Effect of time and photoactivated face on bond strength of brackets and on degree of monomer conversion.

OBJECTIVE: To evaluate the effect of four different photoactivation protocols (according to "photoactivated faces" - mesial/distal, cervical/incisal or center - and "photoactivation time" - 6-3 s) of a high-power photo activator (Valo Cordless®-Ultradent) on the shear bond strength (SBS) between metal brackets and dental enamel and on the degree of conversion (DC) of an orthodontic resin. MATERIALS AND METHODS: 40 bovine incisor crowns were randomly assigned to 4 groups (n = 10). The brackets were bonded with Transbond XT® resin using 4 protocols according to the "photoactivation protocol" factor (which was subdivided into photoactivated faces and photoactivation time): V3C = 3 s + center; V6C = 6 s + center; V3M3D = 3 s on mesial + 3 s on distal; V3C3I = 3 s on cervical + 3 s on incisal. All the samples were stored for 4 months (water,37ºC) and then subjected to a SBS test (100KgF,1 mm/min). 40 resin discs were made to evaluate the monomer degree of conversion. Data from the SBS and DC were assessed by One-way ANOVA and Tukey's test (5%). Bond failures were analyzed according to the Adhesive Remnant Index (ARI) and evaluated by the Kruskal-Wallis test (5%). RESULTS: There was a statistically significant difference (p = 0.008) in the One-way ANOVA result for SBS values between all groups, but the protocols showed statistically similar results (p ≥ 0.05-Tukey's tests) concerning the photoactivated faces (V6C, V3M3D and V3C3I) and photoactivation time (V3C and V6C) factors individually. There was no statistically significant difference (p ≥ 0.05) in the One-way ANOVA result for DC values. CONCLUSION: The SBS and DC values will vary depending on the protocol applied. CLINICAL RELEVANCE: It is possible to maintain the bracket fixation quality with the use of a high-power LED photo activator associated with a shorter photoactivation time. However, it is assumed that not all types of protocols that might be applied will provide quality bonding, such as V3C, V3M3D and V3C3I, which may - depending on the SBS and DC values - affect the final treatment time, due to brackets debonding, or increase of possibility of damage to dental enamel during bracket removal. Clinical studies are suggested to confirm the hypotheses of this research.

Efeito do armazenamento em longo prazo sobre as características mecânicas dos elásticos de látex e sintéticos / Effect of long-term storage on the mechanical characteristics of latex and synthetic elastics

Este estudo objetivou determinar o efeito do armazenamento em longo prazo nas características mecânicas dos elásticos intermaxilares e o período apropriado para substituição no uso clínico. 270 elásticos (135 látex e 135 sintéticos), 3/16" médio, foram submetidos a testes de tração uniaxial com estiramento de 200% até 600% dos seus diâmetros internos. Os elásticos foram divididos nos grupos "Como Recebidos" (CR, n = 15); armazenados em refrigerador por 3 anos (n = 60), e armazenados à temperatura ambiente por 3 anos (n = 60). Os grupos de elásticos armazenados foram subdivididos em 4 subgrupos (n = 15 cada): sem estiramento prévio (SEP); estiramento prévio simulando o ambiente intraoral por 24 horas (EP24h), 48 horas (EP48h) e 72 horas (EP72h). Quanto aos elásticos de látex, as forças expressadas pelo grupo SEP, independente da temperatura de armazenamento, permaneceram similares às forças do grupo CR. Elásticos armazenados em temperatura ambiente de SEP até EP72h perderam aproximadamente 25 gF (p = 0.001), enquanto os refrigerados perderam em média 10 gF (p = 0.05). Sobre os elásticos sintéticos, o grupo SEP, independente da temperatura de armazenamento, ganhou, em média, 50 gF (p = 0.001) em comparação ao grupo CR. Os armazenados em temperatura ambiente, desde SEP até EP72h, perderam em média 30 gF (p = 0.001), enquanto os refrigerados perderam aproximadamente 50 gF (p = 0.001). Concluiu-se que os elásticos ortodônticos armazenados em longo prazo em suas embalagens originais expressam forças maiores do que os elásticos novos, e ao usar clinicamente elásticos armazenados a longo prazo, as substituições podem ser feitas a cada 72 horas sem perda da eficiência mecânica (AU)

This paper aimed to determine the effect of long-term storage on latex and non-latex intermaxillary elastics, and the proper time between substitutions. 270 elastics (135 latex and 135 non-latex elastics), medium force and standard size of 3/16", underwent uniaxial tensile tests with increase from 200% to 600% of their inner diameter. Each type was divided into groups of as received elastics (AR - n = 15), 3 years stored under refrigeration (n=60), and e years stored at room temperature (n=60). The stored groups were divided into 4 subgroups (n = 15): no previous stretching (NPS), pre-stretched si mulating the intraoral environment during 24 hours (PS24h), 48 hours (PS48h), and 72 hours (PS72h). About the elastics of latex, the forces expressed by the NPS at room temperature remained equal to the AR, while the forces of the refrigerated NPS had increased ±70 gF on average (p = 0.001). PS24h to PS72h at room temperature showed loss of ±20 gF (p = 0.001) when compared to the NPS or to AR. Non-latex - NPS, regardless of the temperature of storage, increased forces ± 70gF (p = 0.001) when compared to the AR. Starting at PS24h to PS72h, it was seen an average loss of ± 40gF (p = 0.001) when compared to the NPS. All 3 years stored non-latex elastics forces increased ± 30gF (p = 0.01) when compared to the AR. It was concluded that orthodontic elastics long-term stored in their original packages shows higher average forces than new elastics, and the replacement, when using long-term stored could be every 72 hours (AU)

É possível realizar tracionamento ortodôntico cirúrgico em incisivo com dilaceração radicular? / Is it possible to perform surgical orthodontic traction on incisor with root dilaceration?

