ORIGINAL ARTICLE
A comparative study of most suitable miniplate ﬁxation for
mandibular symphysis fracture using a ﬁnite element model
Akiko Kimura,1 Tomohisa Nagasao,1 Tsuyoshi Kaneko,2 Junpei Miyamoto1 and Tatsuo Nakajima1
1Department of Plastic and Reconstructive Surgery, School of Medicine, Keio University, Tokyo, Japan
2Department of Plastic and Reconstructive Surgery, National Center for Child Health and Development
Tokyo, Japan(Received for publication on July 5, 2005)(Revised for publication on November 8, 2005)(Accepted for publication on November 24, 2005)

Abstract. The purpose of this study is to determine the most stable ﬁxation method for mandibularsymphysis fractures by comparing the mechanical characteristics of models ﬁxed at different positions
with different numbers of plates. Fractures were generated in 3-dimensional ﬁnite element models, andwere ﬁxed with a single miniplate, parallel double miniplates, or perpendicular double miniplates. A
300 N perpendicular load was then applied on the left molar region, and a ﬁnite element analysis was
performed. We compared vertical gaps between the fractured surfaces, maximum stress within thescrew/plating system, and maximum stress around screw holes in the bone. Compared to the single
miniplate, both the parallel and perpendicular double miniplates demonstrated signiﬁcantly less stressin the screw/plating system and screw holes in the bone. In addition, the perpendicular double miniplates had signiﬁcantly smaller vertical gaps between fracture surfaces when compared to the single
miniplate. Comparing parallel and perpendicular double miniplate ﬁxations, less stress was foundaround the screw holes of the perpendicular miniplate models than those of the parallel miniplatemodels. There were no differences in vertical gaps or maximum stress within the screw/plating systems
between the 2 double miniplate ﬁxations. These results suggest that perpendicular double miniplateﬁxation is more suitable for ﬁxing mandibular symphysis fractures. (Keio J Med 55 (1): 1–8, March
2006)
Key words: ﬁnite element analysis, mandibular symphysis fracture, miniplate, mechanical stresshigher proportion of symphysis fractures (14.5–40%)
due to a more fragile symphysis caused by overcrowdingof unerupted teeth.10,11
While stabilization is as important for symphysis
fractures as other mandibular fractures, there has been
relatively little study on an optimal method of internal ﬁxation. This may be because, as the shape of thesymphysis region is simpler than that of the angles orcondyles, surgeons could assume that differences in ﬁxation methods were less important. Little data exist on
the selection of the number and positions of a plate,
and these decisions are typically made empirically. To
address this uncertainty, we used 3-dimensional FEA toinvestigate whether or not the stability of the fracturesurface differs with different plating strategies.

Introduction
The mandible is the most frequent site among facial
fractures.1,2 Fractures with displacements are often
treated by open reduction and internal ﬁxation using
miniplates.1,3,4 When planning a surgical strategy for
mandibular fractures, it is most important to obtain arigid initial ﬁxation to bear the masticatory load.
Mechanical analyses using a ﬁnite element analysis(FEA) have demonstrated that stability at the fractureinterface differs with different plating strategies in bothangle fracture models5,6 and condyle fracture models.7
Along with these fractures, the symphysis is one of themost frequent facture sites,8–12 making up 18–20% of
mandibular fractures in adults.2,9 Children experience a

Reprint requests to: Dr. Akiko Kimura, Department of Plastic and Reconstructive Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan, e-mail: profak@infoseek.jp
1

2

Kimura A, et al: Miniplate ﬁxation in symphysis fracture model

Material and Methods

Generating fractures and ﬁxing with different plating
strategies

CT scans and design of 3-dimensional mandible models
Computer models of adult human edentulous mandibles were created from CT scans of 8 dry humanmandibles possessed by Department of Plastic andReconstructive Surgery, School of Medicine, Keio University, as previously described by Nagasao, et al.13
Every ﬁfth coronal plane slice (1 mm each in thickness) was picked, and the outer edge of the corticalbone and the boundary between the cortical bone andthe cancellous bone were traced. Twenty to 30 points
on the traced line were plotted on XYZ coordinates,
and these points were then combined with straight lines
to produce a wire frame. Then, adjacent wire frames
were connected to each other. Therefore, 3-dimensional
mandibular models composed of cortical bone and cancellous bone were created. The 8 mandibular models
had different heights and widths. The coordinate dataof mandibular models were imported to a personal
computer (CF-Y2DW1AXR, Panasonic, JAPAN; CPU:
1.3 MHz Cash memory: 512 MB, HDD: 40 GB). And,all surgical simulations and analyses were performed
using ﬁnite element analysis software (ANSYS Ver.
8.0, ANSYS Inc., Canonsburg, Pa., USA). Models wereassigned with an orthogonal X-Y-Z coordinate system(Fig. 1): the X-axis was assigned as medio-lateral, theY-axis cranio-caudal, and the Z-axis antero-posterior.

