Effects of Mini-Implant-Assisted Rapid Palatal Expansion on Incisive Canal Morphology and Tooth–Canal Relationship

Abstract

The objective of this study was to identify the change in incisive canal (IC) morphology and tooth–canal relationship after mini-implant-assisted rapid palatal expansion (MARPE). Pretreatment and posttreatment cone-beam computed tomography images of 30 subjects were retrospectively evaluated. The dimensional and volume changes of the IC after MARPE treatment were evaluated, and the tooth–canal relationship and positional relationship between the maxillary central incisors were additionally compared in the group where the root apex of the maxillary central incisors was higher than the IC oral opening. The mediolateral and labiopalatal widths of the IC were significantly increased in all three levels after MARPE treatment (p < 0.01). The amount of increase was greater in the mediolateral direction than in the labiopalatal direction. The anteroposterior distance from the mesial point of the maxillary central incisors to the anterior margin of the IC was significantly decreased only in the oral opening level in the samples where the apices of the maxillary central incisors were located more superior to the oral opening of the IC (p < 0.05). The mediolateral distance between the mesial points of the maxillary central incisors and the distance between the root apex of the maxillary central incisors significantly increased after MARPE (p < 0.001). However, the distance between the crown tips of the maxillary central incisors did not significantly increase, even after MARPE treatment (p > 0.05). The volume of the IC significantly increased after MARPE treatment (p < 0.001), and the average increase in the total volume of the IC was about 65%. MARPE increased the width and volume of the IC and did not result in a clinically significant change in the root–canal relationship.