Resumo Introdução: O traumatismo dental na dentição decídua pode influenciar o desenvolvimento dos sucessores permanentes e causar um deslocamento da coroa em relação à raiz dental, gerando uma curvatura definida como dilaceração, que em grande parte dos casos impede a irrupção normal do dente permanente. Diversas são as possibilidades de tratamento, desde exodontia ao tratamento ortocirúrgico. Objetivo: O presente trabalho tem o objetivo de relatar um caso clínico de incisivo central superior esquerdo (21) com dilaceração radicular cujo tratamento envolveu procedimento cirúrgico e tracionamento ortodôntico ancorado no disjuntor maxilar. Resultado: O desfecho do tratamento foi satisfatório, visto que o dente incluso foi reposicionado e a má oclusão da paciente foi corrigida. Conclusão: O tracionamento ortocirúrgico de incisivo superior permanente com dilaceração radicular é desafiador e com prognóstico incerto. Contudo, seu reposicionamento é possível quando se realiza um diagnóstico, planejamento periodontal e biomecânico adequado (AU)

Abstract Introduction: Dental trauma in the primary dentition can influence the development of permanent successors and cause a displacement of the crown in relation to the dental root, generating a curvature defined as laceration, which in most cases prevents the normal eruption of the permanent tooth. There are several treatment possibilities, from extraction to orthosurgical treatment. Objective: The present study aims to report a clinical case of a left upper central incisor (21) with root laceration whose treatment involved a surgical procedure and orthodontic traction anchored in the maxillary breaker. Result: The treatment outcome was satisfactory, since the included tooth was repositioned and the patients' malocclusion was corrected. Conclusion: Orthosurgical traction of the permanent upper incisor with root dilaceration is challenging and has an uncertain prognosis. However, its repositioning is possible when a diagnosis, periodontal and biomechanical planning is performed.(AU)

Tratamento da atresia maxilar associada à sobremordida acentuada em paciente Classe II de Angle ­ relato de caso / Tratamento da atresia maxilar associada à sobremordida acentuada em paciente Classe II de Angle ­ relato de caso

Resumo O tratamento precoce das más oclusões é preconizado principalmente pela possibilidade de tratamento ortopédico. Uma Classe II não tratada pode trazer prejuízos na fala, deglutição, respiração e, consequentemente, na qualidade de vida do paciente. Quando há alterações transversais, verticais e anteroposteriores associadas, os tratamentos tornam-se mais desafiadores. O objetivo desse estudo foi apresentar um caso clínico de um paciente com má oclusão de Classe II em fase de crescimento, com mordida cruzada posterior unilateral, falta de espaço na arcada superior e sobremordida profunda associada à curva de Spee acentuada no arco mandibular. Com o tratamento planejado, foi alcançado um resultado estético e funcional adequado com correção da Classe II de Angle, criação de espaço no arco para alinhamento dos caninos, correção da mordida cruzada e da sobremordida acentuada. Concluiu-se que a disjunção palatina para correção de mordida cruzada posterior e o uso de mecânica com cantilevers para correção precoce da curva de Spee foram satisfatórios neste caso clínico. Conhecer biomecânica e seus efeitos otimizam o tratamento (AU)

Abstract The early treatment of malocclusions is recommended by the possibility of orthopedic treatment. An untreated Class II can impair speech, swallowing, breathing and, consequently, the patient's quality of life. When transverse, vertical, and anteroposterior changes are associated, treatments become more challenging. This study aimed to present a clinical case of a patient with Class II malocclusion in the growth phase, with unilateral posterior crossbite, lack of space in the upper arch, and deep overbite associated with the sharp Spee curve in the mandibular arch. With the planned treatment, an adequate aesthetic and functional result was achieved with Angle Class II correction, creating space in the arch for alignment of the canines, correction of the cross bite, and the marked overbite. It was concluded that the palatal disjunction for posterior crossbite correction and the use of cantilever mechanics for early correction of the Spee curve were satisfactory in this clinical case. Knowing biomechanics and its effects optimize the treatment (AU)

Retinal damage related to high-intensity light-emitting diode exposure: An in vivo study.

