Clinical recognition of mouth breathers by orthodontists: A preliminary study


A routine diagnosis of a patient’s breathing status performed by an orthodontist normally includes visual assessment, medical history, clinical examination of habitual lip posture, size and shape of the nostrils, reflex control of the alar muscle and respiratory tests, and the dental mirror test. The objective of this study was to test the recognition of mouth breathers in young persons by an orthodontist and agreement with an otolaryngologist’s reference diagnosis when routine assessments were carried out.


Three independent and blind evaluations were conducted on the same day by 2 orthodontists independently (anamnesis and breathing tests, respectively) and an otolaryngologist (rhinoscopy, nasal endoscopy, and visual assessment). The weighted kappa coefficient was used to test intraexaminer and interexaminer agreement. The frequencies of answers and findings were reported for each breathing status.


Fifty-five volunteers composed the sample of this study; 20 participants were nasal breathers, and 35 participants were classified as mouth breathers (and subdivided into mouth breathers with airway obstruction and mouth breathers by habit) by the otolaryngologist. The weighted kappa coefficient showed poor interrater agreement for most comparisons.


Recognition of mouth breathing in young persons by orthodontists is poor.


  • Regular allergic episodes should be considered in breathing pattern diagnosis.

  • Orthodontists were able to identify correctly most nasal breathers.

  • Orthodontists have poor methodology to define mouth breathers.

  • There is poor agreement among various ways of assessing breathing problems.

  • Subjects should be referred to an otolaryngologist when any sign is identified.

Nasal breathing promotes proper growth and development of the craniofacial and dentofacial complexes in accordance with the theory of the functional matrix of Moss and Salentijn. This theory is based on the principle that normal nasal respiratory activity influences and favors harmonious growth and development by adequately interacting with mastication and swallowing and other functions of the head and neck region.

Mouth breathing has a multifactorial etiology that may vary from an anatomic obstruction, such as palatine and pharyngeal tonsil hypertrophy, septal deviation, nasal polyps, nasal turbinate hypertrophy, allergic rhinitis, overweight, oral habits, and neuromuscular diseases, or indirectly from deleterious oral habits. In particular, allergic rhinitis, depending on its intensity, frequency, and duration, might lead to persistent mouth breathing and, consequently, deform the dental arch and alter facial harmony. The most common cause of mouth breathing is nasal obstruction, specifically adenoid hypertrophy, in the pediatric population.

Children with mouth breathing have a higher tendency for clockwise rotation of the growing mandible, with a disproportionate decrease in posterior facial height and an increase in anterior lower face height. The latter is often associated with a retrognathic mandible and an open bite. However, Harvold et al showed in a study with young growing rhesus monkeys that when a nasal obstruction or tonsil-like obstruction was almost completely blocking, a few dentofacial changes could be observed; this means that moderate obstructions do not necessarily lead to craniofacial alterations. Orthodontic treatment seeks to solve dentofacial and craniofacial alterations, and a multidisciplinary approach may be necessary, with participation of pediatric surgeons, otolaryngologists, allergists, and speech therapists.

The orthodontist may be the first health care professional to monitor the craniofacial growth and development time of childhood. Young patients should be referred to an otolaryngologist when signs or symptoms of mouth breathing are identified to improve their quality of life and prevent any adaptive dental and facial changes.

Alternative methods of airway evaluation associated with a multidisciplinary approach have been used, including nasal resistance tests or rhinomanometry, rhinoscopy, fluoroscopy, magnetic resonance imaging, nasal endoscopy, lateral cephalograms, and computed tomography scans.

Nasal endoscopy is the reference standard for assessing the nasopharynx by an otolaryngologist with a standardized grading system for the evaluation of airway obstruction. However, nasal findings may be restricted by septal deviation, size of adenoids and nasal turbinates hypertrophy, and nasal polyps and tumors, since the endoscope fiber optic may be blocked by these anatomic structures.

The diagnostic routine of the breathing status accomplished by an orthodontist normally includes visual assessment (97.2%), clinical medical history (87.2%), and clinical examination of habitual lip posture, size and shape of the nostrils, reflex control of the alar muscle, and respiratory tests (59%) such as the dental mirror test. Moreover, orthodontists’ ability to recognize a patient’s breathing status confirmed by an otolaryngologist’s diagnostic analysis has not been adequately documented.

