Correlation between mechanical properties and stabilization time of chemical bonds in glass-ionomer cements

Abstract The objective was to evaluate the compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), and Knoop microhardness (KH) of different conventional restorative glass-ionomer cements (GICs) and to correlate these mechanical properties (MP) with the stabilization time (ST) of their chemical bonds. Eighteen GICs were tested: Bioglass [B], Chemfil Rock [CR], Equia Forte [EF], Gold Label 2 [GL2], Gold Label 9 [GL9], Glass Ionomer Cement II [GI], Ionglass [IG], Ion Z[ IZ], Ionomaster [IM], Ionofil Plus [IP], Ionostar Plus [IS], Ketac Molar Easymix [KM], Magic Glass [MG], Maxxion R [Ma], Riva Self Cure [R], Vidrion R [V], Vitro Fil [VF] and Vitro Molar [VM]. The mechanical strength tests were performed in a universal testing machine. KH readings were done with a diamond indenter. STs were examined by Fourier Transform Infrared spectroscopy (FTIR). Data were analyzed with ANOVA and Tukey test (p<0.05). The Spearman rank test was used to evaluate the dependence between the MPs and ST results. The highest MP values were EF, GL2, GL9, GI and KM and the lowest for MG, MA, B, VF and IM. The longest ST was for GL2 and the shortest was for B. ST correlated positively with MP. GICs with longer chemical bonds ST are generally stronger and the ST value obtained from FTIR was useful in predicting the strength of GICs tested.

Effect of the ceramic translucency on the long-term water sorption and solubility of resin cements

Aim: The aim of this study was to evaluate the influence of the translucency of ceramic on water sorption and solubility of resin cements over time. Methods: Lithium disilicate ceramic slides (15x15x1 mm), A1 in color and with different translucencies (high-medium-low) were manufactured; and a glass slide with similar dimension was used as control. Under every slide, 15 specimens (8x0.5 mm) from each resin cement were prepared: light-cured (RelyX Veneer); conventional dual-cured (RelyX ARC); and self-adhesive dual-cured (Rely-X U200). The specimens were then sub-divided according to the period of evaluation (immediately, after 6 and 12 months of storage) (n=5). To evaluate the loss or gain of mass, the specimens were dried until a constant mass was reached. Subsequently, they were divided according to the respective period of storage at 37°C in distilled water and weighed immediately following removal from water. After each period, specimens underwent a new dehydration. Values from water sorption and solubility were calculated and statistically analyzed (Anova 3-way/Tukey test). Results: The lower translucency resulted in greater water sorption and solubility for all cements, regardless of the experimental period. The self-adhesive dual-cured cement showed higher water sorption under all experimental periods and had worse values after 1 year aging. Differences among solubility could only be detected after aging, and the light-cured material had higher values after 6 and 12 months. Conclusions: It could be concluded that the low degree of translucency can negatively influence the passage of light and interfere on the durability of the resin cement. The conventional dual-cured resinous agent seemed to be less affected by such condition

Effect of ultrasonic and Nd: Yag laser activation on irrigants on the push-out bond strength of fiber post to the root canal

Abstract Objective: This in vitro study aimed to compare the efficacy of irrigants using various irrigation activation methods to the push-out bond strengths of fiber post to root canal luted with self-adhesive resin cement (SARC). Methodology: Forty-eight decoronated human canines were used. The specimens were divided into four groups corresponding with the post-space irrigation process and were treated as follows: distilled water (DW) (Control) group received 15 mL of DW; sodium hypochlorite (NaOCl)+ethylenediaminetetraacetic acid (EDTA) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW; passive ultrasonic irrigation (PUI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was agitated with an ultrasonic file; and laser activated irrigation (LAI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was irradiated with Nd: YAG laser. Fiber posts were luted with SARC, and a push-out test was performed. Data was analyzed using one-way analysis of variance and Tukey HSD test. Results: The bond strength values for the groups obtained were as follows: Control (10.04 MPa), NaOCl+EDTA (11.07 MPa), PUI (11.85 MPa), and LAI (11.63 MPa). No statistically significant differences were found among all experimental groups (p>0.05). The coronal (12.66 MPa) and middle (11.63 MPa) root regions indicated a significantly higher bond strength compared with the apical (9.16 MPa) region (p<0.05). Conclusions: Irrigant activation methods did not increase the bond strength of fiber post to canal.

Influence of activation mode, fatigue, and ceramic interposition on resin cements' diametral tensile strength

Abstract This study evaluated the influence of activation modes, on Diametral Tensile Strength (DTS) of dual cured resin cements subjected to a Mechanical Fatigue test (MF). Four dual-cured resin cements (RelyX UNICEM [U], RelyX ARC [A], ENFORCE [E] and Nexus 2 [N]) were activated by three different curing modes as follows: Self-Curing (SC), Dual Cure activation with photoactivation executed directly (DC) and Dual Cure activation with Photoactivation Through Porcelain (DCTP). After 24 hours, half of the sample was subjected to 30.000 fatigue cycles at 1 Hz frequency and 12 N load. Then, all specimens were subjected to DTS test in Instron Universal Testing Machine and data were analyzed by three-way ANOVA and Tukey's Test (5%). The results of DTS test means (MPa) and standard deviation, for each cement factor activated by SC, DC and DCTP was respectively: U (28.12 ± 5.29; 37.44 ± 6.49 and 40.10 ± 4.39), A (49.68 ± 8.42; 55.12 ± 5.16 and 63.43 ± 6.92), E (49.12 ± 3.89; 56.42 ± 8.88 and 56.96 ± 6.45) and N (61.89 ± 11.21; 59.26 ± 9.47 and 62.56 ± 10.93). Turkey's test indicated that DC is related to the highest DTS values; Nexus 2 DTS remained the same independently of activation mode and that the Porcelain disk interposition enhanced DTS only for RelyX ARC the ANOVA statistical test indicated that MF didn't alter the DTS values for all experimental groups. MF results clinical implication is that all cements tested exhibited, in an immediate loading, good cross linked bonds quality.