INTRODUCTION: The objective of this investigation was to evaluate the effects of high-intensity light-emitting diode (LED) light from a curing device on the retinas of Wistar rats. METHODS: Six male Wistar rats were used, and their ocular structures were the focus of this study. During the photostimulation of each animal, the right eye of the animal, considered the control sample, was covered with a removable polyvinyl chloride cap, and the contralateral eye, the experimental sample, was exposed to high-intensity LED light, 3200 mW/cm2 (VALO Ortho; Ultradent Products, South Jordan, Utah) for 144 seconds from a distance of 30 cm. The animals were exposed to the LED light 3 times on the same day to investigate if any acute inflammatory changes in the retina occurred. Seven days after the photostimulation sessions, the animals were anesthetized and perfused with paraformaldehyde solution. After which, the eyes were resected and processed histologically. The histologic sections were analyzed stereologically and histomorphometrically to measure the parameters of the retina under investigation. RESULTS: There was a statistically significant increase in total retinal volume in the experimental group because of the increased volume of the ganglion cell layers, inner plexiform layers, outer nuclear layers, and the cone and rod extensions. There was no statistically significant difference in terms of density. However, there was a statistically significant increase in the nuclear area of the cells in all the studied layers in the group exposed to high-intensity LED light. In addition, hyperchromatic cells that are suggestive of pyknosis were observed. CONCLUSIONS: An acute but short protocol of exposure of high-intensity LED light to the eye caused morphometric alterations in the retinal structures, specifically in the nuclear area of the photosensitive cells.

Capacidade dos ortodontistas em predizer a tendência de crescimento craniofacial a partir da análise morfológica de telerradiografias laterais / Capability of orthodontists to predict craniofacial growth trend using morphological analysis of lateral teleradiographies

Objetivo: Avaliar a capacidade dos ortodontistas em determinar a tendência de crescimento craniofacial pela análise morfológica da telerradiografia lateral. Material e métodos: Três telerradiografias laterais representativas de cada tendência de crescimento (vertical, equilibrado e horizontal) foram selecionadas. As telerradiografias laterais foram digitalizadas e recortadas nas regiões da cabeça da mandíbula, ramo da mandíbula, ângulo goníaco, plano mandibular, chanfradura da mandíbula, sínfise mandibular, plano oclusal e ângulo interincisal. Os recortes e as telerradiografias completas foram distribuídas aleatoriamente em um questionário eletrônico que foi aplicado a 105 profissionais divididos em três grupos de acordo com o tempo de formação como ortodontistas. Os ortodontistas deveriam definir qual a tendência de crescimento que as imagens radiográficas sugeriam, a partir da observação da morfologia das estruturas anatômicas em destaque. Resultados: Os ortodontistas demonstraram grau de concordância pobre para a cabeça da mandíbula na tendência de crescimento horizontal. Uma concordância quase perfeita foi observada para o ângulo goníaco e para o plano mandibular na tendência vertical, para a chanfradura mandibular e para o plano mandibular na tendência horizontal e, quando todas as estruturas anatômicas foram analisadas nas telerradiografias completas. Não houve diferenças significativas na análise morfológica realizada pelos grupos estudados. Conclusão: Os ortodontistas demonstraram diferentes graus de concordância na análise morfológica da telerradiografia lateral, a depender da estrutura anatômica e da tendência de crescimento craniofacial analisada. Implicações clínicas: A predição da tendência de crescimento craniofacial por meio da observação de estruturas anatômicas na telerradiografia lateral parece ser uma ferramenta alternativa de diagnóstico para a análise cefalométrica. (AU)

Objective: To assess orthodontist's capability to predict the craniofacial growth trend by observing the morphology of anatomical structures in lateral cephalograms. Materials and Methods: Three lateral cephalograms representing each growth trend (vertical, balanced, and horizontal) were selected. The lateral cephalograms were digitized and cut in the regions of the mandible head, mandible ramus, gonial angle, mandibular plane, mandibular notch, mandibular symphysis, occlusal plane and interincisal angle in order to centralize the condy- lar process. An electronic questionnaire comprised by the edited images and the complete cephalograms was applied to 105 orthodontists divided into three study groups according to the orthodontic practice time. The orthodontists should define which was the growth trend that the radiographic images suggested by the observation of the anatomic structures highlighted. Results: The orthodontists demonstrated a poor degree of agreement for the mandible head in the horizontal growth trend. An almost perfect agreement was observed for the gonial angle and the mandibular plane in the vertical trend, for the mandibular notch and the mandibular plane in the horizontal trend, and when all anatomic structures were analyzed in complete cephalograms. No significant intergroup differences were observed. Conclusion: The orthodontists showed different degrees of agreement in the morphological analysis of lateral cephalograms depending on the anatomical structure and the craniofacial growth trend analyzed. Clinical implications: Prediction of craniofacial growth trend through observation of anatomical structures on lateral cephalograms seems to be an alternative diagnostic tool for cephalometric analysis.(AU)

Can we expect similar behavior among CuNiTi 35°C wires?

