[Experimental study on the biomechanical stability of different internal fixators for use in the mandible]

Finite element analysis of low-profile reconstruction plates for atrophic mandibles: a comparison of novel 3D grid and conventional plate designs

OBJECTIVES

This study aimed to compare the reconstruction with type 2.4 and three-dimensional (3D) grid plates relating the areas of weakness to anatomical regions of force incidence in atrophic mandibles with and without segmentation using finite element analysis (FEA).

MATERIALS AND METHODS

Strength and force quality in the mandible were also determined. The atrophic mandible models with and without segmentation were divided into four groups, and the behavior of each plate was analyzed using finite element analysis. In the atrophic mandible without segmentation using the type 2.4 reconstruction plate, the highest stress concentration in the plate was observed in the posterior region of the mandibular body and in the grid type 3D reconstruction plate was observed in the mandibular angle.

RESULTS

In the segmented atrophic mandible with the 2.4 reconstruction plate, higher stress concentration was observed in the mandibular segment defect. Analysis of the 3D grid-like reconstruction plate revealed that the geometry of the plate conferred greater stiffness to the assembly, as the most significant stress concentration was observed at the mandibular angle.

CONCLUSION

The width of the plate design may influence the strength, not the thickness.

Three-dimensional Locking Plate and Conventional Miniplates in the Treatment of Mandibular Anterior Fractures

Context

Three-dimensional (3D) locking plates has been designed with the hypothesis that this will overcome the disadvantages of both the systems and also advantages of both systems will be combined for the management of mandibular fractures.

Aims

The purpose of this study was to evaluate the efficacy of 2-mm 3D locking miniplate in the management of anterior mandibular fracture and to compare it with Champy's miniplate.

Settings and Design

A prospective, randomized, clinical trial was carried out in thirty patients who were divided equally in two groups.

Subjects and Methods

Group I and Group II patients were treated with 2-mm 3D locking plates and 2-mm standard miniplates, respectively. They were evaluated according to the outcomes of the study, that is, working time, wound dehiscence, infection, segmental mobility, postoperative occlusion, need for postoperative intermaxillary fixation (IMF), and radiological evaluation of reduction and fixation.

Statistical Analysis Used

Student's t-test and Mann-Whitney test were used to compare the two systems. The data were analyzed using Statistical Package for the Social Science version 14.0. The P value was taken as significant when <0.05 (confidence interval of 95% was taken).

Results

The mean duration of procedure for Group I was found to be 49.33 min, whereas for Group II was 59.67 min. There was significantly greater pain on day 1 and at 1 week in Group II patients. 6.7% (n = 1) of both groups showed incidence of infection. Postoperative stability was adequate in most cases except in one patient (n = 1) of 3D locking system, which was revealed as postoperative occlusal disharmony, unsatisfactory radiological reduction of the fracture fragments, and the segmental mobility. There was no incidence of wound dehiscence, tooth damage, and nerve damage in either group.

Conclusions

The result of the study can conclude that there is no major difference between both systems in terms of treatment outcome.

A Prospective Randomized Clinical Trial Comparing 3D and Standard Miniplates in Treatment of Mandibular Symphysis and Parasymphysis Fractures

PURPOSE

To compare the efficacy of the 3D miniplates to standard miniplates in the osteosynthesis of mandibular symphysis and parasymphysis fractures on the basis of clinical parameters and radiographic evaluation.

PATIENTS AND METHODS

A prospective randomized clinical trial was conducted to treat consecutive mandibular symphysis and parasymphysis fractures. The patients were randomly divided into 2 groups. The patients underwent osteosynthesis in group A with 3D titanium miniplates and in group B with conventional titanium miniplates. The cause of trauma, the number of days from injury to surgery, average age and gender were all reviewed. The assessment of the patients was done at 1, 3, and 6 weeks and 3 months using the clinical parameters and radiographic evaluation.

RESULTS

Eighty patients with isolated symphysis or parasymphysis fracture met the inclusion criteria. In our study, 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. Similarly Radiological evaluation did not show any statistically significant difference in reduction between the 2 groups. 3D plates are difficult to adapt and use sometimes, but operative time is less with them in treatment of symphysis and parasymphysis fractures.

CONCLUSION

The use of 3D miniplates for symphysis and parasymphysis fracture fixation was efficacious enough to bear the masticatory load during osteosynthesis of the fracture. Although 3D miniplate system is difficult to adapt and difficult to use in cases of fractures involving the mental nerve, they provide the advantage of less operative time and less implant material in treatment of symphysis and parasymphysis fracture, with clinical results almost similar to those seen with conventional miniplate osteosynthesis.

Experimentelle und klinische Studie zur Stabilität einer Osteosyntheseplatte für den atrophen Unterkiefer

BACKGROUND

The high rate of complications led us to develop a new osteosynthesis plate for the treatment of the fractured atrophied mandible. The development of the new so-called pencil-bone plate is based on the 2.0 mini-plate system manufactured by the Medartis Company.

MATERIAL AND METHODS

Finite elements (FE) analysis of the new plate as well as flexibility experiments were undertaken, and 14 patients with 16 fractures of the atrophied mandible were treated with the pencil-bone plate between October 2000 and November 2001.

RESULTS

The results clearly show that the pencil-bone plate reacted in both the FE model and the static flexibility experiment in a more stable way than a standard 2.0 plate. In 13 patients, healing proceeded without serious complications; all of the patients showed subjective, nearly unchanged chewing, speaking, and swallowing abilities and no complications occurred when wearing dentures. One patient underwent surgical intervention after a new trauma.

CONCLUSION

The clinical outcome of the treated fractures confirmed the experimental results, which proved the high stability of the plate in the area of the fracture site. Due to the mini-plate format the intraoral application of the plate is possible without problems. The intraoral access allows rapid operation followed by a minimum of morbidity. A great advantage of the small dimension system is the unrestricted wearing of dentures after the application.