Effectiveness of plant-derived proanthocyanidins on demineralization on enamel and dentin under artificial cariogenic challenge

Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries. Objective The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin. Material and Methods Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride – 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy. Results The means were subjected to statistical analysis using the ANOVA and Fisher's PLSD tests (

Fatigue survival and damage modes of lithium disilicate and resin nanoceramic crowns

Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture. Objective: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns. Methodology: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05). Results: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference. Conclusions: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns

Shrinkage stress and elastic modulus assessment of bulk-fill composites

Bulk-fill composites were introduced in dentistry to accelerate clinical procedures while providing adequate outcomes. Concerns regarding the use of bigger composite increments rely on the polymerization shrinkage and shrinkage stress, which may generate gaps on the adhesive interface and result in a reduced success rate. Objective: To evaluate the polymerization shrinkage stress of different bulk-fill resin composites and their elastic modulus. Materials and Methods: Fourteen specimens were made for each of the nine different resin composites (seven with 12 mm3 and seven with 24 mm3): Surefill SDR flow (SDR), X-tra Base (XB), Filtek Bulk Fill Flowable (FBF), Filtek Z350XT Flow (Z3F); Tetric Evo Ceram Bulk Fill (TBF), X-tra Fil (XF), Filtek Bulk Fill (FBP), Admira Xtra Fusion (ADM) and Filtek Z350 XT (Z3XT). Linear shrinkage stress was evaluated for 300 s with the aid of a linear shrinkage device adapted to a Universal Testing Machine. For each composite group, seven additional specimens (2x2x25 mm) were made and Young’s modulus was evaluated with a 3-point bending device adapted in a Universal Testing Machine with 0.5 mm/min crosshead speed and 50 KgF loading cell. Results: For 12 mm3 specimens, three-way ANOVA showed that only SDR and TBF generated lower stress after 20 s. Considering 300 s, TBF, SDR, and XF generated the lowest stress, followed by ADM, FBP, XB, and FBF, which were similar to Z3XT. Z3F generated the highest stress values for all time points. Considering 24 mm3 specimens after 20 s, all bulk fill composites generated lower stress than Z3XT, except XB. After 300 s, SDR, FBP, and ADM generated the lowest stress, followed by TBF and XF. For elastic modulus, one-way ANOVA showed that FBF, SDR, Z3F, and ADM presented the lowest values, followed by XB and TBF. FBP, Z3XT, and XF presented the highest elastic modulus among the evaluated composites. Conclusions: Bulk-fill resin composites presented equal to lower shrinkage stress generation when compared to conventional composites, especially when bigger increments were evaluated. Bulk-fill composites showed a wide range of elastic modulus values, but usually similar to “regular” composites

Shrinkage stress and elastic modulus assessment of bulk-fill composites

Bulk-fill composites were introduced in dentistry to accelerate clinical procedures while providing adequate outcomes. Concerns regarding the use of bigger composite increments rely on the polymerization shrinkage and shrinkage stress, which may generate gaps on the adhesive interface and result in a reduced success rate. Objective: To evaluate the polymerization shrinkage stress of different bulk-fill resin composites and their elastic modulus. Materials and Methods: Fourteen specimens were made for each of the nine different resin composites (seven with 12 mm3 and seven with 24 mm3): Surefill SDR flow (SDR), X-tra Base (XB), Filtek Bulk Fill Flowable (FBF), Filtek Z350XT Flow (Z3F); Tetric Evo Ceram Bulk Fill (TBF), X-tra Fil (XF), Filtek Bulk Fill (FBP), Admira Xtra Fusion (ADM) and Filtek Z350 XT (Z3XT). Linear shrinkage stress was evaluated for 300 s with the aid of a linear shrinkage device adapted to a Universal Testing Machine. For each composite group, seven additional specimens (2x2x25 mm) were made and Young’s modulus was evaluated with a 3-point bending device adapted in a Universal Testing Machine with 0.5 mm/min crosshead speed and 50 KgF loading cell. Results: For 12 mm3 specimens, three-way ANOVA showed that only SDR and TBF generated lower stress after 20 s. Considering 300 s, TBF, SDR, and XF generated the lowest stress, followed by ADM, FBP, XB, and FBF, which were similar to Z3XT. Z3F generated the highest stress values for all time points. Considering 24 mm3 specimens after 20 s, all bulk fill composites generated lower stress than Z3XT, except XB. After 300 s, SDR, FBP, and ADM generated the lowest stress, followed by TBF and XF. For elastic modulus, one-way ANOVA showed that FBF, SDR, Z3F, and ADM presented the lowest values, followed by XB and TBF. FBP, Z3XT, and XF presented the highest elastic modulus among the evaluated composites. Conclusions: Bulk-fill resin composites presented equal to lower shrinkage stress generation when compared to conventional composites, especially when bigger increments were evaluated. Bulk-fill composites showed a wide range of elastic modulus values, but usually similar to “regular” composites

