Mini-implant and Nance button for initial retraction of maxillary canines: a prospective study in cast models Mini-implante e botão de Nance para retração inicial de caninos superiores: estudo prospectivo em modelos

OBJECTIVE: Bone anchorage is a key factor for the successful management of some malocclusions for it allows the application of continuous forces, decreases treatment time and is independent from patient compliance. METHODS: The goal of this work was to establish a dental model comparison in order to measure the anchorage loss after the initial retraction of upper canines between the two groups. Group A used mini-implants and Group B used Nance button. All patients had two models cast (M1 and M2). The first models were taken on baseline (M1) and the other models were taken after canine retraction (M2). RESULTS: All measurements were pooled and submitted to statistical analysis. In order to verify the inter-examiner systematic error a paired t-test was performed. Dahlberg's formula was used to estimate the casual error. For comparison purposes between Before and After stages, a paired t-test was done. For the comparison between mini-implant and Nance button groups, a Student t-test was applied. All tests adopted a 5% (p