The objective of this study was to compare the recognition of mouth breathers in young persons by the routine orthodontic assessment with an otolaryngologist using a clinical diagnostic assessment.

Material and methods

This cross-sectional blind comparative clinical study was approved by the research ethics committee of Universidade Federal Fluminense in Niterói, Rio de Janeiro, Brazil. Initially, this study involved 125 consecutive young patients from the Department of Orthodontics. Before the study started, participants and their parents or guardians were informed and signed a written consent form to participate in the research and to allow the use of their orthodontic records.

Eligibility criteria included (1) age from 10 to 25 years, (2) no recent surgery (in the prior 6 months), (3) no infections or inflammatory diseases in the airways at the time of examination, (4) no confirmed syndromes, (5) no neurologic disorders, (6) no facial anomalies, and (7) no previous orthodontic therapy. The participants were instructed to not use nasal spray on the day they were examined.

Three independent evaluations were conducted on the same day by 2 orthodontists (J.G.C., A.A.C-S.) and 1 otolaryngologist (G.S.C.). The orthodontist responsible for anamnesis, who had more than 20 years of clinical practice, administered a questionnaire to each participant and the parents or guardians (when necessary) about health problems, incidence of sinusitis or tonsillitis, use of medications, speech therapy, allergies, breathing problems, open mouth breathing, stuffy nose, sneezing frequency, snoring, dry mouth on awakening, suffocation or breathlessness, water drinking during the night, daytime sleepiness, use of nasal spray, physical activities, and deleterious habits ( Appendix 1 ).

Another orthodontist, responsible for the clinical examination, who had more than 10 years of clinical practice, assessed ( Appendix 2 ) the participant in the sitting position, with straight head and breathing normally. Two breathing tests were conducted: the first was an observation of nasal movement while the participant was breathing, and subsequently, the clinical mirror test was performed in which a mirror is positioned under each nostril for 30 seconds to observe fogging or condensation.

According to the evaluations, after the participants were assessed, they were classified as mouth breathers or nasal breathers by each orthodontist independently to isolate findings obtained from the anamnesis and clinical examinations and to check whether one of them contributed more to an ascertained recognition. Each orthodontist reached this definition for each patient based on his or her personal experience and on literature recommendations (in the case of clinical examination).

The otolaryngologist, who had more than 25 years of clinical practice, then examined the participants clinically, in the upright rest position without exercise. Initially they were examined with rhinoscopy to diagnose obstructions or alterations in the nasal cavity space, such as septum deviation and nasal turbinates hypertrophy. The tonsils were observed with and without a tongue depressor. A topical decongestant spray (0.05% xymetazoline) was administered to each participant; immediately after that, a topical anesthetic spray (2% xylocaine) was applied into each nostril. The participants were oriented to aspire solutions to improve absorption and achieve greater comfort during nasal endoscopy. The nasal endoscopy was performed using a rigid fiberoptic 30° endoscope, and digital images of the nasal cavity and its adjacent structures up to the cavum were captured and recorded during the examination. Immediately after the examination, clinical records were completed ( Appendix 3 ), and some characteristics were included, such as the amplitude of the adenoids, nasal turbinates and palatine tonsils, the classification of Mallampati et al, nasal septum position, and Cottle’s classification. Each participant’s body mass index was calculated and registered.

After the nasal endoscopy, alterations of nasal turbinates were evaluated once again under the effect of the topical decongestant and the anesthetic to verify the behavior of these tissues. When there was a decrease of nasal turbinates, it indicated that the obstructions were temporary due to a mucous-vascular component of resistance, such as turbinates hypertrophy, and it was probably a consequence of unknown allergic processes.

The severity of adenoid obstruction was evaluated through nasal endoscopy in the following way: grade 1, less than 25% obstruction; grade 2, 25% to 50% obstruction; grade 3, 50% to 75% obstruction; and grade 4, more than 75% obstruction.

The classification of Mallampati et al correlates tongue size to pharyngeal size in the following way: Class I means visualization of the soft palate, larynx, uvula, and anterior and posterior pillars of the tonsils; Class II means visualization of the soft palate, larynx, and uvula; Class III means visualization of the soft palate and the base of uvula; and Class IV means only the hard palate is visible.

