Addition of zirconium oxide to Biodentine increases radiopacity and does not alter its physicochemical and biological properties

Abstract Objectives: To evaluate the radiopacity of Biodentine (BD) and BD associated with 15% calcium tungstate (BDCaWO4) or zirconium oxide (BDZrO2), by using conventional and digital radiography systems, and their physicochemical and biological properties. Materials and Methods: Radiopacity was evaluated by taking radiographs of cement specimens (n=8) using occlusal film, photostimulable phosphor plates or digital sensors. Solubility, setting time, pH, cytocompatibility and osteogenic potential were also evaluated. Data were analyzed using one-way ANOVA and Tukey post-test or two-way ANOVA and Bonferroni post-test (α=0.05). Results: BD radiopacity was lower than 3 mm Al, while BD ZrO2 and BD CaWO4 radiopacity was higher than 3 mm Al in all radiography systems. The cements showed low solubility, except for BDCaWO4. All cements showed alkaline pH and setting time lower than 34 minutes. MTT and NR assays revealed that cements had greater or similar cytocompatibility in comparison with control. The ALP activity in all groups was similar or greater than the control. All cements induced greater production of mineralized nodules than control. Conclusions: Addition of 15% ZrO2 or CaWO4 was sufficient to increase the radiopacity of BD to values higher than 3 mm Al. BD associated with radiopacifiers showed suitable properties of setting time, pH and solubility, except for BDCaWO4, which showed the highest solubility. All cements had cytocompatibility and potential to induce mineralization in Saos-2 cells. The results showed that adding 15% ZrO2 increases the radiopacity of BD, allowing its radiography detection without altering its physicochemical and biological properties.

Enamel surface evaluation after bracket debonding and different resin removal methods

OBJECTIVE: To assess enamel surface under scanning electron microscopy (SEM) after resin removal and enamel polishing procedures following brackets debonding, as well as compare the time required for these procedures. METHODS: A total of 180 deciduous bovine incisors were used. The enamel surface of each tooth was prepared and brackets were bonded with light cured Transbond XT composite resin. Brackets were removed in a testing machine. The samples were randomized and equally distributed into nine groups according to the resin removal and polishing technique: Group 1, 30-blade tungsten carbide bur in high speed; Group 2, 30-blade tungsten carbide bur in high speed followed by a sequence of 4 Sof-lex polishing discs (3M); Group 3, 30-blade tungsten carbide bur in high speed followed by Enhance tips (Dentsply). All groups were subdivided into (a) unpolished; (b) polished with aluminum oxide paste; and (c) polished with water slurry of fine pumice. Subsequently, the enamel surface was assessed and statistical analysis was carried out. RESULTS: There were statistically significant differences in enamel roughness and removal time among all groups. Groups 3a, 3b and 3c appeared to be the most efficient methods of removing resin with low damages to enamel. Groups 2a, 2b and 2c were the most time consuming procedures, and Group 2a caused more damages to enamel. CONCLUSION: The suggested protocol for resin removal is the 30-blade tungsten carbide bur in high speed followed by Enhance tips and polishing with aluminum oxide paste. This procedure seems to produce less damages and is less time consuming. .

OBJETIVO: avaliar a superfície do esmalte, por meio de microscopia eletrônica de varredura, após descolagem de braquetes e o polimento do esmalte, com diferentes técnicas de remoção de resina, bem como comparar o tempo necessário para a realização do procedimento. MÉTODOS: foram utilizados 180 dentes bovinos decíduos. A superfície do esmalte dos dentes foi preparada e realizada a colagem dos braquetes com resina Transbond XT. Os braquetes foram removidos em máquina de ensaio mecânico. Foram formados, aleatoriamente, nove grupos, de acordo com o tipo de remoção da resina e de polimento, sendo: Grupo 1, broca de tungstênio de 30 lâminas em alta rotação; Grupo 2, broca de tungstênio de 30 lâminas em alta rotação e sequência de quatro discos Soflex (3M); Grupo 3, broca de tungstênio de 30 lâminas em alta rotação e pontas de acabamento Enhance (Dentsply). Todos os grupos foram subdividido em (a) sem polimento, (b) polimento com pasta de óxido de alumínio e (c) polimento com pedra-pomes. As superfícies foram avaliadas e foi realizada análise estatística. RESULTADOS: houve diferença estatística entre os grupos em relação à rugosidade de superfície e ao tempo de remoção. Os grupos 3a, 3b e 3c demonstraram ser os métodos mais eficientes de remoção da resina, promovendo pouco dano à superfície do esmalte. Os grupos 2a, 2b e 2c consumiram maior tempo de procedimento, e o grupo 2a causou maior dano ao esmalte. CONCLUSÃO: sugere-se como protocolo de remoção o uso de broca de tungstênio de 30 lâminas para remoção do maior volume da resina, pontas de acabamento Enhance e polimento com a pasta de óxido de alumínio, por produzirem menor dano. .

Effect of adhesive remnant removal on enamel topography after bracket debonding

INTRODUCTION: At orthodontic treatment completion, knowledge about the effects of adhesive remnant removal on enamel is paramount. OBJECTIVE: This study aimed at assessing the effect of different adhesive remnant removal methods on enamel topography (ESI) and surface roughness (Ra) after bracket debonding and polishing. METHODS: A total of 50 human premolars were selected and divided into five groups according to the method used for adhesive remnant removal: high speed tungsten carbide bur (TCB), Sof-Lex discs (SL), adhesive removing plier (PL), ultrasound (US) and Fiberglass burs (FB). Metal brackets were bonded with Transbond XT, stored at 37oC for 24 hours before debonding with adhesive removing plier. Subsequently, removal methods were carried out followed by polishing with pumice paste. Qualitative and quantitative analyses were conducted with pre-bonding, post-debonding and post-polishing analyses. Results were submitted to statistical analysis with F test (ANOVA) and Tukey's (Ra) as well as with Kruskal-Wallis and Bonferroni tests (ESI) (P < 0.05). RESULTS: US Ra and ESI were significantly greater than TCB, SL, PL and FB. Polishing minimized Ra and ESI in the SL and FB groups. CONCLUSION: Adhesive remnant removal with SL and FB associated with polishing are recommended due to causing little damage to the enamel. .

INTRODUÇÃO: na finalização do tratamento ortodôntico, torna-se relevante o conhecimento da ação dos métodos de remoção do remanescente resinoso sobre o esmalte. OBJETIVO: o objetivo do estudo foi avaliar o efeito de métodos de remoção do remanescente de resina após a descolagem do braquete e do polimento na rugosidade (Ra) e topografia (ESI) do esmalte. MÉTODOS: foram selecionados 50 pré-molares humanos, divididos em cinco grupos, de acordo com o método empregado para a remoção da resina residual: broca carbide tungstênio em alta rotação (BCT), discos Sof-Lex (SL), alicate removedor de resina (AL), ultrassom (US) e pontas Fiberglass (PF). Braquetes metálicos foram colados com Transbond XT, armazenados a 37° por 24 horas antes da descolagem com alicate removedor de braquete, sendo aplicados posteriormente os meios de remoção e executado o polimento com pasta de pedra-pomes. Realizou-se análises qualiquantitativas, com avaliações antes da colagem dos braquetes, após a descolagem e após o polimento, sendo os valores obtidos submetidos à análise estatística com teste F (ANOVA), de Tukey (Ra) e testes de Kruskal-Wallis e Bonferroni (ESI) (p < 0,05). RESULTADOS: a Ra e o ESI do US foram significativamente maiores do que BCT, SL, AL e PF. O polimento reduziu a Ra e ESI dos grupos SL e PF. CONCLUSÃO: a remoção do adesivo resinoso com SL e PF associados ao polimento são os métodos mais indicados por ocasionarem as menores alterações do esmalte. .

Propriedades físico-químicas e biológicas de cimento experimental à base de Portland associado a diferentes radiopacificadores / Physical, chemical and biological properties of an experimental Portland-based cement with different radiopacifier agents

