Biomechanical and chemical behavior of various bioactive materials in class II restorations / Desempeño biomecánico y químico de diferentes materiales bioactivos en restauraciones clase II

The aim of this in vitro study was to evaluate the biomechanical and chemical behavior of various bioactive materials in class II MOD restorations. Forty- eight standardized class II MOD cavities were prepared in sound extracted human molar teeth. The specimens were divided into four groups according to the restorative material: Group 1 (Filtek™ Z350 XT), Group 2 (Biodentine™ as a liner, and then restored with Filtek™ Z350 XT), Group 3 (Cention N™), and Group 4 (Activa™ Bioactive-Restorative). The samples were tested for fracture resistance by subjecting them to a compressive load in a Universal testing Machine. The failure modes of each specimen were evaluated. The alkalinizing potential and calcium ion release of the materials were measured. SEM-EDAX analyses were also performed for all materials. Data were analyzed using ANOVA and post hoc Tukey test (p<0.05). Group 1 showed the higher fracture resistance (p<0.05). Group 3 had greater fracture resistance values but no statistical difference from Group 4. Biodentine™ showed greater biomineralization potential. Class II MOD restorations of Group 1 displayed the higher fracture resistance; however, it was highly associated with catastrophic failure. Conversely, Biodentine™ presented a more significant bioactivity potential, and its use, as in Group 2, promoted the most favorable failure mode.

El objetivo de este estudio, in vitro, fue evaluar el desempeño biomecánico y químico de varios materiales bioactivos en restauraciones clase II MOD. Se prepararon cuarenta y ocho cavidades clase II MOD estandarizadas en dientes molares humanos extraídos. Las muestras se dividieron en cuatro grupos según el material de restauración: Grupo 1 (Filtek™ Z350 XT), Grupo 2 (Biodentine™ como base y luego restaurado con Filtek™ Z350 XT), Grupo 3 (Cention N™) y Grupo 4 (Activa™ Bioactivo-Reparador). La prueba de resistencia a la fractura fue realizada en una máquina de ensayo universal Instron. Se evaluaron los modos de falla de cada espécimen. Se midió el pH y la liberación de iones de calcio de los materiales. Se realizaron análisis SEM-EDAX. Los datos se analizaron mediante ANOVA y la prueba post hoc de Tukey (p<0,05). El grupo 1 mostró la mayor resistencia a la fractura (p<0,05). El Grupo 3 tuvo mayores valores de resistencia a la fractura que el Grupo 4, pero sin diferencia estadística. Biodentine™ mostró un mayor potencial de biomineralización. Las restauraciones Clase II MOD del Grupo 1 mostraron la mayor resistencia a la fractura; sin embargo, estuvo altamente asociado con fallas irreparables. Por el contrario, Biodentine™ presentó un potencial de bioactividad más significativo y su uso, como en el Grupo 2, promovió el modo de falla más favorable.

Mechanism of action of Bioactive Endodontic Materials

Abstract A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Resumo Uma busca contínua de materiais bioativos com capacidade de substituir o tecido pulpar danificado, com efetiva capacidade de selamento e biocompatibilidade, tem representado a atenção e foco de muitos estudos ao longo das últimas décadas. Este estudo envolve uma revisão narrativa da literatura desenvolvida por meio de pesquisas representativas encontradas no PUBMED/MEDLINE e pesquisas em livros didáticos associadas ao mecanismo de ação de materiais bioativos (hidróxido de cálcio, agregado de trióxido mineral (MTA) e cimentos de silicato de cálcio). A presente análise reflexiva das particularidades dos elementos químicos destes materiais bioativos, considerando o mecanismo de ação tecidual e antibacteriano, possibilita um melhor entendimento das características e similaridades no comportamento tecidual. A pasta de hidróxido de cálcio continua sendo a substância antibacteriana de escolha como medicação intracanal para o tratamento das infecções do sistema de canais radiculares. Este fato se deve a disponibilidade química de íons cálcio e hidroxila do hidróxido de cálcio aos tecidos, e a inibição enzimática bacteriana. Os cimentos de silicato de cálcio, dentre os quais inclui o MTA, apresentam uma resposta biológica favorável ao estímulo à deposição de tecido mineralizado nas áreas seladas e em contato com tecido conjuntivo. Este fato é decorrente da similaridade entre os elementos químicos, em especial devido a dissociação iônica, ao potencial estímulo de enzimas teciduais, e a contribuição com um meio alcalino decorrente do pH destes materiais. O comportamento dos materiais bioativos, em especial o MTA e os novos cimentos de silicato de cálcio na atividade de selamento biológico mostraram efetivos. A endodontia contemporânea atualmente conta com o potencial de materiais bioativos com propriedades análogas capaz de estimular o selamento biológico em perfurações radiculares laterais e de furca, em obturações radiculares, capeamento pulpar, pulpotomia, apicificação e procedimentos endodônticos regenerativos, além de outras condições clínicas.

