Niobium oxyhydroxide as a bioactive agent and reinforcement to a high-viscosity bulk-fill resin composite

Abstract Objective The present in vitro study incorporated niobium oxyhydroxide fillers into an experimental high-viscosity bulk-fill resin composite to improve its mechanical performance and provide it a bioactive potential. Methodology Scanning electron microscopy synthesized and characterized 0.5% niobium oxyhydroxide fillers, demonstrating a homogeneous morphology that represented a reinforcement for the feature. Fillers were weighed, gradually added to the experimental resin composite, and homogenized for one minute, forming three groups: BF (experimental high-viscosity bulk-fill resin composite; control), BF0.5 (experimental high-viscosity bulk-fill resin composite modified with 0.5% niobium oxyhydroxide fillers), and BFC (commercial bulk-fill resin composite Beautifil Bulk U, Shofu; positive control). In total, 10 specimens/groups (8 × 2 × 2 mm) underwent flexural strength (FS) tests in a universal testing machine (Instron) (500N). Resin composites were also assessed for Knoop hardness (KH), depth of cure (DoC), degree of conversion (DC), elastic modulus (E), and degree of color change (ΔE). The bioactive potential of the developed resin composite was evaluated after immersing the specimens into a simulated body fluid in vitro solution and assessing them using a Fourier-transformed infrared spectroscope with an attenuated total reflectance accessory. One-way ANOVA, followed by the Tukey's test (p<0.05), determined FS, DC, KH, and ΔE. For DoC, ANOVA was performed, which demonstrated no significant difference between groups (p<0.05). Conclusions The high-viscosity bulk-fill resin composite with 0.5% niobium oxyhydroxide fillers showed promising outcomes as reinforcement agents and performed well for bioactive potential, although less predictable than the commercial resin composite with Giomer technology.

Evaluation of contact angle and mechanical properties of resin monomers filled with graphene oxide nanofibers

Abstract This in vitro study synthesized hybrid nanofibers embedded in graphene oxide (GO) and incorporated them into experimental resin composite monomers to evaluate their physical-mechanical properties. Inorganic-organic hybrid nanofibers were produced with precursor solutions of 1% wt. GO-filled Poly (d,l-lactide, PLA) fibers and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) characterized the morphology and chemical composition of the spun fibers. Resin composite monomers were developed and a total of 5% nanofibers were incorporated into the experimental materials. Three groups were developed: G1 (control resin monomers), G2 (resin monomers/PLA nanofibers), and G3 (resin monomers/inorganic-organic hybrid nanofibers). Contact angle (n=3), flexural strength (n=22), elastic modulus (n=22), and Knoop hardness (n=6) were evaluated. The mean of the three indentations was obtained for each sample. The normality of data was assessed by QQ Plot with simulated envelopes and analyzed by Welch's method (p<0.05). Overall, SEM images showed the regular shape of nanofibers but were non-aligned. Compositional analysis from EDS (n=6) revealed the presence of carbon and oxygen (present in GO composition) and Si from the functionalization process. The results of contact angle (°) and hardness (Kg/mm2) for each group were as follow, respectively: G1 (59.65±2.90; 37.48±1.86a), G2 (67.99±3.93; 50.56±1.03b) and G3 (62.52±7.40; 67.83±1.01c). The group G3 showed the highest Knoop hardness values (67.83 kg/mm2), and the flexural strength of all groups was adversely affected. The experimental resin composite composed of hybrid nanofibers with GO presented increased hardness values and hydrophilic behavior.

Resumo Este estudo in vitro sintetizou nanofibras híbridas embebidas em óxido de grafeno (GO), incorporando-as à uma resina composta experimental de monômeros para avaliar suas propriedades físico-mecânicas. Nanofibras híbridas inorgânica-orgânicas foram produzidas com soluções precursoras de fibras poli (d, l-lactídeo, PLA) preenchidas com GO a 1% em peso e microscopia eletrônica de varredura (MEV) e espectroscopia de raio-X de energia dispersiva (EDS) caracterizaram a morfologia e composição química das fibras. Monômeros de resina composta foram desenvolvidos e um total de 5% de nanofibras foi incorporado aos materiais experimentais. Três grupos foram desenvolvidos: G1 (monômeros de resina controle), G2 (monômeros de resina/ nanofibras de PLA) e G3 (monômeros de resina/nanofibras híbridas inorgânico-orgânicas). Ângulo de contato (n=3), resistência à flexão (n=22), módulo de elasticidade (n=22) e dureza Knoop (n=6) foram avaliados. A média das três endentações foi obtida para cada amostra. A normalidade dos dados foi avaliada pelo QQ Plot com envelopes simulados e analisada pelo método de Welch (p<0,05). No geral, as imagens de MEV mostraram forma regular de nanofibras, mas não alinhadas. A análise composicional de EDS (n=6) revelou a presença de carbono e oxigênio (presentes na composição do GO) e Si resultante do processo de funcionalização. Os resultados do ângulo de contato (°) e dureza (Kg/mm2) para cada grupo foram os seguintes, respectivamente: G1 (59,65±2,90; 37,48±1,86a), G2 (67,99±3,93; 50,56±1,03b) e G3 (62,52±7,40; 67,83±1,01c). G3 apresentou os maiores valores de dureza Knoop (67,83 kg/mm2), e a resistência à flexão de todos os grupos foi prejudicada. A resina composta experimental composta por nanofibras híbridas com GO apresentou maiores valores de dureza e comportamento hidrofílico.