O objetivo do estudo foi avaliar as propriedades físicas, químicas e biológicas de um cimento experimental à base de Portland contendo diferentes agentes radiopacificadores. Os cimentos foram divididos em 6 grupos: 1. MTA-Angelus branco (controle), 2. cimento Portland branco (CP), 3. CP com 20% de óxido de zircônio (OZ), 4. CP/50% OZ, 5. CP com 20% de tungstato de cálcio (TC) e 6. CP/50% TC. As proporções foram determinadas em peso (80 e 50% de CP para 20 e 50% de radiopacificadores, respectivamente). Os cimentos experimentais foram manipulados utilizando 0,3 mL de líquido composto por 80% de água destilada e 20% de propilenoglicol, em volume. A caracterização dos materiais foi realizada em microscopia eletrônica de varredura (MEV), no modo EDS e em difratômetro de raios-X (XRD). Para os testes de radiopacidade, escoamento, espessura de filme e solubilidade foram seguidas as especificações no 57 da ANSI/ADA (2000). Na determinação do tempo de presa, foi empregada a norma ASTM C266/2008. Na análise do pH e liberação de íons cálcio foram analisados os períodos de 3, 24, 72 e 168 horas. Para análise da descoloração dentária, foram realizadas análises em espectrofotômetro, estereomicroscopia e MEV. Para análise da resposta inflamatória, foi utilizado o teste de implantação em subcutâneo de ratos. A utilização do óxido de zircônio e do tungstato de cálcio em combinação com o cimento Portland resultou no desenvolvimento de cimentos que exibiram uma radiopacidade próxima (20% de radiopacificadores) ou acima (50%) do recomendado pela norma no 57 da ANSI/ADA; tempo de presa mais prolongado, espessura de filme menor e escoamento mais elevado em comparação com o MTA-Angelus; solubilidade adequada e comparável ao MTA-Angelus, elevado pH e liberação de íons cálcio superior ao MTA-Angelus nos períodos iniciais e similar aos 7 dias, ausência de descoloração dentária e resposta inflamatória semelhante ao MTA-Angelus...

The aim of the study was to evaluate the physical, chemical and biological properties of an experimental calcium silicate-based cement with different concentrations of the radiopacifiers zirconium oxide and calcium tungstate. The materials were divided in 6 groups: 1. White MTA (control), 2. White Portland cement (PC), 3. PC with 20% zirconium oxide (ZO), 4. PC/50% ZO, 5. PC with 20% calcium tungstate (CT) and 6. PC/50% CT. The proportions were determined by weight. The cements were manipulated using 0.3 mL of liquid composed of 80% distilled water and 20% propylene glycol. The control was manipulated according to manufacturers instructions. The characterization of the materials was performed using scanning electron microscopy (SEM) in EDS mode and X-ray diffractometrer (XRD). For radiopacity, flowability, film thickness and solubility test, the specifications no 57 of ADA (2000) was followed. To determine the setting time, ASTM C266/2008 specifications was followed. For pH and calcium ion release assessment, the periods of 3, 24, 72 and 168 hours were evaluated. The analysis of dental discolouration was performed using spectrophotometer, stereomicroscopy and SEM. To evaluate the inflammatory response, the test of subcutaneous implantation in rats was used. The use of zirconium oxide and calcium tungstate in association with Portland cement resulted in development of cements with radiopacity nearly (20% radiopacifiers) or above (50%) the recommended by ANSI/ADA specifications n a 57, more prolonged setting time, lower film thickness and higher flowability in comparison with MTAAngelus, an adequate and comparable solubility with MTA-Angelus, high pH and calcium ion release higher than MTA-Angelus in the initial periods and similar at 7 days, absence of dental discolouration and inflammatory response similar to that presented by MTA-Angelus...

Influence of radiopaque fillers on physicochemical properties of a model epoxy resin-based root canal sealer

Objective: To verify the influence of radiopaque fillers on an epoxy resin-based sealer. Material and Methods: Experimental sealers were formulated by adding 20%, 40%, 60%, 80%, 100% and 120% of calcium tungstate, ytterbium trifluoride or barium sulphate by weight to an epoxy-resin-base. Setting time, flow, film thickness, radiopacity, sorption, solubility, pH and push-out bond strength were evaluated. Results: The setting time ranged from 373 to 612.66 min, the flow varied from 13.81±0.49 to 22.49±0.37 mm, and the film thickness ranged from 16.67±5.77 to 33.33±11.54 µm. The lowest pH was 5.47±0.53, and the highest was 6.99±0.03. Radiopacity varied from 0.38±0.04 to 2.57±0.21 mmAl and increased with the amount of filler. Calcium tungstate sealers had a higher sorption and solubility than other sealers. There was no significant difference in the push-out bond strength among the fillers at the 120% concentration. CONCLUSION: The inorganic fillers evaluated and their concentrations affect the physicochemical properties of an epoxy resin-based root canal sealer. .

The effect of bur preparation on the surface roughness and reline bond strength of urethane dimethacrylate denture base resin.

