Infections associated with locking reconstruction plates: a retrospective review

Bone reconstruction of extensive maxillomandibular defects in adults

Reconstruction of significant maxillomandibular defects is a challenge that has been much discussed over the last few decades. Fundamental principles were developed decades ago (bone bed viability, graft immobilization). Clinical decision-making criteria are highly relevant, including local/systemic factors and incision designs, the choice of material, grafting technique, and donor site morbidity. Stabilizing particulated grafts for defined defects-that is, via meshes or shells-might allow significant horizontal and vertical augmentation; the alternatives are onlay and inlay techniques. More significant defects might require extra orally harvested autologous bone blocks. The anterior iliac crest is often used for nonvascularized augmentation, whereas more extensive defects often require microvascular reconstruction. In those cases, the free fibula flap has become the standard of care. The development of alternatives is still ongoing (i.e., alloplastic reconstruction, zygomatic implants, obturators, distraction osteogenesis). Especially for these complex procedures, three-dimensional planning tools enable facilitated planning and a surgical workflow.

A novel alloplastic grid reconstruction plate for the mandible - Retrospective comparative clinical analysis of failure rates and specific complications

PURPOSE

This study aimed to investigate the effect of three different osteosynthesis plate systems on failure rates and complications after continuity-interrupting mandibular resections with alloplastic reconstructions.

MATERIALS AND METHODS

Records of respective patients from 2010 to 2020 were analyzed retrospectively. The analyses included the osteosynthesis plate type (2.4 MANDIBULAR (RP1: MANDIBULAR [Medicon®, Tuttlingen, Germany]; RP2: Modus® Reco 2.5 [Medartis®, Basel, Switzerland]; and RP3: Modus 2 Mandible [Medartis®, Basel, Switzerland]), extent & location of the defect, age, sex, radiotherapy, and nicotine abuse. In case of failure, timepoint, and the problem, namely oral/extraoral dehiscence, screw loosening, and plate fractures that led to removal, were analyzed. Complications were classified according to Clavien-Dindo system.

RESULTS

A total of 136 patients were included. The mean follow-up time was 18 ± 26 months. Survival rates after 1, 2, and 5 years were 69.9%, 66.9%, and 64.7%, respectively. Although survival was not significantly associated with the reconstruction system, the most frequent complications were seen in cases of RP1 & RP2 when compared to RP3 (p = 0.033). In brief, dehiscences were seen significantly less often in cases of RP3 (12.5%) when compared to RP1 (44.7%) and RP2 (26.9%; p = 0.024). Fractures of the osteosynthesis systems occurred in 3 of 4 cases (75%) with RP1, in 1 of 4 cases (25%) using RP2, and in no single case using the RP3 system (p = 0.03). Most of the observed complications occurred up to 12 months postoperatively. A total plate survival rate of 64.7% and a total plate complication rate of 47.8% were seen.

CONCLUSION

In conclusion, it seems that RP3 should be preferred over RP1 and RP2 regarding failure rates and complications.

Efficacy of locking miniplates in managing mandibular fractures without intermaxillary fixation

Background:

Aims:

Materials and Methods:

Results:

Conclusion:

Complications of Poly-l-Lactic Acid and Polyglycolic Acid (PLLA/PGA) Osteosynthesis Systems for Maxillofacial Surgery: A Retrospective Clinical Investigation

