Changes in maxillofacial morphology due to improvement of nasal obstruction in rats

To investigate the effect of release of experimentally introduced nasal obstruction on maxillofacial morphology and percutaneous arterial oxygen saturation (SpO₂ ) in rats.

Six-week-old male Wistar rats (n = 36) were divided into a control group (n = 6) and a nasal obstruction group (n = 30). In the nasal obstruction group, the right nostril was occluded with silicon, which was subsequently removed after a given experimental period (days 7, 21, 35, 49 and 63). These animals were then divided into groups D7, D21, D35, D49 and D63 (each n = 6), according to the day at which the obstruction was released. The SpO₂ was measured in rats with nasal obstruction at five experimental points. The maxillofacial morphology in rats on the first day and 63 days after the start of the experiment was evaluated by microcomputed tomography.

The SpO₂ was still lower at 2 weeks after the improvement of the nasal obstruction in the D49 group than in the control group. In addition, the height of the nasal maxillary complex of the D35, D49 and D63 groups was significantly decreased compared with the control group.

The results of this study suggest that long-term unilateral nasal obstruction in growing rats may affect the growth of the nasomaxillary complex and reduce the SpO₂ permanently. Therefore, early improvement of nasal obstruction in rats during the growth period may improve the SpO₂ and cranial development and promote normal growth and development.