Xu and Zhang

Int Chin J Dent 2003; 3: 45-52.

Individualized reconstruction of major mandibular defect based on
craniomaxillofacial correlationship
Liqun Xu, MD, and Chenping Zhang, MD
Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, Shanghai
Second Medical University, Shanghai, P. R. China
Purpose: To find a solution for individualized contour reconstruction of severe mandibular defect based on
craniomaxillofacial correlationship.
Materials and Methods: Total 10 adults with normal occlusion were included in this study.

Aftercephalometric analysis, accuracy of regression equations of mandibular contour variables from ourprevious series studies on mandibular contour correlation was testified by statistical analysis. Meanwhile,the data of mandibular contour variables and lateral inferior arc curve of mandible were supplied for one
patient with severe mandibular defect for individualized reconstruction.
Results: No statistical difference (p>0.05) was presented between the values of mandibular contour
variables from two different methods (actual measurements and mathematical calculations). Moreover,aesthetic profile was obtained postoperatively in this clinical case.
Conclusion: Analysis of mandibular contour correlation could provide very important data for
individualized reconstruction of severe mandibular defect. (Int Chin J Dent 2003; 3: 45-52.)
ClinicalSignificance:

Correlation

study

of

mandibularcontour

versusthree

dimentionalcranio-maxillofacial structures provided a beneficial exploration for individualized reconstruction of severe
mandibular defect with loss of primary position.
Key Words: Contour, Correlation, Mandible, Reconstruction.

Introduction
To date free vascularized autogenous bone graft is still the main and optimal method for reconstructionof mandibular defect. Oral maxillofacial surgeons are often challenaged by accurately positioning andshaping the neomandible for those with cross-midline major mandibular defects due to loss of primaryanatomic position. After performing a series of basic studies on mandibular contour correlation versus
three dimentional craniomaxillofacial structures, we found that there existed significant quantitative
correlationship between mandibular contour, determined by ArGo, GoPg, GoGo, and craniomaxillofacial
structures.1 The aim of this paper was to verify the reliability and practicability of previous conclusions.
Meanwhile, combined with a typical case, a new method of mandibular contour reconstruction wasintroduced in details.

45Xu and Zhang

Int Chin J Dent 2003; 3: 45-52.

Materials and Methods
Total 10 Han tribe adults (>18 years) with normal occlusion from East-China were included in this study.
Of them, five were male and five were female respectively. The mean age was 41.1 years. The criteria ofnormal occlusion was characterized by neutral occlusion, normal range of over bite and over jet, without
dental displacement and history of orthodontic and orthognathic treatment. All subjects took biplanar(lateral and frontal view) cephaloradiography (Figs. 1 and 2) followed by cephalometric analysis. Good
exposure and clear appearance in every X-ray film were guaranteed.

12Fig. 1. Markers and linear parameters in lateral cephalometric tracing. 2 (Ba-A) represents
projecting distance between Ba point and A point on Frankfort plane; 3 (Ba-Ar) represents
projecting distance between Ba point and Ar point on Frankfort plane; 6 (Ptm-A) represents
projecting distance between Ptm point and A point on Frankfort plane; 7 (Ba-S) represents
projecting distance between Ba point and S point on Frankfort plane; 10 (N-A) represents
projecting distance between N point and A point on the plane vertical to Frankfort plane; 11(Ba-S(H)) represents projecting distance between Ba point and S point on the plane vertical toFrankfort plane; 13 (Ar-Go) represents distance between Ar point and Go point; 14 (Go-Pg)
represents distance between Ar point and Go point.
Fig. 2. Markers and linear parameters in frontal cephalometric tracing. 15 Zyg (L,R) represents
distance between bilateral Zyg points; 16 Lc (L,R) represents distance between bilateral Lc points;
18 Mx (L,R) represents distance between bilateral Mx points; 20 Go (L,R) represents distance
between bilateral Go points.
According to the results of correlation study of mandibular contour, we measured various linear variables
directly on tracing-paper in terms of different genders as follow: ArGo, GoPg, GoGo, MxMx, BaA,ZygZyg for male, ArGo, GoPg, GoGo, NA, PtmA, BaA, ZygZyg, BaS, BaS(H), BaAr, LcLc for female.
Upon regression equations of mandibular contour1 (Tables 1 and 2), calculated values of mandibular46

Xu and Zhang

Int Chin J Dent 2003; 3: 45-52.

contour variables (ArGo, GoPg, GoGo), which were compared to the actual measured values of mandibular
contour variables directly from radiography by the paired t-test procedure of SAS (version 6.12), wereobtained to testify the reliability and feasibility of equations.

Results
Tables 1 through 4 show the analysis results.
Table 1.

Results of regression analysis between mandibular contour variables andcraniomaxillofacial parameters in females.

Parameters

Intercepts

NAPtmA

ArGo

0.0166

0.56740.7006GoPg

1.9716GoGo

1.0581

Table 2.

Results of regression analysis between mandibular contour variables andcraniomaxillofacial parameters in males.