Fig. 1 3-dimensional ﬁnite element fractured mandibular modelﬁxed with a single plate. A 300 N load was simulated perpendicular tothe left molar region.

Next, we conﬁgured complete symphysis fracturesthat run on the midline in the sagittal plane, with fractured surfaces apposing each other.
Models of titanium ﬁxation plates (4 holes, thickness
1 mm) were positioned in 3 different ways as describedlater on the buccal cortical bone surfaces, and ﬁxed
with unicortical cylindrical screws (diameter 2 mm).
Although these screw models were designed without agroove, screws were united to the plates and buried
in bone so that screw models were designed to be mechanically the same as actual screws.
These plates were curved along with mandibular
contour and connected to the mandible only by screws.
So, forces in the plates were transmitted to bones onlyby the screws.
The comparative conditions of miniplates were as
follows (Fig. 2):
1. Single miniplate
2. Parallel double miniplates
3. Perpendicular double miniplates
The upper screws in both double miniplate models
were positioned at the same location as those of thesingle miniplate model. The lower screws in the parallel
miniplate models were positioned parallel to the upper
ones at the inferior margin of the mandible. In otherwords, the long axis of all screws in the parallel miniplate model was parallel to the Z-axis.
In the perpendicular miniplate model, the lower
screws were driven into the inferior surface of the mandible. The long axis of the lower screws was parallel tothe Y-axis.
Screws were labeled #1: posterosuperior, #2: anterosuperior, #3: posteroinferior, and #4: anteroinferior(Fig. 2).
A 4 mm-diameter titanium dental implant wasimbedded vertically into the left molar region. The
head of the implant was given a cubic shape to simplify
masticatory load calculations (Fig. 2).
Four models (intact mandible, symphysis fracturewith single miniplate ﬁxation, parallel double miniplateﬁxation, and perpendicular double miniplate ﬁxation)from 8 individuals, a total 32 models, were created forthe analyses. Each model was divided into 59,000–
79,000 elements. Each element was tetrahedron-shaped,
iso-parametric, and contained 10 nodes. All materials inthis model were accounted for as isotropic, homogenous, and linearly elastic. We obtained the material
properties for cortical bone, cancellous bone, and plating systems from previously reported data (Table
1).13–15

Keio J Med 2006; 55 (1): 1–8

3

Fig. 2 Three types of plate ﬁxation. Single miniplate: One curved miniplate was placed with four unicortical screws at the middle of the buccal
cortical bone surface. Parallel double miniplates: Two parallel curved miniplates were placed with four unicortical screws, each on the inferior
and the middle buccal cortical bone surfaces. Perpendicular double miniplates: One curved miniplate was placed on the middle buccal corticalbone surface and the other on the inferior surface, with four unicortical screws each. Screws were labeled as #1: posterosuperior site, #2: anterosuperior site, #3: posteroinferior site, and #4: anteroinferior site.

Table 1

Evaluation and statistical analysis

Material Properties Used for the Calculations

Cortical Bone
Cancellous Bone
Titanium

Elastic Modulus (MPa)Poisson’s Ratio

8700–15000
500–1500
105000–110000

0.3–0.33
0.3
0.34–0.35

MPa; Mega Pascal.

Constraints, loading, and solution
Six regions including condylar processes, coronoid
processes, and mandibular angles, were ﬁxed to zerodisplacement. A masticatory load on the left molar region was simulated with a 300 N force perpendicular tothe dental implant (Fig. 1), which is the mean single
molar bite force in healthy young adults.16 It was
assumed that the maximum masticatory load was applied to the molar region through the implant during
mastication and clenching.

The vertical gaps between the upper surfaces of thebilateral mandible fragments at the fracture site, themaximum stress within the screw/plating system, andthe maximum stress around the bone screw holes were
evaluated.
All stress values were recorded in MPa (Mega
Pascals ¼ N/mm 2 ). Data were compared for signiﬁcantdifferences using the Mann-Whitney U test, with Pvalues < 0.05 being signiﬁcant. All calculations weremade using SPSS Ver. 10 for Windows (SPSS Inc.,
Chicago, USA).
Results
Stress distribution
The contour map of intact mandible models showedthat von Mises stresses decreased gradually with distance from the loading region; little stress was found at

4

Kimura A, et al: Miniplate ﬁxation in symphysis fracture modelFig. 3 Stress distributions in the intact mandibular model by a 300 N vertical load. Stress was mainly localized around the loading region. MPa;
Mega Pascal.

Fig. 4 Contour maps of the stresses within the screws by a 300 N vertical load. Different scales were used for fractured models because of thedifference in the stress levels. Stresses were concentrated within the screws near the fracture site (#2 and #4) in all groups. Each model had adisplacement of the borders of the fractured surface of varying degrees. MPa; Mega Pascal.

Fig. 5 Gaps between the upper borders of the fractured surfaces.
There was no signiﬁcant difference in the distance of the gaps between
the perpendicular double miniplates models and the parallel double
miniplates models, while there was signiﬁcant difference between
the perpendicular double miniplates models and the single miniplatemodel.

Fig. 6 Contour maps of the stress around #2 bone screw holes. The
stress concentration was determined around the #2 bone screw hole ineach group (upper row). Close-up (lower row) shows that perpendicular double miniplates had the least stress around the #2 bone screw
hole among these three ﬁxations. MPa; Mega Pascal.

Keio J Med 2006; 55 (1): 1–8
Table 2

5

Maximum von Mises Stresses at #2 Screws and Screw Holes and Gaps between the Fractured Surface in the Different Plates Fixation

Fixation

Single plate

Double plates

Positions of plates

ParallelMaximum stress at #2 screw (MPa)Maximum stress at #2 screw hole (MPa)Gap between the upper borders of the fractured surface (mm)PerpendicularMedianRange

MedianRange

Median

Range

15.50
13.91
0.293

8.7–16.4
7.0–21.4
0.22–0.6

10.32
6.6
0.255

4.6–17.0
3.8–8.8
0.14–0.42

7.97
2.61
0.171

6.2–12.5
1.2–4.4
0.01–0.31

MPa; Mega Pascal.

the symphysis region (Fig. 3). In symphysis fracture
models, von Mises stresses were concentrated within
the #2 and #4 screws, regardless of ﬁxation patterns(Fig. 4).
Gaps between the upper surfaces of the bilateral mandible fragments at the fracture site
Each ﬁxation method had a gap at the upper borderof the fractured surfaces (Z-axis, Table 2). The perpendicular miniplate models demonstrated signiﬁcantly
smaller gaps than the single miniplate models (p ¼
0.028, Fig. 5), but there was no signiﬁcant differencein the gaps of the upper border of the fractured surface between the parallel and perpendicular miniplatemodels.
Maximum stress around screw/plating systems
Comparing the 3 ﬁxation models, mechanical stresswithin screw/plating systems differed (Fig. 4). In the
single models, the maximum stress was found withinscrew #2. In the parallel models, the stress within screw#2 was reduced and appeared to be dispersed to screw#4. In the perpendicular models, the maximum stress
was found in the middle of the inferior plate.
Among these models, there were no statistically signiﬁcant differences in stress within screw #2, although
there was a trend for the stress to be lowest in the perpendicular models and highest in the single models(Table 2).
Maximum stress at bone screw holes
The lowest maximum stress around screw hole #2
was found in the perpendicular models, followed by theparallel models, and ﬁnally the single models (Fig. 6,
Table 2); these differences were signiﬁcant (Fig. 7).
Discussion
The purpose of surgical ﬁxation for mandibular

PlatesFig. 7 Maximum stress around #2 bone screw holes. The perpendicular double miniplates had signiﬁcantly lower stress, followed by theparallel double miniplates, and then the single miniplate.

fractures is to secure the reduced fragments duringosteogenesis to permit sound healing. Inevitable frequent masticatory loads can cause motion at the fracture site, and interfere with the healing process. As aresult, nonunion can occur in symphysis fractures, therate of which has been reported to be 3.7%.12 Inadequate stabilization or reduction was an important causeof nonunions.24 Therefore, we sought the most effectiveﬁxation method to stabilize a fracture, which results inless mechanical stress on the mandible, in this study.
The symphysis is one of the most frequent sites ofmandibular fractures in children, and comprises about
20% of adult mandibular fractures.9 Symphysis fractures with displacement are often ﬁxed with 1 or 2
miniplates. Although there have been some reports onmechanically appropriate positions for miniplates inmandibular angle5,6 and condyle fractures,7 few suchstudies exist for symphysis fractures.

