Introduction: Sydromic craniosynostoses, Crouzon, Apert, and Pfeiffer syndromes, share many common abnormalities of the cranial and midfacial skeleton that have been well documented. However, little attention has been paid towards the mandible. In general, examination of the mandible has been restricted to data observed on the lateral cephalograms. The mandible has been described as near normal to mildly abnormal 1,2. The purpose of this study was to document mandibular abnormalities and relationships as seen on the posterior-anterior cephalograms and to document changes seen with growth.

Materials and Methods: Fifteen patients with syndromic craniosynostoses (2 Apert, 11 Crouzon, 2 Pfeiffer) (11 female, 4 male) were examined. All patients had at least seventeen years of follow up with serial posterior-anterior cephalograms taken at age five, ten and fifteen years of age. The cephalograms were analyzed for bicondylar width, bigonial width, and cranial base/ramus angulation. All points and measurements were verified independently by two investigators and confirmed by a third. The findings were compared with University of Michigan, Center for Human Growth and Development standard normative data of posterior-anterior cephalometric findings3.

Results: In females, at all time points, there was statistically significant reduction in the bicondylar width. The bigonial width showed no reduction. The resulting bicondylar/bigonial ratios were significantly reduced and the ramal cranial base angles were significantly increased. In males, there was statistically significant reduction in the bicondylar width all groups with the exception of the ten year group (ten year p = 0.055). The resulting bicondylar/bigonial ratios were statistically significantly reduced in all groups and the ramal cranial base angles were statistically significantly increased in all groups with the exception of the left side in the ten year group (left side ramal angle p = 0.058).

Conclusions: The mandible in the sydromic craniosynostoses has significant abnormalities which include constriction of the bicondylar width with a near normal bigonial width. These findings suggest a narrowing at the cranial base with resulting restriction of normal transverse mandibular growth at the condyle with near normal transverse growth at the gonion. Consequently, the ramus is torqued inward, forming a greater angle with the cranial base. Significantly, this study demonstrates the value of examining the transverse dimensions of the face in sydromic craniosynostosis and gives a greater understanding of the disease process, specifically, growth abnormalities at the cranial base.

Reference:

1. Costaras-Volarich M, Pruzansky S: Is the mandible intrinsically different in Apert and Crouzon syndromes? Am. J. Orthod. 85(6) 475-487, 1984.

2. Kreiborg S: Crouzon syndrome: a clinical and roentgenocephalometric study. Scand J Plast Reconst Surg, Suppl. 18, 1981.

3. Basyouni AA, Nanda SK. An Atlas of the Transverse Dimensions of the Face. Needham Press, 2001.

Tables:

Females:

Age / Nl Bi-Con / Sub Bi-Con / p / Nl Bi-Gon / Sub Bi-Gon / p / Nl Bi-Con/
Bi-Gon / Sub Bi-Con/
Bi-Gon / p
5 / 87.03
+/- 3.44 / 74.82
+/- 5.57 / <0.0001 / 75.2
+/- 3.91 / 74.4
+/- 7.63 / 0.735 / 1.16
+/- 0.05 / 1.01
+/- 0.08 / <0.0001
10 / 94.12
+/- 3.76 / 79.14
+/- 4.70 / <0.0001 / 83.8
+/- 4.02 / 83.1
+/- 8.10 / 0.788 / 1.12
+/- 0.05 / 0.96
+/- 0.06 / <0.0001
15 / 101.22
+/- 3.86 / 82.4
+/- 4.74 / <0.0001 / 91.2
+/- 4.54 / 89.7
+/- 10.50 / 0.661 / 1.11
+/- 0.05 / 0.93
+/- 0.09 / <0.0001
Age / Side / Mean normal angle/ degrees / Mean subject angle/degrees / p-value
5 / Right / 81.9 +/- 2.73 / 90.7 +/- 4.38 / <0.0001
5 / Left / 81.8 +/- 3.04 / 88.5 +/- 3.61 / <0.0001
10 / Right / 83.9 +/- 2.80 / 94.0 +/- 4.47 / <0.0001
10 / Left / 83.4 +/- 2.34 / 92.2 +/- 3.16 / <0.0001
15 / Right / 84.2 +/- 2.86 / 94.4 +/- 4.55 / <0.0001
15 / Left / 84.3 +/- 2.88 / 92.7 +/- 4.34 / <0.0001

Males:

Age / Nl
Bi-Con / Sub
Bi-Con / p / Nl
Bi-Gon / Sub
Bi-Gon / p / Nl Bi-Con/
Bi-Gon / Sub Bi-Con/
Bi-Gon / p
5 / 87.87
+/- 3.43 / 79.75
+/- 4.35 / 0.028 / 77.02
+/- 4.32 / 80.0
+/- 2.27 / 0.072 / 1.14
+/- 0.06 / 1.00
+/- 0.06 / 0.009
10 / 95.92
+/- 2.69 / 84.0
+/- 7.87 / 0.055 / 87.04
+/- 4.46 / 92.75
+/- 0.96 / <0.0001 / 1.11
+/- 0.06 / 0.91
+/- 0.09 / 0.019
15 / 103.92
+/- 2.90 / 90.63
+/- 6.18 / 0.021 / 95.93
+/- 4.81 / 102.13
+/- 4.21 / 0.052 / 1.09
+/- 0.06 / 0.89
+/- 0.09 / 0.021
Age / Side / Mean normal angle/ degrees / Mean subject angle/degrees / p-value
5 / Right / 82.6 +/- 2.97 / 90.0 +/- 4.08 / 0.032
5 / Left / 83.2 +/- 2.88 / 90.9 +/- 3.33 / 0.014
10 / Right / 84.2 +/- 2.93 / 94.1 +/- 3.17 / 0.005
10 / Left / 85.3 +/- 3.09 / 92.8 +/- 5.12 / 0.058
15 / Right / 85.7 +/- 3.16 / 94.5 +/- 4.36 / 0.024
15 / Left / 85.8 +/- 2.69 / 96 +/- 4.97 / 0.024