Two second-generation PLLA/PGA bioresorbable osteosynthetic plate systems for oral and maxillofacial surgery are available in Japan. The two systems have different PLLA-PGA component ratios (RapidSorb^®, 85:15; Lactosorb^®, 82:18) and plate and screw shapes. We conducted a retrospective study to compare our clinical evaluation and examine the incidence of postoperative complications between the two plate systems. A retrospective survey was conducted in 148 patients (midfacial fracture/trauma (68.2%) and dentofacial deformity patients (31.8%); males (54.7%); median age, 37.5 years) treated using maxillofacial osteosynthetic plate systems. The complications included plate exposure (7.4%), infection, (2.7%), and plate breakage (0.7%). Multivariate logistic regression analysis showed a significant correlation between sex (female), plate system (Lactosorb^®), number of plates, and pyriform aperture and periorbital sites of plate placement (p < 0.05). Additionally, the propensity score-adjusted model showed a significant correlation between Lactosorb^® and postoperative complications (odds ratio 1.007 (95% confidence interval, 1.001–1.055), p < 0.01). However, the two plate systems showed a low incidence rate of complications, and the plate integration and survivability were similar using 2.0-mm or 1.5-mm resorbable plate regardless of the plate system. Our findings suggest that female sex and a greater number of plates are risk factors for postoperative complications, whereas pyriform aperture and periorbital plate placements reduce the risk.

Effects of long-term plate fixation with different fixation modes on the radial cortical bone in dogs

The aim of this study was to examine the effect of long-term locking plate fixation on the cortical bone of the canine radius. Locking compression plates were fixed to the left and right radius in dogs (n = 3). The left radius was fixed with a locking head screw (Locking Plate group, LP). The locking compression plate was compressed periosteally in the right radius using a cortex screw (Compression Plate group, CP). Radial bones from dogs that were euthanized for other purposes were collected as an untreated control group (Control group). After euthanasia at 36 weeks following plate fixation, radial bones were evaluated for bone mineral density and underwent histological analysis. Bone metabolic markers were analyzed by quantitative polymerase chain reaction (qPCR). Statistical analyses were performed for comparisons between groups. The LP group showed no significant difference in bone mineral density after plate fixation, whereas the CP group showed significantly lower bone mineral density. Histological analysis indicated that the number of osteoclasts and rate of empty lacunae increased significantly in the CP group relative to the Control and LP groups. qPCR analysis indicated increased expression of inflammatory cytokines, such as tumor necrosis factor-alpha, interleukin-6, and tumor necrosis factor ligand superfamily member 11 in the CP group, whereas Runt-related transcription factor 2, an osteoblast marker, was similar in all groups. The expression of hypoxia-inducible factor-1α in the CP group was also increased relative to that in the Control and LP groups. Thus, locking plate fixation is a biologically superior fixation method that does not cause implant-induced osteoporosis in the bone in the long term.

Reconstruction plate-related complications in mandibular continuity defects

PURPOSE

The purpose of this study was to evaluate the complications associated with the use of reconstruction plates with or without non-vascularized bone graft in reconstruction of mandibular segmental defects caused by trauma and tumor resection and to analyze various factors that are associated with the development of complications.

METHODS

A retrospective observational study was conducted, and the investigated variables included the age and gender of the patients, etiology of the defect, the site of the defect, the size of the defect, whether bone graft was used or not, type of plate used, and whether the reconstruction was immediate or delayed. The outcome variables were the postoperative complications and the success rate.

RESULTS

Fifty-one patients were enrolled in this study; the etiology of mandibular defect was trauma in 39 patients (76.5%) and resection of benign or malignant tumors in 12 patients (23.5%). The complication rate was (58.8%) and the success rate was (94.1%); the only factor that significantly increased the incidence of postoperative complications was the size of the defect.

CONCLUSION

Reconstruction plates demonstrated a high success rate despite the high complication rate. Segmental defects caused by trauma were smaller than those created after tumor resection and the only factor that increased complication rate was the size of the defect; other factors did not affect the complication rate.

Locking Miniplate Osteosynthesis of Anterior Mandibular Fractures-Quo Vadis?

PURPOSE

This study compared the clinical stability and efficacy of locking miniplates with those of standard miniplates in the osteosynthesis of anterior mandibular fractures using bite force recordings and other clinical parameters.

