Treatment and posttreatment effects of a novel magnetic palatal expansion appliance with reactivation system in dogs.

INTRODUCTION

This study aimed to compare the effects of a novel magnetic palatal expansion appliance (MPEA) during the expansion and maintenance period with that of a screw expansion appliance.

METHODS

Based on previous research, the MPEA had a reactivation system that was modified for a broader working range and more stable expansion. Thirty-six male beagle dogs were assigned to a magnetic expansion (ME; n = 12), screwed expansion (SE; n = 12) or control (n = 12) group. Half of the dogs from each group were evaluated only during 5 weeks of activation, whereas the rest were evaluated for 5 weeks of activation and 8 additional weeks of retention. Nonmagnetic metal marking implants were implanted on both sides of the midpalatal suture of all dogs. Three-dimensional assessment of treatment and posttreatment dental and skeletal effects were conducted using cone-beam computed tomography. The width of the midpalatal suture, mineralization and deposition rate of bone, and fluorescence integral optical density were calculated during the expansion and retention periods using tetracycline fluorescence labeling.

RESULTS

There were increases in the value of all cone-beam computed tomography parameters in the SE and ME groups during the expansion period, and the increase was significantly greater than that of the control group (P <0.01). However, there was no significant difference in the values of any parameters during the retention period. The width of the midline sutures, mineralization and deposition rate of bone, and integral optical density in the 2 experimental groups were significantly higher than those of the control group (P <0.01), and there was no significant difference between the SE and ME groups. After the retention period, the values of all tetracycline fluorescence evaluation parameters of the experimental groups decreased significantly.

CONCLUSIONS

The novel MPEA with a reactivation system was able to expand the midpalatal suture effectively. Dental and skeletal expansion effects are similar to those of the screw expansion appliance. Wearing the appliance as a retainer can effectively maintain the expansion effect. The new bone formation rate was accelerated during the expansion process and decreased to normal levels during the retention period.