Background: The clinical success of relining depends on the ability of reline resin to bond to denture base. Surface preparations may influence reline bond strength of urethane-based dimethacrylate denture base resin. Aim: To investigate the effect of bur preparation on the surface roughness (R a ) of eclipse denture base resin and its shear bond strength (SBS) to an intra-oral self-curing reline material. The mode of reline bonding failure was also examined. Materials and Methods: Twenty-four cylindrical Eclipse™ specimens were prepared and separated into three groups of eight specimens each. Two groups were subjected to mechanical preparation using standard and fine tungsten carbide (TC) burs and the third group (control) was left unprepared. The R a of all specimens was measured using a contact stylus profilometer. Subsequently, relining was done on the prepared surface and SBS testing was carried out a day later using a universal testing machine. Results: One-way ANOVA revealed significant differences (P<0.05) in R a and SBS values for all the groups. Post-hoc Tukey's HSD test showed significant differences (P<0.05) between all the groups in the R a values. For SBS also there were significant differences (P<0.05), except between standard bur and control. Conclusions: 1) There was a statistically significant difference in the R a of Eclipse™ specimens prepared using different carbide burs (P<0.05). 2) There was a statistically significant difference in the relined SBS (P<0.05) when prepared using different burs, but the difference between the standard bur and the control group was not statistically significant.

Comportamento biológico, físico e químico do cimento Portland associado a diferentes radiopacificadores / Biological, physical and chemical comportament of the Portland sealer associated with differents radiopacifying agents

Objetivo do presente estudo foi avaliar algumas propriedades físicas, químicas, comportamento biológico em tecido subcutâneo de ratos e caracterísitcas superficiais do cimento Portland (CP) associado a diferentes radiopacificadores (óxido de bismuto (OB), tungstato de cálcio (TC) e óxido de zircônio (OZ). As propriedades físicas analisadas foram radiopacidade, tempo de presa, solubilidade e características superficiais, enquanto que às químicas foram pH e liberação de ions cálcio, e a biocompatibilidade foi analisada in vivo em tecido subcutâneo de rato. A metodologia para a realização das propriedades físicas, foram as recomendadas pela ISO 6876/2001 e n.57 ADA/2000, com pequena modificação para o tempo de presa que além da agulha com peso de l00g foi utilizado também agulha com peso de 453,6 para determinação do tempo de presa final conforme norma da ASTM. As características superficiais foram realizadas em microscopia eletrônica de varredura. Para o pH e liberação de íons cálcio, os materiais foram acondicionados em dente de acrílico com cavidades retrógradas e imersos em 15 mL de água MilliQ. Nos períodos de 3, 24, 72 e 168 horas os dentes eram trocados de frasco e mensurou-se seu pH por meio de pHmetro e cálcio com uso de espectrofotômetro de absorção atômica da água que o material estava imerso. Para a biocompatibilidade os materiais foram colocados em tubos de polietileno e implantados no dorso de 15 ratos, que foram mortos após 7, 15 e 30 dias da implantação. Os dados foram comparados estatisitcamente pelo teste de Kruskal-Wallis e Miller ou ANOVA e tukey, dependendo da normalidade ou não dos dados, sendo empregado nível de significância foi de 5%. Os resultados mostraram diferença significante (P<0,05) para o tempo de presa inicial entre todos os materiais, enquanto que no tempo de presa final só não ocorreu diferença (P>0,05) entre o óxido de bismuto e tungstato de cálcio...

The aims of this study were to evaluate some physicochemical properties, subcutaneous tissue response and scanning electron microscope surface characteristics related to Portland cementassociated with the following radiopacifiersagents: bismuth oxide (BO), calcium tungstate (CT) and zirconium oxide (ZO). The physical properties evaluated were: radiopacity, setting time, solubility and scanning electron microscope study of the cements surface. The chemical properties evaluated were: pH and calcium íon release. The biocompatibility test was performed in subcutaneous tissue of rats. For the study of the physical properties, the methodologies ISO 6876/2001 e n.57 ADA/2000SO with slight variations for the setting time test were used. For the setting time test the 100g needle was used. Determination of the final setting time was performed also using the 453,6g needle according to the ASTM criteria. The surface characteristics were studied using scanning electron microscopy. For the pH and calcium ion release tests, the samples were inserted into root-end cavities prepared in acrylic teeth. Immediately, after being filled, all specimens were immersed in 15 mL of Milli-Q water. Evaluations were performed at periods of 3 hours, 24 hours, 72 hours, and 168 hours for assessment of the pH and calcium ion release. After each measurement, the specimens were moved to new tubes containing fresh MiIIi-Q water. The measurements were carried out using a pH meter. The calcium ions release was measured using an atomic absorption spectrophotometer equipped with a calcium-specific hollow cathode lamp. To evaluate the biocompatibility polyethylene tubes were filled with the samples and implanted into the subcutaneous tissue of 15 rats. The biological response was evaluated at 7, 15 and 30 days. The data was statistically compared using the kruskal-wlilis and Miller test or by using the ANOVA-Tukey test, according to the presence or absence of normal distribution...