According to Cottle’s classification, the septal deformities were classified by area: 1 area means the nasal vestibule; 2 area of the nasal valve means the region corresponding to the borderline between the upper and lower lateral cartilage, soft tissue adjacent to the piriform aperture, and floor of the nasal cavity and nasal septum; 3 attical area means the region behind and above the nasal valve in the nasal bones; 4 anterior turbinate area means the region corresponding to the cartilaginous and bony septum, opposite the turbinates; and 5 posterior turbinate area means the region adjacent to the choana.

During nasal endoscopy when the obstruction or narrowing in the nasopharynx made it impossible to further introduce the nasal endoscopy fiberoptic into the cavum, the computed tomography examinations routinely included in the patients’ clinical records were available and accessed by the otolaryngologist to verify the size of the adenoids.

During the otolaryngologist’s clinical evaluation, many signs were observed, such as the distance between the septum and turbinates, retro tongue freeway space, narrow alar base, dry mouth, labial competence, labial posture, tooth positions, chin, facial height, dark circles under the eyes, and self-reported mouth breathing.

Ultimately, the participants were diagnosed by the otolaryngologist as nasal breathers or mouth breathers, and the latter were further classified as mouth breathers with airway obstruction (MBAO) or mouth breathers by habit (MBH). This classification was performed by the otolaryngologist, by considering a combination of the examinations previously described; however, no quantitative index was used for that purpose. Nasal breathing corresponded to the physiologic pattern and did not have obstructive respiratory characteristics. MBAO were characterized by any airway obstructions observed on clinical evaluation by the otolaryngologist as previously described. MBH were characterized by the ability to breathe through the nose—ie, without permanent obstacles in the airway; however, they persisted in breathing through the mouth. This diagnosis was considered the reference against which the examinations performed by the orthodontists were compared.

The data collected from the 3 records were tabulated and analyzed by a blind researcher.

Statistical analysis

All assessments of breathing status from the questionnaires were repeated by the orthodontist responsible for anamnesis and also analyzed by the orthodontist responsible for the clinical examination 1 month later, blinded and independently, only through the answers in the records. No patient was recalled for reexamination. The latter orthodontist considered the answers and his own clinical experience to establish his recognition of each patient. The level of agreement among the evaluators was statistically analyzed using the weighted kappa test. The agreement between the original recognition from the questionnaires by the orthodontist responsible for anamnesis and its repetition, and the same analysis from the other orthodontist was statistically checked using the weighted kappa test, indirectly assessing the error of the method.

Descriptive analyses were used to provide frequencies of answers from the anamnesis, according to the otolaryngologist’s diagnostic breathing status, and the Pearson chi-square test or the Fisher exact test was used to test differences. Descriptive statistics and the Pearson chi-square test were also used to assess the frequency of findings in the otolaryngologist’s examination according to her diagnosis. Odds ratios associated with the presence or absence of characteristics were also calculated. For these descriptive statistics, the findings (adenoid hypertrophy, nasal turbinates hypertrophy, tonsil hypertrophy, and septum deviation) were characterized as none to mild obstruction or moderate to severe obstruction.

The sensitivity and specificity of the orthodontists in detecting mouth breathers were also calculated.

The significance level was set at 5%. Data were analyzed with the Statistical Package for the Social Sciences software (version 17; SPSS, Chicago, Ill).


The body mass index values of the participants indicated that 76.3% of them were considered to be at a healthy weight or underweight, and 23.7% were overweight or obese.

The sample included 55 volunteers who were receiving treatment at the orthodontic clinics of Universidade Federal Fluminense. Twenty participants were considered by the otolaryngologist to be nasal breathers (12 female, 8 male; age range, 10-23 years; mean age, 15.3 ± 3.64 years), whereas 35 participants were classified as mouth breathers (22 female; 13 male; age range, 10-23 years; mean age, 15.9 ± 2.94 years).

The weighted kappa coefficient showed poor (below 0.2) interrater agreement for most comparisons ( Table I ). When only mouth breathers (diagnosed by the otolaryngologist) were considered and the participants recognized as nasal breathers by each orthodontist were tested for agreement with those diagnosed by the otolaryngologist as MBH, the agreement was fair (between 0.2 and 0.39) for anamnesis and poor (below 0.2) for clinical examination, as shown in Table II .

