Changes in Craniofacial Morphology Induced by Unilateral Nasal Obstruction in Mice of Different Ages.

Background: Nasal obstruction in humans leads to mouth breathing and subsequent hypoxia in the entire body. Furthermore, nasal obstruction in growing children affects craniofacial growth and development.

Objective: To investigate the effects of unilateral nasal obstruction (UNO) on craniofacial growth in mice of different ages, particularly on the morphology of the nasomaxillary complex and mandible.

Methods: Mice aged 3, 6 and 12 weeks were selected as representatives of juvenile, adolescent and adult stages, respectively. A total of 30 male C57BL/6J mice (10 mice each at the ages of 3, 6 and 12 weeks) were used in this study for a 3-week experiment. The mice in each age stage were randomly and evenly assigned to either the control group (C3+3, C6+3 and C12+3) or the experimental group (E3+3, E6+3 and E12+3). The UNO model in experimental group was constructed by plugging the mouse's left nostril, thereby disrupting its normal nasal breathing pattern and inducing hypoxia. The control group underwent the sham procedure. After 3 weeks, the length, width and height of the cranium, nasomaxillary complex and mandible of each group were measured on two-dimensional images constructed by micro-computed tomography. Furthermore, the impact of UNO on mouse growth was evaluated through the measurement of femoral length.

Results: In juvenile mice, UNO inhibited the growth of cranial width, cranial height and mandibular length. In adolescent mice, UNO impeded the growth of the femoral length, cranial length, nasomaxillary length and mandibular length. In adult mice, no significant negative effects of UNO on craniofacial growth were found.

Conclusion: Referring to the experimental results, in addition to actively treating nasal obstruction in patients, it is important to monitor the growth of the mandible in juveniles, as well as the nasomaxillary and mandibular growth in adolescents during orthodontic clinical practice.