Effect of different root dentin pretreatment protocols on the bond strength of fiber posts cemented with core buildup material / Efeito de diferentes protocolos de pré tratamento de dentinas radiculares na força de adesão de pinos de fibra cimentados com material de núcleo de preenchimento

Objective: The purpose of the study was to evaluate the push out bond strength of fiber posts -after cementaion with core build up material and dentin pretreatment using different adhesive protocolsin different root regions. Material and Methods: 28 endodonticaly treated human premolars were divided into 4 groups. The post spaces were treated with 1 of 4 different dentin bonding protocols: total etch light cured adhesive, solobond m; total etch dual cured adhesive, Excite f DSC; self-etching light cured adhesive, single bond universal; or selfetching dual cured adhesive, futura bond dc. Fiber posts, were luted with dual cured core material. The roots were cut into 2-mm-thick sections, in cervical, middle, and apical regions. Push-out tests were performed with a universal testing machine, and bond strength values (MPa) were calculated. Data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (a=.05). Failure modes were examined under stereo microscope. Results: The highest mean bond strength values were obtained for self-etch dual cured adhesive, (9.69 MPa). The Total etch light cured adhesive (2.81 MPa) showed the lowest bond strength. Self-etch light-polymerized and total etch dual-polymerized adhesives provided similar bond strengths (5.37, 5.72 respectively). The regional bond strength values were reduced significantly in apical post space (P<0.01). The most predominant failure type was mixed failure followed by adhesive failure. Conclusion: Dentin pretreatment using self-etch dual cured adhesives prior to fiber posts cementation offers a high bond strength. While using total-etch light cured adhesives is not recommended due to the low bonding quality.(AU)

Objetivo: O objetivo do estudo foi avaliar a força de adesão dos pinos de fibra após o cimentação com material de núcleo e o pré-tratamento da dentina utilizando diferentes protocolos adesivos em diferentes regiões radiculares. Material e Métodos: 28 pré-molares humanos tratados endodonticamente foram divididos em 4 grupos. Os condutos foram tratados com 1 de 4 diferentes protocolos de união à dentina: adesivo fotopolimerizável total, solobond m; adesivo de polimerização dual de condicionamento total, Excite f DSC; adesivo fotopolimerizável autocondicionante, Single Bond universal; ou adesivo de dupla curado autocondicionante, futura bond dc. Núcleos de fibra, foram cimentados com material resinoso e polimerizados. As raízes foram cortadas em seções de 2 mm de espessura, nas regiões cervical, média e apical. Testes de push-out foram realizados com uma máquina de testes universal, e os valores de resistência de união (MPa) foram calculados. Os dados foram analisados com análise de variância de 1 e 2 fatores e testes de comparação múltipla de Tukey (a = 0,05). Modos de falha foram examinados sob estéreo-microscópio. Resultados: Os valores médios mais elevados de resistência adesiva foram obtidos para o adesivo dual autocondicionante (9,69 MPa). O adesivo fotopolimerizável Total etch (2,81 MPa) apresentou a menor resistência de união. Os adesivos autocondicionantes fotopolimerizáveis e os de condicionamento tal duais, proporcionaram forças de adesão semelhantes (5,37, 5,72, respectivamente). Os valores de força de união regional foram significativamente reduzidos na região apical (P<0,01). O tipo de falha mais predominante foi falha mista seguida de falha adesiva. Conclusão: O pré-tratamento com dentina utilizando adesivos duais autocondicionantes antes da cimentação dos pinos de fibra oferece uma alta resistência de união. Enquanto que os adesivos de condicionamento total fotopolimerizáveis não sforam recomendados devido à baixa qualidade da adesão proporcionada. (AU)

Alternativas de tratamientos de superficie para adhesión de cerámica de disilicado de litio / Alternatives of surface treatments for adhesion of lithium disilicate ceramics

Introduction: the clinical success of a restoration is strongly associated with the quality and durability of the ceramic-cement resin interface. In order to obtain an adequate union between these materials of different nature surface treatments are used and achieve mechanical retention or chemical interaction. Objectives: to check if any method promotes a true chemical bond between lithium disilicate ceramics and resin cement. As well as determineif there is any treatment that reports bonding values comparable to hydrofluoric acid and silane (gold standard). Methods: a systematic literature review was developed based on the PRISMA strategy, where the databases were searched: Science Direct, Pubmed (MEDLINE), EMBASE, Springer Journal, SciELO with MeSH and free terms from 2005 to November 2016 for articles in English and Spanish on surface treatments for lithium disilicate. Results: from 58 publications selected a sample of 21 articles. Two articles reported high risk of bias. Conclusions: hydrofluoric acid and silane continue to be the method with the highest and most reliable adhesion values in the literature. Universal adhesives are an alternative to promote chemical adhesion additional to the silane. Diamond burs, Nd: YAG and Er: YAG laser are not recommended as surface treatments(AU)

