A influência do jateamento na cimentação de bandas ortodônticas

Abstract

OBJETIVO: comparar a resistência ao cisalhamento de cinco materiais utilizados na cimentação de bandas ortodônticas: um cimento de ionômero de vidro convencional (Ketac Cem), dois cimentos de ionômero de vidro modificados por resina (3M Multicure Glass Ionomer Cement e Fuji Ortho LC) e duas resinas compostas modificadas por poliácidos (Ultra Band-Lok e Transbond Plus). METODOLOGIA: sobre a superfície de um segmento de banda (6 x 6mm) foi posicionada uma matriz com um orifício de 3mm de diâmetro na qual foi inserido o material para cimentação. Metade da amostra foi jateada com partículas de óxido de alumínio. Os corpos-de-prova foram armazenados a 37ºC por 24 horas em umidade relativa de 100% e submetidos ao teste de cisalhamento a uma velocidade de 0,5mm/min. Utilizou-se ANOVA e o teste de comparações múltiplas de Tukey para comparar os grupos em cada tipo de superfície estudada (com ou sem jateamento), e o teste t Student para amostras pareadas para a comparação dos grupos jateados e não-jateados (p=0,01). RESULTADOS: nos grupos não-jateados, Ultra Band-Lok apresentou uma resistência de união significativamente maior (p<0,01) que a obtida pelos outros materiais, os quais não apresentaram diferença significante entre si. Após o jateamento, as resinas compostas modificadas por poliácidos apresentaram uma resistência de união significativamente maior (p<0,01) que a obtida pelos demais cimentos, sendo que 3M Multicure Glass Ionomer apresentou um valor de união superior (p<0,01) ao obtido pelo Ketac Cem e Fuji Ortho LC. CONCLUSÃO: o jateamento aumentou significativamente (p<0,01) a resistência de união em todos os grupos.

Assessment of the mechanical properties of glass ionomer cements for orthodontic cementation

“…In the analysis of shear bond strength, Multi-Cure Glass Ionomer showed higher values than others, however, with no significant difference. Similar results were already observed by Weissheimer et al 23,24 These materials have no chemical union to the metal, so these results may be explained for the greater mechanical imbrication presented by these materials. 5,9,12,13 In the initial proposition of the study, the analysis of cement remnant on the enamel surface after the shear test would be performed.…”

“…20,26 Furthermore, these materials are light cured, which reduces the total setting time and prevents larger exposure to moisture. 8,12,15,23,24 The conventional glass ionomer cements showed similar results and only the microhardness for Meron was significantly higher than Ketac Cem. Unlike these results, Aguiar et al 2 observed better mechanical properties of conventional GIC Ketac Cem in comparison to Meron, however, these authors did not analyze the microhardness of the materials.…”

“…These findings are in accordance with other authors who have observed better mechanical properties of this type of material in comparison with conventional GICs. 5,[12][13][14][15]23,24 The inclusion of resinous components such as HEMA and Bis-GMA in resin-modified GICs may be consider as responsible for better mechanical properties of these materials. 20,26 Furthermore, these materials are light cured, which reduces the total setting time and prevents larger exposure to moisture.…”

“…As an alternative, several authors proposed sandblasting with aluminum oxide of the inner surface of bands as a way to obtain higher imbrication and higher mechanical union strength to the bands. [12][13][14][15]23,24 These results show that the resin-modified GIC has better mechanical properties compared to conventional GICs. However, results of shear bond strengths were similar among the three materials, possibly indicating that they have similar clinical performance, for use in orthodontics.…”

“…[2][3][4][5][6]16,21,25,27 Specifically in use with orthodontic bands, these features become very important to reduce the incidence of caries and periodontal diseases and provide appropriate union strength between teeth and bands. 9,10,13,18,23,24 However, the conventional GICs have disadvantages which can compromise its mechanical performance, such as the susceptibility to moisture during the initial setting reaction, which may extend up to one hour. 1,4,5,7,20 In order to eliminate these deficiencies, some years ago resin-modified glass ionomers materials were developed, which have the acid-base reaction complemented by a photopolymerization reaction, reducing the time of the setting process and exposure to moisture and thus avoiding excessive water uptake of the oral cavity.…”