OBJECTIVE: This paper aims to verify the thermodynamic, mechanical and chemical properties of CuNiTi 35ºC commercial wires. METHODS: Forty pre-contoured copper-nickel-titanium thermodynamic 0.017 x 0.025-in archwires with an Af temperature of 35°C were used. Eight wires from five different manufacturers (American Orthodontics® [G1], Eurodonto® [G2], Morelli® [G3], Ormco® [G4] and Orthometric® [G5]) underwent cross-sectional dimension measurements, tensile tests, SEM-EDS and differential scanning calorimetry (DSC) tests. Parametric tests (One-way ANOVA and Tukey post-test) were used, with a significance level of 5%, and Pearson's correlation coefficient test was performed between the Af and chemical elements of the wires. All sample tests and statistical analyses were double-blinded. RESULTS: All wires presented standard dimensions (0.017 x 0.025-in) and superelastic behavior, with mean plateau forces of: G1 = 36.49N; G2 = 27.34N; G3 = 19.24 N; G4 = 37.54 N; and G5 = 17.87N. The Af means were: G1 = 29.40°C, G2 = 29.13°C and G3 = 31.43°C, with p>0.05 relative to each other. G4 (32.77°C) and G5 (35.17°C) presented statistically significant differences between each other and among the other groups. All samples presented Ni, Ti, Cu and Al in different concentrations. CONCLUSIONS: The chemical concentration of the elements that compose the alloy significantly influenced the thermodynamic and mechanical properties.

Can we expect similar behavior among CuNiTi 35°C wires?

ABSTRACT Objective: This paper aims to verify the thermodynamic, mechanical and chemical properties of CuNiTi 35ºC commercial wires. Methods: Forty pre-contoured copper-nickel-titanium thermodynamic 0.017 x 0.025-in archwires with an Af temperature of 35°C were used. Eight wires from five different manufacturers (American Orthodontics® [G1], Eurodonto® [G2], Morelli® [G3], Ormco® [G4] and Orthometric® [G5]) underwent cross-sectional dimension measurements, tensile tests, SEM-EDS and differential scanning calorimetry (DSC) tests. Parametric tests (One-way ANOVA and Tukey post-test) were used, with a significance level of 5%, and Pearson's correlation coefficient test was performed between the Af and chemical elements of the wires. All sample tests and statistical analyses were double-blinded. Results: All wires presented standard dimensions (0.017 x 0.025-in) and superelastic behavior, with mean plateau forces of: G1 = 36.49N; G2 = 27.34N; G3 = 19.24 N; G4 = 37.54 N; and G5 = 17.87N. The Af means were: G1 = 29.40°C, G2 = 29.13°C and G3 = 31.43°C, with p>0.05 relative to each other. G4 (32.77°C) and G5 (35.17°C) presented statistically significant differences between each other and among the other groups. All samples presented Ni, Ti, Cu and Al in different concentrations. Conclusions: The chemical concentration of the elements that compose the alloy significantly influenced the thermodynamic and mechanical properties.

RESUMO Objetivo: O presente artigo teve como objetivo verificar as propriedades termodinâmicas, mecânicas e químicas de fios CuNiTi 35°C comerciais. Métodos: Foram utilizados 40 arcos termodinâmicos pré-contornados de cobre-níquel-titânio de 0,017" x 0,025" e temperatura Af de 35°C. Oito fios de cinco fabricantes diferentes (American Orthodontics® [G1], Eurodonto® [G2], Morelli® [G3], Ormco® [G4] e Orthometric® [G5]) foram submetidos a medições de suas secções transversais, testes de tração, MEV-EDS e calorimetria diferencial (DSC). Foram utilizados testes paramétricos (One-way ANOVA e pós-teste de Tukey), com nível de significância de 5%, e foi realizado o teste do coeficiente de correlação de Pearson entre a temperatura Af e os elementos químicos dos fios. Todos os testes das amostras e análises estatísticas foram duplo-cegos. Resultados: Todos os fios apresentavam dimensões padronizadas (0,017" x 0,025") e comportamento superelástico, com forças médias de platô de G1 = 36,49 N; G2 = 27,34 N; G3 = 19,24 N; G4 = 37,54 N; e G5 = 17,87 N. As médias de Af foram: G1 = 29,40°C, G2 = 29,13°C e G3 = 31,43°C, com p> 0,05 entre si. G4 (32,77°C) e G5 (35,17°C) apresentaram diferenças estatisticamente significativas entre si e entre os demais grupos. Todas as amostras apresentaram Ni, Ti, Cu e Al em diferentes concentrações. Conclusões: A concentração química dos elementos que compõem a liga influenciou significativamente as propriedades termodinâmicas e mecânicas.

Low-level laser therapy (830 nm) on orthodontic pain: blinded randomized clinical trial.

The objective of this research was to compare the effect single low-level laser therapy (LLLT) irradiation on pain perception in patients having fixed appliance treatment in the clinic of orthodontics. Sixty-two patients were recruited to participate in this randomized, double-blinded, placebo-controlled study. The patients were assigned to four groups: group I-laser on the right side; group II-placebo on the right side; group III-laser on the left side; group IV-placebo on the left. The laser or placebo was applied before separation, 24 and 48 h after separation of their first permanent molars in the lower arch. Just after the separation, the average of the pain for the placebo group was 1.6, significantly greater than the average of 1.1 registered for the laser group (p = 0.013). After 24 h and before the new irradiation, the values registered among the different groups did not show any differences. In relation to the gender, only after the first irradiation in placebo group, the female had a level of pain (0.1) significantly higher (p = 0.04) compared to male, and after 48 h, the group where the laser was applied had a difference (p = 0.04) among the gender with a value of lower pain for men (0.6) than for women (1.6).The laser irradiation to minimize the pain was only effective when applied immediately after treatment and separation. In general way, there were no differences between the genders, except after the first placebo group irradiation in which the female had a significantly higher level of pain compared to male and after 48 h. The pain cycle observed in this study had its peak in 24 h, both for laser's and placebo's group.

