Abstract

CLARO, Cristiane Aparecida de Assis; ABRAO, Jorge; REIS, Sílvia Augusta Braga  and  LAGANA, Dalva Cruz. Stress distribution in a photoelastic model resulting from intrusion of mandibular incisors using Ricketts utility arch. Dental Press J. Orthod. [online]. 2011, vol.16, n.5, pp. 89-97. ISSN 2176-9451.  http://dx.doi.org/10.1590/S2176-94512011000500014.

OBJECTIVE: The present study is concerned with stress distribution in a photoelastic model, caused by lower incisor intrusion using utility arch. The stress levels on the radicular thirds of each lower incisors were compared and the stress concentration differences on each incisor were evaluated. METHODS: Fifteen intrusion utility arches were made up. The activation force of 50 gf was measured in the midline. The photoelastic model was observed using a circular polariscope in a dark field configuration, and, then, photographed. Frontal photographs were analyzed, and the fringe order in each region was registered. The method replicability was assessed by the Kappa weighted analysis. The comparison between the stress levels was carried out using Kruskall-Wallis test followed by the Dunn test at p<0.05. RESULTS AND CONCLUSIONS: The cervical regions were identified with the highest stress levels. By comparing the fringe order among the teeth it could be concluded that the highest stress levels are located in the central incisors. Therefore the cervical region can be more prone to resorptions as well as the central incisors, where higher stresses are concentrated.

Keywords : Photoelasticity; Intrusion; Biomechanics; Root resorption.