentarium consisting of trocar, cannula, and cheek retractor were used; and in both the groups, semirigid fixation was done using two miniplates with around a distance of 1cm.

RESULTS

Total of 15 patients were treated, 10 with transbuccal approach and 5 with submandibular approach. It has been found that both techniques fulfill the functional requirements of the patients. Patients treated with submandibular approach developed obvious unsightly scars, whereas transbuccal approach results in minimal scarring.

CONCLUSION

The results associated with clinical observations suggest that transbuccal approach is a superior and less time consuming approach than extraoral approach, but it requires special instruments, lots of skill by the operating surgeon in using the armamentarium, and a skilled assistant.

Biomechanical evaluation of plating techniques for fixing mandibular angle fractures: the introduction of a new 3D plate approach

PURPOSE

The aim of this study was to comparatively evaluate the use of a three-dimensional (3D) square-shaped plate for the treatment of mandibular angle fractures.

MATERIALS AND METHODS

Synthetic mandible replicas were used to evaluate the effectiveness of the 3D square plate along with three other mandibular angle plating techniques. The plating techniques consisted of: (1) a 3D miniplate (2 x 2 holes, square, 2 mm); (2) a 3D miniplate (6 x 2 holes, curved, 2 mm); (3) two miniplates (four holes, straight, 2 mm and 1.6 mm); and (4) one single miniplate (four holes, straight, 2 mm). Each group was subjected to incisal and homolateral molar region loading by a tensile materials testing machine (Monsanto Tensometer 20). Load stiffness values and peak measurements of the fracture gap distraction at the superior aspect of the mandible were measured. The mean values (+/-standard deviation) were derived and compared using one-way analysis of variance, with statistical significance set at p < 0.05.

RESULTS

For homolateral molar loading, statistically significant differences existed within groups (p < 0.05). For incisal edge loading, no statistically significant differences were found for stiffness among the fixation methods tested. Gap distraction at the superior aspect of the mandible was limited for three of the groups tested.

CONCLUSION

Under the conditions tested, the 3D square plate system provided the most favorable mechanical behavior.

The biophysics of mandibular fractures: an evolution toward understanding

BACKGROUND

Predicting outcomes based on a variety of fixation techniques remains problematic in the treatment of mandible fractures. There is inherent difficulty in comparing the hundreds of published articles on the subject because of the large number of variables, including injury patterns, assessment techniques, treatment approach, device selection and application, and definition of outcome.

METHODS

The authors review the behavior of the human mandible. Behavior of the intact mandible, multiple fracture scenarios, and small and large (single and multiple) plating applications are reviewed.

RESULTS

Several misconceptions in the literature are clarified. Factors that will resolve the dichotomy between clinical results and current biomechanical theories are presented such that a more logical biomechanical model may be used to approach fixation of the mandibular fracture being treated.

CONCLUSIONS

Current mandibular biomechanics theory must be expanded to reflect the complex nature of the system and to more accurately describe conditions that exist in the physical world. Otherwise, further analysis in advancements in outcome and treatment will be relegated to chance.

Biomechanical comparison of different plating techniques in repair of mandibular angle fractures

OBJECTIVE

The purpose of this study was to evaluate the biomechanical behaviors of different miniplate fixation techniques for treatment of fractures of the mandibular angle.

STUDY DESIGN

Twenty sheep hemimandibles were used to evaluate 4 different plating techniques. The groups were fixated with Champy technique, biplanar plate placement, monoplanar plate placement, and 3-dimensional (3D) curved angle strut plate. A custom-made 3-point biomechanical test model was used for the samples. Each group was tested with compression forces by an Instron Lloyd LRX machine. The biomechanical behavior of the groups for the forces (N) that caused displacement of 1.75 mm were compared using the Instron software program and displacement graphics.

RESULTS

The variance analyses showed that biplanar plate placement had more favorable biomechanical behavior than Champy technique and monoplanar plate placement (P < .05). In addition, the 3D curved angle strut plate technique had more favorable biomechanical behavior than the Champy technique (P < .05) but was not significantly different from biplanar or monoplanar plate placement techniques (P > .05).

CONCLUSION

The study demonstrated that 3D strut plates or dual miniplate techniques had greater resistance to compression loads than the Champy technique. In addition, biplanar plate orientation may provide a more favorable biomechanical behavior than monoplanar plate placement.

One miniplate versus two in the management of mandibular angle fractures: A prospective randomised study

We compared the use of one miniplate (n=36) with that of two miniplates (n=26) for the treatment of the mandibular angle in a randomised trial. There were no significant differences between the groups in total morbidity (22/36 compared with 14/26) or for individual complications. We conclude that two miniplates seem to confer no extra benefit to patients, but a much larger trial would be required to show this conclusively.

Mandibular mechanics after osteotomy and distraction appliance placement I: Postoperative mobility of the osteotomy site

PURPOSE

Fixation at the osteotomy site for mandibular distraction osteogenesis (DO) is probably not rigid, especially during mastication. Micromotion may affect the course of DO. This study aimed to measure the mobility of the fresh distractor-fixed osteotomy site in response to mastication and masticatory muscle stimulation.

MATERIALS AND METHODS

Twenty-eight domestic pigs, 6 to 8 weeks old, underwent osteotomy of the right mandible and placement of a distractor appliance. Immediately after surgery, displacement at 3 different locations (superior-lateral, inferior-lateral, and inferior-medial) of the osteotomy site was assessed using ultrasound piezoelectric crystals or differential variable reluctance transducers (DVRTs). The amount of lengthening or shortening at each location was measured during mastication and muscle stimulation. Displacement was also measured for bilateral osteotomy during muscle stimulation from a subgroup of 12 pigs.

