A study of 2 bone plating methods for fractures of mandibular symphysis and body

EDWARD ELLIS III. A STUDY OF 2 BONE PLATING METHODS FOR FRACTURES OF MANDIBULAR SYMPHYSIS /BODY. J ORAL MAXILLOFAC SURG 69:1978-1987, 2011.

PRESENTED BY – DR. SHEETAL KAPSE

GUIDED BY – DR. RAJASEKHAR G.

AUTHOR

Professor and Chair, Department of Oral and

Maxillofacial Surgery, University of Texas

Health Science Center, San Antonio, TX.

EDWARD ELLIS III

CONTENTS

• Introduction• Aim of the study• Patients and methods• Surgical technique• Results • Discussion• Cross references• Conclusion• References

INTRODUCTION• Fractures of the symphysis and body of the mandible are

extremely common injuries.

• When open reduction and internal fixation is chosen as treatment, many internal fixation schemes can be employed.

• Perhaps the most common is the application of 2 small (mini-) plates or 1 larger plate, with or without an arch bar.

• Based on surgeon preference, experience, availability of internal fixation hardware, or other factors rather than documented outcome measurements.

Aim of the study

• To evaluate outcomes in patients treated by 1 of these 2

internal fixation schemes for fractures of the mandibular

symphysis or body.

PATIENTS AND METHODS

• All patients treated by open reduction and internal fixation of a symphysis and/or

body fracture of the mandible from January 1, 1998, through December

31,2009, at Parkland Hospital, Dallas, Texas.

Inclusion criteria 1. intraoral surgical approach2. simple (linear, noncomminuted) fracture 3. 2 miniplates secured with locking or nonlocking 2.0-mm monocortical screws or 1

larger/thicker plate secured with bicortical 2.0-mm locking screws across the fracture4. teeth present in area of fracture5. arch bar placed during surgery and maintained postoperatively for at least 5 weeks6. no postoperative intermaxillary fixation7. minimum follow-up of 5 -7 weeks8. sufficient documentation to be included (medical records, radiographs, photographs)

Evaluation parameters

1. Infection (diagnosed clinically, not with cultures)

2. Dehiscence of the incision not related to infection (no

purulence)

3. Duration between surgery and dehiscence of incision

and/or infection

4. Exposure of bone plate(s)

5. Need for plate removal

6. Damage to tooth roots

7. Malocclusion attributable to symphysis/ body fracture

8. Clinical union at last visit

Surgical techniqueTwo methods of internal fixation

C, Intraoperative photograph showing application of 1 larger, stronger plate.

A, Photograph showing relative thickness of the 2 plates. Miniplate (left) is 1 mm thick and the other plate (right) is 1.25 mm thick.

B, Intraoperative photograph showing the application of 2 miniplates.

The additional thickness of the larger plate combined with an increase in the width of the plate confers more than 3 as much volume of metal in the plate, giving it more than 2 the in-plane bending strength and 2.5 out-of-plane bending strength compared with the miniplate.

Results

Discussion

• The application of an arch bar and 2 miniplates or 1 larger, stronger bone plate can be considered “rigid” fixation, meaning that the fixation is stable enough. Any differences in outcomes between the 2 groups in this study would unlikely be due to differences in stability imparted to the fracture.

• Application of a second plate higher on the lateral surface of the mandible can result in more complications than when 1 stronger plate is applied to the lateral cortex along the inferior border.

• Cawood JI: Small plate osteosynthesis of mandibular fractures. Br J Oral Maxillofac Surg 23:77, 1985

• Nakamura S, Takenoshita Y, Oka M: Complications of miniplate osteosynthesis for mandibular fractures. J Oral Maxillofac Surg 52:233, 1994

• Dehiscence in this sample occurred with a much higher frequency in those cases in which 2 miniplates were used (6%), and it was most commonly associated with exposure of the plate located just below the incision (5%).

• Tooth root injuries in the present sample occurred exclusively in the 2-plate group, albeit at a very low incidence (n = 4/265, 1.5%).

• In the premolar to premolar dentoalveolar areas, one will see that the facial plate of bone is very thin (2.0 – 2.5 mm) and the roots are immediately within.

• Cawood JI: Small plate osteosynthesis of mandibular fractures. Br J Oral Maxillofac Surg 23:77, 1985

• Nakamura S, Takenoshita Y, Oka M: Complications of miniplate osteosynthesis for mandibular fractures. J Oral Maxillofac Surg 52:233, 1994

Cross references

• In front of the mandibular foramen, or, accurately, in front of

the canine, 2 malleable plates, 4.5 mm apart, are required to

prevent torsion moments.

• The inferior plate is inserted first, then the sub-apical one.

• The aim of this study was to make a comparative evaluation of the mechanical behaviour of 4 different internal fixation systems for mandibular symphysis fractures.

• 40 polyurethane mandible replicas (Nacional, Jaú, SP, Brazil) were used. The load resistance values were measured at load application displacements of 1, 3, 5, and 10 mm.

Fixation of group with lag

screw technique, with A, frontal

and B, side views.

Fixation of group with 2 perpendicular

miniplates, withA, frontal and B, inferior-superior

views.

Fixation of group with 1 miniplate in the tensionzone. Fracture reduction

was achieved with relief of the acrylic devices.

Fixation of group with 2 parallel miniplates, 1 in the tension zone and the other in the compression zone.

Distortion of the mandible during unilateral molar loading. The distortion of the mandibular body can be described as a combination of sagittal bending, torsion and lateral transverse bending. Patterns of stress and deformation at the mandibular symphysis. Jaw deformation during function. MC, medial convergence; CR, corporal rotation; DVS, dorso-ventral shear.

Conclusion

• The 2 plating techniques used in the present study show very

good outcomes, but the application of a second bone plate

increased the incidence of wound dehiscence, plate exposure,

and need for plate removal.

• The use of 2 miniplates was associated with more post-

operative complications than the use of 1 stronger plate, but

both techniques produced sufficient stability for healing.

References

1. Cawood JI: Small plate osteosynthesis of mandibular fractures. Br J Oral Maxillofac Surg 23:77, 1985

2. Nakamura S, Takenoshita Y, Oka M: Complications of miniplate osteosynthesis for mandibular fractures. J Oral Maxillofac Surg 52:233, 1994

3. Champy M et al. Mandibular osteosyntesis by miniature screwed plates via a buccal approach. J Max-Fac Surg. 1978;6:14-21

4. R. C. W. Wong, H. Tideman, L. Kin, M. A. W. Merkx: Biomechanics of mandibular reconstruction: a review. Int. J. Oral Maxillofac. Surg. 2010; 39: 313–319.