Introduction: Sydromic craniosynostoses, Apert, Crouzon, 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 (Pruzansky, Kreiborg).  The purpose of this study was to document mandibular abnormalities and relationships as seen on the posterior-anterior cephalograms and to document changes due to growth.

Materials and Methods:  Fifteen patients with syndromic craniosynostoses (2 Apert, 11 Crouzon, 2 Pfeiffer) (4 male, 11 female) 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 findings (Basyouni, Nada. Atlas of Transverse Dimensions of the Face. 2000).

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.

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

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