Maquete de Máquina de Ensaio Universal: Ferramenta de Ensino Odontológico sob a Óptica de um Aluno de Graduação

Ao iniciar o curso de Odontologia, os alunos se deparam com uma disciplina intitulada Materiais Dentários. Essa disciplina possui dificuldades inerentes ao ensino de partes de seu conteúdo, como as propriedades mecânicas dos materiais odontológicos. Tal fato se deve, provavelmente, à presença de uma linguagem própria e de conceitos mecânicos e físicos que fogem do cotidiano do aluno de graduação de Odontologia; somando-se a isso, temos um meio virtualizado onde esses alunos estão inseridos. Esse conjunto pode trazer dificuldades para a apreensão de conteúdo ao estudante, uma vez que existem diversas maneiras de assimilação de novas informações. O professor, portanto, deve compreender de onde advém a dificuldade dos alunos em apreender os conteúdos e então traçar estratégias para a melhoria do ensino. Assim, o objetivo do presente trabalho é expor como uma Maquete de Máquina de Ensaio Universal pode tornar inteligíveis conceitos abstratos das propriedades dos materiais dentários, permitindo o aprimoramento da compreensão de tais noções por parte dos alunos de graduação em Odontologia e o aperfeiçoamento do ensinoIn the beginning of the Dentistry course students take a subject called Dental Materials. This subject presents difficulties inherent to the content, like the mechanical properties of dental materials. This is probably due to the presence of a particular vocabulary and of mechanical and physical concepts that are far from the Dentistry student everyday; in addition to that these students are living in a virtual world. This set of characteristics can bring difficulties to student’s learning, once there are many ways to take in new information. Thus, the teacher must understand where does the students’ learning difficulty come from and create strategies to improve teaching. The purpose of this work is to expose how a Universal Testing Machine Model can make concepts of dental materials properties more intelligible, enhancing Dentistry graduation students’ learning, and also improving the teachin

Análise da microdureza Vickers de zircônia Y-TZP pré-sinterizada para a usinagem e posterior aplicação como copings

A zircônia Y-TZP é muito utilizada na confecção de coping como material estrutural para próteses odontológicasdevido à sua cor branca/perolada opaca e resistência mecânica. Estas próteses são confeccionadas porusinagem com apoio de um software de CAM (Computer Aided Manufacturing), a partir de blocos prensadose pré-sinterizados. A pré-sinterização consiste em aquecer os blocos compactados a altas temperaturas, comuma taxa lenta de aquecimento até o início da formação dos pescoços entre as partículas, quando proporcionadureza/resistência e usinabilidade. Uma contradição, pois a dureza/resistência mecânica é necessária paraproporcionar estabilidade as forças de corte, mas se muito duro, pode dificultar a usinagem então se deveencontrar uma faixa de compromisso de temperatura entre estabilidade e usinabilidade. Dessa forma, o objetivodo presente trabalho foi investigar a relação entre a microdureza e temperatura de pré-sinterização dazircônia Y-TZP e seu comportamento ao ser submetido à usinagem. O ensaio de microdureza foi escolhidocomo representante de resistência mecânica por ser não destrutivo e de resultado imediato. O pó de zircôniaexperimental foi submetido à prensagem uniaxial seguido de prensagem isostática a frio à 200 MPa e présinterizaçãoentre 900°C e 950°C. Os blocos foram cortados e submetidos ao teste de estabilidade na usinageme ensaio de microdureza Vickers sendo os dados submetidos ao teste de “normalidade” de Anderson-Darlin com p 0,05. Foi utilizada ANOVA de um fator com o teste de Tukey-Kramer para verificar as diferençasentre as médias dos grupos. A investigação demonstrou que a diferença de 50°C na temperatura depré-sinterização, acima de 900°C afetou significativamente a microdureza, contudo os tempos de patamar 2 e4 horas não a influenciou significativamente. A maior temperatura de pré-sinterização dos grupos experimentaistestados possibilitou um melhor comportamento na usinagem com o apoio de um software CAM, sendo amicrodureza similar ao material comercial ZL