Introducción: el éxito clínico de una restauración se asocia fuertemente a la calidad y duración de la interface cerámica-cemento resinoso. Para que exista una adecuada unión entre estos materiales de distinta naturaleza se emplean tratamientos de superficie para lograr una buena retención mecánica o interacción química. Objetivos: revisar si algún método promueve una verdadera adhesión química entre la cerámica de disilicato de litio y el cemento resinoso, así como determinar si existe algún tratamiento que reporte valores de unión comparables al ácido fluorhídrico y silano (patrón de oro). Métodos: se desarrolló una revisión sistemática de literatura basada en la estrategia PRISMA, donde se buscó en las bases de datos: Science Direct, Pubmed (MEDLINE), EMBASE, Springer Journal, SciELO con términos MeSH y libres desde el 2005 a noviembre de 2016 para artículos en inglés y español sobre tratamientos de superficie para disilicato de litio. Resultados: de 58 publicaciones, se seleccionó una muestra de 21 artículos. Dos artículos reportaron riesgo de sesgo alto. Conclusiones: el ácido fluorhídrico y silano continúan siendo el método con los valores de adhesión más altos y confiables de la literatura. Los adhesivos universales son una alternativa para promover adhesión química adicional al silano. Fresas diamantadas, laser Nd: YAG y Er:YAG no se recomienda como tratamientos de superficie(AU)

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.

Is the bonding of self-adhesive cement sensitive to root region and curing mode?

Abstract Objectives To evaluate the influence of two curing techniques on the degree of conversion (DC) of resin cements and on bond strength (BS) of fiber posts in different regions of root dentin. Material and Methods Twenty single-rooted premolars were endodontically treated, and the post spaces were prepared. The roots were randomly divided into two groups (n=10), according to the activation mode of the resin cement RelyX™ U200 (3M ESPE Saint Paul, MN, USA): conventional (continuous activation mode) and soft-start activation mode (Ramp). The posts (WhitePost DC/FGM) were cemented according to the manufacturer’s recommendations and, after one week, the roots were cross-sectioned into six discs each of 1-mm thickness, and the cervical, medium, and apical thirds of the root canals were identified. The DC was evaluated under micro-Raman spectroscopy and the BS was evaluated by the push-out test. The data were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results Neither the activation mode nor the root regions affected the DC of the resin cement. Higher BS was achieved in the soft-start group (p=0.036); lower BS was observed in the apical third compared to the other root regions (p<0.001). Irrespective of the activation mode and root region, the mixed failure mode was the most prevalent. Conclusion The BS of fiber posts to root canals can be improved by soft-started polymerization. The DC was not affected by the curing mode.

Técnicas para reduzir os efeitos da contração de polimerização das resinas compostas fotoativadas / Techniques for reducing the effects of polymerization shrinkage of composites photoactivated resins

Introdução: uma complicação inerente a todas as resinas compostas é o stress gerado pela contração de polimerização. As resinas compostas da atualidade, após a polimerização, perdem entre 2% a 3% de todo o seu volume. Essa perda pode acarretar em alterações fortemente comprometedoras a nível micro e macroscópico. Objetivo: abordar a importância do uso de técnicas e manobras clínicas, que visam diminuir a contração de polimerização das resinas compostas, reduzindo seus efeitos na cavidade, para que se tenha um procedimento restaurador com elevado índice de sucesso clínico e boa aceitação pelos pacientes. Material e Métodos: foi realizada uma revisão da literatura por meio de uma busca bibliográfica nas seguintes bases de pesquisa online: PUBMED/MEDLINE, LILACS, BBO e SCIENCE DIRECT, através do rastreio de artigos relevantes publicados entre o período de 2000 a 2015. Resultados: comparando as formas de ativação dos compósitos, os compósitos fotopolimerizáveis possuem um menor escoamento e maior stress de contração se comparados a compósitos com ativação química, isso se dá devido à fotoativação que se destaca por ser uma reação rápida quando comparada a outros métodos, não dispondo de tempo para a resina se acomodar na cavidade e ter uma boa interação com o sistema adesivo previamente aplicado, levando a grande parte dos problemas clínicos das restaurações. Conclusão: questionamentos sobre os efeitos da contração de polimerização, ainda não foram completamente elucidados no meio científico, por isso algumas técnicas como a escolha de fotopolimerizadores a LED, manutenção da fase pré gel, manutenção do Fator C e técnica de inserção incremental, podem ser usadas para minimizar os efeitos dessa contração nas restaurações feitas com resina, afim de reduzir insucessos como, sensibilidade pós operatória, infiltração marginal e riscos de agressão pulpar levando a uma maior longevidade dos procedimentos restauradores com materiais resinosos. (AU)

Introduction: a complication inherent in all composite resins is the stress generated by the polymerization contraction. The present composite resins, after polymerization, lose between 2% and 3% of their entire volume. This loss can lead to strongly compromising micro and macroscopic changes. Objective: to address the importance of using technical and clinical maneuvers, which aim to reduce polymerization shrinkage of composite resins, reducing its effects in the cavity, in order to have a restorative procedure with high clinical success rate and good patient acceptance. Material and Methods: a review of the literature through a literature search in the following search online databases was performed: PubMed/MEDLINE, LILACS, BBO and SCIENCE DIRECT, through the screening of relevant articles published between 2000 to 2015. Results: comparing both activation of composites, the dental composites have a lower flow and higher stress of contraction compared to composites with chemical activation, this is the due to photoactivation that stands out for being a quick reaction when compared to other methods, not providing time for the resin to settle in well and have a good interaction with the previously applied adhesive system, leading to much of the clinical problems of restorations. Conclusion: questions about the effects of polymerization shrinkage have not been fully elucidated in the scientific community, so some techniques such as the choice of curing lights to LED, the pre gel phase maintenance, maintenance of Factor C and incremental insertion technique can It is used to minimize the effects of this contraction in restorations made with resin in order to reduce failures as post-operative sensitivity, microleakage and pulp assault risks leading to increased longevity of restorative procedures with resinous materials. (AU)