BaA

ZygZgyBaSBaS(H)BaAr

LcLc-0.56240.7012-0.42490.7575

Parameters

Intercepts

MxMx

ArGo

1.24340.5829GoPg

3.1561GoGo-2.88370.0002-0.92450.4465-0.6556

BaAP-values

0.00010.0001

ZygZygP-values
0.00230.4956
0.76570.00110.58010.0001

Above two tables from Xu L, Zhang C, et al. A study on correlation of mandibular contour. Shanghai Second Medical1
University Academic Dissertation for Master Degree, 2002: 17-31.

No statistical difference was presented between the calculated values of mandibular contour variables
and that of measured values, p>0.05 (Tables 3 and 4).

Case Report
A female patient, 52-year-old, from Fujian province of East-China was admitted to oral maxillofacial
department of Shanghai Ninth People’s Hospital. Seven years ago, she underwent radical oncologicalablation due to suffering rhabdomyosarcoma of floor of mouth. After surgery, major mandibular defectalmost from angle to angle contributing to impairment of oral function and lower facial contour developed,
when she consulted our department (Figs. 3 and 4). From radiographical appearance, the stumps ofmandible were displaced anteriorly, internally and upward due to uncontinuity of the mandible, the primary
position of pogonion and gonion was lost (Figs. 5 and 6). Consequently, how to restore the contour andposition of neomandible was the key to functional reconstruction.

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Xu and Zhang

Int Chin J Dent 2003; 3: 45-52.

Table 3. The calculated values and actual measured values of mandibular contour variables (cm).
No.

Ar-Go
Calculated

Measured

Go-Pg

Go-Go

Calculated Measured

Calculated

Measured

1

5.2

5.5

8.2

7.8

9.9

9.6

2

5.1

5.4

8.3

9.0

10.0

10.5

3

4.7

5.0

7.9

7.5

9.8

10.1

4

4.3

4.4

7.2

7.0

9.7

9.6

5

4.7

4.3

7.9

8.1

10.1

10.1

6

5.7

6.5

8.1

8.1

11.9

11.8

7

5.3

5.5

8.2

8.9

11.4

12.2

8

5.2

5.0

8.0

7.8

10.9

12.1

9

5.4

5.7

7.6

8.4

10.7

11.0

10

5.1

5.2

7.7

8.0

10.6

9.2

Table 4.

The paired t-test results of calculated values and actual measured values of mandibular
contour variables.

Contour variables
ArGo
GoPg
GoGo

Mean
-0.1800-0.15-0.1200s
0.32250.46250.7021t-1.7650-1.0256-0.5405

3p0.1114
0.33180.602045Figs. 3-5. Preoperative frontal view, right lateral view, and frontal cephalometric film.
As usual, biplanar cephalometric radiography was taken for this patient followed by cephalometricanalysis (Figs. 7 and 8). The value of preserved ramus ArGo was equal to 5.1 cm. Other variables values
included NA=6.4 cm, PtmA=5.1 cm, BaS(H)=3.7 cm, BaA=9.35 cm, ZygZyg=13.25 cm, BaAr=1.2 cm,48

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Int Chin J Dent 2003; 3: 45-52.

LcLc=12.15 cm, BaS=2.6 cm, which were input into the regression equations, achieving the calculatedvalues of mandibular contour variables ArGo=5.1401 cm, GoPg=7.2135 cm, GoGo=9.3904 cm.

678Fig. 6. Preoperative lateral cephalometric film showed anterior, internal and upward rotation of
the residual ramus.
Fig. 7. Markers and parameters in lateral cephalometric tracing-paper. The dotted line wassimulation of neomandibular profile based on the data of calculated mandibular contour variables.
Fig. 8. Markers and parameters in frontal cephalometric tracing-paper.
Similar to orthognathic surgery, template surgery was performed depending on the data of mandibularcontour variables.

We simulated mandibular reconstruction and got a satisfied profile on lateralcephalometric tracing-paper (dotted line in Fig. 7). Mandibular contour was composed of posterior borderof ramus (ArGo) and the lateral inferior arc curve of mandibular body. According to our studies on dry
mandibular samples of adults from East-China, the lateral inferior arc curve, determined by GoPg, GoGo,
was a piece of parabola which passed pogonion as origin and was symmetric against centric sagittal axis
(Y=KX2, p<0.01). Consequently, we could obtain the mathematical model of the lateral inferior arc curve(Y=0.3585X2) depending on the data of mandibular contour variables and drew this curve at the ratio of 1:1
to guide fabrication of template of lateral inferior arc curve (Figs. 9 and 10). In addition, the amount oftransplanted free fibula flap (15.4 cm) was predicted. During the operation, we could position and shape
the neomandible upon template with less time (Figs. 11and 12). Postoperatively, satisfactory contour wasobtained (Figs. 13-15).

