title: Effects of orthopedic maxillary expansion on nasal cavity size in growing subjects: a low dose computer tomography clinical trial.
abstract: OBJECTIVE
  The aim of this retrospective clinical trial was to evaluate the effects of rapid maxillary expansion on skeletal nasal cavity size in growing subjects by use of low dose computer tomography.
  
  
  METHODS
  Eight Caucasian children (three male; five female) with a mean age of 9.7 years (SD±1.41) were the final sample of this research that underwent palatal expansion as a first phase of orthodontic treatment. The maxillary expander was banded to the upper first molars and was activated according a rapid maxillary expansion protocol. Low-dose computer tomography examinations of maxilla and of the low portion of nasal cavity were performed before inserting the maxillary expander (T0) and at the end of retention (T1), 7 months later. A low-dose computer tomography protocol was applied during the exams. Image processing was achieved in 3 steps: reslicing; dental and skeletal measurements; skeletal nasal volume computing. A set of reproducible skeletal and dental landmarks were located in the coronal passing through the first upper right molar furcation. Using the landmarks, a set of transverse linear measurements were identified to estimate maximum nasal width and nasal floor width. To compute the nasal volume the lower portion of the nasal cavity was set as region of interest. Nasal volume was calculated using a set of coronal slices. In each coronal slice, the cortical bone of the nasal cavity was identified and selected with a segmentation technique. Dependent t-tests were used to evaluate changes due to expansion. For all tests, a significance level of P<0.05 was used.
  
  
  RESULTS
  Rapid maxillary expansion produced significant increases of linear transverse skeletal measurements, these increments were bigger in the lower portion of the nasal cavities: nasal floor width (+3.15 mm; SD ± 0.99), maximum nasal width (+2.47 mm; SD ± 0.99). Rapid maxillary expansion produced significant increment of the total nasal volume (+1.27 cm(3) ± SD 0.65). The anterior volume increase was 0.58 cm(3) while the posterior one was 0.69 cm(3).
  
  
  CONCLUSIONS
  In growing subjects RME is able to significantly enlarge the dimension of nasal cavity. The increment is bigger in the lower part of the nose and equally distributed between the anterior e the posterior part of the nasal cavity.
authors: Department of Orthodontics, University of Messina, Messina, Italy.
authors: Giancarlo
authors: G
authors: Cordasco
authors: Riccardo
authors: R
authors: Nucera
authors: Rosamaria
authors: R
authors: Fastuca
authors: Giovanni
authors: G
authors: Matarese
authors: Steven J
authors: SJ
authors: Lindauer
authors: Pietro
authors: P
authors: Leone
authors: Paolo
authors: P
authors: Manzo
authors: Roberto
authors: R
authors: Martina
mesh_terms: D002508:Cephalometry / Q000379:methods; D002648:Child; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging; D009295:Nasal Bone / Q000000981:diagnostic imaging*; D009296:Nasal Cavity / Q000000981:diagnostic imaging*; D010155:Palatal Expansion Technique; D011829:Radiation Dosage; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed