Key Takeaway
Mouth breathing during childhood causes backward and downward mandibular rotation, narrower dental arches, and nearly double the rate of posterior crossbite compared to nasal breathing.
Summary
This retrospective study compared craniofacial and dentofacial development between 55 mouth-breathing children and 61 nasal-breathing controls, all undergoing orthodontic treatment. The results clearly demonstrate that chronic mouth breathing during critical growth periods leads to measurable changes in facial structure.
Mouth breathers showed backward and downward rotation of the mandible (clockwise rotation), increased overjet, a steeper mandible plane angle, a higher palatal plane, and narrowing of both the upper and lower dental arches at the level of the canines and first molars. Posterior crossbite was nearly twice as common in mouth breathers (49% vs 26%), and abnormal lip-to-tongue anterior oral seal was significantly more prevalent (56% vs 30%).
These findings provide strong evidence that nasal breathing is essential for normal craniofacial development in children. Nasal obstruction during critical growth periods leads to unfavorable facial growth patterns that require orthodontic intervention to correct.
Methods
- Retrospective study at a tertiary medical center
- 116 pediatric orthodontic patients
- Study group: 55 children with nasal obstruction symptoms/signs (mouth breathers)
- Control group: 61 children who were normal nasal breathers
- Reviewed clinical variables and cephalometric parameters
- Measured mandible plane angle, palatal plane, overjet, and arch widths
Key Results
- Mouth breathers: backward and downward rotation of mandible
- Increased overjet and mandible plane angle in mouth breathers
- Higher palatal plane in mouth breathers
- Narrower upper and lower arches at canines and first molars
- Posterior crossbite: 49% of mouth breathers vs 26% of controls (p=.006)
- Abnormal lip-to-tongue oral seal: 56% vs 30% (p=.05)
- Increased anterior lower facial height in mouth breathers
- Decreased posterior facial height in mouth breathers
Limitations
- Retrospective design limits causal inference
- All subjects were orthodontic patients (selection bias)
- Nasal obstruction assessed by symptoms rather than objective measurement
- Did not quantify duration or severity of mouth breathing
- Single-center study