Restaurações diretas com materiais bioativos: observações clínicas, in vitro e revisão sistemática / Direct restorations with bioactive materials: clinical observations, in vitro and systematic review

O objetivo do ensaio clínico foi avaliar o desempenho clínico de 2 materiais bioativos (Cention N e EQUIA Forte) em comparação a resina composta. O estudo in vitro teve como objetivo avaliar o desenvolvimento de lesões de cárie induzida por desafio cariogênico bacteriano na margem de restaurações em esmalte e dentina com Cention N com e sem adesivo, EQUIA Forte e resina composta. A revisão sistemática teve como objetivo responder a seguinte pergunta: A avaliação clínica de restaurações em dentes permanentes com materiais bioativos evidencia maior sucesso do que restaurações com materiais não bioativos? Para o estudo clínico foram selecionados 120 participantes aleatoriamente divididos em 3 grupos (n=40), TC: Tetric N-Ceram, EF: EQUIA Forte, CN: Cention N. O preenchimento das cavidades foi realizado seguindo as indicações do fabricante. Foi utilizado o dispositivo de fluorescência DIAGNOdentTM Pen para avaliação da recorrência de cárie. No estudo in vitro foram confeccionados 100 espécimes a partir de dentes bovinos. Foram divididos em 5 grupos (n=20) metade em esmalte e metade em dentina: Cention N sem adesivo (CN), Cention N com adesivo (CA), EQUIA Forte (EF); Tetric N-Ceram (TC); e sem restauração (SR). Foram submetidos a envelhecimento térmico; leitura de microdureza Knoop (KHN) inicial, esterilizados e expostos a um desafio cariogênico com Streptococcus mutans por 28 dias. Lesões de cárie artificial foi quantificado por meio de KHN superficial e de subsuperfície, e análise com microscopia de luz polarizada. Os dados foram submetidos a ANOVA 1 fator e teste Tukey no esmalte e teste de Kruskal-Wallis na dentina. Em esmalte os grupos EF, CN, CA apresentaram menor porcentagem de perda da microdureza (%PMS) 57,85%, 63,88% e 66,65% respectivamente. Na dentina, EF, CN e CA apresentaram menores valores de %PMD sendo 31,7%, 34,1% e 40,8% respectivamente. Os valores mais altos de %PMS foram registrados para os grupos TC e SR tanto na dentina como no esmalte. Na revisão sistemática, com base na pergunta de pesquisa e estratégia PICO: P- Dentes permanentes, I- Restaurações (classe I, classe II, classe III, classe V) com materiais bioativos, C- Restauração com materiais não bioativos, O- Retenção; foi traçada a estratégia de busca. Após a obtenção dos estudos eles foram analisados por dois revisores independentes. No total foram 27 ensaios clínicos randomizados, com acompanhamento mínimo de 2 anos, foram os qualificados para realizar a revisão e meta-análise em rede. Os resultados de meta-análise em rede mostraram que em cavidades classe III cimento de ionômero de vidro modificado (CIV modificado), foi significativamente mais propenso a falhas do que a resina composta (RC), em restaurações classe I e II, o compômero foi significativamente mais propenso a falhas do que a RC e em restaurações classe V o cimento de ionômero convencional (CIV convencional) foi significativamente mais propenso a falhas do que o CIV modificado. No estudo in vitro foi evidente o maior potencial de inibição da desmineralização dos materiais bioativos. Na revisão sistemática ficou evidente que a maioria de materiais bioativos apresentam um bom comportamento, em relação as taxas de retenção e desempenho clínico. (AU)