MATERIALS AND METHODS

A prospective randomized double-blinded clinical trial was carried out in patients from various hospitals of Hassan (India). Patients were randomly divided into 2 groups of locking (test) and standard (control) miniplate osteosynthesis. Bite force measurements were performed preoperatively and postoperatively at weekly intervals for 6 weeks using a bite force recorder. As a secondary outcome, patients also were assessed for other clinical parameters that might interfere with successful osteosynthesis at the fracture site. Appropriate statistical testing for intra- and intergroup measurements was carried out.

RESULTS

Forty-eight men 28 ± 12.3 years old met the inclusion criteria (24 patients in each group). A statistically significant difference (P < .05) was found in the incisor bite force between the 2 groups, with values in the locking group exceeding those in the standard group at postoperative weeks 2 and 5. Duration of surgery was shorter in the locking group (P = .015). No relevant difference was found for the other clinical parameters.

CONCLUSIONS

Bite force statistically increased at progressive follow-up visits compared with the preoperative recording in the locking group. Bite force recordings of patients treated with locking plates were higher and statistically relevant compared with those of patients treated with standard miniplates at the incisor region at postoperative weeks 2 and 5. The clinical outcomes of the 2 miniplate systems in the present study were similar; however, the locking miniplates required a relatively shorter operating time, produced less trauma to the periosteum and soft tissues with less hardware, and can be used as a "1-plate-for-all" system.

Comparative evaluation of a single 2.0-mm AO locking reconstruction plate with conventional miniplate osteosynthesis for treatment of linear non-comminuted fractures of symphysis and parasymphsis region of the mandible

The objective of the study was to evaluate and compare the relative efficacy of treating linear non-comminuted mandibular fracture of symphysis and parasymphysis region using single 2.0-mm AO locking reconstruction plate or using two conventional miniplates. In this study, 80 patients of symphysis or parasymphysis fracture were divided randomly in two equal groups and treated with open reduction and internal fixation using two 2.5-mm miniplates or with a single 2.0-mm AO locking reconstruction plate. Operating time in case of open reduction and fixation using a single 2.0-mm locking reconstruction plate was significantly less when compared to open reduction and fixation using two conventional miniplates. Both groups showed satisfactory fracture reduction and healing. No postoperative malocclusion was noted, and both groups showed comparable improvement in masticatory efficiency. In conclusion, fracture fixation using a single 2.0-mm AO locking reconstruction plate without use of a second plate at the superior border for treatment of linear non comminuted mandibular fracture in symphysis and parasymphysis region gives comparable results as with treatment by conventional miniplate system and provides significant savings in operating time, ease of use and decrease in amount of hardware incorporated in the body.

Assessment of Bite Force in Patients Treated with 2.0-mm Traditional Miniplates versus 2.0-mm Locking Plates for Mandibular Fracture

The objective of this study is to analyze the difference in bite forces in patients treated for mandibular fractures with 2.0 mm conventional and locking titanium plating system. A randomized study was performed for the treatment of fractures of mandible. In this study, 20 adult patients with isolated mandibular fracture were included. The patients were randomly allocated into two groups, that is, Group I-2.0 mm nonlocking (traditional) and Group II-2.0 mm locking plates. Bite force was evaluated at 1st, 3rd, and 6th weeks. Comparison of all the assessed parameters between both the groups depicted no significant difference in terms of pain, swelling including the incidence of infection, paresthesia, and hardware failure. Although same was true in case of bite force between both the groups at various time intervals, there was statistically significant increase in the bite force within the group comprising patients in whom locking plates was used between 1st and 3rd weeks follow-up period and highly significant increase in bite force between 1st and 6th weeks of follow-up period. The rapid improvement of bite force values when locking plates were used implies that the locking plate can be used in preference to conventional plates to achieve early mobilization with assured stability in the treatment of mandibular fractures.