Effect of different bonding protocols on degree of monomer conversion and bond strength between orthodontic brackets and enamel.

The objective of the present study was to evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the "surface treatment" factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and "polymerization" factor (R20: Radii-Cal®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wallis and Mann-Whitney tests (5%). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey's test (5%). For the SBS, the factors "polymerization" (R20 = 8.1B; V20 = 13.2A; V3 = 5.2C, p = 0.0001) and "surface treatment" (A = 3.1C; ATxt = 13.6A; Tse = 12.3A; SBU = 6.3B, p = 0.0001) were statistically significant among groups. The highest adhesion value were found for the ATxt/V20 group (22.2A) and the lowest value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p = 1.0). Regarding DC, the factors "polymerization" (R20 = 66.6A; V20 = 58.4B; V3 = 45.1C, p = 0.0001) and "surface treatment" (A = 52B, ATxt = 59.7A, Tse = 51.4B, SBU = 63.8A, p = 0.0001) were statistically significant. Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion.

Effect of different bonding protocols on degree of monomer conversion and bond strength between orthodontic brackets and enamel

Abstract The objective of the present study was to evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the "surface treatment" factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and "polymerization" factor (R20: Radii-Cal®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wallis and Mann-Whitney tests (5%). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey's test (5%). For the SBS, the factors "polymerization" (R20 = 8.1B; V20 = 13.2A; V3 = 5.2C, p = 0.0001) and "surface treatment" (A = 3.1C; ATxt = 13.6A; Tse = 12.3A; SBU = 6.3B, p = 0.0001) were statistically significant among groups. The highest adhesion value were found for the ATxt/V20 group (22.2A) and the lowest value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p = 1.0). Regarding DC, the factors "polymerization" (R20 = 66.6A; V20 = 58.4B; V3 = 45.1C, p = 0.0001) and "surface treatment" (A = 52B, ATxt = 59.7A, Tse = 51.4B, SBU = 63.8A, p = 0.0001) were statistically significant. Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion.

Avaliação de rugosidade, dureza e superfície dos cimentos de ionômero de vidro após diferentes sistemas de acabamento e polimento / Evaluation of roughness, hardness, and surface of ionomer glass cements after submission to different systems of finishing and polishing

Introdução: A rugosidade de superfície é uma limitação que interfere nos desempenhos mecânico e estético do cimento de ionômero de vidro (CIV), sendo necessária a utilização de procedimentos para acabamento e polimento adequados às propriedades desse material. Objetivo: Avaliar o efeito de diferentes sistemas de acabamento e polimento na rugosidade, dureza e superfície de restaurações realizadas com dois tipos de CIV. Material e método: Foram utilizados 100 corpos de prova (CP), divididos em 10 grupos, de acordo com o tipo de CIV (convencional e modificado por resina) e o sistema de acabamento e polimento empregado [C-tira de poliéster (controle); PD-ponta diamantada; DA-discos abrasivos; PE-ponta Enhance; BM-broca multilaminada]. Após sete dias em água destilada, os CP foram avaliados em Microscópio Eletrônico de Varredura (MEV) e submetidos aos testes de rugosidade de superfície e microdureza Vickers. A análise estatística foi realizada com ANOVA dois fatores e pós-Teste de Tukey. Resultado: A análise por MEV indicou superfície mais lisa no grupo BM em ambos os tipos de CIV. Quanto à rugosidade, observou-se diferença estatisticamente significante (p<0,05) entre grupos do CIV convencional, mas não houve diferença entre os tipos de CIV. Com relação à dureza, o CIV convencional apresentou melhores resultados que o modificado por resina. No fator materiais de acabamento e polimento, não se verificou diferença estatisticamente significativa, independentemente do tipo de CIV. Conclusão: os grupos BM apresentaram melhores resultados ao MEV; o tipo de CIV não influenciou os valores de rugosidade; o tipo de polimento não influenciou a dureza.

Introduction: The roughness of glass ionomer cement (GIC) is a limitation that interferes with its mechanical and aesthetic performance, and it is necessary to use appropriate finishing and polishing procedures in restorations produced with this material. Objective: To evaluate the effect of different finishing and polishing systems on roughness, hardness and surface of restorations performed with two types of GIC. Material and method: 100 specimens were made and divided into 10 groups, according to the type of GIC (conventional and resin modified GIC) and the finishing and polishing system used (C (Control) - Mylar strip; PD - diamond burs; DA - abrasive disks; PE - Enhance system; BM - carbide burs). After 7 days in distilled water, the specimens were evaluated by Scanning Electron Microscopy (SEM) and submitted to surface roughness and Vickers microhardness tests. Statistical analysis was performed by two-way ANOVA and Tukey post-test. Result: SEM analysis demonstrated a smoother surface in BM group in both types of GIC. Regarding roughness, a statistically significant difference (p <0.05) was observed between some groups of conventional GIC, but there was no difference between GIC types. Regarding hardness, conventional GIC showed better results than resin-modified GIC; Concerning to finishing and polishing materials factor, there was no statistically significant difference, regardless of the type of GIC. Conclusion: BM groups presented better results on SEM; The type of GIC did not influence the roughness values; The type of polishing did not influence the hardness.