Mechanical and optical properties of conventional restorative glass-ionomer cements - a systematic review

Objectives To perform a systematic review of test methodologies on conventional restorative glass-ionomer cement (GIC) materials for mechanical and optical properties to compare the results between different GICs. Material and Methods Screening of titles and abstracts, data extraction, and quality assessments of full-texts were conducted in search for in vitro studies on conventional GICs that follow the relevant specifications of ISO standards regarding the following mechanical and optical properties: compressive strength, flexural strength, color, opacity and radiopacity. Sources The Latin American and Caribbean Health Sciences (LILACS), Brazilian Bibliography of Dentistry (BBO) databases from Latin-American and Caribbean System on Health Sciences Information (BIREME) and PubMed/Medline (US National Library of Medicine - National Institutes of Health) databases were searched regardless of language. Altogether, 1146 in vitro studies were selected. Two reviewers independently selected and assessed the articles according to pre-established inclusion/exclusion criteria. Among all the properties investigated, only one study was classified as being of fair quality that tested compressive strength and was included. It was observed that many authors had not strictly followed ISO recommendations and that, for some properties (diametral tensile strength and microhardness), there are no guidelines provided. Conclusions It was not possible to compare the results for the mechanical and optical properties of conventional restorative GICs due to the lack of standardization of studies

Mechanical and optical properties of conventional restorative glassionomer cements - a systematic review

Objectives: To perform a systematic review of test methodologies on conventional restorative glass-ionomer cement (GIC) materials for mechanical and optical properties to compare the results between different GICs. Material and Methods: Screening of titles and abstracts, data extraction, and quality assessments of full-texts were conducted in search for in vitro studies on conventional GICs that follow the relevant specifications of ISO standards regarding the following mechanical and optical properties: compressive strength, flexural strength, color, opacity and radiopacity. Sources: The Latin American and Caribbean Health Sciences (LILACS), Brazilian Bibliography of Dentistry (BBO) databases from Latin-American and Caribbean System on Health Sciences Information (BIREME) and PubMed/Medline (US National Library of Medicine - National Institutes of Health) databases were searched regardless of language. Altogether, 1146 in vitro studies were selected. Two reviewers independently selected and assessed the articles according to pre-established inclusion/exclusion criteria. Among all the properties investigated, only one study was classified as being of fair quality that tested compressive strength and was included. It was observed that many authors had not strictly followed ISO recommendations and that, for some properties (diametral tensile strength and microhardness), there are no guidelines provided. Conclusions: It was not possible to compare the results for the mechanical and optical properties of conventional restorative GICs due to the lack of standardization of studies

INFLUÊNCIA DA DESINFECÇÃO NA ESTABILIDADE DIMENSIONAL LINEAR DE 3 MATERIAIS DE MOLDAGEM. ESTUDO IN VITRO.