Review of Maxillofacial Hardware Complications and Indications for Salvage

From 2002 to 2006, more than 117,000 facial fractures were recorded in the U.S. National Trauma Database. These fractures are commonly treated with open reduction and internal fixation. While in place, the hardware facilitates successful bony union. However, when postoperative complications occur, the plates may require removal before bony union. Indications for salvage versus removal of the maxillofacial hardware are not well defined. A literature review was performed to identify instances when hardware may be salvaged. Articles considered for inclusion were found in the PubMed and Web of Science databases in August 2014 with the keywords maxillofacial trauma AND hardware complications OR indications for hardware removal. Included studies looked at human patients with only facial trauma and miniplate fixation, and presented data on complications and/or hardware removal. Fifteen articles were included. None were clinical trials. Complication data were presented by patient, fractures, and/or plate without consistency. The data described 1,075 fractures, 2,961 patients, and 2,592 plates, nonexclusive. Complication rates varied from 6 to 8% by fracture and 6 to 13% by patient. When their data were combined, 50% of complications were treated with plate removal; this was consistent across the mandible, midface, and upper face. All complications caused by loosening, nonunion, broken hardware, and severe/prolonged pain were treated with removal. Some complications caused by exposures, deformities, and infections were treated with salvage. Exposed plates were treated with flaps, plates with deformities were treated with secondary procedures including hardware revision, and hardware infections were treated with antibiotics alone or in conjunction with soft-tissue debridement and/or tooth extraction. Well-designed clinical trials evaluating hardware removal versus salvage are lacking. Some postoperative complications caused by exposure, deformity, and/or infection may be successfully treated with plate salvage. We propose an algorithm using this review and clinical expertise. We also propose that a national databank be created where surgeons can uniformly compile their patient information and examine it in a standardized format to further our understanding of clinical management.

Bite Force Evaluation of Conventional Plating System Versus Locking Plating System for Mandibular Fracture

AIMS AND OBJECTIVES

To compare and evaluate the variation in recorded bite forces in patients with mandibular fractures undergoing open reduction and rigid internal fixation using standard 2.0 versus 2.0 mm locking miniplates.

MATERIALS AND METHODS

A prospective randomized study was conducted for the treatment of mandibular fractures. Twenty adult patients with 31 mandibular fractures requiring an open reduction and internal fixation were included in the study. The sample was divided into two groups depending upon whether the patients received 2.0 mm non-locking (standard) or 2.0 mm locking miniplates for rigid fixation respectively. Bite force was evaluated at 1st, 3rd and 6th week after the open reduction and rigid fixation using miniplates.

RESULTS

A statistically significant difference was not found in the clinical parameters such as pain, swelling, infection, paresthesia, hardware failure, and mobility between the fracture segments. The results showed that amongst locking vs non-locking miniplates, the former showed a greater bite force enhancement when compared to baseline values(post-trauma).A comparison between 2nd day post-operative vs 6th week post-operative values showed a significant increase in bite force in Group 1 (non-locking) (p < 0.05) whereas the values Were highly significant (p < 0.001) in Group 2 (locking Plate).

CONCLUSION

The findings were suggestive that the efficacy of locking miniplates plate in mandibular fracture was superior in terms of bearing the masticatory loads during osteosynthesis of the fracture. However, the clinical results were almost similar to those seen with non-locking miniplate osteosynthesis.

Effectiveness of 2.0 mm Standard and 2.0 mm Locking Miniplates in Management of Mandibular Fractures: A Clinical Comparative Study

To compare and evaluate the effectiveness of 2.0 mm locking miniplates versus 2.0 mm standard miniplates in treatment of mandible fractures. Sixty randomly selected patients who sustained mandibular fractures were selected for this study. The fractured fragments were stabilized using 2.0 mm locking miniplates in 30 cases and in the remaining 30 cases the fractured fragments were fixed with conventional 2.0 mm miniplates. Post-operative stability was assessed with radiographs at 7th day, 1st, and 3rd months. The stability of the reduced fracture was assessed clinically and both the types of plates were assessed with an OPG or conventional radiographs. This study shows favorable results on use of locking miniplates in mandibular fractures. The results show that there were no significant differences in the post-operative complications between the conventional and the locking plate/screw mandibular systems. The locking plate/screw system was more rigid than conventional plate/screw system, thereby reducing the need and duration of intermaxillary fixation (IMF).