Stability of beta-titanium T-loop springs preactivated by gradual curvature

ABSTRACT Objective: Evaluate changes in the force system of T-Loop Springs (TLS) preactivated by curvature, due to stress relaxation. Methods: Ninety TLSs measuring 6 x 10 mm, produced out with 0.017 x 0.025-in TMA® wire and preactived by gradual curvature, were randomly distributed into nine groups according to time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief, by trial activation. The other eight groups were tested after 24, 48 and 72 hours, 1, 2, 4, 8 and 12 weeks, respectively. Using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amount of horizontal force, moment and moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation, in an interbracket distance of 23 mm. Results: The horizontal forces decreased gradually among the groups (p< 0.001) and the moments showed a significant and slow decrease over time among the groups (p< 0.001). All groups produced similar M/F ratios (p= 0.532), with no influence of time. Conclusions: The TLSs preactivated by curvature suffered a gradual deformation over time, which affected the force system, specifically the moments, which affected the horizontal forces produced.

RESUMO Objetivo: avaliar as mudanças no sistema de forças das molas T pré-ativadas por curvatura, devido ao alívio de tensão estrutural. Métodos: noventa molas em forma de "T", medindo 6 mm x 10 mm, confeccionadas com fio de beta-titânio TMA® de 0,017" x 0,025" e pré-ativadas por curvatura gradual, foram distribuídas aleatoriamente em nove grupos, de acordo com o momento de avaliação. O Grupo 1 foi testado imediatamente após a pré-ativação da mola e liberação do estresse, por meio de simulação da ativação. Os outros oito grupos foram divididos conforme o intervalo de tempo testado: após 24, 48 e 72 horas; 1, 2, 4, 8 e 12 semanas. Usando um transdutor de momentos acoplado a um indicador digital para extensometria e adaptado a uma máquina universal de ensaios, as magnitudes da força horizontal, do momento e da proporção momento/força (M/F) foram registradas a cada 0,5 mm de desativação a partir da ativação inicial de 5 mm, utilizando-se uma distância interbraquetes de 23 mm. Resultados: as forças horizontais reduziram-se gradualmente nos grupos (p< 0,001) e o momento apresentou uma queda lenta e significativa ao longo do tempo (p< 0,001). Todos os grupos tiveram proporções M/F semelhantes (p= 0,532), não influenciadas pelo período de tempo. Conclusões: as molas pré-ativadas por curvatura gradual sofreram deformação progressiva ao longo do tempo, o que afetou o sistema de forças - especificamente o momento -, alterando as forças horizontais produzidas.

Influence of temperature and humidity on the long-term storage of latex and non-latex orthodontic elastics.

OBJECTIVES: The objective of this study was to evaluate the influence of long-term storage on latex and non-latex orthodontic elastics. MATERIALS AND METHODS: The sample consisted of 300 orthodontic elastics, 150 latex and 150 non-latex (American Orthodontics® *(AO) and Morelli®) of medium force and a standard size of 3/16'' divided into 20 groups, 10 for each manufacturer, with 15 specimens each. The groups (G1*-G10* and G1-G10) were made up based on the manufacturer, storage temperature (ambient and refrigerated), material, and ambient humidity (exposed and non-exposed). The elastics were stretched and their forces measured in five progressive increases of 100% of their inner diameter, starting at a level of 200% stretching, by the MESDAN LAB 3000® (MESDAN, Italy) testing machine. The tests were carried out at two different times: immediately in as-received state and again after 1 year. Data were analysed using SPSS 16.0 software, the Student's t-test, one-way analysis of variance (ANOVA) and the Tukey's post-test. RESULTS: There was a statistically significant difference between the average forces exerted by the latex elastics compared to the non-latex elastics for all distention levels evaluated, except for 300%; however, the different storage conditions of temperature and humidity did not interfere in the mechanical properties. CONCLUSION: Both the latex and non-latex elastics may be stored under any of the conditions tested in the present study, since there were no changes in the potential of the force exerted by the elastics in relation to their percentage stretch over a 1-year period.

Estudo comparativo in vitro da resistência ao desgaste entre o cimento de ionômero de vidro pó/líquido e o encapsulado / Comparative study in vitro wear resistance between powder/liquid glass ionomer cement and encapsulated

