Anatomy and Pathophysiology of Adenotonsillar Obstruction

The adenoids are lymphoid tissue located in the nasopharynx (posterior to the nasal cavities), while the tonsils are lymphoid tissue in the oropharynx (lateral walls of the throat). Both are part of Waldeyer's ring—a circular arrangement of lymphoid tissues protecting the upper respiratory and gastrointestinal tracts. In childhood, adenotonsillar tissue normally enlarges during immune system development, peaking in size around ages 4-7 years. This developmental enlargement is physiologic and usually regresses by early adolescence.

However, in some children, adenotonsillar tissue enlarges excessively, creating partial or complete airway obstruction. This obstruction leads to mouth breathing (chronic compensation for nasal obstruction), sleep-disordered breathing, and eventual obstructive sleep apnea (OSA). The chronic oral breathing triggers a cascade of craniofacial changes affecting tooth development, jaw growth, and malocclusion formation.

Brodsky Grading Scale and Clinical Assessment

Otolaryngologists use the Brodsky Scale (1989) to standardize adenotonsillar size assessment:

Grade 1: Small; tonsils occupy less than 25% of the oropharyngeal space (between the tonsil pillars) Grade 2: Moderate; tonsils occupy 25-50% of the oropharyngeal space Grade 3: Large; tonsils occupy 50-75% of the oropharyngeal space Grade 4: Very large; tonsils occupy greater than 75% of the oropharyngeal space and nearly or completely obstruct the airway Grade 3-4 tonsils are considered pathologically enlarged, particularly when accompanied by respiratory symptoms (snoring, witnessed apneas, daytime somnolence, mouth breathing). Adenoid enlargement is more difficult to assess clinically since adenoids are not directly visible without nasopharyngoscopy. However, clinical signs include persistent nasal obstruction, hyponasal speech (speaking through the nose—"hyponasal" changes /m/ sounds to /n/), and mouth breathing.

Mouth Breathing Consequences: "Adenoid Facies"

Chronic mouth breathing from adenotonsillar obstruction creates characteristic craniofacial changes termed "adenoid facies" or "long-face syndrome". These changes occur because mouth breathing fundamentally alters the pressure gradients affecting jaw and palatal development:

Palatal Changes: The hard palate develops a high vault (Gothic arch appearance) instead of the normal gently curved shape. This occurs because normal palatal development requires nasal airflow creating pressure on the palatal tissues. When mouth breathing replaces nasal breathing, loss of palatal pressure allows the palate to form a narrower, higher arch. The maxillary width simultaneously decreases—narrow maxilla with constricted dental arch form. Vertical Dimension Changes: Instead of normal anteroposterior jaw growth, chronic mouth breathers develop excessive vertical growth. The anterior facial height (distance from nasal base to chin) increases disproportionately, creating the "long face" appearance. The ratio of anterior facial height to posterior facial height increases significantly. This vertical growth pattern continues into adulthood if the airway obstruction persists. Dental Consequences of Narrow Maxilla:
  • Crowding of maxillary teeth due to reduced arch width
  • Anterior open bite (failure of anterior teeth to contact in occlusion)
  • Class II malocclusion with maxillary protrusion (anterior teeth tipped forward)
  • High-arched palate reducing floor space for the tongue
  • Mandibular retrognathism (backward position of lower jaw) relative to maxilla
Anterior Open Bite: The excessive vertical growth combined with tongue posture changes creates anterior open bite—the anterior teeth fail to contact even when the posterior teeth are in full closure. The tongue, compensating for airway obstruction, maintains a low-forward position and prevents upper and lower anterior teeth from contacting. This anterior open bite creates esthetic and functional problems and is significantly more common in mouth breathers than nasal breathers.

Obstructive Sleep Apnea in Children and Polysomnographic Criteria

Obstructive Sleep Apnea (OSA) occurs when airway collapse during sleep causes repeated oxygen desaturation and arousal. In children with adenotonsillar hypertrophy, the adenoids and tonsils directly obstruct the airway during sleep when muscle tone decreases. Children with Grade 3-4 adenotonsillar enlargement have substantially elevated OSA risk. Polysomnography (Sleep Study) Criteria:
  • Apnea-Hypopnea Index (AHI): Number of apneas + hypopneas (shallow breathing) per hour of sleep
  • Normal children: AHI <1 event/hour
  • Mild OSA: AHI 1-5 events/hour
  • Moderate OSA: AHI 5-10 events/hour
  • Severe OSA: AHI >10 events/hour
  • Oxygen Saturation: SpO2 nadir (lowest oxygen saturation) during events should remain >90%. Values <85% indicate severe OSA.
  • Arousal Index: Number of sleep arousals per hour. Normal <5-8/hour; elevated in OSA.
Many children with severe adenotonsillar hypertrophy show AHI >10 events/hour on sleep study, meeting criteria for moderate-to-severe OSA. A landmark trial (Marcus et al., 2013) found that children with OSA treated with adenotonsillectomy showed significant improvements in AHI, oxygen saturation, and daytime sleepiness compared to observation alone. Dental Implications: Pediatric dentists must screen for OSA risk factors—excessive daytime somnolence, classroom inattention, behavioral problems, poor sleep quality, and presence of anterior open bite or high-arched palate. Referral to sleep medicine for polysomnography is appropriate when clinical suspicion is high.

Malocclusion Patterns Associated with Adenotonsillar Obstruction

Class II Division 1 Malocclusion: The most common malocclusion in mouth breathers, characterized by maxillary protrusion and/or mandibular retrusion. The excessive vertical growth creates a Class II molar relationship, and the anterior teeth are often proclined (tipped forward) due to tongue positioning. Overjet (horizontal overlap of anterior teeth) is frequently increased. Anterior Open Bite: Specific to airway obstruction cases. The anterior teeth fail to occlude despite posterior teeth in full contact. The open bite magnitude often correlates with adenoid size and severity of obstruction—children with very large adenoids show greater anterior open bite. Narrow Maxillary Arch: The maxilla is constricted transversely (buccolingually narrower than normal). This creates crowding of maxillary teeth and can restrict maxillary sinus pneumatization during development, affecting craniofacial morphology. Posterior Crossbite: A transverse maxillary deficiency relative to the mandible creates posterior crossbites, where mandibular molars are buccal to maxillary molars in one or both posterior regions.

These malocclusion patterns do not spontaneously resolve when adenotonsillar tissue shrinks—they persist as the hard tissue (bone, teeth) remains in the deviated position. Therefore, early intervention to restore nasal breathing can prevent malocclusion development.

Surgical and Orthodontic Management

Adenotonsillectomy (Surgical Removal): Removal of obstructing adenoid and tonsillar tissue is the definitive treatment for adenotonsillar obstruction causing OSA or significant airway compromise. The Marcus et al. (2013) study demonstrated that adenotonsillectomy in children with OSA provided 50-80% improvement in AHI and resolution of OSA in 50-60% of cases. Success rates are highest when surgery is performed relatively early—before permanent malocclusion patterns develop (ideal age 4-8 years). Timing of Surgery: Performed when clinical obstruction symptoms exist AND either (1) polysomnographic confirmation of OSA, or (2) failure to thrive, recurrent infections, or behavioral/educational impact. Surgery should not be delayed indefinitely hoping for spontaneous regression—waiting allows progressive malocclusion development that may require subsequent orthodontics. Rapid Maxillary Expansion (RME): In children where adenoid size is moderate but symptomatic, or as adjunctive therapy post-adenotonsillectomy, RME can expand the maxillary arch width and increase nasal airway space. RME involves applying a palatal screw appliance to widen the maxilla. Studies show RME can reduce OSA severity by increasing nasal airway dimensions. When combined with adenotonsillectomy, RME may provide superior outcomes compared to surgery alone. Orthodontic Correction of Malocclusion: Post-adenotonsillectomy, malocclusion patterns may partially resolve, particularly in young children (<8 years) where craniofacial growth is still responsive to the restored nasal airway. However, established malocclusion (anterior open bite, Class II) often persists and requires comprehensive orthodontic treatment. Starting orthodontics after adenotonsillar obstruction is resolved ensures the orthodontist is working with restored normal airway function, improving treatment stability.

Orthodontist-ENT Collaboration

Optimal management requires early communication between pediatric dentist, orthodontist, and otolaryngologist:

1. Pediatric Dentist screens for adenoid facies, anterior open bite, and OSA risk factors 2. ENT evaluation confirms adenotonsillar size via Brodsky grading and considers sleep study 3. Orthodontist documents malocclusion severity and discusses surgical/RME timing 4. Coordinated surgical timing: Adenotonsillectomy ideally performed before permanent Class II or anterior open bite develops 5. Post-surgical follow-up: Reevaluation at 6-12 months post-operatively to assess spontaneous malocclusion improvement or determine need for comprehensive orthodontics

This multidisciplinary approach prevents unnecessary extensive orthodontic treatment if early airway intervention resolves malocclusion patterns, while ensuring surgical intervention is timely if needed.

Long-Term Outcomes and Retention

Spontaneous Malocclusion Resolution: In children aged 5-8 years at adenotonsillectomy, anterior open bite often closes spontaneously as tongue posture normalizes with restored nasal breathing. However, children presenting with established malocclusion at age 10+ usually do not experience spontaneous resolution—orthodontic intervention is necessary. Post-Adenotonsillectomy Stability: Growth studies (Zettergren-Wijk et al., 2006) show that children treated with adenotonsillectomy for OSA demonstrate improved vertical growth patterns and increased posterior facial height (normalizing the long-face dimension) in the years immediately following surgery. This suggests that early surgical intervention can "reset" the growth trajectory toward more normal morphology. Combined RME + Adenotonsillectomy: In children with significant maxillary constriction and OSA, combining RME with adenotonsillectomy (Hasegawa et al., 2012) provides superior outcomes—increased nasal airway space from RME combined with adenotonsillar removal restores breathing most effectively.

Summary

Adenotonsillar hypertrophy is a common childhood condition with profound craniofacial consequences when causing chronic mouth breathing and obstructive sleep apnea. The Brodsky Grading Scale (Grade 3-4 indicating pathologic enlargement) guides clinical assessment. Mouth breathing creates predictable malocclusion patterns: narrow maxilla, high-arched palate, anterior open bite, and Class II molar relationship—collectively termed "adenoid facies." Polysomnographic confirmation of obstructive sleep apnea (AHI >1-5 events/hour in children) guides surgical intervention. Adenotonsillectomy during early childhood (ages 4-8) can prevent or minimize malocclusion development and resolve OSA in 50-60% of cases. In children with established malocclusion or maxillary constriction, rapid maxillary expansion combined with adenotonsillectomy provides superior outcomes. Collaborative management between pediatric dentist, orthodontist, and otolaryngologist ensures timely surgical intervention and appropriate orthodontic planning, optimizing both airway function and craniofacial development in children with obstructive sleep apnea.