The Use of 2.4-mm Locking Plate System in Treating Comminuted Mandibular Fracture by Firearm

Maxillofacial trauma caused by firearms has considerably increased, in which the mandibular body is the site of highest incidence of firearm projectiles. In these cases, the use of titanium plates and screws allows the early restoration of form and function of the mandible with stable and predictable results. Recently, conventional plates have been extensively used to treat comminuted mandibular fractures. Nevertheless, the conventional system presents several limitations such as screw compression against the bone interface and the necessity of precise fit of plate to the bone. To overcome such drawbacks, the locking plates have emerged. The present clinical case reported the operative treatment of mandibular fracture caused by firearm projectiles with the use of locking plate. The indications, advantages, and disadvantages of this system are presented.

Evaluation of fracture healing and subimplant bone response following fixation with a locking miniplate and screw system for mandibular angle fractures in a sheep model

This study aims to establish a mandible fracture model, and to review fracture healing following fixation with a locking miniplate system. Eighteen 2-year-old sheep were divided into three groups of six. Each animal had a single fracture that was anatomically reduced and internally fixed by a single 4-hole plate with two monocortical screws each side of the fracture. The fractures were internally fixed with poorly contoured conventional miniplates or poorly contoured mini-locking plate or well contoured conventional miniplates. Two sheep in each of the three groups were killed at 2, 4 and 8 weeks after surgery. The mandibles were radiographed then decalcified specimens were reviewed microscopically. No clinical difference was observed between the groups. All fractures were at an advanced stage of bony union by 4 weeks. Fracture union appeared radiographically more advanced with the locking plate system. This study established a protocol for simulating a fracture model for the study of fracture healing. A more advanced stage of union was seen for fractures internally fixed with locking plates/screws than with a conventional system. The observations suggest the purported biological benefits of locking miniplate system do exist.

Comparative evaluation of 2.0-mm locking plate system vs. 2.0-mm nonlocking plate system for mandibular fractures--a retrospective study

INTRODUCTION

The purpose of this retrospective study is to evaluate the efficacy of the 2.0-mm locking miniplate/screw system in comparison to the 2.0-mm nonlocking miniplate/screw system in mirror image mandibular fractures.

MATERIAL AND METHOD

A retrospective clinical trial was reviewed in the Department of Oral and Maxillofacial Surgery, Government Dental College, Pt. B.D. Sharma University of Health Sciences Rohtak for a period of 30 months (June 2007 to December 2009). A total of 30 patient pairs with isolated identical mandibular fracture (single or multiple) having 88 fractures were analyzed.

RESULTS

A total of 11 complications that occurred represented 12.5% of the total. Six complications occurred at angle, three in the body and two at parasymphysis. Four complications occurred in the locking group and seven in the nonlocking group, with complication rates accounting for 9% and 16%, respectively. When comparing the overall complication rates according to plates used, the chi-square test showed no statistically significant difference between the locking and nonlocking plates (p > 0.05).

DISCUSSION

Mandible fractures treated with the 2.0-mm locking plates and the 2.0-mm nonlocking plates present similar short-term complication rates.

Efficacy of 2-mm locking miniplates in the management of mandibular fractures without maxillomandibular fixation

BACKGROUND

The management of trauma has evolved greatly over the past many years. Various bone plating systems have been developed to provide stable fixation of mandibular fractures. The introduction of the locking plate/screw system has offered certain advantages over the conventional plating systems. This system does not require intimate adaptation of the miniplates to the underlying bone and has greater stability. This study evaluates the efficacy of locking miniplate/screw system in the treatment of mandibular fractures without maxillomandibular fixation.

