Photoelastic analysis of stress generated by wires when conventional and self-ligating brackets are used: A pilot study

Abstract

OBJECTIVE: By means of a photoelastic model, this study analyzed the stress caused on conventional and self-ligating brackets with expanded arch wires. METHOD: Standard brackets were adhered to artificial teeth and a photoelastic model was prepared using the Interlandi 19/12 diagram as base. Successive activations were made with 0.014-in and 0.018-in rounded cross section Nickel-Titanium wires (NiTi) and 0.019 x 0.025-in rectangular stainless steel wires all of which made on 22/14 Interlandi diagram. The model was observed on a plane polariscope - in a dark field microscope configuration - and photographed at each exchange of wire. Then, they were replaced by self-ligating brackets and the process was repeated. Analysis was qualitative and observed stress location and pattern on both models analyzed. CONCLUSIONS: Results identified greater stress on the region of the apex of premolars in both analyzed models. Upon comparing the stress between models, a greater amount of stress was found in the model with conventional brackets in all of its wires. Therefore, the present pilot study revealed that alignment of wires in self-ligating brackets produced lower stress in periodontal tissues in expansive mechanics.

A Retrospective Study to Evaluate the Intra-Arch Dimensional Changes in Moderate Crowding Cases Treated Non Extraction with a Passive Self-Ligation Appliance.

“…Light continuous forces will produce continuous, frontal resorption and will not overpower the periodontal and orofacial muscltature, and will prevent proclination of anteriors and causes more expansion in the transverse direction. Photoelastic model showed lower stress in periodontal tissue with self-ligating appliance as compared to conventional bracket system (15). Intra arch dimensional changes in both maxillary and mandibular arches in moderate crowding cases treated non-extraction with a passive self ligation appliance (Damon 3MX) were analyzed using digitized models and digital cephalograms.…”

Análise fotoelástica das tensões produzidas por arcos ortodônticos expandidos associados aos bráquetes autoligáveis e convencionais

“…Produto/Equipamento Modelo/ Marca /Distribuidor Arco ortodôntico pré-contornado de níquel-titânio 0.014"/ GAC/ EUA Arco ortodôntico pré-contornado de níquel-titânio 0.014" x 0.025"/ GAC/ EUA (Glickman et al 1970;Brodsky et al, 1975;Clifford et al,1999;Badran et al, 2003;Claro, 2008;Cintra;Armando, 2010;Maia et al, 2010;Claro et al, 2011;Dobranski;Caram, 2013;Galli et al, 2014;Sobral et al, 2014;Abrão et al, 2015;Schwertner et al, 2017). As pesquisas de Glickman et al (1970) e Brodsky et al (1975) consolidaram esse método ao demonstrar haver uma correlação positiva entre as tensões produzidas nos modelos fotoelásticos, que reproduziram estruturas biológicas, e a avaliação histológica delas.…”

“…A literatura reporta a leitura qualitativa das tensões geradas pela fotoelasticidade (Badran et al, 2003;Dobranski et al, 2009;Maia et. al., 2010;Dobranski;Caram, 2013;Sobral et al, 2014). Nesta pesquisa, essa análise permitiu identificar visualmente a intensidade e local de ocorrência das tensões com base no número da ordem de franjas fotoelásticas estabelecida pela American Society For Testing Materials (Quadro 2.1).…”

“…Badawi et al (2009) e Pandis et al (2009) mensuraram-nas por meio de transdutores mecânicos multiaxiais, em modelos que continham dentes artificiais mal posicionados. Sobral et al (2014), por meio do método da fotoelasticidade, analisaram as distribuições de tensão em protótipo fotoelástico que continha dentes alinhados.…”

Método da fotoelasticidade como adjuvante em pesquisas ortodônticas

“…O alinhamento e nivelamento deste apinhamento dentário se refere a uma das primeiras etapas do tratamento ortodôntico corretivo, para a qual grande variedade de fios são propostos (Badran et al, 2003, Chiang et al, 2018. Diferentes investigações in vitro têm sido conduzidas para avaliar as propriedades mecânicas de arcos de alinhamento inicial (Badran et al, 2003, Sobral et al, 2014, Chiang et al, 2018, muito embora ainda não haja consenso a respeito do método mais apropriado para a avaliação das suas propriedades mecânicas (Badran et al, 2003, Sobral et al, 2014, Chiang et al, 2018.…”