6

A possible reason for this paucity is that the anterior
surface of the symphysis region is moderately convex
and easily accessed, so it might be accepted as axiomatic where the miniplates should be placed.
However, the anterior surface of the symphysis region forms an angle with the inferior surface, presenting
multiple options for positioning plates and screws. We
hypothesized that in the symphysis fracture, the fracture stability will differ with the positions of plates andscrews chosen. We tried to answer this question using
3-dimentional FEA.
In this study, we created 3-dimensional mandibular models to simulate the 3 ﬁxation techniques.
In vivo strain gauge measurements are alternatives to
FEA,17–19 but stress-measuring areas and the numberof measuring devices are limited due to the volume of
the gauge. FEA permits an analysis of stress from arbitrary points, and provides other useful information suchas on distances, stress, and behavior of the wholemodel. There are many reports on FEA for angle fractures,5 condylar fractures,7 and other mandibular conditions.5,7,13,15,20,21 We, therefore, determined that
FEA was suitable for this application.
The masticatory load we simulated was a 300 N vertical load on the left molar region. While masticatory
motion is actually like a teardrop cycle,22 which means
the frontal plane trace of a molar is like a teardrop nota straight line, the vector mostly consists of a verticalcomponent (Y-axis, Fig. 1), so we considered a verticalload to be a reasonable approximation.
We evaluated 3 items for plate stability: 1. gaps between the upper border of the fractured surfaces, 2.
maximum stress within the screw/plating systems, and 3.
maximum stress around the bone screw holes. Stresswithin the screw/plating systems and bone screw holes
can cause screw loosening and incomplete stability of
the fractured surfaces, therefore, low stress is favorable
for stability. The gap between the upper borders of thefracture surfaces is a direct indicator of stability. The
upper borders of the fractured surface were appropriately evaluated by Y-axis motion, as they were hardly
affected by X-axis motion (Figs. 1 and 4).
It was derived from animal experiments using thedog23 that fracture displacement should not exceed 150
mm for proper healing. From our ﬁndings, the perpendicular miniplate models give the best result that isclose to that of the dog experiment (Table 2, Fig. 4).
Unless applying maximum bite force, sound healing
would be expected with perpendicular ﬁxation. In vivo
strain measurements demonstrate that the maximum
stress around screw holes peaks at 2 weeks postoperatively when maximum bite force is applied;17
therefore, achieving stability of the fracture site is essential for 2 to 3 weeks.
The parallel miniplates models demonstrated signiﬁ-

Kimura A, et al: Miniplate ﬁxation in symphysis fracture modelFig. 8 Mechanism of stress transmission. These are the cross sectionsof mandibular symphysis regions (upper row: resting state; lower row:
loading state). When a vertical load is applied (arrows), stresses weretransmitted to screws (arrowheads). In the single miniplate model, thestress was concentrated at the screw end that is connected to the plate.
In the parallel double miniplates model, stress was dispersed over thetwo screws. In the perpendicular double miniplates model, verticalstress was mainly transmitted to the inferior screws, whose long axis isin the same direction to the load. Ultimately the stresses on the screws
were transmitted to the whole plate.

