Thin-plate spline analysis of craniofacial morphology in subjects with adenoid or tonsillar hypertrophy.

AIM: To compare the skeletal features of subjects with adenoid hypertrophy (AG) with those of children with tonsillar hypertrophy (TG) using thin-plate spline (TPS) analysis. MATERIALS AND METHOD: Lateral cephalograms of 20 subjects (9 girls and 11 boys; mean age 8.4 ± 0.9 years) with AG and 20 subjects (10 girls and 10 boys; mean age 8.2 ± 1.1 years) with TG. The TPS software computed the average configurations of the craniofacial landmarks for all the subjects. Average configurations were subjected to a cross-sectional comparison between AG and TG. Statistical analysis of shape differences was performed by means of permutation tests with 1000 random permutations on Goodall F statistics. Statistical computations for centroid size analysis were performed with a computer software program and the differences in size in the two groups were tested by means of Mann-Whitney U-tests. RESULTS: There were statistically significant shape differences in facial configuration for the comparison between AG and TG (P = 0.034). AG showed an upward dislocation of the anterior region of the maxilla, a more downward/backward position of the anterior region of the mandibular body and an upward/backward displacement of the condylar region. Conversely TG showed a downward dislocation of the anterior region of the maxilla, a more upward/forward position of the anterior region of the mandibular body and a downward/forward displacement of the condylar region. Significant differences in size were found between the groups; centroid size was significantly greater in TG when compared with AG (P = 0.043). CONCLUSION: Subjects with AG exhibited features suggesting a more retrognathic mandible while those with TG showed features suggesting a more prognathic mandible.