Objective: to evaluate the effect of disinfection on the dimensional stability of three different impression materials. Material and methods: using a specific matrix (ADA.1933 standard), molds were obtained in addition silicone, polyether and alginate (n=60) which were subdivided into 6 subgroups (I- control (washed only); II- Bacterend OX 0, 5%; III- Bacterend OX 1%; IV- Bacterend OX 2%; V- hydrogen peroxide 1%- BlueM VI-sodium hypochlorite 1%). Measurements were taken, by a single calibrated operator, using a comparator microscope (Mitutoyo MFG. Co. Ltd., Japan), of the metal matrix and each specimen, at determined points. Measurements were taken 3 times and the average was calculated. The formula (A-B/Ax100) was used for each specimen. The data were tabulated and statistically analyzed. To evaluate the difference between groups, the quantitative variable was tested for normal distribution with the Shapiro-Wilk test. The difference between two groups was evaluated by the Man-Withney test (p<0.05) Results: Compared to the control groups, subgroups II, III and V did not show dimensional changes in the 3 impression materials; subgroups IV (in materials AS and P) and all subgroups VI showed statistically significant dimensional changes. Conclusion: Based on the data collected, it seems reasonable to conclude that 0.5% or 1% peracetic acid in equilibrium and 1% hydrogen peroxide do not promote dimensional changes in addition silicone molds (VPS), polyether (Impregum) or alginate ( Hydrogun). Peracetic acid in equilibrium at 2% concentration should not be used on silicones and 1% sodium hypochlorite on any of the materials.Objetivo: evaluar el efecto de la desinfección sobre la estabilidad dimensional de tres materiales de impresión diferentes. Material y métodos: utilizando una matriz específica (norma ADA.1933), se obtuvieron moldes además de silicona, poliéter y alginato (n=60) los cuales se subdividieron en 6 subgrupos (I- control (solo lavado); II- Bacterend OX 0 , 5%; III- Bacterend OX 1%; IV- Bacterend OX 2%; V- peróxido de hidrógeno 1%- BlueM VI- hipoclorito de sodio 1%). Las mediciones fueron tomadas por un único operador calibrado, utilizando un microscopio comparador (Mitutoyo MFG. Co. Ltd., Japón), de la matriz metálica y de cada muestra, en puntos determinados. Se tomaron medidas 3 veces y se calculó el promedio. Para cada muestra se utilizó la fórmula (A-B/Ax100). Los datos fueron tabulados y analizados estadísticamente. Para evaluar la diferencia entre grupos, se probó la distribución normal de la variable cuantitativa con la prueba de Shapiro-Wilk. La diferencia entre dos grupos fue evaluada mediante la prueba de Man-Withney (p<0,05) Resultados: Comparados con los grupos control, los subgrupos II, III y V no mostraron cambios dimensionales en los 3 materiales de impresión; los subgrupos IV (en materiales AS y P) y todos los subgrupos VI mostraron cambios dimensionales estadísticamente significativos. Conclusión Con base en los datos recopilados, parece razonable concluir que un 0,5% o un 1% de ácido peracético en equilibrio y un 1% de peróxido de hidrógeno no promueven cambios dimensionales además de los moldes de silicona (VPS), poliéter (Impregum) o alginato (Hydrogun). El ácido peracético en equilibrio al 2% de concentración no debe usarse en siliconas y el hipoclorito de sodio al 1% en ninguno de los materiales.Objetivo: avaliar o efeito da desinfecção na estabilidade dimensional de três diferentes materiais de moldagem. Material e métodos: utilizando matriz específica (norma ADA.1933) foram obtidos moldes em silicone de adição, poliéter e alginato (n=60) que foram subdivididos em 6 subgrupos (I- controle (apenas lavados); II- Bacterend OX 0,5%; III- Bacterend OX 1%; IV- Bacterend OX 2%; V- peróxido de hidrogênio 1%- BlueM VI-hipoclorito de sódio 1%). Foram realizadas medidas, por um único operador calibrado, em microscópio comparador (Mitutoyo MFG. Co. Ltd., Japão), da matriz metálica e de cada espécime, em pontos determinados. As medidas foram realizadas 3 vezes e a média foi calculada. Foi utilizada a fórmula (A-B/Ax100) para cada espécime. Os dados foram tabulados e analisados estatisticamente. Para avaliar a diferença entre grupos, a variável quantitativa foi testada para distribuição normal com o teste de Shapiro-wilk. A diferença entre dois grupos foi avaliada pelo teste de Man-Withney (p<0,05) Resultados: Comparados aos grupos controle, os subgrupos II, III e V não mostraram alterações dimensionais nos 3 materiais de moldagem; os subgrupos IV (nos materiais AS e P) e todos os subgrupos VI mostraram alteração dimensional estatisticamente significantes. Conclusão Com base nos dados coletados parece lícito concluir que o ácido peracético em equilíbrio 0,5% ou 1% e o peróxido de hidrogênio 1% não promovem alterações dimensionais nos moldes em silicone de adição (VPS), poliéter (Impregum) ou alginato (Hidrogun). Ácido peracético em equilíbrio na concentração 2% não deve ser utilizado em silicones e hipoclorito de sódio 1% em nenhum dos materiais.       &nbsp

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

Objective: This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods: Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: postsintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results: The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions: Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement