Role of the Frontal Sinus as a Functional Matrix in Cranio-facial Growth

Craniofacial growth is believed to be a multifactorial process involving both genetic and epigenetic factors and how epigenetic functional matrices stimulate the transduction of regulatory signals. OBJECTIVES: This study assessed skeletal facial growth patterns as they related to the pneumatization of the frontal sinus, as a possible functional matrix for Class II growth stimulation. EXPERIMENTAL METHODS: Lateral cephalometric radiographs of 118 subjects, of which 62 had a Class I skeletal diagnosis and 56 a Class II, were measured. Skeletal diagnosis was established using the ANB angle so that an angle >4 degrees was diagnosed as Class II. An angle of 0-4 degrees was diagnosed as a Class I skeletal pattern. Sinus size was established using the SCION computer program (National Institute of Health) and accepted anatomical landmarks to measure the area of the frontal sinus from the scanned radiographs. Data were analyzed employing the two-sample test and analysis of covariance to determine the correlation between sinus size and skeletal malocclusion. RESULTS: With reasonable confidence, Class I subjects were shown to have a larger sinus size than Class II subjects (T value=1.85 and Probability Level=0.067). When controlling for changes in age, it was found that Class I subjects have a statistically significantly larger (Probability Level < 0.05) sinus size than Class II subjects (F ratio=5.11 and a Probability level=0.026). CONCLUSIONS: Unexpectedly, Class II skeletal patterns did not produce larger frontal sinus pneumatization, nor sinus enlargement with age. Pneumatization was more consistent with Class I skeletal patterns. Accordingly, the frontal sinus does not appear to be a functional matrix for Class II growth stimulation.