cantly less stress than the single miniplate models inboth the screw/plating system and bone screw holes, but
no signiﬁcant difference was found in the gap at theupper borders of the fractured surfaces.
The perpendicular miniplate models also demonstrated less stress than the single miniplate models inboth the screw/plating system and bone screw holes,
while having signiﬁcantly smaller gaps at the upper
border of the fractured surfaces.
Less stress was demonstrated around the screw holesof the perpendicular miniplate models than those of theparallel miniplate models, but there were no differencesin the gaps or the maximum stress within the screw/
plating systems.
These data indicate that double miniplate ﬁxation
can lead to better stability regardless of plate position,
however, more stress would occur around bone screw
holes in parallel miniplates ﬁxation. As illustrated inFig. 8, this phenomenon can be explained by the relationship between the vector of masticatory load andthe inferior screws (Fig. 8). Plating systems are mainly
subject to a downward force along the Y-axis (Fig. 8,
arrows). Miniplates resist shear forces along the Y-axis
as well as bending that would lead to a gap along the Xaxis. In the parallel models, shear forces were applied
to the screws embedded perpendicular to the Y-axis(Fig. 8, center; Fig. 9 left, dot areas). While one end of
the screw was connected to the miniplate, the other end
was free (Fig. 9 left, circle). Applying a masticatoryload, the stress was resisted only by the junction of theKeio J Med 2006; 55 (1): 1–8

7

the inferior alveolar artery, than at the outer side supplied by mandibular periosteum.25
Regarding the skin incision, intraoral incision is usually employed for the exposure of mandibular symphysis fractures, and the inferior surface of the mandible
can also be exposed from this incision excluding theneed of another incision for perpendicular miniplate
placement.
Even though we started our simulation study withtitanium plates and a vertical load, we are planning toperform analyses using different materials and different
loads such as anteroposterior shear load that would
cause considerable fracture movement along the Z-axis.
Fig. 9 Schema of mandible and screw/plating systems. Frontal views(upper ﬁgures) and axial views (lower ﬁgures) of the fractured mandible fragments. In parallel double miniplates models, stress wastransmitted to the long axis of screws because they were embedded
perpendicular to the loading vector (lower left, dot areas). One of theends was imbedded directly in cancellous bone (lower left, circle). In
the perpendicular double miniplates models, the screws only transmitted the stress because the long axis of the screws was parallel to theloading vector. The stress was resisted by the plate that was vertical tothe masticatory vector (lower right, dot areas). Both ends of the plates
were ﬁrmly stabilized with screws; therefore the plate could endure
the stress securely.

screws and miniplate (Fig. 8 center, arrow heads).
In the perpendicular models however, the screws
only transmitted the stress because their long axis wasparallel to the force, and the stress was resisted by theplate instead of the screws vertical to the masticatory
load (Fig. 9 right, dot areas). Because both ends of theplates were ﬁrmly stabilized with screws, the plates
could endure the stress well (Fig. 9 right, dot areas).
Therefore, in the perpendicular models, less stressoccurred around bone screw holes, despite no difference being found within the screw/plating systems between the perpendicular models and the parallel models. Additionally, plate ﬁxed on the inferior surface
directly secures X-axis motion, and can contribute to
the stability of the entire fractured surface.
In conclusion, the perpendicular double miniplateﬁxation was found to provide better stability for thefractured surfaces and less stress at the bone screw
holes, giving them favorable ﬁxation for mandibularsymphysis fractures.
Although, in the actual operation, perpendicular
double miniplate ﬁxation needs a wider exposure, we
think that a complete reduction of the dislocated segments under a wider exposure leads to better stability,
and contributes to sound osseous healing. Because neovascularization at fractured site, which is essential forosseous healing, occurs faster at the cancellous side ofcortical bone, the blood supply for which is supplied by