MATERIALS AND METHODS

This was a prospective study analyzing 20 patients with undisplaced or minimally displaced mandibular fractures, who reported to Department of Oral and Maxillofacial Surgery, Government Dental College and Research Institute, Bangalore. The selected cases were treated by open reduction and internal fixation using the 2.0 mm locking plate/screw system.

RESULTS

Open reduction and internal fixation with the 2.0 mm locking plate/screw system were achieved in all the 20 cases with satisfactory stability of the fracture fragments. The system was found to be reliable and effective intraoperatively. Only two complications were noted in the study.

CONCLUSION

The locking miniplate system was found to be reliable and effective in management of mandibular fractures without postoperative intermaxillary fixation, however further studies with more sample size is required.

In vitro evaluation of conventional and locking miniplate/screw systems for the treatment of mandibular angle fractures

This in vitro study evaluated the influence of the type of miniplate and the number of screws installed in the proximal and distal segments on the stability and resistance of Champy's osteosynthesis in mandibular angle fractures. Sixty polyurethane hemimandibles with bone-like consistency were randomly assigned to four groups (n=15) and sectioned in the mandibular angle region to simulate fracture. The bone segments were fixed by different osteosynthesis methods using 2.0 mm miniplates and 2.0 mm × 6 mm monocortical screws. In groups 1 and 2, two conventional (G1) or locking (G2) screws were installed in each bone segment using a conventional (G1) or a locking (G2) straight miniplate; in groups 3 and 4, three conventional (G3) or locking (G4) screws were installed in the proximal segment and four conventional (G3) or locking (G4) screws were installed in the distal segment using a conventional (G3) or a locking (G4) seven-hole straight miniplate. The hemimandibles were loaded in compressive strength until a 4mm displacement occurred between the segments, vertically or horizontally. Locking plate/screw systems provided significantly greater resistance to displacement than conventional ones (p<.01). Locking miniplates offered more resistance than conventional miniplates. Long locking miniplates provided greater stability than short ones.

Rigid internal fixation of infected mandibular fractures

PURPOSE

To evaluate the treatment outcomes of rigid internal fixation for the management of infected mandible fractures.

PATIENTS AND METHODS

A retrospective chart review of infected mandible fractures managed by a single oral and maxillofacial surgeon at a level I trauma center during a 7-year period was accomplished by independent examiners. All patients were treated with incision and drainage, culture and sensitivity testing, extraction of nonsalvageable teeth, placement of maxillomandibular fixation when possible, fracture reduction with bone debridement and decortication, rigid internal fixation of the mandible by an extraoral approach, and antibiotic therapy. The medical and social history was contributory in most patients. The analysis was stratified by the differentiation of the fractures into 2 groups: those with soft tissue infections in the fracture region versus those with hard tissue-infected fractures (biopsy-proven osteomyelitis).

RESULTS

A total of 44 patients were included in this study, with an average follow-up of 18.2 months from the date of surgery (range 3 to 48). The treatment protocol was successful in all 18 patients (100%) with soft tissue infected mandibular fractures and 24 (92%) of 26 patients with hard tissue-infected fractures.

CONCLUSIONS

A protocol consisting of concomitant incision and drainage, mandibular debridement, fracture reduction, and stabilization with rigid internal fixation can be effectively used for single-stage management of infected mandible fractures.

Skeletal stability after mandibular setback surgery: bicortical fixation using a 2.0-mm locking plate system versus monocortical fixation using a nonlocking plate system

PURPOSE

This study was conducted to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with bicortical plate fixation versus monocortical plate fixation.

PATIENTS AND METHODS

Of a group of 40 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with bicortical plate fixation using a locking plate system and the other 20 underwent SSRO with monocortical plate fixation using a conventional plate system. The time-course changes in condylar long-axis and skeletal stability were assessed through axial, frontal, and lateral cephalograms.

RESULTS

Significant differences were found between the 2 groups in changes of the left condylar angle between the initial and 1-month measurements (P = .0454) and in ANB between the 1- and 3-month measurements (P = .0206); however, no significant differences were found between the 2 groups in the other measurements in each time interval.