The objective of the clinical trial was to evaluate the clinical performance of 2 bioactive materials (Cention N and EQUIA Forte) compared to composite resin. The in vitro study aimed to evaluate the development of caries lesions induced by bacterial cariogenic challenge at the margin of enamel and dentin restorations with Cention N with and without adhesive, EQUIA Forte and composite resin. The systematic review aimed to answer the following question: Does the clinical evaluation of restorations in permanent teeth with bioactive materials show greater success than restorations with nonbioactive materials? For the clinical study, 120 participants were randomly selected and divided into 3 groups (n=40), TC: Tetric N-Ceram, EF: EQUIA Forte, CN: Cention N. The filling of the cavities was performed following the manufacturer's instructions. The DIAGNOdentTM Pen fluorescence device was used to assess caries recurrence. In the in vitro study, 100 specimens were made from bovine teeth. They were divided into 5 groups (n=20) half in enamel and half in dentin: Cention N without adhesive (CN), Cention N with adhesive (CA), EQUIA Forte (EF); Tetric N-Ceram (TC); and without restoration (SR). They were subjected to thermal aging; initial Knoop microhardness (KHN) reading, sterilized and exposed to a cariogenic challenge with Streptococcus mutans for 28 days. Artificial caries lesions were quantified using surface and subsurface KHN and analysis with polarized light microscopy. Data were submitted to 1-way ANOVA and Tukey test on enamel and Kruskal-Wallis test on dentin. In enamel, groups EF, CN, CA had the lowest percentage of microhardness loss (%PMS) 57.85%, 63.88% and 66.65% respectively. In dentin, EF, CN and CA presented lower %PMD values, being 31.7%, 34.1% and 40.8% respectively. The highest %PMS values were recorded for the TC and SR groups in both dentin and enamel. In the systematic review, based on the research question and PICO strategy: P- Permanent teeth, I- Restorations (class I, class II, class III, class V) with bioactive materials, C- Restoration with non-bioactive materials, O- Retention; the search strategy was designed. After obtaining the studies, they were analyzed by two independent reviewers. In total, 27 randomized clinical trials, with a minimum followup of 2 years, were qualified to perform the review and network meta-analysis. The results of network meta-analysis showed that in class III cavities modified glass ionomer cement (modified GIC) was significantly more prone to failure than composite resin (RC), in class I and II restorations, the compomer was significantly more prone to failure than RC and in class V restorations the conventional ionomer cement (conventional GIC) was significantly more prone to failure than the modified GIC. In the in vitro study, the greatest potential for inhibiting the demineralization of bioactive materials was evident. In the systematic review it was evident that most bioactive materials have a good behavior in relation to retention rates and clinical performance (AU).

Effectiveness of Two Bioactive Restorative Materials in Dental Hard Tissues Remineralization as Indicated by Laser Fluorescence

Twenty extracted human sound premolars were selected and grouped into four groups and two class V cavity preparations, facial and lingual, were prepared at the cervical one-third of the crown of each tooth and extending into the root cementum to make a total of 40 cavities (n=10). The teeth were soaked in a demineralizing solution of pH 4.5 for 72 hours and a tooth surface conditioner was applied to remove remnants of the smear layer. Three laser fluorescence readings were recorded by DIAGNOdent pen for each cavity at enamel margin, dentin floor, and cementum margin. The groups were restored with four different restorative materials Cavit, temporary filling material (control), Ketac-Fil; a conventional glass-ionomer, and two bioactive restorative materials; Glass Carbomer and Biodentine. The restored teeth were stored in mineral water (37°C) for three weeks and brushed twice daily with Tooth Mousse toothpaste. The teeth were longitudinally cut into halves in the middle of the restorations and three DIAGNOdent pen readings were recorded at the same previous sites. Data were collected and statistically analyzed by one-way ANOVA and Tukey’s post-hoc-test at (p˂0.05). The results showed a significant increase in DIAGNOdent pen readings after soaking in the demineralizing solution in all tooth hard tissues, while a significant decrease was noted after the application of the restorations and storage in the three groups, other than control, indicating that both examined bioactive restorative materials were suitable for enhancing remineralization and subsequently arresting the three-tooth hard tissues carious lesions as the conventional glass-ionomer.

Protección pulpar directa en dientes de cabra: un modelo experimental / Direct pulp capping in goat teeth: an experimental model

Objetivos: Evaluar la utilidad de un modelo animal mamífero como la cabra, a fin de estudiar biomateriales indicados para protección pulpar directa. Materiales y métodos: Bajo anestesia general, se realizaron exposiciones pulpares en las caras vestibulares de los ocho incisivos inferiores de cuatro (n=4) cabras de raza criolla. En cada animal, 6 (n=6) exposiciones fueron protegidas con un material experimental (ACPc), y las 2 (n=2) restantes, con un material de control a base de MTA (WMTA). En total se realizaron 24 (n=24) protecciones con ACPc y 8 (n=8) con WMTA. Las cabras fueron separadas en dos grupos de dos (n=2) animales cada uno. Bajo anestesia general, los dientes se extrajeron a los 30 (Grupo 1) y 60 días (Grupo 2), se fijaron en formol búffer fosfato al 10% y se procesaron para el estudio histológico de rutina. Los animales no fueron sacrificados. En cada período, se analizaron 12 (n=12) protecciones pulpares con ACPc y 4 (n=4) con WMTA. Resultados: Grupo 1: Once (n=11) pulpas protegidas con ACPc presentaron puente dentinario completo e inflamación crónica remanente. En un caso no hubo puente dentinario y la pulpa estaba crónicamente inflamada. Las 4 (n=4) pulpas protegidas con WMTA presentaron puente dentinario e inflamación crónica. Grupo 2: Las 12 (n=12) pulpas protegidas con ACPc se encontraban normales, con puente dentinario completo, buena irrigación y capa de odontoblastos continua. Las 4 (n=4) pulpas protegidas con WMTA revelaron condiciones similares. Los resultados se analizaron mediante el test de probabilidad exacta de Fischer (P<0,05). Con respecto al factor inflamación, hubo diferencias significativas (P<0,001) entre los resultados obtenidos a 30 y 60 días, pero no hubo diferencias entre ACPc y WMTA (P>0,05) dentro de cada uno de los períodos de observación. En cuanto a la presencia de puente dentinario, no hubo diferencias significativas (P>0,05) entre ACPc y WMTA en ambos períodos de observación. Conclusiones: Los resultados sugieren que la cabra constituye un modelo animal adecuado para los ensayos de protección pulpar directa (AU)

Aim: To evaluate the suitability of the goat as an animal model for the study of biomaterials indicated for direct pulp capping. Materials and methods: Under general anaesthesia, pulp exposures were performed on the buccal surfaces of the eight mandibular incisors of four (n=4) healthy Creole goats. The exposures were capped with two biomaterials developed for PPD. In each animal, 6 (n=6) exposures were capped with an experimental material (ACPc) while for the remaining 2 (n=2) exposures a white MTA (WMTA) was used as the control. A total of 24 (n=24) direct pulp capping with ACPc and 8 (n=8) with WMTA were done. The goats were separated into two groups of two (n=2) animals each. The teeth were extracted after 30 days (Group 1) and 60 days (Group 2) and fixed in 10% phosphate buffered formalin and processed for routine histology. The animals were not euthanized. In each period, 12 (n=12) PPD with ACPc and 4 (n=4) with WMTA were analyzed. Results: Group 1: Eleven (n=11) pulps capped with ACPc showed complete dentin bridges and chronic inflammation. In one case without dentin bridges the pulp was chronically inflamed. The four pulps capped with WMTA revealed the presence of dentin bridges and chronic inflammation. Group 2: Twelve pulps protected with ACPc showed a complete dentin bridges. In addition, well irrigated and healthy pulp tissues along with a continuous odontoblast palisade were observed. The four pulps capped with WMTA revealed similar features. In cases showing dentin bridges, a few numbers of empty spaces as well as odontoblast like cell inclusions were detected. The results were analyzed by the Fisher's exact test (P<0.05). With respect to the inflammation factor there were significant differences between the 30 and 60-day observation periods (P<0.001), but no differences were observed between ACPc and WMTA (P>0.05) within each of the observation periods. When the presence or absence of a dentin bridges was analyzed, no significant differences (P>0.05) were found between materials at each observation period. Conclusions: The results suggest that the goat seems to be an appropriate animal model for direct pulp capping evaluation (AU)