Mandibular angle fractures account for 23-42% of facial fractures and are commonly caused by motor vehicle accidents and assaults. The angle is prone to fractures due to its thin cross-section and presence of impacted third molars. Fractures are classified as vertically or horizontally favorable/unfavorable based on the direction of the fracture line and effect of muscle forces. Traditionally, rigid plate fixation and intermaxillary fixation were used but caused complications. Currently, semi-rigid fixation using a single miniplate placed along the superior border based on Champy's lines of osteosynthesis is the standard approach, allowing early function with low complications.

2. Dr. Ahmed M. Adawy
Professor Emeritus, Dep. Oral & Maxillofacial Surg.
Former Dean, Faculty of Dental Medicine
Al-Azhar University

3. Mandibular angle fractures account for 23% to 42% of all
facial fractures (1). The most common causes of
mandibular angle fractures are motor vehicle accident and
assaults or violence. There are two main proposed reasons
why the angle of the mandible is commonly associated
with fractures. The first reason is the presence of a thinner
cross-sectional area relative to the neighboring segments
of the mandible (2). Second is the presence of third
molars, particularly those that are impacted, which
weakens the region (3)

4. An importance of classification of mandibular angle
fractures relates to direction of the fracture line and effect
of muscle action on the fracture fragments. Thus, fractures
have been classified as:
a. Vertically favorable or unfavorable
b. Horizontally favorable or unfavorable
Muscles attached to the ramus masseter, temporalis and
medial pterygoid displace the proximal segment upward
and medially when the fractures are unfavorable;
conversely these same muscles tend to impact the bone,
minimizing displacement in horizontal and vertical
favorable fractures (4)

5. Attachment of muscles on the lateral
and medial sides of the mandible

6. Favorable / Unfavorable Fracture Lines

7. The traditional way of treating mandibular angle fracture
involves reestablishment of a functional dental occlusion
with either close reduction and intermaxillary fixation or
open reduction and internal fixation with or without
intermaxillary fixation. Patients treated with
intermaxillary fixation have a restricted airway and loose
excess weight. Further, intermaxillary fixation for 8 weeks
may cause marked thinning and disruption of the normal
organization of the articular cartilage. In addition the use
of intermaxillary fixation significantly increased the time
patients spent off work (5)

8. Upper and lower border
wiring osteosynthesis. A non-
rigid technique that should be
Supplemented with
intermaxillary fixation

9. Rigid internal fixation and early return to function have
eliminated the use of wire osteosynthesis and prolonged use
of intermaxillary fixation. Meanwhile, rigid fixation is
associated with rapid primary bone healing, excellent
stabilization at the fracture site, and increased postoperative
three-dimensional stability, and results in early and
complete restoration of function (6).Traditionally absolute
rigid fixation, with reconstruction plate, was believed to be
critical to proper union, particularly with comminuted
fractures (7). It has been stressed that no other means could
be capable of supporting full functional load and
withstanding tension forces while maintaining fractures
fragments in anatomic position

10. Rigid fixation of a comminuted angle fracture
with reconstruction plate

11. The principle of rigid fixation, however, have an inherent
set of disadvantages. The bicortical screws used cause
sensory disturbances along path of inferior alveolar nerve
in many cases. The possibility of injury to the marginal
mandibular branch of facial nerve is high. Postoperative
malocclusion rates are also high which attributed to the
difficulties in bending the rigid plate. Extraoral scar
through which the plate is inserted is an additional
complication. Worth mentioning, it has been
demonstrated that, up to a point, increased rigidity is
associated with increased complications (8)

12. In 1978, Champy et al.(9) proposed the intraoral
application of monocortical miniplates to treat mandibular
angle fractures. They showed that miniplates achieved the
goal of osteosynthesis by neutralizing undesirable tensile
forces while retaining favorable compressive forces during
function. They studied these movements with regard to a
mathematical model of the mandible and as a result was
able to determine the ideal line of osteosynthesis to
overcome these displacing forces. By placing the plate at
the most biomechanically favorable site, the thickness of
the plate can be kept to a minimum with consequent
advantage of increased malleability

13. Masticatory muscles
produce tension at
upper border and
compression at lower
border. Thus, under
most functional
situations, fractures
of the angle tend to
open at the superior
border

14. Champy’s Ideal Lines of Osteosynthesis
Monocortical “tension banding” osteosynthesis neutralizes
distraction and torsion during physiologic stress

