Morphometric growth changes of the nasopharyngeal space in subjects with different vertical craniofacial features Jong Eon (Ernie) Park, a Sophie Gray, b Hamza Bennani, c Joseph S. Antoun, d and Mauro Farella e Dunedin, New Zealand Introduction: The purpose of this study was to morphometrically investigate the growth pattern of the adenoids in growing subjects with hyperdivergent and hypodivergent vertical craniofacial features. Methods: In this retro- spective study, we used a longitudinal sample of lateral cephalometric radiographs of 28 hyperdivergent and 30 hypodivergent subjects from 4 to 13 years of age. The radiographs were obtained from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection. Measurements were made using digital tracings of the lateral cephalograms and point distribution models. Mixed-model analyses were used for statistical analysis. Results: The mean distance between the sphenoid bone and the posterior nasal spine increased up to 5.3 mm over a 9-year span (95% CI, 4.1-6.5 mm; P \0.001). Furthermore, the mean distance between the sphenoid bone and the posterior nasal spine differed significantly (P 5 0.029) between facial types; it was consistently greater (1.8 mm; 95% CI, 0.2-3.3 mm) in the hyperdivergent group. The nasopharyngeal airway area showed a trend to increase with age up to 12-fold (P \0.001). A significant interaction (P 5 0.004) was found between age and facial type. Assessment of the adenoid shapes showed greater convexities in the hyperdivergent group, which were observable from an earlier age and for a longer duration. Conclusions: Clear differences in the morphometric growth pattern of the adenoids were found between facial types. Evaluation of adenoid shapes showed more prominent convexities that lasted longer in the long facial types than in the short facial types. (Am J Orthod Dentofacial Orthop 2016;150:451-8) H ypertrophic adenoids have been shown to be a significant risk factor for pediatric sleep breathing disorders, such as obstructive sleep apnea (OSA). 1-4 Several studies have shown that restriction of the upper airways caused by enlarged adenoids, and hence mouth breathing, may also be directly linked to specific craniofacial morphologies such as the long face syndrome. 5-8 A study conducted on monkeys, where varying degrees of nasal respiratory obstruction were simulated, further supported these findings. 9 Although variations exist, the typical characteristics of this long facial morphology include increased anterior facial height, incompetent lips, steep mandibular plane angle, anterior open bite, and retrognathic mandible. 4-7,10 The term “long face syndrome” encompasses a variety of facial types with specific clinical and cephalometric features including the so-called adenoid face 10 that has been asso- ciated with mouth breathing and OSA. 7 Although various theories have been postulated on how nasopharyngeal re- striction alters craniofacial morphology, this is still a mat- ter of debate. It is unclear whether alterations in the facial skeleton predispose a person to OSA, or whether these alterations are caused by OSA. 7 Results from investigations into the growth pattern of the adenoid tissues have also been somewhat contro- versial. Several findings from the early to mid-20th cen- tury, including Scammon's curves of systematic growth, have demonstrated that lymphatic tissues undergo rapid growth from infancy until a peak about 10 to 13 years of age. 8,11-13 Subsequent regression in maturity follows. On the contrary, research in this field in later years generally proposed a different pattern of growth where From the University of Otago, Dunedin, New Zealand. a Research fellow, Discipline of Orthodontics, Faculty of Dentistry. b Professional practice fellow, Discipline of Orthodontics, Faculty of Dentistry. c PhD candidate, Department of Computer Science. d Senior lecturer, Discipline of Orthodontics, Faculty of Dentistry. e Professor and chair, Discipline of Orthodontics, Faculty of Dentistry. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Mauro Farella, Discipline of Orthodontics, Faculty of Dentistry, University of Otago, 310 Great King St, Dunedin 9016, New Zealand; e-mail, mauro.farella@otago.ac.nz. Submitted, March 2015; revised and accepted, February 2016. 0889-5406/$36.00 Copyright Ó 2016 by the American Association of Orthodontists. All rights reserved. http://dx.doi.org/10.1016/j.ajodo.2016.02.021 451 ORIGINAL ARTICLE