New material perspective for endocrown restorations: effects on mechanical performance and fracture behavior

Abstract The aim of this study was to investigate the mechanical performance and the fracture behavior of endocrown restorations prepared using distinct restorative materials. A total of 42 sound molars with similar crown size and shape were cut at 2 mm above the cementoenamel junction and endodontically treated. They were categorized according to the restorative material used to fabricate endocrown restorations (n=7), namely, conventional composite (Filtek™ Z350 XT), bulk fill composite (Filtek™ Bulk Fill), conventional composite modeled using resin adhesives (SBMP: Scotchbond™ Multipurpose Adhesive; or SBU: Scotchbond™ Universal Adhesive), and IPS e.max lithium disilicate (Ivoclar Vivadent; positive control). Unprepared sound teeth were used as negative control. All endocrowns were bonded using a self-adhesive cement (Rely-X™ U200). The teeth were submitted to fatigue (Byocycle) and fracture (EMIC DL500) testing. Load-to-fracture (in N) and work-of-fracture (Wf, in J/m2) values were analyzed by ANOVA (p < 0.05). The endocrowns did not fracture or de-bond upon fatigue, showing similar load-to-fracture and work-of-fracture values, regardless of the restorative material (p > 0.05). The endocrowns fabricated by combining Z350 and SBMP had the least harsh fractures, in contrast to endocrowns prepared using Z350 only, which exhibited an equilibrium between repairable and irrepairable fractures. The e.max endocrowns exhibited more aggressive failures (root fracture) than other groups, resulting in higher rates of irrepairable fractures. In conclusion, dental practitioners may satisfactorily restore severely damaged nonvital teeth using the endocrown technique. Composite endocrowns prepared using resin adhesive as modeler liquid or using bulk fill material may result in less aggressive failures, thus providing a new material perspective for endocrown restorations.

Translucency and color stability of resin composite and dental adhesives as modeling liquids - A one-year evaluation

Abstract The aim of this study is to evaluate the influence of modeling liquids on the translucency and color shade of resin composites (RCs) after one year of storage. RC specimens were prepared using either a conventional insertion technique (control; without modeling liquid) or a restorative dental modeling insertion technique (RDMIT) with dental adhesives as modeling liquids (Scotchbond™ Multi-Purpose [SBMP; 3M ESPE] or Adper™ Single Bond 2 [SB; 3M ESPE]). The initial colors of the specimens were obtained with a digital spectrophotometer and the CIEL*a*b* color system, after which specimens were stored (37°C) in distilled water or red wine for 12 months. Color measurements were reassessed after 6 and 12 months of storage, and scanning electron microscopy was performed after 12 months. Translucency and color change (ΔE*) were calculated and analyzed using ANOVA and Tukey's test (α = 5%). RC samples prepared via RDMIT showed a translucency similar to that of control samples. ΔE* was also less intense for RCs containing SBMP than for RCs containing SB. Specimens stored in wine showed a clear pattern of degradation, especially in the control group, and surface degradation seemed to be less intense for specimens prepared with SBMP and SB than for specimens without. Specimens stored in water did not show clear evidence of surface degradation. RDMIT appears to be an interesting approach to reduce ΔE* in RCs over time without negative effects on the translucency of the material. However, the modeling liquid should feature a hydrophobic composition, similar to that used in the SBMP group, the achieve the best results.

Knowledge and attitudes of students and dentists about the use and cementation of intra-radicular posts / Conhecimentos e atitudes de estudantes e dentistas sobre o uso e cimentação de pinos intrarradiculares

Objectives: The aim of the study was assess the knowledge and attitudes of students and dentists about the use and cementation of intra-radicular posts. Material and Methods: This cross-sectional study interviewed 150 students and 150 dentists in the city of Pelotas (Brazil). A questionnaire containing questions regarding restorative choice in teeth with large coronal destruction, level of confidence for the use of post and resin cement, function of intra-radicular posts and social-demographic characteristics was applied. Data were analysed using descriptive analysis and associations were tested through logistic regression using 95% confidence intervals. Results: The analysis showed that students presented an odd to choose prefabricated posts 127% greater than the dentists for anterior teeth, 105% greater to choose self-adhesive resin cement and 46% greater to choose conventional resin cement. Considering posterior teeth, students presented an odd to choose prefabricated posts 40% smaller than the dentists and an odd 51% greater to choose conventional resin cement. Conclusion: The formation level (students or dentists) was directly related to clinical choices of the interviewed. The use of prefabricated posts seems to be related to the location of the tooth in the arch, with pre-fabricated posts being more indicated for anterior teeth. Use of pre-fabricated posts in teeth with large coronal destruction is accepted in the literature. However, dentists are still not confident to use of pre-fabricated fiber posts especially in posterior teeth with large coronal destruction. (AU)

Objetivo: o objetivo do estudo foi avaliar o conhecimento e as atitudes dos alunos e dentistas sobre o uso e cimentação de pinos intra-radiculares. Material e Métodos: este estudo transversal entrevistou 150 estudantes e 150 dentistas na cidade de Pelotas (Brasil). Foi aplicado um questionário contendo perguntas sobre a escolha restauração em dentes com grande destruição coronária, nível de confiança para o uso de pinos e cimento resinoso, função dos pinos intra-radiculares e características sociodemográficas. Os dados foram analisados utilizando análise descritiva e as associações foram testadas através de regressão logística usando intervalos de confiança de 95%. Resultados: A análise mostrou que os alunos apresentaram uma chance para escolher pinos pré-fabricados 127% maior que os dentistas para dentes anteriores, 105% maior para escolher cimento resinoso autoadesivo e 46% maior para escolher o cimento resinoso convencional. Considerando os dentes posteriores, os estudantes apresentaram uma chance para escolher os pinos pré-fabricados 40% menor do que os dentistas e uma chance 51% maior para escolher o cimento resinoso convencional. Conclusão: O nível de formação (estudantes ou dentistas) está diretamente relacionado às escolhas clínicas dos entrevistados. O uso de pinos pré- fabricados parece estar relacionado à localização do dente no arco, com pinos pré-fabricados sendo mais indicados para os dentes anteriores. O uso de pinos pré-fabricados em dentes com grande destruição coronária é aceito na literatura. No entanto, os dentistas ainda não estão confiantes para o uso de pinos pré-fabricados de fibra, especialmente em dentes posteriores com grande destruição coronária. (AU)