15. Semi-rigid fixation
of fractured mandibular
angle using a four holes
2mm thickness miniplate

16. Gradually, due to simplicity and minimal complications, the
“semi-rigid” technique, has gained popularity as a standard
treatment approach in different trauma centers. Accordingly,
the AO/ASIF have changed the principle of “rigid fixation”
to “functionally stable fixation”. Currently, the four revised
principles of the AO/ASIF are as follows:
1) Anatomic reduction
2) Functionally stable fixation (previously “rigid fixation”)
3) Atraumatic surgical technique
4) Immediate active function (10)

17. The technique involves placement of a single
monocortical noncompression miniplate on the superior
border of the mandible, either on the external oblique
ridge using an intraoral approach or against the outer
surface of the mandible using an transbuccal approach.
Some in vitro studies suggest that using a second
miniplate along the inferior border theoretically creates a
second osteosynthesis line and helps stabilize the fixation
protecting the fractures against rotation and torsion (11).
Whether one or two miniplates should be used at the
mandibular angle fracture is still debatable

18. Placement of upper border miniplate and a
second miniplate along the lower border

19. However, clinical studies provide a different picture. Ellis
noted that the application of 2 mini-plate is associated with
significant complications; 29% as compared to a single one;
2.5% (8). To overcome the disadvantages of 2 plates
application and to provide additional stability with a use of a
single plate, 3- dimensional (3D) plates were developed (12). It
consists of two 4- hole miniplates joined by 4 interconnecting
cross struts. This provides room for additional screw placement
adding to torsional and 3D stability of the fracture. A recent
meta-analysis of the use of 3D plates in angle fractures
demonstrated that the geometry of the plate assures a good
stability in the three-dimensions of the fracture sites and
provides good resistance against torque forces. Further it was
noted that 3D plates are associated with lower complication
rates as compared to standard miniplate fixation (13)

20. Displaced mandibular angle fracture.
A 3-D plate provides adequate fixation

22. 1. Bormann KH, Wild S, Gellrich NC, et al. Five-year retrospective study of
mandibular fractures in Freiburg, Germany: incidence, etiology, treatment,
and complications. J Oral Maxillofac Surg. 67:1251,2009.
2. Schubert W, Kobienia BJ, Pollock RA. Cross-sectional area of the
mandible. J Oral Maxillofac Surg. 55:689,1997.
3. Dodson TB. Third molars may double the risk of an angle fracture of the
mandible. Evid Based Dent. 5:78,2004.
4. Fonseca RJ, Walker RW, Betts NJ, et al. Oral and Maxillofacial Trauma
3rd Ed. Vol. 1:487-490, 2005.
5. Brown JS, Grew N, Taylor C, et al. Intermaxillary fixation compared to
miniplate osteosynthesis in management of the fractured mandible: An
audit. Br J Oral Maxillofac Surg. 29:308,1991.
6. Souyris F, Lamarche JP, Mirfakhrai AM. Treatment of mandibular
fractures by intraoral placement of bone plates. J Oral Surg. 38:33,1980.
7. Scolozzi P, Richter M. Treatment of severe mandibular fractures using
AO reconstruction plates. J Oral Maxillofac Surg. 61:458,2003.
8. Ellis E 3rd. Treatment methods for fractures of the mandibular angle. Int J
Oral Maxillofac Surg. 28:243,1999.
9. Champy M, Lodde JP, Schmidt R, et al. Mandibular osteosynthesis by
miniature screwed plates via a buccal approach. J Oral Maxillofac Surg.
6: 14,1978.

23. 10. Ellis E 3rd. Treatment methods for fractures of the mandibular angle. Int
J Oral Maxillofac Surg. 28: 243,1999.
11. Alkan A, Çelebi N, Özden B, et al. Biomechanical comparison of
different plating techniques in repair of mandibular angle fractures. Oral
Surg Oral Med Oral Pathol Oral Radiol Endod. 104:752,2007.
12.Farmand M, Dupoirieux L. The value of 3-dimensional plates in
maxillofacial surgery. Rev Stomatol Chir Maxillofac. 93:353,1992.
13. Al-Moraissi EA, El-Sharkawy TM, El-Ghareeb TI, et al. Three-
dimensional versus standard miniplate fixation in the management of
mandibular angle fractures: a systematic review and meta-analysis. Int J
Oral Maxillofac Surg. 43:708,2014.