Resistência ao cisalhamento de bráquetes ortodônticos metálicos em dentes submetidos ao clareamento dentário / Orthodontic metal brackets resistance in whitened teeth subjected to shear strength

Introdução: pacientes adultos estão mais exigentes na busca pela estética oral, com isso, tem-se aumentando o uso de sistemas clareadores. Alguns estudos demonstram que há uma diminuição da resistência dos bráquetes após o clareamento. Objetivo: analisar a resistência as forças de cisalhamento de bráquetes em dentes submetidos ao tratamento clareador com peróxido de hidrogênio (H2O2). Metodologia: foram utilizados 30 dentes pré-molares, divididos aleatoriamente entre os três grupos: Grupo I: colagem direta dos bráquetes em dentes não clareados; Grupo II: colagem direta dos bráquetes em dentes clareados e submetidos ao teste de cisalhamento 15 dias após o clareamento, Grupo III: colagem direta dos bráquetes em dentes 24 horas dias após o clareamento. A colagem foi feita com o sistema Transbond XT. Os resultados obtidos nesse estudo foram registrados em Megapascal (MPa) e submetidos ao teste estatístico de Tukey segunda as normas da ANOVA. Resultados e Discussão: o grupo II não obteve diferença estatística significante em relação ao grupo I (controle), porém houve redução na resistência adesiva entre o grupo I e grupo III clareado com peróxido de hidrogênio à 35% na qual a colagem dos bráquetes foi realizada 24 horas após o clareamento dentário. Conclusão: recomenda-se um período de espera para a colagem dos bráquetes na superfície do esmalte submetido ao clareamento dentário.

Introduction: adult patients are demanding in regard of oral aesthetics. Therefore, there is increasing use of bleaching systems. Some studies show that there is a decrease in resistance of the brackets after dental bleaching. Objective: to analyze the strength of brackets shear strength in teeth submitted to bleaching treatment with hydrogen peroxide (H2O2). Method: a total of 30 premolars were randomly divided among the three groups. Group I: direct bonding of brackets on non-whitened teeth; Group II: direct bonding of brackets on whitened teeth and subjected to shear strength test 15 days after bleaching, Group III: direct bonding of brackets 24 hours days after bleaching. The bonding was performed with Transbond XT system. The results of this study were reported in Megapascal (MPa) and subjected to statistical Tukey test according to the ANOVA guidelines. Results and Discussion: group II did not presented difference statically significant compared to the group control (group I). However, there were reduction on the adhesion resistance between the group I and Group III, in which the brackets bonding was performed 24 hours after the dental bleaching with 35% hydrogen peroxide. There was a reduction in statistically significant bond strength between groups I and III. Conclusion: it is recommended a resting period to be done the placement of brackets on the surface of the enamel whitening submitted.

Histological evaluation after electrothermal debonding of ceramic brackets.

Aim: To evaluate the histological changes following electrothermal debonding (ETD) of ceramic brackets. Materials and Methods: A total of 50 first premolar teeth from 14 patients were divided into two groups: Group I consisted of 20 teeth which served as control, and the brackets were debonded using conventional pliers. (7 teeth were extracted 24 hours after conventional debonding, 7 teeth were extracted 28 to 32 days after conventional debonding and 6 teeth were extracted 56-60 days after conventional debonding). Group II consisted of 30 teeth and the brackets were debonded using the ETD unit. (10 teeth were extracted 24 hours after ETD, 10 teeth were extracted 28 to 32 days after ETD and 10 teeth were extracted 56-60 days after ETD. Immediately after extraction, the teeth were sectioned and prepared for histological examination. Results: The pulp was normal in most samples of the control group. In group II, mild inflammation was observed in the 24 hour sample while the 28 to 32 day sample showed signs of healing. The 56-60 day sample showed that the pulp was similar to the control group in 6 out of the 10 samples. Conclusion: The ETD of ceramic brackets did not affect the pulp and the changes which were observed, were reversible in nature

