The Effects of Two Different Palatal Expanders on Nasal and Pharyngeal Airway Volumes as Measured by CBCT

Document Type : Original Article


1 BDS 2002 Ain Shams University- A resident in Master Degree program, Orthodontic Department, Faculty of dental medicine for girls, Al-Azhar University.

2 Assistant Professor, Orthodontic Department –Faculty of Dental Medicine for girls Al-Azhar University

3 Professor of ENT, Head of ENT Department –Faculty of Medicine for girls- Al-Azhar University


Objective: To evaluate and compare the effect of memory palatal split screw (Memorax) to that of conventional Hyrax rapid palatal expanders on nasal and pharyngeal airway volumes, which were measured and recorded by Cone beam computed tomography (CBCT). Materials and Methods: This study was conducted over 14 subjects of adolescent patients with bilaterally constricted maxillary arches, the sample contained 12 females and 2 males, with age ranged from 12ys to 15ys, with a mean of 13.6 ± 1.4. The sample was divided into two age matched groups, the Memorax group
(N=7) subjects with a mean age of 13.5 ± 0.4, received the memory palatal split screw appliance (Memorax). The Hyrax group (N=7) subjects with a mean of 13.4 ± 1 were received the conventional Hyrax palatal expander. For all subjects taking part in the study, maxillofacial CBCTs and NOSE questionnaire records were taken before expansion (T1) and after 3 months at the time of removal of the expanders (T2). Data were explored for normality using Kolmogorov-Smirnov test of normality. Paired t test was used to compare mean values of before and after treatment. Independent (unpaired) test
was used to compare between the two groups. Results: Memorax showed a significant increase in nasal airway volume as well as naso- , palato- and total pharyngeal airway volume. While Hyrax showed a non- significant decrease in the palatopharyngeal airway volume. Both groups showed a non- significant difference in the glossopharyngeal
airway volume as well as in the NOSE questionnaire results. Conclusion: Memorax could be used in patients suffered from symptomatic nasal obstruction due to bilateral maxillary constriction, in order to improve their breathing as a primary purpose as well as treating malocclusion. It also may be advantageous because it shortens the maxillary
expansion period, provides additional expansion in the retention period and generates light forces relative to the conventional Hyrax screw.