Resorption of roots of different dimension induced by different types of forces

Abstract

Root resorption is a variable to be considered in inducedtooth movement (ITM). It is related to root morphology and alveolarbone crest, and also to the types of forces exerted by mechanotherapy.This histometric study evaluated the predominance of root resorptionamong roots of different dimensions, following ITM with differenttypes of forces and at different time intervals. The study was conductedon 54 rats divided into three groups, according to the type of force:continuous (CF), continuous interrupted (CIF) and intermittent (IF), atperiods of 5, 7 and 9 days. The percentage of resorption between mesiobuccalroots of larger dimension and intermediate roots of smaller dimensionwas assessed. The evaluations were performed on the AxioVisionsoftware, and the non-parametric analysis of variance for repeatedmeasures in independent groups was further applied, consisting of ascheme of two factors, and complemented by the Dunn test at a significancelevel of 5%. The intermediate roots presented a higher percentageof resorption, which was gradual at the periods evaluated for the threetypes of forces, but mainly for CF. Comparing the intermediate rootswith the mesiobuccal roots, there was a statistically significant difference(p < 0.05) in the CF group at day 7 and day 9, and in the FI group,at day 9. The intragroup analysis evidenced a statistically significantdifference (p < 0.05) between the 5th and the 9th day for the intermediateroot in the CF group. The intergroup analysis did not reveal any statisticallysignificant difference (p > 0.05) in individually analyzed roots.