Soportes de autoligado en ortodoncia / Orthodontic brackets

Fundamento: el sistema de ligado del arco al soporte debe ser seguro, fuerte, rápido, confortable para el paciente, fácil de usar y producir poca fricción. Objetivo: argumentar el manejo de las técnicas fijas con el uso de los soportes de autoligado. Conclusiones: los soportes de autoligado constituyen una opción novedosa en ortodoncia, pero en Cuba se han utilizado poco. Se clasifican en pasivos y activos. El sistema Damon, Vision LP y Time son los más utilizados entre los pasivos y el Speed e In Ovation entre los activos. Se describen cuatro fases de tratamiento para usar la técnica con este tipo de soportes y a pesar de su alto costo, es más ventajosa que las técnicas precedentes.

Background: the system bound to the orthodontic bracket arch must be safe, strong, rapid and comfortable for the patient, easy to use and must provoke little friction. Objective: to argue about the management of fixed techniques with the use of brackets. Conclusions: brackets constitute a newfangled option in orthodontics, but in Cuba it has been rarely used. They are classified into passive and active. Damon system, Vision LP and Time are the mostly used among the passive ones and the Speed and In Ovation among the active ones. Four phases of treatment are described to use the technique of these orthodontic brackets and in spite of its high cost; it is more advantageous than the previous techniques.

Avaliação do efeito de tratamentos superficiais sobre a força de adesão de braquetes em provisórios de resina acrílica / Assessment of the effect of different surface treatments on the bond strength of brackets bonded to acrylic resin

OBJETIVO: avaliar a influência do tratamento de superfície de resinas acrílicas na resistência ao cisalhamento de braquetes colados com resina composta. MÉTODOS: foram confeccionados 140 discos de resina acrílica autopolimerizável (Duralay®), divididos aleatoriamente em 14 grupos (n=10). Em cada grupo, os corpos de prova receberam um tipo diferente de tratamento de superfície: grupo 1 = sem tratamento de superfície (controle); grupo 2 = silano; grupo 3 = jato de óxido de alumínio (JOA); grupo 4 = JOA + silano; grupo 5 = broca diamantada; grupo 6 = broca diamantada+ silano; grupo 7 = ácido fluorídrico; grupo 8 = ácido fluorídrico + silano; grupo 9 = ácido fosfórico; grupo 10 = ácido fosfórico + silano; grupo 11 = monômero de metilmetacrilato (MMA); grupo 12 = MMA + silano; grupo 13 = Plastic conditioner (Reliance®); grupo 14 = Plastic conditioner (Reliance®) + silano. Após o preparo de superfície, os corpos de prova foram analizados através da rugosimetria. Posteriormente, foram colados braquetes (Morelli®) de incisivo central "standard edgewise" com resina fotopolimerizável Transbond XT®; de acordo com as instruções do fabricante. RESULTADOS: o agente umectante à base de silano não teve um efeito estatisticamente significativo sobre os valores de força de adesão; os tratamentos com JOA e broca produziram maiores mudanças topográficas na superfície da resina acrílica, bem como os maiores valores de rugosidade; observou-se uma correlação não linear entre a força de adesão e a rugosidade de superfície; tratamentos com monômero e JOA resultaram nas maiores forças de adesão. CONCLUSÕES: o silano não foi capaz de aumentar a força de adesão entre braquete e resina acrílica. Sugere-se mais estudos sobre este tema, pois a força de adesão obtida foi muito baixa.

OBJECTIVE: To evaluate the influence of the surface treatment of acrylic resins on the shear bond strength of brackets bonded with composite resin. METHODS: Were fabricated 140 discs with autopolymerizing acrylic resin (Duralay™) and divided into 14 groups (n = 10). In each group, the specimens received a different type of surface treatment. Group 1= untreated surface (control), group 2= silane, group 3= aluminum oxide blasting (AOB), group 4= AOB + silane, group 5= diamond bur, group 6= diamond bur + silane, group 7= hydrofluoric acid, group 8= hydrofluoric acid + silane, group 9= phosphoric acid, group 10= phosphoric acid + silane, group 11= methylmethacrylate monomer (MMA), group 12= MMA + silane, group 13= plastic conditioner (Reliance®); group 14= plastic conditioner (Reliance™) + silane. After surface treatment the specimens were analyzed using a surface roughness tester. Subsequently, standard edgewise central incisor brackets (Morelli™) were bonded using Transbond XT™ light-cure adhesive system, according to the manufacturer's instructions. RESULTS: The silane-based wetting agent had no statistically significant effect on bond strength values. Treatments with AOB and bur generated the highest topographical changes on the surface of acrylic resin as well as the highest roughness values. A nonlinear correlation was found between bond strength and surface roughness. Monomer + AOB treatment yielded the highest bond strength values. CONCLUSIONS: Silane failed to increase the bond strength between brackets and acrylic resin. We encourage further studies on this subject since the bond strength achieved in our study was extremely low.