RESULTS

The osteotomy site demonstrated significant mobility during power strokes of mastication with an average magnitude of 0.3 to 0.4 mm. Distinct patterns of displacement were associated with different locations, and the patterns varied between chewing sides. The most common pattern was lengthening at the superior-lateral and shortening at both inferior sites. Similar amounts of displacement were observed during the stimulation of jaw-closers (masseter and medial pterygoid), but the patterns produced by these muscles did not completely explain the masticatory pattern. Opening the osteotomy to 1.5 mm did not alter the displacements observed during muscle stimulation. Bilateral osteotomy tended to decrease displacement.

CONCLUSIONS

The study demonstrates that during mastication and masticatory muscle stimulation, an acute mandibular osteotomy site is mobile despite fixation by a distractor appliance.

Comparison of different fixation methods following sagittal split ramus osteotomies using three-dimensional finite elements analysis. Part 1: advancement surgery-posterior loading

The purpose of this study was to evaluate the mechanical behavior of different fixation methods used in bilateral sagittal split ramus osteotomy (BSSRO). Part 1 comprises of the results of the analysis for mandibular advancement, four different fixation configurations of six hole fragmentation mini plates with monocortical screws and lag screws and posterior loading conditions in the molar and premolar region. The finite element analysis method (FEA) appears suitable for simulating complex mechanical stress situations in the maxillofacial region. The mechanical behavior of selected lag screws with linear or triangular configuration and double parallel or single oblique six hole mini plates with monocortical screws were compared by FEA after 5 mm BSSRO advancement procedure. Four separate three-dimensional finite element models of the mandible were created to simulate the BSSRO and corresponding fixation methods. These models consisted of 122,717 elements and 25,048 nodes. The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer's information. 500 N posterior occlusal loads were simulated on the distal segments. The commercial finite element solver MSC Marc software was utilized to calculate the stress fields on both the segments and fixative appliances. It was concluded that the use of 2.0mm lag screws placed in a triangular configuration following the BSSRO advancement surgery provides sufficient stability with any rotational movement and less stress fields at the osteotomy site, when compared with the other rigid fixation methods used in the current study.

Treatment modalities for mandibular angle fractures

PURPOSE

Management of mandibular angle fractures is often challenging and results in the highest complication rate among fractures of the mandible. Optimal treatment for angle fractures remains controversial. Historically, treatment of mandible fractures included intraoperative maxillomandibular fixation (MMF) along with rigid internal fixation. More recently, noncompression plates miniplates, which produce only relative stability, have gained popularity. The absolute necessity of intraoperative MMF as an adjunct to internal fixation has also become controversial. The current trends in the management of simple, noncomminuted mandibular angle fractures are examined.

MATERIALS AND METHODS

A survey was submitted to North American and European AO ASIF (Arbeits-gemeinschaft fur Osteosynthesefragen Association for the Study of Internal Fixation) faculty in July 2001. Statistical analysis of results included both Fisher's exact and chi-square tests. Results were considered significant if P <.05.

RESULTS

One hundred ten of 127 potential responses were received (87%). Among 104 surgeons who treat mandible fractures, 86 (83%) treat more than 10 mandibular fractures per year. Preferred techniques for simple, noncomminuted mandibular angle fractures in this group were: single miniplate on the superior border (Champy technique) with or without arch bars (44 surgeons, 51%); tension band plate on the superior border and nonlocking, bicortical screw plate on the inferior border (11 surgeons, 13%); dual miniplates (9 surgeons, 10%); a locking screw plate on the inferior border only (6 surgeons, 7%), and 3-dimensional plates (5 surgeons, 6%). Eleven surgeons (13%) gave multiple answers. Although only 13% of surgeons surveyed primarily use the combination of tension band and nonlocking, bicortical screw plates, many surgeons (73%) continue to use this technique in certain circumstances. Within this group, 32 (51%) place screws in a neutral position, while 31 (49%) place screws in an eccentric position, resulting in compression. For simple noncomminuted angle fractures, the number of surgeons performing internal fixation without MMF were: 14 often (16%); 20 occasionally (23%); 17 seldom (20%); and 35 never (41%). Surgeons treating more than 10 versus those who treat less than 10 fractures per year, International versus North American faculty, and Oral and Maxillofacial surgeons (OMS) versus non-OMS surgeons were compared. Surgeons who treat more than 10 fractures per year favor the Champy technique over the tension band and bicortical plate combination (44 [51%] vs 11 [13%]), while those surgeons who treat less than 10 per year favor the tension band and bicortical plate combination over the Champy technique (9 [50%] vs 3 [17%]; P < .01, Fisher exact test). International faculty are less likely to use intraoperative MMF than North American faculty (29 [81%] vs 31 [43%]; P < .01, Fisher exact test). OMS surgeons are less likely to use the tension band and bicortical plate combination than non-OMS surgeons (22 [56%] vs 42 [90%]; P < .017, Fisher exact test).

CONCLUSION

This survey suggests an evolution in the management of mandibular angle fractures. A single miniplate plate on the superior border of the mandible has become the preferred method of treatment among AO faculty. When using large, inferiorly based plates more surgeons are now favoring neutral rather than eccentric screw placement. Intraoperative MMF is not considered mandatory by some surgeons in certain circumstances.