Discussion
Many authors had developed a variety of techniques for restoration the primary mandibular contour.
There were about three methods in summary: (1) Precontour reconstruction plate technique,2 which could
be used to record and keep the primary position of mandibular stumps after mandiblectomy, guided shaping
the neomandible, but this technique was only indicated for those without destruction or erosion of buccal
cortical bone. (2) Surgical template techniques, which could be subdivided into two types. Indirect method
was that template was made depending on the preoperative lateral cephaloradiography and CT scan, and49Xu and Zhang

Int Chin J Dent 2003; 3: 45-52.

modified in reference to the measurements of mandibular specimen in the course of operation.3 Direct
method was that prothesis was obtained preoperatively by intraoral surgical stents.4

910Fig. 9. The parabola of lateral inferior arc curve (1:1).
Fig. 10. The guided template of lateral inferior arc curve.

111213Fig. 11. The volume prediction of the vascularized fibular flap.
Fig. 12. The prefabrication of the reconstructive titanium plate and fibular osteotomy.
Fig. 13. Postoperative frontal picture.

14Figs. 14-15. Postoperative right lateral picture and postoperative panoramic view.

15However, surgical template techniques were indicated for those without high need for rehabilitation of50

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Int Chin J Dent 2003; 3: 45-52.

occlusion relationship such as endentulous patients. (3) Splint and plate technique, by which primary
position of mandibular stumps was fixed to maxillary splint. Meanwhile, gonion or pogonion could bemarked by titanium plate extended from splint.5 This technique was adopted in the situations where theabove two techniques were unsuitable. But application of these techniques had a prerequisite that there
should exist primary mandible without displacement of mandibular position before mandibularreconstruction.

In the situations where primary mandibular position lost such as secondary major

mandibular defect even total mandibular defect or mandibular contour had severe destruction, it was
tremendous challenge for reconstructive surgeon to restore the position and contour of neomandible.
Usually upon maxillary dental arc and clinical experience, bone graft could be shaped to match maxilla.
Obviously, this technique was inaccurate and time-consuming. According to two Chinese reports,6,7 thelateral inferior arc curve of mandible and lateral superior arc curve were two complete different parabola(p<0.05), so shaping neomandible by maxillary dental arc was unreasonable and often brought about
secondary deformity such as retrognathic abnormality or neomandibular angles eversion. Meanwhile,
previous study confirmed that mandibular contour had individual characteristics,8 also it was not proper touse normal mean values of mandible replacing that of individual mandible contour variables.
Quantitative correlationship between mandibular contour and craniomaxillofacial structures had been
established according to the consistent principle of mandible-craniomaxillary structures.9 We could predictmandibular contour by three dimensional craniomaxillary structures.

It was a worthy trial for

individualized reconstruction of major mandibular defect. In addition, to warrant the success of complex
operation and to decrease statistical error as possible as we could, simulation surgery was performed asorthognathic surgery to testify the data of mandibular contour variables.

Conclusion
In conclusion, it was feasible for clinical application of mandibular contour correlationship by provementof this study, but there existed difference in aspects of tribes and areas, further correlation study ofmandibular contour was necessary.
Acknowledgment
We were grateful to professor Jia-Wei Zheng for his revision of manuscript and good suggestions.

References
1. Xu L, Zhang C, et al. A study on correlation of mandibular contour. Shanghai Second Medical University Academic
Dissertation for Master Degree 2002; 17-31.
2. Spiessl B, Rahn B. Reconstruction of segmental defects in tumor surgery, Internal fixation of the mandible: A manual ofAO/ASIF principles. Berlin: Springer-Verlag; 1989. p. 290-308.
3. Hidalgo DA. Aesthetic improvements in free-flap mandible reconstruction. Plast Reconstr Surg 1991; 88: 574-85.
4. Markowitz BL, Roumanas E, Calcaterra T. Surgical stents for composite mandible reconstruction. Plast Reconstr Surg
1995; 96: 194-8.

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Int Chin J Dent 2003; 3: 45-52.

5. Reece GP, Martin JW, Lemon JC, Jacob RF. Mandible fragment fixation during reconstruction: the splint-and-platetechnique. Ann Plast Surg, 1993, 31: 128-33.
6. Zhu X, Yang Z. The study on lateral middle arc curve of mandible. Acad Rep Xinjiang Med Coll 1990; 13: 145-7.
7. Wang D, Zhu X. The study on lateral inferior arc curve of mandible. Chin Anatom J 1986; 9(Suppl): 6-8.
8. Wang X, Zhang Z, Gao K, et al. Frontal cephalometric study of Chinese beauty population. J Comprehensive Stomatol
1988; 4: 195-200.
9. Pi X. Oral anatomicophysiology. Beijing: People Health Press; 1998. p. 60.

Reprint request to:
Dr. Chenping ZhangDepartment of Oral and Maxillofacial Surgery, Ninth People’s Hospital
Shanghai Second Medical University
Zhizhaoju Road, No. 639, Shanghai 200011, P. R. China
FAX: +86-021-63136856 E-mail: h9mfsl@online.sh.cn
Received on February 25, 2002. Revised on August 13, 2002. Accepted on March 13, 2003.
Copyright ©2003 by the Editorial Council of the International Chinese Journal of Dentistry.

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