Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part One: Superior Repositioning Surgery

Evaluation of different fixation methods with finite element analysis in total mandibular subapical osteotomy

PURPOSE

The purpose of the study was to evaluate the stress distribution in various miniplates that were used in cases that underwent advancement with total mandibular subapical osteotomy (TMSO) using finite element analysis (FEA).

MATERIAL AND METHOD

Cone beam computed tomography (CBCT) images of a patient with appropriate bone tissues were used as a reference for the modeling of the mandible. In all mandibular models, horizontal TMSO was performed in a region 5 mm away from the apex of the teeth and vertical TMSO was performed in the retromolar region, 10 mm posterior to the second molar tooth. After TMSO, the dentoalveolar segment was advanced 3 mm and miniplates were placed symmetrically at four points for fixation. Four different miniplates with 2.0 mm thickness were used. Three different forces were applied to the models. Stress distribution on the models was evaluated using maximum von Mises stress values.

RESULTS

The maximum von Mises stress occurred in Y + I and Y + L models following the application of 300 N force from the incisal. An evaluation of posterior unilateral force indicated that the stress was remarkably high in the models with a posterior I-plate. The stress in the Y + I model was higher under unilateral force compared to the stress in other models. Under posterior bilateral force, the maximum von Mises stress values ​​occurred in the I-plates of T + I, Y + I, and L + I models (1006, 1012, and 1004 MPa, respectively).

CONCLUSION

Within the limitations of our study, we found that the ideal stress distribution was in the T + L and L + L plate combinations in the plates used for fixation after advancement with TMSO.

Evaluation of different stable internal fixation in unfavorable mandible fractures under finite element analysis

INTRODUCTION

The mandibular angle fracture is the most common fracture between this type of injury in jaw bone and also is the type of fracture treatment that presents a larger number of complications, and a series different osteosynthesis types have been studied over the years by the world literature. The finite element method is a form of mathematical analysis, which is based on dividing a structure into a finite number of small areas. It has the ability tomathematically model structures, making it possible to apply forces anywhere.

MATERIAL AND METHODS

For this study, a three-dimensional mandible with an unfavorable angle fracture was simulated. Five different types of fixations were evaluated: group 1, Champy technique with one 4-holes miniplate, 2.0 system; group 2, technique with two parallel 4-holes conventional miniplates, 2.0 system; group 3, technique with two parallel 4-holes locking miniplates, 2.0 system; group 4, technique with one reconstruction 6-holes plate, 2.8 system in base jaw; and group 5, technique with one reconstruction 6-holes plates, 2.8 system in jaw body + one parallel 4-holes conventional miniplate, 2.0 system.

RESULTS

The results showed that strains are better distributed through the locking miniplate and screws system and presented less stress concentration when compared with the conventional ones. The Champy technique had the worst results about of all groups. The use of the locking system shows less stress compared to the non-locking system, and the presence of a reconstruction plate associated with a mini plate does not lead to increased stability compared with an isolated reconstruction plate.

Three-Dimensional Finite Element Analysis of Different Plating Techniques for Unfavorable Mandibular Angle Fractures

The purpose of the current study was to assess the biomechanical behavior of 5 different fixation schemes for unfavorable mandibular angle fractures using the three-dimensional finite element analysis method. Five different miniplate fixation schemes were modeled for the fixation of unfavorable mandibular angle fractures. A double parallel miniplate (M1), which was placed at the halfway point of the mandibular angle height; a 1/3 superior-positioned miniplate (M2); a single miniplate (M3), which was placed at the halfway point of the mandibular angle height (1/2 middle-positioned); a 1/3 inferior-positioned miniplate (M4); and an X-miniplate which was placed at the halfway point of the mandibular angle height (M5). The lowest mechanical stresses were detected in the double miniplate model when compared with the other schemes, whereas 1/3 inferior-positioned miniplate had the highest stress and displacement values. The authors suggest that the double miniplate is an adequate rigid fixation technique, whereas the 1/3 inferior-positioned miniplate configuration should not be used in case of unfavorable mandibular angle fracture.

Evaluating the biomechanical effects of implant diameter in case of facial trauma to an edentulous atrophic mandible: a 3D finite element analysis

Background

Rehabilitation using an implant supported overdenture with two implants inserted in the interforaminal region is the easiest and currently accepted treatment modality to increase prosthetic stabilization and patient satisfaction in edentulous patients. The insertion of implants to the weakend mandibular bone decreases the strength of the bone and may lead to fractures either during or after implant placement. The aim of this three dimensional finite element analysis (3D FEA) study was to evaluate the biomechanical effects of implant diameter in case of facial trauma (2000 N) to an edentulous atrophic mandible with two implant supported overdenture.

Methods

Three 3D FEA models were simulated; Model 1 (M1) is edentulous atrophic mandible, Model 2 (M2), 3.5x11.5 mm implants were inserted into lateral incisors area of same edentulous atrophic mandible, Model 3 (M3), 4.3x11.5 mm implants were inserted into lateral incisors area of same edentulous atrophic mandible.

Results

In M1 and M2 highest stress levels were observed in condylar neck, whereas highest stress values in M3 were calculated in symphyseal area.

Conclusions

To reduce the risk of bone fracture and to preserve biomechanical behavior of the atrophic mandible from frontal traumatic loads, implants should be inserted monocortically into spongious bone of lateral incisors area.

Biomechanical Evaluation of Different Plating Methods Used in Mandibular Angle Fractures With 3-Dimensional Finite Element Analysis: Favorable Fractures

PURPOSE

The aim of the present study was to evaluate the performances of 5 different plating techniques for fixation of favorable mandibular angle fractures using the 3-dimensional finite element analysis (FEA) method.

MATERIALS AND METHODS

Five different miniplate placement configurations were considered for the fixation of favorable mandibular angle fractures. The following models were created: a double parallel miniplate (M1) placed at the halfway point of the mandibular angle height; a one-third superior-positioned miniplate (M2); a single miniplate (M3) placed at the halfway point of the mandibular angle height (one-half middle-positioned); a one-third inferior-positioned miniplate (M4); and an X-shape miniplate (M5).

RESULTS

The M1 and M4 miniplates showed the lowest mechanical stress compared with the other configurations, whereas the M3 and M5 miniplates showed the highest stress levels.

CONCLUSION

For favorable mandibular angle fractures, the authors suggest the M1 miniplate or, if used alone, the M4 miniplate is adequate for rigid fixation.