10.59987/ads/2018.4.175-183
Objective: evaluate the correlation between skeletal changes in 2D dimensions and volume changes of the upper airways before and after rapid maxillary expansion (RME) therapy in children with obstructive sleep apnoea (OSA) by Cone Beam computed tomography (CBCT) and between volume of the upper airways and clinical data.
Methods: 23 children with OSA and malocclusion underwent CBCT scans with a Dentascan and 3D reconstruction program before (T0) and 4 months after (T1) RME. Patients underwent an ENT visit with auditory and respiratory tests, including a daytime sleepiness questionnaire, a 19-channel polysomnography, and an orthognatodontic examination.
Results: in all cases opening of the mid-palatal suture was demonstrated. Nasal osseous width, volume of the total upper airways, nasal cavity and nasopharynx and oropharynx increased significantly (P, .05), and enlarged nasopharyngeal volume was correlated to increased nasal width at the PNS plane (P, .05). Posterior suture, pterygoideus process, maxillary width and Nasal cross-sectional width (PNS) (W-PNS) have an excellent and statistically significant correlation coefficient with Total upper airway volume (V-TA) Nasal cavity volume (V-NC) (Nasopharyngeal airway volume (V-NPA) Oropharyngeal airway volume (V-OPA), while Anterior and middle suture have an excellent and statistically significant correlation coefficient only with Oropharyngeal airway volume (V-OPA).
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Annali di stomatologia
Computed tomography
Rapid maxillary expansion in OSA children: Cone Beam CT skeletal and nasomaxillary complex airway volume changes evaluation and correlation
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Original Article
2022-08-09
2022-08-09
2018-12-01
2023-12-04
175-183
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G. Mampieri
2018
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Department of Clinical Sciences and Translational Medicine, University Tor Vergata, Rome, Italy
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Rapid maxillary expansion in OSA children: Cone Beam CT skeletal and nasomaxillary complex airway volume changes evaluation and correlation
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                                                                                               Original article


Rapid maxillary expansion in OSA children:
Cone Beam CT skeletal and nasomaxillary complex
airway volume changes evaluation and correlation

Paola Pirelli*                                            Conclusion
Valeria Fiaschetti**
Aldo Giancotti*                                           Enlarged Posterior suture, pterygoideus process, maxil-
Roberta Condò*                                            lary width and Nasal cross-sectional width (PNS) showed
Gianluca Mampieri*                                        a direct correlation to increased airways volume, bring-
                                                          ing a functional improvement. The increase in volume
* Department of Clinical Sciences and Translational       of the nasal cavity and nasopharynx, with expansion of
   Medicine, University Tor Vergata, Rome, Italy          the nasal osseous width and maxillary width causing by
** Department of Biomedicine and Prevention, University   RME treatment had a positive effect on children affected
   Tor Vergata, Rome, Italy                               by chronic snoring and OSA. The results show that the
                                                          RME therapy can restore and improve a normal nasal
                                                          airflow with disappearance of obstructive sleep breath-
Corresponding author:                                     ing disorder.
Aldo Giancotti
Department of Clinical Sciences and Translational Medi-   Introduction
cine, University Tor Vergata, Rome, Italy
                                                          The Orthodontic treatment options in OSAS children
                                                          have emerged in the past decade for children with
Abstract                                                  OSAS (1-3). The nasomaxillary complex provides ante-
                                                          rior bony support for the upper airways, and orthodontic
Objective: evaluate the correlation between skeletal      treatment affects these structures, causing changes in
changes in 2D dimensions and volume changes of            the airways to some extent. RME can help to increase
the upper airways before and after rapid maxillary        nasopharyngeal and oropharyngeal space for children
expansion (RME) therapy in children with obstruc-         with upper jaw restriction. This means that orthodontists
tive sleep apnoea (OSA) by Cone Beam computed             have the responsibility to understand the physiology of
tomography (CBCT) and between volume of the up-           upper airways (2-3). Katyal et al (4) showed how children
per airways and clinical data.
                                                          with narrow dentoalveolar transverse width and reduced
Methods: 23 children with OSA and malocclusion
                                                          nasopharyngeal and oropharyngeal sagittal dimensions
underwent CBCT scans with a Dentascan and 3D
                                                          had a high risk for sleep-disordered breathing. Many
reconstruction program before (T0) and 4 months
                                                          studies have reported the influence of RME on the upper
after (T1) RME. Patients underwent an ENT visit with
                                                          airways, though the results were different due to various
auditory and respiratory tests, including a daytime
                                                          subjects and expansion methods (5).
sleepiness questionnaire, a 19-channel polysom-
                                                          Imaging 3D software programs have been extremely
nography, and an orthognatodontic examination.
                                                          useful in assessing the benefits of RME. In recent times
Results: in all cases opening of the mid-palatal su-
                                                          a three-dimensional method of investigation (3D-CT)
ture was demonstrated. Nasal osseous width, vol-
ume of the total upper airways, nasal cavity and na-      has been used to study the effects of RME treatment (6-
sopharynx and oropharynx increased significantly          8) using low dose protocol (9). The same author (9, 10)
(P, .05), and enlarged nasopharyngeal volume was          studied the treatment and post-treatment skeletal effects
correlated to increased nasal width at the PNS plane      of RME, using low dose CT in growing subjects.
(P, .05). Posterior suture, pterygoideus process,         The CBCT systems are operated at a lower patient dose
maxillary width and Nasal cross-sectional width           than the MDCT systems, which are used for wide ranges
(PNS) (W-PNS) have an excellent and statistically         of exposure protocols in dental clinics (11) and have
significant correlation coefficient with Total upper      become a standard technique for dentomaxillofacial CT
airway volume (V-TA) Nasal cavity volume (V-NC)           imaging (12-14).
(Nasopharyngeal airway volume (V-NPA) Oropha-             They have also proven vital for structural comparisons
ryngeal airway volume (V-OPA), while Anterior and         between pre and post-clinical treatment and for the
middle suture have an excellent and statistically sig-    evaluation of the morphological changes caused by
nificant correlation coefficient only with Oropharyn-     the treatment, because they improved the visualization
geal airway volume (V-OPA).                               of anatomical structures by rendering unnecessary the
                                                          superimposition of conventional radiographs (15). Fur-
Keywords: Rapid Maxillary Expansion, OSA chil-            thermore, these programs enhance the accuracy of re-
dren, Computed tomography.                                search findings, besides improving the effectiveness of

Annali di Stomatologia 2018; IX (4): 175-183                                                                          175
      Rapid maxillary expansion in OSA children

      any techniques applied, while facilitating the use of com-   The patients were scanned in orthostatic position with
      puter tools for 3D image manipulation, be it by itself or    the Frankfurt plane perpendicular to the floor, keeping the
      associated with other software (14, 15).                     teeth in centric occlusion and the tongue in the position
      The purpose of this study was to evaluate the correlation    at the end of swallowing (against the palate), breathing
      between skeletal changes in 2D dimensions and volume         smoothly, and no swallowing. The digital imaging and
      changes of the upper airways before and after rapid          communications in medicine (DICOM) data were import-
      maxillary expansion (RME) therapy in children with ob-       ed into Dolphin Imaging software (Chatsworth, CA, USA)
      structive sleep apnoea (OSA) by Cone Beam computed           and used for the measurements described. Volumetric
      tomography (CBCT) and between volume of the upper            measurements were carried out with the aid of Dolphin®
      airways and clinical data.                                   Imaging v. 11.7 software, using the “Airways Volume” tool,
                                                                   and density was set at 55 for all patients.
                                                                   The images were evaluated in three views (sagittal, coro-
      Materials and methods                                        nal and axial), thus delimiting the nasomaxillary complex,
      Subjects                                                     and then calculating the volume in cubic millimetres.
                                                                   Numerical evaluation of the various parameters was
      78 children were selected from a sample of 120 patients
                                                                   based on the identification and registration of a group of
      presenting malocclusion (45 boys and 33 girls) with the
                                                                   reference points, identified on the CT images reformat-
      average age of 8.5 years (range: 5-12 years) present-
                                                                   ted on different planes.
      ing oral breathing, snoring and OSA symptoms. Patients
                                                                   Before landmark identification, the three-dimensional
      presenting adeno-tonsillar hypertrophy and body mass
                                                                   volumetric images were oriented with the Dolphin imag-
      index more than 24 kg/m2 were excluded from this sam-
                                                                   ing software as follows: coronal plane (horizontal line
      ple. Furthermore, a subsequent selection excluding the
                                                                   through orbital bilaterally), sagittal plane (Frankfurt hori-
      younger population was made: in order to reduce the
                                                                   zontal), and axial plane (Crista galli to basion). The Dol-
      probabilistic effects of ionizing radiation ―the stochas-
                                                                   phin software allowed automatic volume calculation after
      tic radiation effect― children between 5 and 9 years of
                                                                   segmenting the area of interest by setting the threshold
      age were excluded. Moreover, only patients with a good
                                                                   value of 55.
      polysomnography were selected, and patients who did
                                                                   The material was measured twice by the same author,
      not undergo second CT control or who had image arti-
                                                                   with at least one week interval between T0 and T1.
      facts in the first or second control were excluded. At the
                                                                   The following parameters were measured in millimetres:
      end of the screening the selected sample for the study
                                                                   (1) Suture opening was measured at three levels on the
      consisted of 23 patients with mixed dentition, an aver-
                                                                       axial plane: anterior edge, middle and posterior na-
      age age of 10.5 years (range 9 e12 years), an average
                                                                       sal spine. At T0 the measurement of the midpalatal
      apnoea/hypopnea index (AHI0) of 14.1 (±2.4), and an
                                                                       suture at three different levels was considered equal