References
1. Erol B, Tanrikulu R, Görgün B: Maxillofacial fractures. Analysis
of demographic distribution and treatment in 2901 patients (25year experience). J Craniomaxillofac Surg 2004; 32: 308–313
2. Al Ahmed HE, Jaber MA, Abu Fanas SH, Karas M: The patternof maxillofacial fractures in Sharjah, United Arab Emirates:
a review of 230 cases. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2004; 98: 166–170
3. Eppley BL: Use of resorbable plates and screws in pediatricfacial fractures. J Oral Maxillofac Surg 2005; 63: 385–391
4. Kim YK, Kim SG: Treatment of mandible fractures using bioabsorbable plates. Plast Reconstr Surg 2002; 110: 25–31
5. Cox T, Kohn MW, Impelluso T: Computerized analysis ofresorbable polymer plates and screws for the rigid ﬁxation ofmandibular angle fractures. J Oral Maxillofac Surg 2003; 61:
481–487
6. Feller KU, Schneider M, Hlawitschka M, Pfeifer G, Lauer G,
Eckelt U: Analysis of complications in fractures of the mandibular angle – a study with ﬁnite element computation andevaluation of data of 277 patients. J Craniomaxillofac Surg 2003;
31: 290–295
7. Wagner A, Krach W, Schicho K, Undt G, Ploder O, Ewers R:
A 3-dimensional ﬁnite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis incases of fractures of the condylar process. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 2002; 94: 678–686
8. Fridrich KL, Pena-Velasco G, Olson RA: Changing trends withmandibular fractures: a review of 1,067 cases. J Oral Maxillofac
Surg 1992; 50: 586–589
9. Boole JR, Holtel M, Amoroso P, Yore M: 5196 mandible fractures among 4381 active duty army soldiers, 1980 to 1998. Laryngoscope. 2001; 111: 1691–1696
10. Thoren H, Iizuka T, Hallikainen D, Lindqvist C: Different patterns of mandibular fractures in children. An analysis of 220
fractures in 157 patients. J Craniomaxillofac Surg 1992; 20: 292–
296
11. Tanaka N, Uchide N, Suzuki K, Tashiro T, Tomitsuka K, Kimijima Y, Amagasa T: Maxillofacial fractures in children. J Craniomaxillofac Surg 1993; 21: 289–293
12. Lamphier J, Ziccardi V, Ruvo A, Janel M: Complications ofmandibular fractures in an urban teaching center. J Oral Maxillofac Surg 2003; 61: 745–749
13. Nagasao T, Kobayashi M, Tsuchiya Y, Kaneko T, Nakajima T:
Finite element analysis of the stresses around endosseous
implants in various reconstructed mandibular models. J Craniomaxillofac Surg 2002; 30: 170–177
14. Sertgöz A, Güvener S: Finite element analysis of the effect

8

15.

16.

17.

18.

19.

Kimura A, et al: Miniplate ﬁxation in symphysis fracture modelof cantilever and implant length on stress distribution in an
implant-supported ﬁxed prosthesis. J Prosthet Dent 1996; 76:
165–169
Maurer P, Holweg S, Schubert J: Finite-element-analysis ofdifferent screw-diameters in the sagittal split osteotomy of themandible. J Craniomaxillofac Surg 1999; 27: 365–372
Ferrario VF, Sforza C, Serrao G, Dellavia C, Tartaglia GM:
Single tooth bite forces in healthy young adults. J Oral Rehabil
2004; 31: 18–22
Sugiura T, Horiuchi K, Yoshioka M, Sugimura S, Tsutsumi S:
Direct in vitro Strain measurement of miniplates during mandibular osteogenesis. Nihon Rinsho Biomechanics gakkaishi
1998; 19: 347–351 (in Japanese)
Haug RH, Peterson GP, Goltz M: A biomechanical evaluationof mandibular condyle fracture plating techniques. J Oral Maxillofac Surg 2002; 60: 73–80
Haug RH, Fattahi TT, Goltz M: A biomechanical evaluation ofmandibular angle fracture plating techniques. J Oral Maxillofac
Surg 2001; 59: 1199–1210

20. Nagasao T, Kobayashi M, Tsuchiya Y, Kaneko T, Nakajima T:
Finite element analysis of the stresses around ﬁxtures in various
reconstructed mandibular models – part II (effect of horizontalload). J Craniomaxillofac Surg 2003; 31: 168–175
21. Gallas Torreira M, Fernandez JR: A three-dimensional computer model of the human mandible in two simulated standard
trauma situations. J Craniomaxillofac Surg 2004; 32: 303–307
22. Rilo B, Fernandez J, Da Silva L, Martinez Insua A, Santana U:
Frontal-plane lateral border movements and chewing cycle characteristics. J Oral Rehabil 2001; 28: 930–936
23. Soballe K: Hydroxyapatite ceramic coating for bone implant ﬁxation. Mechanical and histological studies in dogs. Acta Orthop
Scand Suppl 1993; 255: 1–58
24. Mathog RH, Toma V, Clayman L, Wolf S: Nonunion of themandible: an analysis of contributing factors. J Oral Maxillofac
Surg 2000; 58: 746–752
25. Nakajima M, Okada S: Microvascular changes during osseoushealing after mandibular segmental resection. Nihon kokugeka
gakkaishi 1994; 40: 1049–1057 (in Japanese)