Table I
Agreement between methods of assessment of clinical recognition of nasal and mouth breathers tested by the weighed kappa coefficient (n = 55)
Clinical examination (orthodontist) Weighted kappa ( P value)
Nasal breather Mouth breather Total
Anamnesis (orthodontist)
Nasal breather 38 3 41 0.174 (0.144)
Mouth breather 11 3 14 SE 0.140
Total 49 6 55 CI, –0.101 to 0.449
Otolaryngologist examination
Anamnesis (orthodontist)
Nasal breather 17 24 41 0.134 (0.178)
Mouth breather 3 11 14 SE 0.094
Total 20 35 55 CI, –0.050 to 0.318
Otolaryngologist examination
Clinical examination (orthodontist)
Nasal breather 20 29 49 0.131 (0.050)
Mouth breather 0 6 6 SE 0.055
Total 20 35 55 CI, 0.023 to 0.238
CI , Confidence interval.

Table II
Agreement between methods of assessment of clinical recognition of breathing status (orthodontist x OL) in participants diagnosed as mouth breathers (OL) when considering nasal breathers (by the orthodontist) = mouth breathers by habit (by the OL)
Otolaryngologist examination Weighted kappa ( P value)
Anamnesis (orthodontist)
MBAO 7 4 11 0.276 (0.093)
Nasal 8 16 24 SE 0.161
Total 15 20 35 CI, –0.039 to 0.592
Clinical examination (orthodontist)
MBAO 3 3 6 0.054 (0.698)
Nasal 12 17 29 SE 0.141
Total 15 20 35 CI, –0.222 to 0.331
OL , Otolaryngologist; MBAO , mouth breathers with airway obstruction; MBH , mouth breathers by habit; CI , confidence interval.

The weighted kappa coefficient used to assess inconsistency in the diagnosis and that measured agreement between the original recognition from the anamnesis and its repetition was 0.371 ( P <0.0001), and the coefficient between the 2 orthodontists based on the questionnaire was 0.305 ( P = 0.004).

Frequencies of characteristics collected during the anamnesis according to the reference diagnostic by the otolaryngologist (nasal and mouth breathers) are shown in Table III . The main issues for mouth breathers were breathing problems, open-mouth breathing, snoring, dry mouth on awakening, drinking water during the night, daytime sleepiness, and use of nasal spray. No statistically significant difference was observed. The conditions that both nasal and mouth breathers mentioned were health problems, allergies, stuffy nose, sneezing frequency, suffocation or breathlessness, physical activities, and deleterious habits.

Table III
Frequency of record answers (orthodontic anamnesis) from nasal and mouth breathers (classified by the otolaryngologist) and from mouth breathers subdivided into mouth breather with airway obstruction (MBAO) and mouth breathers by habit (MBH)
Characteristic Nasal breathers (n = 20) Mouth breathers (n = 35) MBAO (n = 15) MBH (n = 20)
Tonsillitis or sinusitis 9 (45%) 10 (28.6%) 6 (40%) 4 (20%)
Medical treatment 20 (50%) 9 (25.7%) 6 (40%) 3 (15%)
Speech therapy 10 (50%) 11 (31.4%) 8 (53.3%) 3 (15%)
Allergies 12 (60%) 18 (51.4%) 7 (46.7%) 11 (55%)
Breathing problems 6 (30%) 14 (40%) 7 (46.7%) 7 (35%)
Open mouth 10 (50%) 22 (62.9%) 12 (80%) 10 (50%)
Stuffy nose 11 (55%) 18 (51.4%) 10 (66.7%) 8 (40%)
Sneezing frequency 8 (40%) 13 (37.1%) 6 (40%) 7 (35%)
Snoring 4 (20%) 13 (37.1%) 8 (53.3%) 5 (25%)
Dry mouth on awakening 10 (50%) 23 (65.7%) 11 (73.3%) 12 (60%)
Daytime sleepiness 6 (30%) 16 (45.7%) 7 (46.7%) 9 (45%)
Nasal spray 2 (10%) 10 (28.6%) 5 (33.3%) 5 (25%)
Deleterious habits 10 (50%) 17 (48.6%) 6 (40%) 11 (55%)
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Dec 12, 2018 | Posted by in Orthodontics | Comments Off on Clinical recognition of mouth breathers by orthodontists: A preliminary study
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