Influence of different types of rapid maxillary expansion on root resorption: a systematic review.

OBJECTIVES: This study aimed to assess the influence of different types of rapid maxillary expansion on root resorption (RR). METHODS: Literature searches were carried out electronically in five English and two Chinese databases. Randomized controlled trials (RCTs), controlled clinical trials (CCTs), cohort studies, and case-control studies were included. The data were extracted by three authors. The risk of bias in the RCTs and nonrandomized studies were assessed in accordance with corresponding scales. RESULTS: Among the 400 articles identified, seven were included for the final analysis. Three studies were graded as high value of evidence, while two and another two studies were graded as moderate value and low value, respectively. According to the available evidence, the tooth-borne maxillary expansion caused more obvious RR of anchorage teeth than the bone-borne one. In addition, the Haas-type palatal acrylic pads could not effectively reduce the degree of RR. The difference in the design of the retainer between the tooth-borne maxillary expansion (the use of a band or wire framework to connect the anchorage tooth) did not cause the difference in the incidence and degree of RR. CONCLUSIONS: Clinical evidence suggested that bone-borne maxillary expansion may decrease the amount of RR, while the amounts of resorption did not significantly differ between Haas and Hyrax and between different retainer types of Hyrax.