Photoelastic analysis of stress generated by Connecticut Intrusion Arch (CIA)

Abstract

Objective: The present in vitro study evaluated, by means of the photoelastic technique, the effects generated by the Connecticut Intrusion Arch (CIA), with a 90o bend on the distal surface of molar tubes and using the 4 x 2 appliance on the anterior and posterior regions of the upper dental arch. Methods: Five models were manufactured, in which two different clinical situations were correlated: 1) use of intrusion arch not cinched back and transpalatal bar for anchorage (Group 1); 2) use of intrusion arch cinched back and transpalatal bar for anchorage (Group 2). Stress generated in the apical and middle regions of tooth roots of maxillary anterior teeth and maxillary first molars was evaluated.Results: Taking a reference value of 1.0 MPa = 100%, qualitative descriptive analysis was performed, which showed uniformity between stress values in the apical region of anterior teeth of both groups (G1 and G2). In the posterior region, for models with the arch cinched back (G2), stress remained within 100%. As for G1 models (with the arch not cinched back), variations in the mesial surface of first molars were observed, with an increase of 20% in the generated stress. The apical region did not undergo any changes, while in the distal region of molars there was a decrease of 20% in stress.Conclusion: Laboratory results revealed differences in stress between Groups 1 and 2 in the molar region, thereby indicating that there was a tendency towards mesial root tipping of first molars when the distal end of the CIA was not cinched back.

A prospective clinical trial of the effects produced by the Connecticut intrusion arch on the maxillary dental arch

“…4,8,17 However, there is variation in the literature regarding dental arch segmentation, particularly in terms of the number of teeth in the posterior region involved, with possibilities including molars and premolars, 6,11 molars, premolars and canines, 2,11,16,17 or first molars only. 3,13 Regarding the side effects in the posterior anchorage unit, it has been acknowledged that there was a significant clockwise moment generated on maxillary molars during intrusion of incisors, which results in both a tendency toward extrusion 8,19,24 and distal crown tipping. 6,7,13,19,21 It has been shown that a transpalatal bar 12 can be used to help minimize the anchorage unit side effects.…”

“…3,9,12 The location of the point of force application in relation to the center of resistance (Cr) of the anterior segment involved in segmented intrusion mechanics with intrusion arches can change incisor axial tipping, which is not always desirable. 6,8,12,13 A more anterior location of the point of force application causes flaring, 2,6,8 whereas a more posterior location can produce uprighting of the anterior teeth. 6 The Cr for all four normally positioned incisors is located in a region between the distal side of the canine 14 and the distal side of the lateral incisor.…”

Análise fotoelástica da distribuição de tensões nas raízes dos dentes anteroinferiores decorrentes de diferentes mecânicas de retração

“…A escolha da fotoelasticidade se deu por ser uma metodologia comprovada e aceita como uma das melhores para a avaliação das tensões sobre os corpos estudados (Zak, 1935;Glickman et al, 1970;Brodsky et al, 1975;Rossato, 1982;Campos Júnior et al, 1985;Chaconas et al, 1989;Laganá, 1992;Clifford et al, 1999;Matsui et al, 2000;Badran et al, 2003;Mota, 2005;Nakamura et al, 2007;Claro, 2008;Dobranszki et al, 2009;Maia et al, 2011;Cebrián-Carretero et al, 2012;Claro et al, 2014;Schwertner et al, 2017;Abrão et al, 2018). Este método permite a observação direta das tensões existentes quando um modelo fotoelástico é submetido ao carregamento, podendo ser fotografado e avaliado quanto às diferenças de tensão de franjas (Campos Júnior et al, 1985).…”

“…Este método permite a observação direta das tensões existentes quando um modelo fotoelástico é submetido ao carregamento, podendo ser fotografado e avaliado quanto às diferenças de tensão de franjas (Campos Júnior et al, 1985). Em Odontologia foi comprovada uma correlação positiva entre a fotoelasticidade e cortes histológicos, o que validou a fotoelasticidade como um simulador de estruturas periodontais (Glickman et al, 1970;Brodsky et al, 1975); é possível encontrar um grande número de estudos odontológicos que fazem uso da fotoelasticidade (Zak, 1935;Glickman et al, 1970;Brodsky et al, 1975;Rossato, 1982;Campos Júnior et al, 1985;Chaconas et al, 1989;Laganá, 1992;Clifford et al, 1999;Matsui et al, 2000;Badran et al, 2003;Mota, 2005;Nakamura et al, 2007;Claro, 2008;Dobranszki et al, 2009;Maia et al, 2011;Cebrián-Carretero et al, 2012;Claro et al, 2014;Schwertner et al, 2017;Abrão et al, 2018).…”

“…Quanto ao material utilizado na fotoelasticidade, os estudos ou fazem uso de resina fotoelástica (Brodsky et al, 1975;Chaconas et al, 1989;Laganá, 1992;Matsui et al, 2000;Nakamura et al, 2007;Claro, 2008;Maia et al, 2011;Cebrián-Carretero et al, 2012;Claro et al, 2014;Schwertner et al, 2017;Abrão, 2018) ou de gelatina (Clifford et al, 1999;Badran et al, 2003;Mota, 2005;Dobranszki et al, 2009;Schiavon, 2010). Este é um aspecto de grande importância, pois o material deve suprir as necessidades dos pesquisadores, não apresentar tensões residuais e ser de baixo custo (Schiavon, 2010).…”