In vitro evaluation of bond strength of four self-etching cements

Indirect restorations need to be attached with adhesive luting agents to prevent them from becoming dislodged and provide adequate marginal sealing. The aim of this study was to evaluate bond strength to dentin of selfetching resin cements. Materials and methods: 75 flat dentin surfaces were randomly distributed among 5 groups, according to cements used; Group 1: RelyxU100 (3M/ESPE), Group 2: Bis Cem (Bisco), Group 3: Max Cem (Kerr), Group 4: SeT PP (SDI) and Group 5: Relyx ARC (3M/ESPE), control. Ceramic test cylinders (IPS Empress 2 / IvoclarVivadent) 4.1 mm across were prepared and attached to the dentin surfaces using the different cements. A constant 25N load was applied for 1 minute and they were lightpolymerized. Following storage for 24 hours at 100% humidity and 37 °C, the specimens were tested for bond strength under shear strain in an Instron testing machine at a crosshead speed of 1 mm/minute; at 7, 14 and 21 days. Data were analyzed by ANOVA and Tukey's test. There were significant differences between materials (p < 0.0001), but not between times or material/time interaction. RelyX ARC (Control Group) had the highest bond strength (15.52 MPa). Among the selfetching cements, the best behavior was found for Relyx U100 (10.80MPa), followed by BisCem (6.36 MPa), MaxCem (5.45 MPa) and SeTPP (3.17 MPa). The bond strength of the selfadhesive cements evaluated was lower than that for resin cements which require previous treatment of the dental substrate (control group). This should be taken into account during clinical selection, in particular for tooth preparations with poor retention (AU)

Las restauraciones indirectas deben ser fijadas por medio de agentes cementantes, para evitar su desprendimiento y mantener un adecuado sellado marginal. El objetivo de este trabajo fue evaluar la resistencia adhesiva a dentina de los cementos resinosos de autograbado. Materiales y métodos: Se utilizaron 75 superficies planas de dentina, distribuidos aleatoriamente en 5 grupos, según los medios cementantes; GRUPO 1: RelyxU100 (3M/ESPE), GRUPO 2: Bis Cem (Bisco), GRUPO 3: Max Cem (Kerr), GRUPO 4: SeT PP (SDI) y GRUPO 5: Relyx ARC (3M/ESPE), control. Se confeccionaros probetas cilíndricas de cerámica (IPS Empress 2 / IvoclarVivadent) de 4,1 mm de diámetro, las que fueron fijadas a las superficies de dentina mediante los distintos cementos. Se aplicó una carga constante de 25N durante 1 minuto y se realizó la fotopolimerización. Después de 24 horas de almacenamiento en un medio con 100 % de humedad a 37° C, las probetas fueron sometidas a ensayo de resistencia adhesiva bajo tensiones de corte en máquina Instron, con una velocidad del cabezal de 1 mm/minuto; a los 7, 14 y 21 días. Los datos fueron analizados mediante ANOVA y test de Tukey, mostrando diferencias significativas entre los materiales (p < 0,0001), no así respecto al factor tiempo ni a su interacción. El mayor valor de resistencia adhesiva lo presentó RelyX ARC (Grupo control) (15,52MPa), De los cementos autograbantes, el mejor compor ta miento se obtuvo en Relyx U100 (10,80MPa), seguido por BisCem (6,36MPa), MaxCem (5,45MPa) y SeTPP (3,17MPa): Los cementos autoadhesivos evaluados presentaron menor resistencia adhesiva que los cementos resinosos que requieren tratamiento previo del sustrato dentario (grupo control). Esto debería ser considerado cuando se realiza su selección clínica, sobre todo en preparaciones dentarias poco retentivas (AU)

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

Abstract Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

Efeito de adição de rodamina B e fluoresceína sódica a sistemas adesivos não simplificados: aspectos fotofísicos e físico-químicos / Effect of addition of rhodamine B and fluorescein to conventional etch-and-rinse and self-etching adhesive systems: photophysical and physical-chemical aspects