Abordagem conservadora de lesões cariosas profundas: uma revisão de literatura / Conservative approach to deep carious lesions: a literature review

O presente trabalho tem como objetivo realizar uma revisão de literatura e discutir os mais atuais conceitos sobre abordagem conservadora de lesões cariosas profundas, facilitando o manejo clínico. Para que essa abordagem conservadora seja implementada, é imprescindível que se conheça a composição estrutural e funcional do biofilme para, assim, entender a evolução da doença cárie que acomete a estrutura dentária. No entanto, quando se trata de um dente com lesão de cárie ativa com grande comprometimento de esmalte e dentina, procedimentos operatórios mais invasivos e restauradores podem ser necessários, mesmo que fundamentados na maior preservação possível de estrutura dentária. As evidências mais atuais encontradas na literatura recomendam a remoção seletiva do tecido cariado que consiste na dentina infectada, ou seja, clinicamente amolecida, e restauração definitiva na mesma sessão. Portanto, desde que o dente apresente vitalidade pulpar clinicamente confirmada, acredita-se que a preservação estratégica da dentina, poderá aumentar as chances de sucesso no tratamento, evitando possível exposição da polpa dentária. Adicionalmente, ao optar por práticas conservadoras no contexto da Odontologia de mínima intervenção, resultará em um significativo aumento na longevidade das restaurações sempre associando promoção de saúde ao paciente(AU)

This paper aims to conduct a literature review and discuss the most current concepts on conservative approach to deep carious lesions in permanent posterior teeth, facilitating clinical management. For this conservative approach to be implemented, it is essential to know the structural and functional composition of the biofilm in order to understand the evolution of the caries disease that affects the dental structure. However, when it comes to a tooth with an active caries lesion with major enamel and dentin compromise, more invasive and restorative surgical procedures may be necessary, even if based on the greatest possible preservation of the dental structure. The most current findings in the literature recommend the selective removal of carious tissue consisting of infected dentin, that is, clinically softened, and definitive restoration in the same session. Therefore, as long as the tooth has clinically confirmed pulp vitality, it is believed that the strategic preservation of dentin may increase the chances of successful treatment, avoiding possible exposure of the dental pulp. Additionally, when opting for conservative practices in the context of Minimally Invasive Dentistry, it will result in a significant increase in the longevity of restorations, always associating health promotion to the patient(AU)

Efeito de diferentes protocolos fotoativadores e espessura dos incrementos na dureza de resinas Bulk fill / Effect of lightcure protocols and increment thickness in the hardness of Bulk fill composites

As resinas Bulk fill surgiram com o intuito de facilitar a restauração de cavidades profundas. A fotoativação adequada é extremamente importante para que a resina bulk fill ofereça propriedades mecânicas satisfatórias e, longevidade na restauração. Este estudo avaliou a influência da espessura do incremento na microdureza Knoop (KHN) de três resinas bulk fill (n = 5). Cinquenta amostras foram divididas de acordo com o material (Filtek Z250, Filtek One Bulk Fill e Filtek Bulk Fill Flow), espessura (2mm e 4 mm) e tempo de fotoativação (20 e 40s) - Z2502mm20s, Z2502mm40s, One2mm20s, One2mm40s, One4mm20s, One4mm40s, Flow2mm20s, Flow2mm40s, Flow4mm20s e Flow4mm40s. As análises KHN foram realizadas no topo e na base de cada amostra. Os dados foram submetidos à ANOVA a 1 critério e ao Teste de Tukey (p< 0,05). A média e desvio padrão (+/-) dos seguintes grupos foram (Z2502mm20s) 0,85 (+/- 0,01); (Z2502mm40s) 0,92 (+/- 0,01); (One2mm20s) 1,05 (+/- 0,08); (One2mm40s) 0,95 (+/- 0,04); (One4mm20s) 0,93 (+/- 0,04); (One4mm40s) 0,97 (+/ - 0,04); (Flow2mm20s) 0,92 (+/- 0,05); (Flow2mm40s) 0,89 (+/- 0,04); (Flow4mm20s) 0,79 (+/- 0,04) e (Flow4mm40s) 0,90 (+/- 0,03). Os grupos da Filtek One Bulk apresentaram um valor significativamente maior, demonstrando uma polimerização suficiente mesmo na base de incrementos com 4 mm. Concluiu-se que o aumento na espessura do incremento de resinas bulk fill não afetou negativamente a fotoativação(AU)

Bulk fill composites emerged, allowing the restoration of deep cavities easily. Appropriate lightcuring is crucial to bulk fill composite presents satisfactory mechanical properties and restoration longevity. This study evaluated the influence of thickness increment on Knoop microhardness (KHN) of three dental bulk fill composites (n=5). Fifty samples were divided according to composite (Filtek Z250, Filtek One Bulk Fill and Filtek Bulk Fill Flow), thickness (2mm and 4 mm) and time lightcuring (20 and 40 s) - Z2502mm20s, Z2502mm40s, One2mm20s, One2mm40s, One4mm20s, One4mm40s, Flow2mm20s, Flow2mm40s, Flow4mm20s e Flow4mm40s. KHN analysis were performed on the top and the base of each specimen. Data were subjected to one-way ANOVA and Tukey test (p< 0,05). The mean and standard deviation (+/-) of following groups were (Z2502mm20s) 0,85(+/-0,01); (Z2502mm40s) 0,92(+/- 0,01); (One2mm20s) 1,05(+/-0,08); (One2mm40s) 0,95(+/-0,04); (One4mm20s) 0,93 (+/-0,04); (One4mm40s) 0,97(+/-0,04); (Flow2mm20s) 0,92(+/- 0,05); (Flow2mm40s) 0,89(+/-0,04); (Flow4mm20s) 0,79(+/-0,04) e (Flow4mm40s) 0,90(+/-0,03) Filtek One Bulk groups present significantly higher value, demonstrating sufficient polymerization even on the base of 4 mm increments. It was concluded that the increase in the thickness increment of Bulk fill composites did not negatively affect the lightcure(AU)