CONCLUSIONS

Our findings suggest no significant differences in postoperative time-course changes between bicortical plate fixation using a locking plate system and monocortical plate fixation using a conventional plate system.

Risk factors for development of infection in patients with mandibular fractures located in the tooth-bearing area

PURPOSE

The aim was to identify the main risk factors for infection in patients with mandibular fractures located in the tooth-bearing area.

MATERIAL AND METHODS

Seven hundred and eighty-nine case histories were retrospectively reviewed regarding treatment results and nature of complications developed. The data concerning possible risks were analysed statistically to find out those factors that seemed to have a significant influence on the development of infection.

RESULTS

The incidence of infection in patients with mandibular fractures located in the tooth-bearing area was determined by the following risk factors: social and organizational conditions of medical care, trauma pattern, preexisting medical status and treatment tactics. The main contributory factors were delayed medical care, accompanying pathological disorders, angular location, multiple and comminuted fractures and the type of antibiotic used.

Failure Strength of 2.0 Locking Versus 2.0 Conventional Synthes Mandibular Plates: A Laboratory Model

PURPOSE

This laboratory study compared the performance of locking versus nonlocking Synthes (Synthes, Paoli, PA) 2-mm mandibular fixation plates. The purpose of the study was to determine if there are physical or mechanical properties to support the use of one rigid fixation device over the other.

MATERIALS AND METHODS

A bovine rib model was selected for this study because they closely approximate characteristics of the human mandible. Two experimental groups composed of 10 locking and 10 nonlocking 2-mm plates were secured to randomly selected osteotomized bovine ribs using 10-mm monocortical screws. The specimens were loaded using a 4-point bending system to the point of failure using a MTS model 309.00 servo-hydraulic testing system (MTS Systems Corp, Eden Prairie, MN) with a custom fabricated fixator. The data was obtained with TestStar 2 version 4.0 and TestWare Sx 4.0 software (MTS Systems Corp), and analyzed to determine if there was any difference in performance between the 2 mandibular plate designs.

RESULTS

Overall, there were no statistically significant differences between the locking and conventional 2-mm mandibular plate. Of the 20 samples tested, 1 (nonlocking) had a unique early screw failure (pullout) inconsistent with any other samples and was not analyzed. Of the remaining 19 samples, 17 produced a yield failure, bend, or stretch rather than a plate fracture. Both of the plate fractures occurred in the nonlocking plates. Although the data suggested that this mode of failure was more common in nonlocking plates, the difference between both groups in the mode of failure did not achieve statistical significance (chi2 = 2.0, P = .16). Thus, yield was the predominant mode of failure for both types of devices. The force at which each device failed was also similar in both groups. The force of failure for the nonlocking plates was 559.9 N (SD = 247.9), whereas the locking plate failure strength was 637.8 N (SD = 276.3; t (17) = 0.6, P = .53). The results indicated that there was no suggestion that one plate might be stronger than the other.

CONCLUSIONS

In this laboratory model, no significant differences were found between the 2 types of mandibular plates. Although studies have shown the locking system to be more rigid, this study suggested that the type and degree of failure are more likely related to bone quality and surgical technique when using the 2-mm mandibular plate. Additional prospective studies are needed to correlate these results in patient models.

A review and update of new methods for immobilization of the mandible

In 1948, Dr Kurt H Thoma, a leading authority of the day, published a paper on new methods for immobilization of the mandible in the first issue of this Journal. He reviewed the state of the art for management of patients with fractures of the mandible. By reviewing the paper now we can see how difficult to treat some of the injuries he saw were. This paper assesses his patient management in light of today's knowledge and experience. It discusses changes in therapy that have occurred during this over fifty-year time span. Although many things have changed since then, what has not changed is our desire to provide the best care for our patients using currently available scientific knowledge and clinical evidence.