Imaging Sci Dent.  2012 Jun;42(2):83-88. 10.5624/isd.2012.42.2.83.

Does hyrax expansion therapy affect maxillary sinus volume? A cone-beam computed tomography report

• Darsey DM
• English JD
• Kau CH
• Ellis RK
• Akyalcin S

• KMID: 1974413
• DOI: http://doi.org/10.5624/isd.2012.42.2.83

Abstract

PURPOSE
The aim of this study was to investigate the initial effects of maxillary expansion therapy with Hyrax appliance and to evaluate the related changes in maxillary sinus volume.
MATERIALS AND METHODS
Thirty patients (20 females, 10 males; 13.8 years) requiring maxillary expansion therapy, as part of their comprehensive orthodontic treatment, were examined. Each patient had cone-beam computed tomography (CBCT) images taken before (T1) and after (T2) maxillary expansion therapy with a banded Hyrax appliance. Multiplanar slices were used to measure linear dimensions and palatal vault angle. Volumetric analysis was used to measure maxillary sinus volumes. Student t tests were used to compare the pre- and post-treatment measurements. Additionally, differences between two age groups were compared with Mann-Whitney U test. The level of significance was set at p=0.05.
RESULTS
Comparison of pre-treatment to post-treatment variables revealed significant changes in the transverse dimension related to both maxillary skeletal and dental structures and palatal vault angle, resulting in a widened palatal vault (p<0.05). Hard palate showed no significant movement in the vertical and anteroposterior planes. Nasal cavity width increased on a mean value of 0.93mm(SD=0.23, p<0.05). Maxillary sinus volume remained virtually stable. No significant age differences were observed in the sample.
CONCLUSION
Hyrax expansion therapy did not have a significant impact on maxillary sinus volume.

Keyword

Palatal Expansion Technique; Maxillary Sinus; Cone-Beam Computed Tomography

MeSH Terms

Cone-Beam Computed Tomography
Female
Humans
Hyraxes
Maxillary Sinus
Nasal Cavity
Palatal Expansion Technique
Palate, Hard

Figure

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  Fig. 1 A. Dental width measurements are carried out using both premolars and the canine. B. Palatal vault angle measurement is made at a point coronally at the palatal root of the first molars.

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  Fig. 2 The width of the incisive canal (A), the greater palatine foramen to contralateral greater palatine foramen distance (B), the infraorbital foramen to contralateral infraorbital foramen distance (C) are recorded on the axial images that are created perpendicular to the midsagittal plane for each of the anatomic landmark.

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  Fig. 3 A. Nasal cavity width is made on axial images. B. Boundary lines are drawn surrounding the sinus cavity in the axial, coronal, and sagittal views individually to help assist with the maxillary sinus volume measurement.

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