      average minimum oxygen saturation of 75.8 (±8.3) %.
                                                                       to 0 in order to level the different values before RME
      Selection criteria included: malocclusion with upper jaw
                                                                       treatment that were in the range of 0-0.3.
      contraction, oral breathing, snoring and OSA symptoms
                                                                   (2) Maxillary base width was calculated on the axial
      (documented by polysomnography), no adenotonsillar
                                                                       plane between the vestibular border of buccal corti-
      hypertrophy, body mass index less than 24kg/m2.
                                                                       cal plate (left and right respectively). The points were
      Patients underwent an ENT visit with auditory and respira-
                                                                       joined using a line tangent to the dental root of the
      tory tests, including a daytime sleepiness questionnaire,
                                                                       first molar.
      a 19-channel polysomnography, an orthognatodontic ex-
                                                                   (3) The distance between the apices of the pterygoid
      amination and CB CT scans with a Dentascan and 3D
                                                                       processes (left and right) was calculated on the axial
      reconstruction program, before (T0) and 4 months after
                                                                       plane.
      (T1) RME. All the clinical investigations were carried out
                                                                   (4) Nasal cross-sectional (ANS) height (H-ANS): The
      before orthodontic therapy (T0), after 2 months (T1) with
                                                                       height of nasal cavity at the cross-section passing
      the device still on, and 4 months after the end of the
                                                                       through ANS on Coronal plane reconstruction.
      orthodontic treatment (T2).
                                                                   (5) Nasal cross-sectional (ANS) width (W-ANS): The
      This study was approved by Ethical Committee and
                                                                       greatest width of nasal cavity at the cross-section
      the informed consent was obtained from the parents or
                                                                       passing through ANS on coronal plane reconstruction.
      guardians of all patients.
                                                                   (6) Nasal cross-sectional height (midpoint) (H-mid): The
      Specific evaluations were made regarding the following
                                                                       height of nasal cavity at the cross-section passing
      parameters: maxillary suture width at anterior, middle
                                                                       though the midpoint between ANS and PNS on coro-
      and posterior level; nasal width; right and left molar an-
                                                                       nal plane reconstruction. (Fig. 1)
      gulation and pterygoid processes distance. Vertical and
                                                                   (7) Nasal cross-sectional width (midpoint) (W-mid): The
      horizontal dimensions and volume of the nasal cavity,
                                                                       greatest width of nasal cavity at the cross-section
      nasopharyngeal, oropharyngeal and the total pharynge-
                                                                       passing through the midpoint between ANS and PNS
      al airway volume were compared before and after RME.
                                                                       on coronal plane reconstruction. (Fig. 1)
      Correlations between changed volume and dimensions
                                                                   (8) Nasal cross-sectional height (PNS) (H-PNS): The
      were explored.
                                                                       height of nasal cavity at the cross-section passing
                                                                       through PNS on coronal plane reconstruction.
      Data collection                                              (9) Nasal cross-sectional width (PNS) (W-PNS): The
      CBCT scans examinations (Newtom 5GXL) were per-                  greatest width of nasal cavity at the cross-section
      formed before expansion (T0) and after 4 months’ reten-          passing through ANS on coronal plane reconstruction.
      tion (T1) by the same operator.                              The cavity volume was measured in mm3 by 3D images

176                                                                                   Annali di Stomatologia 2018; IX (4): 175-183
P. Pirelli et al.




             Figure 1.


(1) Nasal cavity volume (V-NC) bound by lines connect-         Results
     ing the anterior nasal spine (ANS) to the tip of the
     nasal bone, then to nasion (N), then to sella (S), then   The table 1 summarizes the results.
     to posterior nasal spine (PNS).                           In all the 23 cases, an opening of the midpalatal suture
(2) Nasopharyngeal airways volume (V-NPA): The line            was obtained, with resulting effects at different levels.
     passing through PNS and S is its anterior border, the
     line parallel to the Frankfurt horizontal plane (FHP)     Midpalatal suture
     passing through PNS point is the inferior border,         In all cases we obtained the opening of the midpalatal
     pharyngeal posterior wall is the posterior border.        suture. The increase at the anterior level of the suture
(3) Oropharyngeal airways volume (V-OPA): The line             showed an average opening of 4.1 mm. This increase is
     parallel to FHP passing through the tip of the uvula      evident with the appearance of an interincisive space,
     is the inferior border pharyngeal anterior wall is the    the hallmark of the midpalatal suture opening that was
     anterior border and pharyngeal posterior wall is the      always present in all cases; 3.1 mm at the medium level
     posterior border.                                         of the suture; 1.95 at the posterior level of the suture.
(4) Total upper airway volume (V-TA): The line passing         (Fig. 2)
     through PNS and S is its anterior border, the top of
     the epiglottis is its inferior border, pharyngeal ante-
                                                               Maxillary width
     rior wall is the anterior border and pharyngeal poste-
     rior wall is the posterior border added to nasal cavity   RME therapy is responsible for the expansion of the
     volume (V-NC).                                            maxilla with an average cross-sectional increase of
Rhinomanometric and polysomnography was performed              3.5 mm. There were individual variations, although all
before, after 2 and 4 months from RME.                         values showed clear differences between T0 and T1,
The following parameters of the polysomnography test           indicating that, in all patients, the manoeuvre had an
were evaluated: Obstructive AHI Range, Nadir SPO2              expansive effect.
(%), Duration of Longest Obstructive Apneas, Duration
of Desaturation (S302<92%) ass% TST and Sleep Ef-              Pterygoid processes
ficiency (%).
                                                               From the study of the pterygoid processes distance, we
Statistical Analysis                                           found an average increase of 2.6 m.
                                                               W-ANS, W-mid, W-PNS, H-ANS, H-PNS and H-mid
The normality of the data was evaluated using the Shap-        We found an average increase respectively of 6.3mm,
iro-Wilk test. Measurements for each patient before and        2.43mm, 3.1mm, 3.9mm, 0.5mm and 1.7mm.
after treatment were compared with Wilcoxon’s paired           In summary, the midpalatal suture was opened in all pa-
matched test. Values are expressed as mean ± standard          tients. A statistically significant difference was observed
deviation. As a threshold of statistical significance, a       between the measurements of the maxillary, nasal cavi-
value of p _ 0.05 was used.                                    ties, and pterygoid processes distance width, performed
The Spearman coefficient, ⍴, was calculated for inter-         before and after treatment.
relationships between 2D and 3D measures.                      W-ANS, W-mid, W-PNS, showed a significant increase,
The statistical treatment of the data was performed with       while H-ANS, H-PNS and H-mid showed a non-statisti-
the Statistical Package for the Social Sciences (SPSS),        cally significant increase.
version 22 for Windows.
Annali di Stomatologia 2018; IX (4): 175-183                                                                                 177
      Rapid maxillary expansion in OSA children

      Table 1. Changes in the Volumes and Dimensions of the Upper Airway and Changes of Skeletal Widths Before (T0) and
      After (T1) Rapid Maxillary Expansion.
                    Parameters             T0 Mean (SD)        T1 Mean (SD)     (T1-T0) Mean (SD)             P value*

                  Anterior suture                    0             4,1                  4,1                    <.001*
                   Middle suture                     0             3,1                  3,1                    <.001*
                  Posterior suture                   0             1,95                 3,1                    <.001*
           Pterygoideus processes                  51,7            54,3                 2,6                    <.001*
                  Maxillary width                  51,6            55,1                 2,6                     .021*
          Total upper airway volume
                                             60.8 (11.5)        70.3 (11.5)           9.4 (5.4)                 .012*
                    (V-TA)
         Nasal cavity volume (V-NC)           32.3 (6.1)        39.5 (6.3)            7.2 (6.3)                 .014*
       Nasopharyngeal airway volume
                                              8.8 (4.2)         10.8 (4.1)            2.0 (4.3)                 .003*
                 (V-NPA)
        Oropharyngeal airway volume
                                             11.37 (2.4)        14.94 (2.9)          3.57 (5.1)                 .004*
                 (V-OPA)
        Nasal cross-sectional height
                                              24.8 (6.3)        28.7 (6.5)            3.9 (6.1)                 .062*
               (ANS) (H-ANS)
         Nasal cross-sectional width
                                              15.4 (6.2)        21.7 (6.4)            6.3 (6.3)                 .008*
               (ANS) (W-ANS)
        Nasal cross-sectional height
                                              29.2 (2.1)        30.9 (2.2)            1.7 (2.3)                 .082*
            (midpoint) (H-mid)
         Nasal cross-sectional width
                                                  29.7 (2)       31.5 (2)              1.8 (2)                  .006*
             (midpoint) (W-mid)
        Nasal cross-sectional height
                                              19.4 (2.4)        19.9 (2.6)            0.5 (2.2)                 .078*
               (PNS) (H-PNS)
         Nasal cross-sectional width
                                              20.7 (4.4)        23.8 (4.7)            3.1 (4.2)                <.001*
               (PNS) (W-PNS)




      Figure 2.


      The increased V-NPA was closely linked to the enlarged      mm3 with a standard deviation of 6,3mm3, the mean na-
      W-PNS.                                                      sopharynx volume was 10.8 mm3 (DS = 4.1 mm3), the
      At T0 the mean total upper airways volume was 60.8          mean oropharynx volume was 14.9 mm3, with a standard
      mm3 (SD = 11,5 mm3), the mean nasal volume was 32.3         deviation of 2.9mm3.
      mm3 with a standard deviation of 6,1mm3, the mean na-       The study shows an increase T0/T1: the total upper air-
      sopharynx volume was 8.8 mm3 (DS = 4.2 mm3), the            ways volume of 9.4mm3 (SD = 5.4 mm3), the nasal vol-
      mean oropharynx volume was 11.3mm3, with a standard         ume of 7.2 mm3 with a standard deviation of 6,3mm3, the
      deviation of 2.4 mm3.                                       nasopharynx volume of 2.0 mm3 (DS = 4.3 mm3), the
      At T1 the mean total upper airways volume was 70.3          oropharynx volume of 3.5 mm3, with a standard devia-
      mm3 (SD = 11,5 mm3), the mean nasal volume was 39.5         tion of 5.1mm3.

178                                                                                Annali di Stomatologia 2018; IX (4): 175-183
P. Pirelli et al.




Figure 3.

The results confirmed the evidence obtained in the de-               tal upper airway volume (V-TA) (respectively p .014,.023,
scriptive analyses, meaning that the increase in total up-           .033, .038; ρ.84,.87,.78,.78), Nasal cavity volume (V-NC)
per airways volume (p < 0.05), nasal volume (p < 0.05),              (respectively p .018,.027, .034, .032; ρ.82,.86,.81,.87),
nasopharynx volume (p < 0.05) and oropharynx (p <                    Nasopharyngeal airway volume (V-NPA) (respectively p
0.05), were statistically significant. (Fig. 3)                      .018,.038, .036, .031; ρ.89,.88,.82,.91), and Oropharyn-
Enlarged nasopharyngeal volume was correlated to in-                 geal airway volume (V-OPA) (respectively p .021,.042,
creased nasal width at the PNS plane (P, .05). Posterior             .039, .039; ρ.87,.89,.81,.72). While Anterior and middle
suture, pterygoideus process, maxillary width and Nasal              suture have an excellent and statistically significant corre-
cross-sectional width (PNS) (W-PNS) have an excellent                lation coefficient only with Oropharyngeal airway volume
and statistically significant correlation coefficient with To-       (V-OPA) (respectively p .047,.031; ρ.78,.75). (Table 2)

Table 2. Correlation Coefficient Between Significant Changes of Upper Airway Volume and Other Variables.
                                             Total upper                              Nasopharyngeal          Oropharyngeal
                                                                  Nasal cavity
            PARAMETERS                     airway volume                               airway volume          airway volume
                                                                 volume (V-NC)
                                               (V-TA)                                      (V-NPA)               (V-OPA)
                                               p value*    ρ      p value*    ρ         p value*     ρ         p value*     ρ

            Anterior suture                    0.676      .37    0.721       .42        0.684      .43         0.047       .78

             Middle suture                     0.564      .46    0.642       .41        0.691      .38         0.031       .75

            Posterior suture                   0.014      .84    0.018       .82        0.018      .89         0.021       .87

      Pterygoideus processes                   0.023      .87    0.027       .86        0.038      .88         0.042       .89

            Maxillary width                    0.033      .78    0.034       .81        0.036      .82         0.039       .81
   Nasal cross-sectional height
                                               0.326      .24    0.289       .27        0.295      .31         0.542       .12
          (ANS) (H-ANS)
    Nasal cross-sectional width
                                               0.321      .52    0.332       .58        0.298      .57         0.284       .52
          (ANS) (W-ANS)
   Nasal cross-sectional height
                                               0.415      .26    0.435       .22        0.447      .21         0.479       .14
       (midpoint) (H-mid)
    Nasal cross-sectional width
                                               0.124      .54    0.147       .57        0.165      .58         0.197        .56
        (midpoint) (W-mid)
   Nasal cross-sectional height
                                               0.235      .25    0.224       .22        0.264      .24         0.297       .18
          (PNS) (H-PNS)
    Nasal cross-sectional width
                                               0.038      .78    0.032       .87        0.031      .91         0.039       .72
          (PNS) (W-PNS)

* Represents a significant correlation, P, .05.

Annali di Stomatologia 2018; IX (4): 175-183                                                                                         179
      Rapid maxillary expansion in OSA children

      Table 3. Polysomnographic data. Note the significant improvement in all the functional parameters achieved at T2. All
      data are displayed as mean _ standard deviation. Abbreviations: TST, total sleep time; T0, before any orthodontic ther-
      apy; T1, after 4 weeks with the device; T2, 4 months after the end of the orthodontic treatment.
                                                             T0                       T1                           T2
                                                     Range 6.1-22.4             Range 0-9.1                 Range 0-26
                OBSTRUCTIVE AHI
                                                    Averange 16.3 2.5         Averange 8.3 2.3            Averange 0.8 1.3
                   Nadir SPo2 (%)                        77.9 ± 8.4               90.2 ± 5.7                  95.4 ± 1.4
                Duration of longest
                                                        39.8 ± 17.2              24.3 ± 12.3                  12.1 ± 6.5
                obstructive apneas
             Duration of desaturation
                                                         18.5 ± 3.2                5.8 ± 1.3                   1.3 ± 1.4
             (S302 < 92%) ASS % TST
                Sleep efficiency (%)                     88.5 ± 9.1               88.9 ± 5.7                  89.8 ± 8.5




      These CBCT changes were associated with changes in              CT), has been used to study the effects of RME treat-
      PSG findings with an AHI ¼ 0.5 (±1.3) and lowest satura-        ment (19) and imaging software programs have been ex-
      tion ¼ 96.1 (±1.8) %.                                           tremely useful in assessing the benefits of RME (20, 21).
      The Table 3 shows polysomnography data in terms of              Respiratory problems associated with transverse maxil-
      average of obstructive AHI Range, Nadir SPO2 (%), Du-           lary deficiency have been widely discussed by orthodon-
      ration of Longest Obstructive Apneas, Duration of De-           tists and otolaryngologists, given the relation between
      saturation (S302<92%) ass% TST and Sleep Efficiency             causes, effects and treatment.
      (%) at T0, after 2 and 4 months from RME.                       RME anchored on teeth is performed more and more
      Polysomnography presents a normalization of recording           in young children with OSA, as the presence of an ab-
      in the AHI in all patients at the end of 4 months.              normal narrow palate is frequently noted with or without
      The baseline rhinomanometric data showed a statisti-            enlarged adenotonsils (22), particularly after the dem-
      cally significant difference between those measured at 2        onstration of incomplete results of tonsillectomy and ad-
      and 4 months (Wilcoxon Z 5–4.86, P5 .000; Wilcoxon Z            enoidectomy (T&A) surgery and reoccurrence of abnor-
      5 –5.39, P 5 .000, respectively). The difference between        mal breathing during sleep post T&A (23, 24).
      rhinomanometric data at 2 and 4 months was also statis-         Today, rapid maxillary expansion is regarded as an im-
      tically significant (Wilcoxon Z 5 –4.86, P 5 .000).             portant method to correct maxillary deficiency and this
      The difference between baseline AHI and that at 2 and 4         technique has been validated by many other authors
      months was statistically significant (Wilcoxon Z 5 –4.0, P      as it makes the splitting of the midpalatal suture pos-
      5 .000; Wilcoxon Z 5 –5.15, P 5 .000, respectively).            sible while producing certain changes in the nasal cavity,
      The difference between AHI at 2 and 4 months was also           which improves breathing (25-27).
      statistically significant (Wilcoxon Z 5 –2.0, P 5 .046).        Increases in nasal width and height, and changes in
      Four months after the end of the orthodontic treatment          nasal volume between pre and post-RME, assessed by
      (T2), all tests showing a normalization of functional ex-       Cone Beam computed tomography, have been observed
      aminations were confirmed.                                      by several authors (28, 29). This was also among the
                                                                      goals of this study, which were confirmed by the results.
      Discussion                                                      It is no doubt that an improved breathing pattern is
                                                                      an important clinical achievement, as observed in this
      A lot of studies have demonstrated the accuracy of the          study immediately following RME. Our patients showed
      CBCT and its low radiation dose on pediatric patients           an increase in nasal cavity volume after RME, with this
      (14-16). The need to reduce the radiation dose also             outcome being confirmed by an image manipulation pro-
      arose to fully adhere to both the Italian regulatory frame-     gram with 3D images, and by quantification of the mea-
      work and the European dosimetric levels, reported by            sured areas.
      the International Commission on Radiological Protec-            The same results were observed in all measures of the
      tion, for which the use of ionizing radiation in the health     nasomaxillary complex.
      field must be justified by the advantages that can derive       We found clear orofacial skeletal modifications related to
      from it. This meant that exposure had to be be kept as          RME, including the changes of the pterygoid processes
      low as reasonably possible, consistently with diagnos-          in our subjects.
      tic needs (17, 18) (a principle of primary importance in        Imaging is only a part of a sleep-disordered-breathing in-
      particular in the pediatric patients). Usage of 3D-CB CT        vestigation, and had to be integrated into the overall re-
      is not new when considering changes in upper-airways            sults, including those obtained during sleep with nocturnal
      morphology following RME. DiCarlo et al. (18) performed         polysomnography; but the 3D-CT provided valid informa-
      a systematic review for coherent protocols with CBCT to         tion on the skeletal changes obtained with treatment.
      measure airways dimensions and morphology. In recent            The results we obtained show that the RME therapy
      times a three-dimensional method of investigation (3D-          widens nasal fossa, thus restoring a normal nasal air-

180                                                                                     Annali di Stomatologia 2018; IX (4): 175-183
P. Pirelli et al.

flow with disappearance of obstructive sleep-disordered       polysomnography presented a normalization of record-
breathing.                                                    ing in the AHI in all patients at the end of the 4 months,
The improvement can be clearly linked to the skeletal         and the baseline rhinomanometric data showed a statis-
expansion caused by the manoeuvre performed on the            tically significant difference between those measured at
suture.                                                       2 and 4 months.
CBCT images before and after RME therapy confirm that         Several methods have been proposed to evaluate
the expansion occurs not only in the maxillary arch but       changes in respiratory efficiency as a result of RME.
also in the nasal cavity. This anatomic change brings         De Filippe et al (36), through the use of morphometric 3D
about an increased patency of the upper airways, re-          analysis and acoustic rhinometry, showed an increase in
storing normal airflow. This patency is the basis for the     cross sectional in the area of the nasal cavities, followed
positive effects induced by the manoeuvre, and it acts        by a 34% decrease in nasal resistances. In fact a follow-
on air exchange, with a net improvement of breathing          up to 60 months confirms the stability of the treatment.
disorders during sleep (30-32).                               Enoki et al (37) evaluated changes in respiratory func-
Increasing of upper jaw cross section also clearly affects    tion in 29 children through the use of three otolaryngol-
the nasal cavities, and it is a true anatomic change that     ogy examinations: nasofibroscopy, acoustic rhino-metria
brings about an increased patency of the upper airways.       and rhinomanometry, carried out before, immediately af-
This increase is also the basis for the positive effects      ter and 90 days after rapid expansion. Rhinonomanome-
induced by the RME manoeuvre on the respiratory func-         try showed a progressive decrease in resistance to both
tion. Associated orthodontic movements can also indi-         inhalation and extraction.
rectly improve the oropharyngeal space by modifying the       Iwasaki et al. (38) investigated the effects of RME on
resting posture of the tongue. (20)                           nasal respiratory flow in terms of pressure and speed in
Several (33, 34) studies demonstrate an increase in the       22 subjects of average age of 9 years. Eighteen patients
volume of the upper airways as a result of lateral dis-       treated with RME benefitted from a 66.7% reduction in
placement of the walls of the nasal cavity, caused by the     nasal resistance and a 46.5% decrease in blood pres-
rapid expansion of the palate. Over the past decade the       sure. In 2015 Fastuca et al (39) evaluated respiratory re-
volumetric airways analysis with CBCT was investigated        sponse following RME on 15 subjects (average age 7.5)
as well as the effects of RME on respiratory function.        and observed a significant correlation between respira-
In our series volume of the total upper airways, the nasal    tory volume and blood oxygen saturation level (spO2).
cavity, the nasopharynx and the oropharynx showed sig-        These results correlate the expansion of the jaw to an
nificant increases, consistent with some previous studies     increase in the diameter of the airways, a decrease in
(29-32). Kim et al (35) demonstrated that volume of the       respiratory resistance, and an improvement in the pa-
nasal cavity increased continuously from pre-expansion        tient’s respiratory pattern. Through polysomnography
to immediately after expansion, and to 1 year after ex-       (PSG) the same authors found an improvement in the
pansion. They reported that nasopharyngeal volume             Apnea-Hypopnea Index (AHI) with a reduction in apneic
showed a significant increase 1 year after expansion,         episodes of 4.2 per hour.
compared with the initial volume.                             In the same year Ghoneima (40) showed how RME had
In addition, we found a correlation between increased         positive effects in terms of pressure reduction, speed
nasal osseous width at the PNS plane and expansion of         and airway resistance, and these changes were capable
nasopharyngeal volume: in fact the cross-sectional area       of changing the airflow pattern from turbulent to laminar.
of the upper airways at the PNS plane enlarged with the       All the effects on respiratory function mentioned above
increase of maxillary width. we also demonstrated in our      make RME the therapy of choice in the case of patients
study how enlarged nasopharyngeal volume was corre-           with OSAS without obvious upper airways obstructions.
lated to increased nasal width at the PNS plane (P, .05),     In fact, under physiological conditions, the nose contrib-
how posterior suture, pterygoideus process, maxillary         utes 50% of respiratory resistance, and RME is able to
width and Nasal cross-sectional width (PNS) (W-PNS)           significantly decrease these resistances (37).
was correlated to increased total upper airway volume         The authors suggest careful evaluation of the maxillary
(V-TA), Nasal cavity volume (V-NC), Nasopharyngeal            skeleton base status as a possible common cause of
airway volume (V-NPA) and Oropharyngeal airway vol-           OSAS and recommend resorting to RME therapy.
ume (V-OPA) , while Anterior and middle suture was            RME can improve nasal airflow, leading to better ventila-
correlated to increased Oropharyngeal airway volume           tory function through increased upper airways volume,
(V-OPA).                                                      so it could be a therapeutic option for nasal obstruction.
Referring to a previous study, the upper airways were         Orthodontists may play an important role in the interdis-
divided into more segments in this study, resulting in sig-   ciplinary treatment of OSAS because a high percentage
nificant changes in all its parts.                            of patients with OSAS suffer from maxillary narrowness.
Kim et al (35) also showed no changes in volumes of the       The authors’ experience shows that RME treatment has
inferior section of the upper airways and MCA, in accor-      a positive effect on children affected by chronic snoring
dance with the data reported in the literature.               and OSA (41, 42). By changing the anatomic structures,
Many studies agree that the expansion of the nasal cav-       RME brings a functional improvement. It is always im-
ity and the increased distance between the side walls         portant to assess the condition of the upper jaw to con-
and the septum caused a reduction in air resistance (36-      sider RME therapy in the multidisciplinary treatment of
40), facilitating physiological breathing. In our series,     OSAS in children.

Annali di Stomatologia 2018; IX (4): 175-183                                                                                181
      Rapid maxillary expansion in OSA children

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Annali di Stomatologia 2018; IX (4): 175-183                                                                                            183
