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

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

2. Professor and Chair, Department of Oral and
Maxillofacial Surgery, University of Texas Health
Science Center, San Antonio, TX.
EDWARD ELLIS III

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

4. • 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.

5. • To evaluate outcomes in patients treated by 1 of these 2
internal fixation schemes for fractures of the mandibular
symphysis or body.

6. • 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 approach
2. 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 fracture
4. teeth present in area of fracture
5. arch bar placed during surgery and maintained postoperatively for at least 5 weeks
6. no postoperative intermaxillary fixation
7. minimum follow-up of 5 -7 weeks
8. sufficient documentation to be included (medical records, radiographs, photographs)

7. 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

8. 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.

10. • 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

11. • 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

13. • 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.

14. • 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.

15. Fixation of
group with lag
screw technique,
with A, frontal
and B, side
views.
Fixation of
group with 2
perpendicular
miniplates, with
A, frontal and B,
inferior-superior
views.
Fixation of group with 1
miniplate in the tension
zone. 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.

16. 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.

17. • 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.

18. 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.