Introdução: Os cimentos de ionômero de vidro possuem limitações devido à sua baixa resistência mecânica, a qual está diretamente relacionada com a proporção pó/líquido e a sua manipulação. Com o intuito de padronizar o proporcionamento e a manipulação, surgiram os cimentos de ionômero de vidro encapsulados, os quais possuem proporção pré-estabelecida e manipulação mecânica. Objetivo: Comparar, in vitro, a resistência ao desgaste entre os cimentos de ionômero de vidro pó/líquido (Riva self cure e Riva light cure) e os encapsulados (Riva self cure e Riva light cure). Material e método: As amostras foram divididas em quatro grupos, tendo sido confeccionados 48 corpos de prova (n=12), sendo 12 para cada grupo, com as seguintes dimensões: 7 mm de diâmetro e 4 mm de espessura. O desgaste foi avaliado de acordo com a massa perdida no processo de escovação (10.000 ciclos). Os valores obtidos na diferença entre a massa inicial e a massa final foram submetidos à análise de variância ANOVA e Teste de Tamhane (p<0,05). Resultado: Segundo os resultados obtidos, todas as amostras sofreram perda de massa estatisticamente significativa e, em ordem crescente de desgaste, temos os cimentos de ionômero de vidro modificado por resina ‒ para os quais não houve diferença significativa entre o sistema pó/líquido (ΔM=11,62 mg e p=0,001) e o encapsulado (ΔM=12,96 mg e p=0,003) (p>0,05) ‒ seguidos pelo convencional pó/líquido (ΔM=20,68 mg e p=0,014) e o convencional encapsulado (ΔM=47,95 mg e p=0,002). Conclusão: Pode-se conseguir uma resistência ao desgaste semelhante e até melhor no sistema pó/líquido.

Introduction: The glass ionomer cements presents limitations because of their low mechanical strength, which is directly related to the powder / liquid proportion and handling. Aiming to standardize the proportioning and handling, first came the encapsulated glass ionomer cements, which have pre-determined ratio and mechanical manipulation. Objective: To compare the in vitro wear resistance of the encapsulated glass ionomer cements (Riva Self Cure and Riva Light Cure) and powder/liquid (Riva Self Cure and Riva Light Cure). Material and method: The samples were divided into four groups which were made 48 specimens (n=12), 12 for each group with 7 mm diameter by 4 mm thick, and the wear was evaluated according to the mass lost in the process of brushing (10,000 cycles). The obtained values on the difference of the initial and final mass were analyzed using ANOVA and Tamhane's test (p<0.05). Result: Resulting found that all groups had loss of statistically significant mass, and in ascending order of wear have the light-cured glass, which there was no statistically significant differences between the powder /liquid ionomer (ΔM=11,62mg p=0.001) and encapsulated (ΔM=12,96mg p=0.003) (p<0,05), followed by conventional self-curing (ΔM=20,68mg p=0.014) and encapsulated self-curing (ΔM=47,95mg p=0.002). Conclusion: Conclude that despite the glass ionomer cement encapsulated standardize the proportion and handling, you can get a similar resistance to wear and even better in powder /liquid.

Stability of beta-titanium T-loop springs preactivated by gradual curvature.

OBJECTIVE: Evaluate changes in the force system of T-Loop Springs (TLS) preactivated by curvature, due to stress relaxation. METHODS: Ninety TLSs measuring 6 x 10 mm, produced out with 0.017 x 0.025-in TMA® wire and preactived by gradual curvature, were randomly distributed into nine groups according to time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief, by trial activation. The other eight groups were tested after 24, 48 and 72 hours, 1, 2, 4, 8 and 12 weeks, respectively. Using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amount of horizontal force, moment and moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation, in an interbracket distance of 23 mm. RESULTS: The horizontal forces decreased gradually among the groups (p< 0.001) and the moments showed a significant and slow decrease over time among the groups (p< 0.001). All groups produced similar M/F ratios (p= 0.532), with no influence of time. CONCLUSIONS: The TLSs preactivated by curvature suffered a gradual deformation over time, which affected the force system, specifically the moments, which affected the horizontal forces produced.

Comparação da resistência à compressão entre o cimento de ionômero de vidro encapsulado e o sistema pó/líquido

Objetivo: comparar a resistência à compressão entre os cimentos de ionômero de vidro (CIVs) encapsulados (Riva self cure®e Riva light cure ®) e os seus correspondentes do sistema pó/líquido (Riva self cure® e Riva light cure®). Materiais e método: para o teste de resistência à compressão, doze corpos de prova foram confeccionados para cada grupo, em matrizes de aço inoxidável com 4,0 mm ± 0,1 mm de diâmetro e 6,0 mm ± 0,1 mm de altura. Os testes foram conduzidos em máquina de ensaios universal Shimadzu®, com velocidade de deslocamento de 1,0 mm/min. Após análise, os dados foram submetidos aos testes estatísticos ANOVA 2 fatores e pós-teste Tamhane. Resultados: houve diferença estatisticamente significativa (p < 0,05) apenas entre os CIVs encapsulados. As médias de resistência à compressão em valores absolutos são de 126,07 MPa para o CIV encapsulado fotopolimerizável, 118,34 MPa para o pó/líquido fotopolimerizável, 95,87 MPa para o encapsulado autopolimerizável e 122,07 MPa para o pó/líquido autopolimerizável. Conclusão: os CIVs encapsulados não apresentam valores superiores de resistência à compressão quando comparados ao sistema pó/líquido.

