Craniofacial growth patterns in Crouzon and Apert syndromes: Is it the same?
Reitsma JH, Ongkosuwito EM, Buschang PH, Prahl-Andersen B. Facial growth in patients with Apert and Crouzon syndromes compared to normal children. Cleft Palate Craniofac J 2012;49:185-93
Crouzon and Apert syndromes are craniofacial anomalies characterized by premature fusion of the craniofacial sutures; this results in midface hypoplasia. It has been debated whether the craniofacial growth pattern in these syndromes is the same. In this study, the authors analyzed the craniofacial growth pattern in patients with Crouzon and Apert syndromes compared with a sample of unaffected normal control subjects. The lateral cephalograms of 62 patients (37 with Crouzon syndrome, 25 with Apert syndrome) and 482 unaffected control subjects were obtained. Clinical diagnoses of Apert or Crouzon syndrome in all 62 patients were genetically confirmed. The lateral cephalograms were traced, and 8 cephalometric measurements were digitized. Multilevel modeling was used to analyze growth changes and compare the 3 groups. The authors reported significant differences in the sagittal and vertical morphologies, with the syndromic groups showing increased lower facial height ratios, increased inclination of the palatal planes, retruded maxillas, and protruded mandibles compared with the control group. The Apert group had a more severe abnormal craniofacial morphology than did the Crouzon group, showing more retruded maxillas, increased palatal plane inclinations, and increased lower facial height ratios. These findings support previous reports indicating significant differences in sagittal and vertical growth patterns in patients with Crouzon and Apert syndromes, with a more abnormal craniofacial morphology in patients with Apert syndrome than in those with Crouzon syndrome. The midface hypoplasia in patients with Crouzon or Apert syndrome highlights that either conventional LeFort III surgery or midface distraction osteogenesis is most likely to be indicated in their management.
Reviewed by Humam Saltaji
Cone-beam computed tomography for third molar assessment
Ueda M, Nakamori K, Shiratori K, Igarashi T, Sasaki T, Anbo N, et al. Clinical significance of computed tomographic assessment and anatomic features of the inferior alveolar canal as risk factors for injury of the inferior alveolar nerve at third molar surgery. J Oral Maxillofac Surg 2012;70:514-20
When assessing for mandibular third molar extraction, risk factors such as stage of development, space, and proximity to the inferior alveolar nerve must be considered. Parasthesia from damage to the inferior alveolar nerve as a complication of third molar extraction has been reported with a frequency of 0.5% to 8%. A reliable predictor of parasthesia is the absence of cortication between the inferior alveolar canal to the mandibular third molars. With the availability of cone-beam computed tomography images in many orthodontic offices, the anatomy of the relationship between the inferior alveolar nerve and the mandibular third molar can be assessed in 3 dimensions instead of the usual 2 dimensions of a conventional panoramic radiograph. This was a retrospective cohort study with consecutive patients for evaluation and extraction of the mandibular third molars. All patients had panoramic radiographs, and those who had a questionable relationship between the inferior alveolar canal and the mandibular third molar received additional computed tomographic imaging. The position and the shape of the inferior alveolar canal as seen on the cone-beam computed tomography image were assessed by 3 examiners; when the assessments differed, resolution was via discussion. The sample consisted of 99 patients (39 men, 60 women; mean age, 31.8 years); their panoramic radiographs showed 145 mandibular third molars (71 right, 74 left). The authors recognized that the study population was small and that a larger population must be examined for multiple factors because of the low frequency of inferior alveolar nerve damage. Considering these limitations, they concluded that, when examining cone-beam computed tomography images, it is important to pay close attention to the absence of cortication between the inferior alveolar canal and the mandibular third molar as well as the shape of the inferior alveolar canal (dumbbell shape) near the mandibular third molar, since both are associated with a higher risk of parasthesia.
Reviewed by Justin Wong