[Shear bond strength of ideal maccoo and brilliant light cure composites in orthodontic bracket bonding to enamel]

Due to the disadvantages of self cure composites, application of light cure composites is suggested in orthodontics but light transmission through metal brackets is in doubt. The aim of this study was to compare shear bond strength [SBS] of Ideal Maccoo and Brilliant composites in bonding steel and ceramic brackets. Eight intact first upper premolars were collected for this experimental invitro study and randomly divided into 4 equal groups. The buccal surfaces were etched and cured by visible light after applying margin bond resin. In the first group Ideal Maccoo composite was applied on the steel bracket base [SI group], bracket positioning in the correct location was done and then curing was performed by visible light for 40 seconds [20 seconds from occlusal and 20 seconds from gingival]. In the second group fascination ceramic brackets with Ideal Maccoo composite [CI group], in the third group ceramic brackets with Brilliant composite [CB group] and in the fourth group steel brackets with Bralliant composite [SB group] were bonded to teeth with the same method. SBS was measured by Zwick testing Machine. To compare the groups, Kolomgrov-Smironov, two way analysis of variance, one way analysis of variance and Tukey tests were used. Mean SBS was 9.71 +/- 3.37, 7.36 +/- 4.40, 5.58 +/- 2.21 and 12.36 +/- 5.77 in SI, CI, CB and SB groups respectively. Tukey test showed significant difference between SB and CB groups [P<0.001], no significant differences was detected between CI and SI, SI and SB and between CI and CB. Ideal Maccoo and Brilliant light cure composites had good capabilities in steel bracket bonding whereas ceramic brackets had lower shear bond strength. In bonding ceramic brackets only Ideal Maccoo composite showed acceptable results

[Comparison of enamel fluoride uptake between three different glass ionomers used in orthodontic banding: an in vitro study]

Decalcification of the teeth remains a problem during orthodontic treatment with fixed appliances. It has been suggested that fluoride-releasing glass ionomer cements could decrease the risk of enamel decalcification under orthodontic bands. The objective of this study was to compare enamel fluoride uptake from three different glass ionomer cements [Aqua Cem, Resilience and Bandite] used for band cementation in permanent teeth in vitro. In an experimental in vitro randomized trial, 33 sound premolars that were extracted for orthodontic purposes were randomly divided into thee groups. In each group one of the glass ionomer cements was tested. A 6 mm diameter adhesive tape was placed over the center of buccal enamel surface of each tooth and then the entire surfaces of them were painted with two layers of an acid protective nail polish. After removing adhesive tapes, brackets were cemented with one of the cements over the window. Then all the specimens were immersed in 5ml deionized water for one month. Brackets were debonded and remnants of cements were removed. The windows were etched with 1mI perchloric acid 0.5 M for 60 seconds and then 4 ml of 0.5 M Total Ionic Strength Adjustment Buffer [TISAB] was added to perchloric acid. Fluoride and calcium concentration of the solutions were determined by Potentiometer and Inductively Coupled Plasma, respectively. The depth of etch and fluoride concentration in the enamel were calculated, and the results were analyzed with one way ANOVA and Kruskal-Wallis test. In Resilience the mean fluoride concentrations group were higher and depths of etch were lower than in the other two groups. But there was no statistically significant difference between them. It seemed that an increase in fluoride uptake may be capable of rendering a tooth more resistant to dental decalcification