A adição de corantes fluorescentes a adesivos odontológicos possibilita a investigação da distribuição espacial desses materiais na interface dente-restauração, utilizando-se a microscopia confocal de varredura a laser (MCVL). A literatura indica falta de padronização na aplicação de agentes fluorescentes com tal finalidade. Esse estudo sistematizou estratégias para a adição de rodamina B (RB) e fluoresceína sódica (FS) a um sistema adesivo convencional de três passos, Adper Scotchbond Multi-Purpose (MP), e um autocondicionante de dois passos, Clearfil SE Bond (SE), considerados "padrão-ouro" na Odontologia. Os objetivos principais foram (a) determinar a menor faixa de concentrações de RB e FS necessária para produzir imagens satisfatórias da interface dentina-adesivo e (b) avaliar o efeito da adição desses corantes sobre algumas propriedades das resinas. Os adesivos foram marcados com RB ou FS em concentrações decrescentes (0,5, 0,1, 0,02 e 0,004 mg/mL) por meio de um método de dispersão semidireto. O comportamento fotofísico/ fluorescente dos adesivos marcados foi investigado por espectroscopia de fotoluminescência e MCVL. Paralelamente, avaliaram-se os adesivos quanto ao grau de conversão (GC) e ao ângulo de contato (AC). Tanto os resultados de GC como os de AC foram submetidos à análise de variância com dois fatores (adesivo e tratamento) com α = 0,05, seguida de teste post-hoc de Tukey. Os máximos comprimentos de onda de emissão e de excitação da RB e da FS foram influenciados pelo meio polimérico e pela concentração de corante de modo geral. A MCVL preliminar de amostras de adesivo polimerizado, realizada sob condições experimentais padronizadas, mostrou que o comportamento fluorescente da RB em MP e SE foi muito semelhante na mesma concentração de corante, mas o mesmo não pôde ser dito do comportamento da FS, que foi notavelmente inferior no adesivo autocondicionante, SE, na concentração mais alta. Em dentina, os adesivos preparados com RB nas concentrações-alvo de 0,1 e 0,02 mg/mL apresentaram fluorescência ótima; já aqueles preparados com 0,004 mg/mL produziram fraco sinal. Adesivos preparados com FS a 0,5 mg/mL apresentaram ótima fluorescência na interface de adesão, enquanto que concentração menor desse corante não produziu sinal suficiente. Padrões morfológicos aparentemente atípicos foram observados na interface de adesão, quando da associação do adesivo SE com o corante FS. A adição de RB e FS nas quatro concentrações indicadas aos adesivos MP e SE não afetou o GC nem o AC em comparação com os grupos de controle correspondentes. Em suma, a RB mostra-se um corante mais versátil que a FS na avaliação morfológica das interfaces dentina-MP e dentina-SE via MCVL. A menor faixa de concentrações de RB nos adesivos MP e SE, na qual é possível produzir imagens satisfatórias das interfaces, situa-se entre 0,1­0,02 mg/mL. Já o corante FS deve ser adicionado a esses adesivos a pelo menos 0,5 mg/mL para produzir níveis de fluorescência satisfatórios na interface de adesão. A não ocorrência de efeitos deletérios sobre a polimerização e a molhabilidade das resinas estabelece uma margem de segurança para a incorporação desses agentes fluorescentes (em concentração ≤ 0,5 mg/mL) nesses sistemas monoméricos.(AU)

The addition of fluorescent dyes to dental adhesives makes it possible to investigate the spatial distribution of such resin-based materials in the tooth-restoration interface, using confocal laser scanning microscopy (CLSM). Literature indicates a lack of standardization on the application of fluorescent agents for this purpose. This work presents strategies for adding rhodamine B (RB) and fluorescein sodium salt (FS) to a three-step etch-and-rinse adhesive system, Adper Scotchbond Multi-Purpose (MP), and a two-step self-etching one, Clearfil SE Bond (SE), both regarded as "gold standard" in restorative dentistry. The main objectives were (a) to determine the lowest range of RB and FS concentrations required to produce suitable images of the dentin-adhesive interface via CLSM and (b) to investigate potential effects of addition of these dyes on some resin properties. The adhesives were labeled with RB or FS at decreasing concentrations (0.5, 0.1, 0.02 and 0.004 mg/mL) by means of a semi-direct dispersion method. The photophysical/fluorescent behavior of the labeled resins was investigated by photoluminescence spectroscopy and by CLSM. The adhesives were also investigated with regards to the degree of conversion (DC) and contact angle (CA). A two-way ANOVA of "adhesive" and "treatment" was conducted on DC and CA separately, followed by Tukey's test. The maximum emission and excitation wavelengths of RB and FS were influenced by the host polymer and the dye concentration in general. The preliminary CLSM of cured adhesive samples, performed with standardized settings, showed that the fluorescent behavior of RB in MP and SE was very similar in the same dye concentration, unlike the behavior of FS, which was lower in the self-etching adhesive for the highest dye concentration. In dentin, the adhesives prepared with RB at the target concentrations of 0.1 and 0.02 mg/mL presented optimal fluorescence; those with 0.004 mg/mL produced poor signal. Adhesives prepared with FS at 0.5 mg/mL presented optimal fluorescence at the bonding interface, whereas lower concentrations of FS did not produce sufficient signal. Atypical morphological features were observed at the bonding interface, when adhesive SE was used with FS. The addition of RB and FS at the four decreasing concentrations to adhesives MP and SE did not affect DC or CA compared to the corresponding controls. In short, RB is more versatile than FS for the morphological characterization of dentin-MP and dentin-SE interfaces via MCVL. The lowest range of RB concentrations in adhesives MP and SE that can produce suitable images of the bonding interface lies between 0.1­0.02 mg/mL. The dye FS should be added to these adhesives at 0.5 mg/mL at least to produce satisfactory fluorescence levels at the bonding interface. Since negative effects on polymerization and wettability of the resins were not observed, the use of RB and FS (in concentration ≤ 0.5 mg/mL) together with MP and SE should be reliable in terms of resin properties.(AU)

Influence of curing protocols on water sorption and solubility of a self-adhesive resin-cement

Aim: To evaluate the effect of different activation protocols on the polymerization of a self-adhesive dual cured resin-based cement. Methods: Thirty disc-shaped specimens were prepared with the resin cement RelyX U200 (3M ESPE) and divided according to three protocols: immediate light-activation for 40 s, delayed light-activation (10 min after manipulation, for 40 s) or self-curing without light-activation. The specimens were desiccated, kept in water at 37 °C for 7 days and desiccated again to calculate water sorption, solubility and mass variation. Data were analyzed by Shapiro-Wilk Test and Wilcoxon tests (α=0.05). Images after the specimens' final desiccation were also made. Results: The Wilcoxon test revealed a significant difference for sorption and mass variation (p<0.05) and the highest value was observed in self-curing or chemical activation group (CA), followed by delayed light-activation (DL) and immediate light-activation (IL). Besides the water sorption parameters, there were also microvoids on the discs from the delayed and no light-activation groups. Conclusions: The light-activation immediately after manipulation is recommended for the evaluated resin cement (Au)

Effect of curing regimes on physical properties of heat cure acrylic resin

This study was conducted to determine the effect of varying curing conditions on the residual monomer concentrations of heat cure acrylic denture resin

Sixty-four disc shaped acrylic resin specimens were processed at four powder-liquid ratios [2.22, 2.00, 1.80 and student-ratio] and cured in a heated water bath using 4 different curing regimes [two with a terminal boil and two without]. The residual monomer concentrations were determined at intervals of 24, 48 and 72 hours using a UV Spectrophotometer

The results indicated a decrease in residual monomer concentration with storage time. Group 4 [student-ratio] and curing by cycle 2B [placing the assembly in the water bath directly at 100°C] showed the highest overall residual monomer concentrations while group 1 [highest powder-liquid ratio] and curing by cycle 1A showed the least overall residual monomer concentrations It was concluded that students dispensing acrylic powder and liquid monomer without calculations would lead to higher residual monomers if a proper curing regime is not followed. Using a 60 minute terminal boil in the polymerization process is strongly recommended. Storing the acrylic denture bases for at least 24-48 hours in water before use will decrease residual monomers being leached into the oral environment

Impression techniques used by dental surgeons in different institutes -a study

The objective of this study was to survey the impression technique used by the dental professionals of different institutes. Impression making is an important step in fabricating complete dentures. An impression is an imprint produced by existence of pressure of one thing into another surface. And this indicate an active role not a passive one and the clinician should understand that impressions are made, not taken. Mucostatic or passive impression was first proposed by Richardson and later popularized by Henry Page. A survey was conducted in dental colleges to get to know about the impression techniques and impression material used by the dental surgeons. It is discouraging to know that 35% of dental surgeons are using base plate custom trays to record secondary impressions. 10% are still using the alginate for secondary impressions. A supportable technique for recording full denture impressions is put forwarded for impression

Caracterização físico-química, mecânica e biológica de cimento autoadesivo aditivado com nanotubos de dióxido de titânio / Physical-chemical, mechanical and biological characterization of reinforcement self-adhesive resin cement titanium dioxide nanotubes

O objetivo desse estudo foi realizar a caracterização do cimento resinoso autoadesivo RelyX U200 aditivado de nanotubos de dióxido de titânio (nt-TiO2) em diferentes concentrações (0,3, 0,6, e 0,9% em peso) quanto às suas propriedades físico-químicas, mecânicas e biológica. Duas condições de polimerização foram analisadas: autopolimerizável (grupos: AC, A03, A06 e A09) e dual (grupos: DC, D03, D06 e D09). Para análise do grau de conversão foi utilizada a espectroscopia de infravermelho com transformada de Fourier com registro do espectro nos tempos de 3, 6, 9, 12 e 15 minutos. Os picos das bandas de comprimento de onda de 1638 cm-1 e de 1608 cm-1 foram identificados para cálculo do grau de conversão. Os dados foram submetidos à ANOVA de medidas repetidas seguido de comparações múltiplas de Tukey (=0,05). A análise de sorção e solubilidade foi realizada por meio da confecção de discos de cimento resinoso (10 mm ø × 2 mm) (n=8) monitorados quanto à sua massa depois de ciclos de hidratação/desidratação. A resistência à flexão em 3 pontos e módulo de elasticidade foram mensurados por meio de barras (2 × 2 × 25 mm) de cimento resinoso (n=10) levadas à máquina universal de ensaios. Para análise de Dureza Knoop utilizou-se microdurômetro com carga de 50g /10 segundos. Nos discos de cimento resinoso de 10 mm ø × 2 mm foram realizadas 5 endentações equidistantes 0,5mm e medidas em aumento de 50×. Para resistência de união ao cisalhamento, sobre discos de zircônia sinterizados foi aplicado o cimento resinoso (n=10) nas dimensões de 3 mm ø × 2 mm. Por meio de dispositivo foram levados à máquina universal de ensaios. Os dados encontrados de sorção e solubilidade e de cada propriedade mecânica foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Exceto para resistência ao cisalhamento que se utilizou o teste de comparação de Fischer (=0,05). Para viabilidade celular (n=8) foi realizado teste de MTT apenas na condição dual. Os grupos estudados foram: DC, D03, D06, D09, CP (controle positivo), CN (controle negativo). Após 24, 48 e 72 horas os níveis de absorbâncias foram analisados por meio de espectrofotometria no leitor de ELISA. Os dados foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Os resultados mostraram que a adição de nt-TiO2, independente da concentração, aumentou os valores de grau de conversão do cimento resinoso para a condição autopolimerizável e dual em todos os tempos estudados. Já para sorção e solubilidade não houve influência nos resultados da concentração de nanotubos inseridos e da condição de polimerização. Para resistência flexural, a adição de nt-TiO2 nas concentrações de 0,3% (A03) e 0,9% (A09) resultou em dados similares ao controle na condição dual (DC). O valor médio de módulo de elasticidade aumentou com a adição de 0,9% (A09), similar a todos os grupos da condição dual, em que adição de nt-TiO2 não influenciou os resultados. A adição de 0,6% (A06 e D06) e 0,9% (A09 e D09) de nt-TiO2 ao cimento aumentou os valores de dureza quando comparado aos grupos controle (AC e DC). Para resistência de união ao cisalhamento, a concentração de 0,3% de nt-TiO2 (A03 e D03) aumentou os valores quando comparado aos grupos A06, D06, A09 e D09 porém sem diferença para os grupos controle (AC e DC). Para viabilidade celular no período de 24h, os grupos D03, D06 e D09 obtiveram resultado similar ao grupo CP, já o grupo DC apresentou valores de absorbância inferiores ao CP, usado como parâmetro de comparação. Em 48 e 72h, todos os grupos experimentais não demonstraram diferença significativa em comparação ao grupo CP. O grupo CN apresentou diferença para os demais em todos dos tempos estudados. A adição de nt-TiO2 ao cimento resinoso autoadesivo representa uma estratégia promissora para potencializar suas propriedades físico-químicas e mecânicas sem prejuízo das propriedades biológicas.(AU)

The aim of this study was to characterize the self-adhesive resin cement RelyX U200 additive, titanium dioxide nanotubes (nt-TiO2), at different concentrations (0.3%, 0.6%, and 0.9% by weight) and to determine their physicochemical, mechanical and biological properties. Two polymerization conditions were analyzed: self-curing (groups AC, A03, A06 and A09) and dual-curing (groups DC, D03, D06 and D09). To analyze the conversion degree, Fourier transform infrared spectroscopy was used, and the spectrum was recorded at 3, 6, 9, 12 and 15 minutes. The peaks of the wavelength bands, 1638 cm-1 and 1608 cm-1, were identified to calculate the degree of conversion. The data were subjected to a repeated-measures ANOVA followed by a Tukey multiple-comparison test (=0.05). The sorption and solubility analysis was performed by making resin-cement discs (10 mm ø × 2 mm) (n=8) and monitoring their masses after the hydration/dehydration cycles. The 3-point flexural strength and the modulus of elasticity of resin-cement bars (2 × 2 × 25 mm) (n=10) were measured using a universal testing machine. The Knoop microhardness was analyzed with a load of 50 g and a time of 10 seconds. On each resin cement disc, 5 equidistant indentations of 0.5 mm were made, and the measures were increased by 50×. To test bonding shear strength, resin cement was applied to sintered zirconia discs (3 mm ø × 2 mm) (n=10). The bonded discs were then taken to the universal testing machine. Their sorption, solubility and each mechanical property were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The shear strength was submitted to a Fischer comparison test (=0.05). To test cell viability (n=8), a MTT assay was performed using only the dual-curing condition. The studied groups were: DC, D03, D06, D09, CP (positive control) and CN (negative control). After 24, 48 and 72 hours, the absorbance levels were analyzed using an ELISA spectrophotometry reader. The data were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The results showed that the addition of nt-TiO2, regardless of concentration, increased the conversion degree values for the self-curing resin cement and for the dual-curing at all times studied. The sorption and solubility were not influenced by the concentration of the nanotubes or the polymerization condition. Regarding flexural strength, the addition of the nt-TiO2 in concentrations of either 0.3% (A03) or 0.9% (A09) resulted in data similar to those in the dual-curing control (DC) condition. The average modulus of elasticity increased with the addition of 0.9% nt-TiO2 (A09), and as with all the groups in the dual-curing condition, the addition of nt-TiO2 did not affect the results. The addition of either 0.6% (A06 and D06) or 0.9% (A09 and D09) of nt-TiO2 cement increased hardness values relative to the control groups (AC and DC). The group with a 0.3% concentration of nt-TiO2 (A03 and D03) showed higher bonding shear strength values than several of the groups with higher concentrations (A06, D06 and D09), but the A09 group had no difference relative to either control group (AC or DC). For cell viability in the 24-h period, the D03 D06 and D09 groups achieved a result similar to that of the CP group with significant difference to the DC group that had lower absorbance values. At the benchmarks of 48 and 72 h, and only the CN group showed a significant difference compared to others. The addition of nt-TiO2 is a promising strategy for improving the physical-chemical and mechanical properties without prejudice the biological properties.(AU)

Correlation between clinical performance and degree of conversion of resin cements: a literature review

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used.

Avaliação da resistência ao cisalhamento e miniflexão de resinas ortodônticas associadas ao primer / Evaluation of the shear bond and mini flexural strength of the orthodontics resins associated with primer

O objetivo desse estudo foi avaliar o efeito da aplicação do primer na resina na resistência ao cisalhamento e flexão em compósitos para colagem ortodôntica. Foram colados braquetes em 60 pré-molares humanos com as resinas Orthobond (G1), Z100 (G2) e Transbond XT (G3). Nos grupos 1, 2 e 3 a colagem foi feita de modo convencional, com a aplicação do primer na superfície condicionada. Nos grupos 4, 5 e 6 o primer foi aplicado na resina presente no braquete. Para o teste de flexão, nos grupos 1, 2 e 3 foram confeccionadas barras com as resinas Orthobond, Z100 e Transbond XT sem misturar com o primer. Nos grupos 4, 5 e 6 o primer foi aplicado nas resinas durante a confecção das barras. Os ensaios de resistência ao cisalhamento e flexão de três pontos foram realizados em máquina Instron com velocidade de 1,0 mm/minuto. Os resultados foram submetidos à Anova dois fatores e ao teste de Tukey (α=0,05). Os resultados mostraram que o Transbond XT apresentou resistência ao cisalhamento significativamente maior do que os outros materiais, e que não houve diferença significante quanto ao método de aplicação do primer. No teste de flexão, a resina Orthobond apresentou resistência significativamente menor do que os outros materiais, e a adição do primer reduziu significativamente a resistência à flexão dos materiais. Concluiu-se que a adição do primer na resina reduziu a resistência à flexão dos materiais e não alterou a resistência de união de braquetes ao esmalte. Dentre as resinas, o melhor desempenho foi apresentado pela Transbond XT...

The aim of this study was to evaluate the effect of primer application in shear bond and flexural strength of composite for orthodontic bonding. Brackets were bonded in 60 human premolars with Orthobond (G1), Z100 (G2) and Transbond XT (G3). In groups 1 to 3 the bond was done in a conventional manner with the application of the primer in the etched surface. In groups 4 to 6 the primer was applied on the primer resin in this bracket. For the flexural test, in groups 1-3 bars were made with the Orthobond, Z100 and Transbond XT without mixing with the primer. In groups 4 to 6 primer was applied to the resin during the manufacture of the bars. Shear bond test and flexural three points test were performed in Instron machine with a speed of 1.0 mm/minute. The results were submitted to Anova two factors and Tukey's test (α=0.05). The results showed that Transbond XT showed significantly higher shear bond resistance than the other materials; there was no significant difference in the primer application method. In the flexural test, the resin Orthobond showed significantly lower resistance than the other materials; adding the primer significantly reduced the flexural strength of the materials. It is concluded that the addition of the primer resin reduced the flexural strength of the material and did not alter the bond strength of brackets to enamel. Among the resins, the best performance was presented by Transbond XT...

Influência da composição e cor de cerâmicas na transmissão de luz e no grau de conversão de cimentos resinosos de ativação dual / Effect of ceramic composition and shade in light transmission and degree of conversion of dual-cure resin cements

O objetivo desta pesquisa foi avaliar a transmitância de diferentes tipos e cores de cerâmicas e seus efeitos no grau de conversão (GC) de dois tipos de cimentos resinosos com modo de polimerização dual. Foram confeccionadas 60 pastilhas com a cerâmica IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) e divididas em 3 grupos: LT, MO e Z, com 20 pastilhas cada um. Nos grupos LT e MO, as pastilhas foram confeccionadas com a cerâmica de dissilicato de lítio de baixa translucidez (LT - low transluscency) e de média opacidade (MO - medium opacity), respectivamente. No grupo Z, as pastilhas foram confeccionadas em zircônia. Cada grupo foi subdividido em 5 subgrupos (n=4), de acordo com a cor da cerâmica: A2; A3,5; B2; C2; D3. No grupo LT, as pastilhas foram prensadas nas cores anteriormente citadas e, nos grupos MO e Z, as pastilhas foram, inicialmente, confeccionadas para simular infraestruturas e, posteriormente, receberem aplicação de cerâmica de revestimento IPS e.max Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) nas mesmas cores. O espectrofotômetro UV 1800 Shimadzu foi utilizado para medir a transmitância de cada espécime de cerâmica (2,0 mm de espessura). Para medir o GC, espécimes dos cimentos resinosos Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein) e Rely X U200 (3M ESPE, St. Paul, MN, USA), com espessura de 100 μm, foram fotopolimerizados sob os discos de cerâmica por 40 s. Espécimes dos cimentos fotoativados sem a interposição da cerâmica foram usados como grupo controle. A polimerização dos cimentos foi avaliada através da espectrometria no infravermelho com transformada de Fourier (FTIR) empregando o método de reflexão atenuada total (ATR) imediatamente após a fotopolimerização. Os resultados foram submetidos aos testes ANOVA a 1 critério e Teste de Tukey (α=5%). Os valores de transmitância foram inferiores a 1%, sendo que as do grupo LT apresentaram, em geral, os maiores valores de transmitância, seguidos dos grupos MO e Z. O GC do cimento...

The aim of the present study was to evaluate the transmittance of different ceramic types and shades and their effects on the degree of conversion (DC) of two dual-cure resin cements. Sixty discs were fabricated with IPS e.max ceramic (Ivoclar Vivadent, Schaan, Liechtenstein) and divided into three groups (n= 20 in each group): LT, MO and Z. For LT and MO groups discs were fabricated with low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, respectively. Discs from Z group were manufactured of zirconia. Each group was divided into five subgroups (n = 4), according to the ceramic shade: A2; A3,5; B2; C2; D3. In the LT group, specimens were heat-pressed in shades cited above and in the MO and Z groups, the discs were initially fabricated as core materials and then veneered with veneer ceramic (IPS e.max Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) in the same shades. A spectrophotometer UV-1800 Shimadzu was used to determine the transmittance percentage of each ceramic specimen (2.0-mm-thick). For DC measurements, the resin cements (Variolink II - Ivoclar Vivadent, Schaan, Liechtenstein and Rely X U200 - 3M ESPE, St. Paul, MN, USA) specimens (thickness: 100 μm) were photocured under the ceramic discs (2.0-mm-thick) for 40 s. Specimens photocured without the ceramics discs were used as control group. ATR/FTIR spectrometry was used to evaluated the extent of polymerization for all cement specimens immediately after photocuring. The results were submitted to one-way ANOVA and Tukey test (α=5%). The transmittance percentage was less than 1% and the LT group had the highest transmittance values, followed by MO and Z groups. The %DC of Variolink II cement was not influenced by the ceramic disc interposition. For Rely X U200 cement, the interposition of some ceramics types/shades (LT A3,5, MO A2, MO A3,5 and Z A3,5) significantly decreased the %DC compared to control group. It was concluded that the transmittance values and %DC...

Assessment of patients wearing auto polymerized acrylic resin fixed partial dentures

This descriptive study was carried out at dental out-patient department of Liaquat medical University Hospital Hyderabad from January 2013 to December 2013. Thirty-five patients wearing auto polymerized [self-cured] fixed partial dentures provided by unqualified and qualified dental practitioners were assessed. Condition of oral health was evaluated on the basis of proper history and clinical examination. Prosthesis condition was also assessed. Oral health of underlying soft and hard tissues was carefully evaluated after removing the prosthesis with the help of slow speed hand piece without jeopardizing oral tissues. It was evident in this study that fixed partial dentures made from auto polymerized [self cure] acrylic resins had adversely affected the oral tissues compelling the patients to visit the qualified dentist for proper treatment of their problems