Ethical approval

This case-series study was written according to the PROCESS guidelines to improve the quality of scientific reports [24]. It was based on the consultation of patients’ records from the Clinics Hospital of the University outpatient clinic for mouth breathers and academic hospital-based services for children with mouth breathing disorders. Mouth-breathing children ranging from 0 to 12 years old are accepted at this service. As this is a retrospective case series report, a priori sample size calculation was not performed.

The study was approved by the Institutional Ethics Committee (CAAE 43321914.2.0000.5149) and was registered at National Clinical Trials (RBR-3sq5hv). All patients and their parents signed informed consent before treatment. The institution is an academic referral center for patients with mouth breathing in a state with 21 million citizens. It is a federal institution run with public governmental funds. One thousand and two patients referred by pediatricians due to mouth breathing problems were screened and treated by a multidisciplinary team between 2012 and 2020. From this vast universe, it was found 15 obstructive sleep apnea children (7 females; 8 males), ages 4.1 to 8.9 years old (mean age of 5.4 years ± 1.3), who presented indications of tonsillectomy and/or adenoidectomy, and attended the inclusion and exclusion criteria described below.

Inclusion criteria

The inclusion criteria were: (a) children under ten years old; (b) OSA diagnosed with polysomnography; (c) Brodsky’s grades 3 or 4 for palatine tonsils obstruction [25]; (d) adenoid hypertrophy greater than 75% diagnosed with flexible nasopharyngolaryngoscopy [26]; (e) indication of T&A; and (f) pre-treatment and follow-up records of CT scans, polysomnography, Doppler echocardiography, and rhinomanometry.

Exclusion criteria

The exclusion criteria included: (a) genetic syndromes and neuromuscular disease; (b) perforation of the nasal septum; (c) pulmonary hypertension due to heart disease; (d) the previous history of adenotonsillectomy; (e) corticosteroids, nasal decongestants or antihistamines; (f) previous orthodontic treatment; (g) presence of any craniofacial disorder; and (h) presence of central apnea.


Eleven patients had been submitted to T&A. Four patients with the indication for the surgical approach of the impaired airways did not receive T&A because authorization from the municipality public health system was not given due to financial problems.

The complete baseline examination (T0) was carried out following the clinical screening consultation with the otorhinolaryngologist. T&A was performed within three months after the first consultation. A second complete examination (T1) was made 18.7 months follow-up after T&A (ranging from 12 to 30 months) in surgical individuals. In non-surgical individuals, T1 exams were collected following the governmental authorization for the surgical intervention, 18 to 24 months post T0. According to the protocol of the outpatient clinic for OSA patients, Doppler echocardiography, polysomnography, rhinomanometry, and computed tomography imaging were performed at (T0) and (T1).


The Doppler echocardiography with color flow mapping was performed with a Philips IE33 device (Philips Healthcare, Amsterdam, Holland). The same pediatric echocardiographer, unaware of the patient’s medical history, performed the examination. The PASP was calculated by using the Bernoulli formula. The upper limit of PASP was considered to be 30 mmHg (Guidelines of the American Heart Association and American Thoracic Society, 2015).

The polysomnography was done with a computerized infant sleep recorder (Alice Recording System 5, Respironics, GA, USA) according to the protocol recommended by the American Academy of Sleep Medicine (AAMS 2014) [27]. An experienced sleep doctor staged the records. Pediatric OSAS is classified as normal (OAHI < 1), mild (OAHI between 1 and 5), moderate (OAHI between 5 and 10), and severe (OAHI ≥ 10), according to the International Classification of Disorders CIDS-3 (2014). The criterion adopted in the current investigation to define obstructive sleep apnea was OAHI > 1 event/hour. The mean minimum saturation (%SpO2) was calculated.

Rhinomanometry was performed with SRE 2000 N 010000300189 RHINOSCAN 0272CFB2 from RHINOSTREAM 03CC5C3. A single senior otorhinolaryngologist conducted the exams. The nasal inspiratory flow values were measured in the left nostril at a transnasal pressure of 150 Pa. The same radiology technician performed multislice computed tomography scanning (MSTC) using Scanner multislice 128 (Somatom, Siemens, Erlangen, Germany), with a tube tension of 120 kV, 240 mA, and 1.57 seconds of exposure time. The patients were laid down in the supine position during the scan process, which better represents the position of the patients during sleep [28].

CT’s image analysis

Using the CT scans, the volumetric measurements of the nasal cavity, nasopharynx, and oropharynx were taken by the same orthodontist, using 11.7 Dolphin Imaging software (Dolphin Imaging & Management Solutions, Chatsworth, CA), according to Bertoz et al. [29]. CT scans had improved diagnosis ability and the capacity to measure airway volume and precisely observe upper airway structures [30]. Three-dimensional morphological assessments of the maxilla and mandible were carried out using two open-source software by an experienced orthodontist (ITK-SNAP, and 3D SLICER, Head orientation of the scans in the same Cartesian system was performed as described elsewhere [31].

T1 scan was manually approximated to T0 (best-fit) in the multiplanar views. Then a fully automated voxel-based registration was performed using the anterior cranial base for total superimposition [32] and the body of the mandible for regional superimposition [33]. Four maxillary and two mandibular landmarks were located simultaneously in the sagittal, coronal, and axial views (Fig. 1). The landmarks were as follows:

  1. 1)

    Anterior nasal spine (ANS) (Fig. 1A);

  2. 2)

    Posterior nasal spine (PNS) (Fig. 1A);

  3. 3)

    Palatal point (PP): mid-palatal point below the nasal septum (Fig. 1B e 1C);

  4. 4)

    Condylion (Co) (Fig. 1D);

  5. 5)

    Alveolar point (AL): the most inferior point of the alveolar process of the palatal surface of the second deciduous molar, on the right and left sides (Fig. 1E);

  6. 6)

    Menton (Me) (Fig. 1F).

Fig. 1
figure 1

Volumetric anatomical landmarks of the nasal cavity, nasopharynx, and oropharynx volume in axial, coronal, and sagittal views

The assessment of the displacement of the landmarks between T0 and T1 was carried out, taking into account the projected linear displacement of landmarks calculated in the X (right-left), Y (anterior–posterior), and Z (superior-inferior) planes; and also the Euclidean 3D displacements. The angular changes of three constructed planes were estimated as pitch (rotation over the X-axis), roll (rotation over the Y-axis), and yaw (rotation over the Z-axis). The following measurements were assessed: (a) palatal angle: the angle formed by PP and AL; (b) palatal point displacement: displacement of PP; (c) palatal length: Euclidean distance between ANS and PNS; (d) menton–condylion length: distance between Co and Me.

Three-dimensional virtual models were visually analyzed with color maps generated from the superimposition of T0 and T1 models. No displacements between models were indicated with green. Outward displacements from T0 to T1 were shown in hot colors (red/yellow), while inward displacements were shown in cold colors (dark/light blue) (Fig. 2).

Fig. 2
figure 2

Color maps of virtual models superimpositions

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