Avaliação do grau de conversão de resinas compostas fotoativadas em diferentes tempos e potências

Introdução: uma polimerização adequada é crucial para a obtenção das propriedades físicas ideais e o desempenho clínico das resinas compostas. Objetivo: avaliar o grau de conversão (GC) e dureza de resinas compostas fotoativadas com diferentes potências e tempos de polimerização. Materiais e método: foram confeccionados oitenta (n = 80) corpos de prova de re-sina composta (FiltekTM Z350 XT na cor A2B) com 4 mm de diâmetro e 2 mm de espessura, desses, quarenta (n = 40) foram destinados à avaliação do grau de conversão e quarenta (n = 40) para dureza. Foram feitos dez (n = 10) corpos de prova para cada grupo avaliado, sendo cinco para avaliar o grau de conversão e cinco, a dureza (P10T2, P7T2, P4T2, P1T2, P10T4, P7T4, P4T4, P1T4). Tendo as resinas do grau de conversão e de dureza fotoativadas por LEDS em 20 segundos na intensidade de potência de 1.000 mW/cm2, 700 mW/cm2, 400 mW/cm2 e 100 mW/cm2, os grupos P10T2, P7T2, P4T2 e P1T2, respectivamente. Os grupos P10T4, P7T4, P4T4 e P1T4 foram polimerizados na mesma intensidade de potência de luz, no entanto, com tempo de 40 segundos. Resultado: em relação ao grau de conversão, as resinas do P1T2 tiveram o menor valor, alcançado em média 22,67%, e o P10T4, com média 87,09%, alcançou o maior valor. Em relação à dureza, as resinas do P1T2 tiveram também a pior média, com 30,93 Kgf/mm², e o P10T4, a melhor média, com 82,02 Kgf/mm². Conclusão: quanto maior a potência do aparelho foto-polimerizador, maior será o GC e a dureza das resinas compostas. Os resultados deste estudo sugerem que um aparelho com intensidade de 100 mW/cm² não oferece um grau de conversão e dureza satisfatório, comprometendo o desempenho do material restaurador.

Superelasticity and force plateau of nickel-titanium springs: an in vitro study.

OBJECTIVE: This paper analyzed whether nickel-titanium closed coil springs (NTCCS) have a different superelastic (SE) behavior according to activation and whether their force plateau corresponds to that informed by the manufacturer. METHODS: A total of 160 springs were divided into 16 subgroups according to their features and activated proportionally to the length of the extensible part (NiTi) of the spring (Y). The force values measured were analyzed to determine SE rates and force plateaus, which were mathematically calculated. These plateaus were compared to those informed by the manufacturer. Analysis of variance was accomplished followed by Tukey post-hoc test to detect and analyze differences between groups. RESULTS: All subgroups were SE at the activation of 400% of Y length, except for: subgroups 4B and 3A, which were SE at 300%; subgroups 4E and 4G, which were SE at 500%; and subgroup 3C, which was SE at 600%. Subgroup 3B did not show a SE behavior. Force plateaus depended on activation and, in some subgroups and some activations, were similar to the force informed. CONCLUSIONS: Most of the springs showed SE behavior at 400% of activation. Force plateaus are difficult to compare due to lack of information provided by manufacturers.

Superelasticity and force plateau of nickel-titanium springs: an in vitro study

abstract Objective: This paper analyzed whether nickel-titanium closed coil springs (NTCCS) have a different superelastic (SE) behavior according to activation and whether their force plateau corresponds to that informed by the manufacturer. Methods: A total of 160 springs were divided into 16 subgroups according to their features and activated proportionally to the length of the extensible part (NiTi) of the spring (Y). The force values measured were analyzed to determine SE rates and force plateaus, which were mathematically calculated. These plateaus were compared to those informed by the manufacturer. Analysis of variance was accomplished followed by Tukey post-hoc test to detect and analyze differences between groups. Results: All subgroups were SE at the activation of 400% of Y length, except for: subgroups 4B and 3A, which were SE at 300%; subgroups 4E and 4G, which were SE at 500%; and subgroup 3C, which was SE at 600%. Subgroup 3B did not show a SE behavior. Force plateaus depended on activation and, in some subgroups and some activations, were similar to the force informed. Conclusions: Most of the springs showed SE behavior at 400% of activation. Force plateaus are difficult to compare due to lack of information provided by manufacturers.

resumo Objetivo: o presente artigo analisou se as molas helicoidais fechadas de níquel-titânio apresentam superelasticidade (SE), de acordo com a ativação, e se o platô de força medido corresponde ao informado pelo fabricante. Material e Métodos: 160 molas foram divididas em 16 subgrupos, de acordo com suas características, e foram ativadas proporcionalmente ao comprimento da parte extensível (NiTi) da mola (Y). Os valores de força obtidos foram analisados para determinar as taxas de SE e os platôs de força, os quais foram calculados matematicamente - sendo esses platôs comparados aos informados pelos fabricantes. Uma análise de variância foi realizada, seguida do teste post-hoc de Tukey, para detectar e analisar as diferenças entre os grupos. Resultados: todos os subgrupos apresentaram SE em ativação de 400% do comprimento Y, com exceção dos subgrupos 4B e 3A (que apresentaram SE a 300%), dos subgrupos 4E e 4G (com SE a 500%) e do subgrupo 3C (que apresentou SE na ativação de 600%). O subgrupo 3B não apresentou comportamento superelástico. Os platôs de força dependeram da ativação e em alguns subgrupos, em determinadas ativações, foram semelhantes à força informada pelo fabricante. Conclusões: a maioria das molas apresentou comportamento superelástico na ativação de 400%. Os platôs de força são difíceis de ser comparados, devido à falta de informações por parte dos fabricantes.