Accuracy of color measurement of endondontically treated teeth after aging / Precisão da medição de cor de dentes tratados endodonticamente após envelhecimento

Objective: The aim of this study was to compare the accuracy of three different modes of a spectrophotometer (Vita Classical, 3D-Master and CIE L*a*b* system) in the evaluation of color alteration in endodontically treated teeth. Material and Methods: The root canal treatment of forty-five sound human canines was performed. Color measurements were performed before the endodontic treatment (baseline), and after 6 months of water storage. Shade matching was performed using a spectrophotometer (Vita Easyshade) in three different modes: Vita Classical, 3D-Master and CIE L*a*b* coordinates. The color change (ΔE value) for the three methods were assessed in each sample and analyzed by multiple linear regression analysis. L*, a* and b* values were analyzed by t-test. The significance level was set at 5%. Results: According to the digital evaluation, no statistically significant differences were found between the CIE L*a*b*,Vita Classical and 3D-Mastermodes. However, a significant difference was found (p < 0.001) for the ΔE values, with the CIE L*a*b* mode presenting greater accuracy to detect color alterations. Conclusion: CIE L *a*b* method properly correlates to Vita Classical and 3D-Master modes. However, Easyshade can easier detect color changes if used in the CIE L*a*b* mode, which leads to more accurate results.

Objetivo: O objetivo deste estudo foi comparar a precisão de três modos diferentes de um espectrofotômetro (Vita Classical, 3D-Master e sistema CIE L*a*b*) na avaliação da alteração de cor em dentes tratados endodonticamente. Materiais e Métodos: O tratamento endodôntico de quarenta e cinco caninos humanos foi realizado. Medições de cor foram realizadas, antes do tratamento endodôntico (imediatamente), e após 6 meses de armazenamento em água. Análise de cor foi realizado utilizando um espectrofotômetro (Vita Easyshade) em três diferentes modos: Vita Classical, 3D-Master e sistema CIE L*a*b*. A mudança de cor (valor ΔE) para os três métodos foram avaliadas em cada amostra e analisados através de análise de regressão linear múltipla. Valores de L*, a* e b* foram analisados através do teste-t. O nível de significância estabelecido foi de 5%. Resultados: De acordo com a avaliação digital, não foram encontradas diferenças significativas entre os métodos CIE L*a*b*,Vita Classical e 3D-Master. No entanto, uma diferença significativa foi encontrada (p < 0,001) para os valores de ΔE, com o modo CIE L*a*b* apresentando uma maior precisão para detectar alterações de cor. Conclusão: O método CIE L *a*b* correlaciona corretamente para os modos Vita Classical e 3D-Master. No entanto, o Easyshade pode detectar alterações de cor, mais facilmente quando utilizado no modo CIE L *a*b*, permitindo resultados mais precisos.

Cleaning methods for removable dentures: a critical reviewof the literature

A literature review was performed including studies that evaluated the use of cleaning protocols for removable dentures through questionnaires, clinical trials, randomized clinical trials, and systematic reviews. Twenty studies were included and the results showed that bad preservation of the prostheses is mainly due to low knowledge about cleaning habits and methods. Also, a wide variety of effective cleaning methods were presented. However, there is no standard protocol for all patients and it should be customized for each patient. It is important to highlight that dentists should give adequate instructions concerning maintenance and hygiene of the prosthesis.

Uma revisão da literatura foi realizada incluindo estudos que avaliaram o uso de protocolos de limpeza para próteses removíveis através de questionários, ensaios clínicos, estudos clínicos randomizados e revisões sistemáticas. Vinte estudos foram incluídos e os resultados mostraram que a má preservação das próteses é principalmente devido ao baixo conhecimento sobre os hábitos e métodos de limpeza. Além disso, foram apresentados uma grande variedade de métodos de limpeza eficazes. No entanto, não existe um protocolo padrão para todos os pacientes, devendo ser personalizado para cada paciente. É importante destacar que os dentistas devem dar instruções adequadas quanto a manutenção e higiene das próteses.

Effects of modeling liquid/resin and polishing on the color change of resin composite

Abstract Modeling liquids/resins have been used to build up resin composite (RC) restorations, although there is a lack of information regarding their effects on the color stability of the latter. Therefore, the purpose of the present study was to evaluate the effects of the presence of modeling liquid between layers of RC and the finishing/polishing state of the material on color change in specimens exposed to red wine staining over time. Specimens were prepared by placing four increments (±0.5 mm thick) of RC (Filtek™ Z350 XT, 3M ESPE) into molds; half of which were prepared by applying modeling liquid (Scotchbond™ Multi-Purpose™ Adhesive, SBMP, 3M ESPE) between the layers of RC, whereas the other half were prepared without SBMP (control). Light-activation was performed after application of the final RC layer using a light-emitting diode (Radii, SDI) curing unit with an irradiance of 900 mW/cm2 for 20 s. Each group was divided according to the surface finishing protocol (n = 7): nothing (non-polished) or polishing with Sof-Lex™/diamond paste (polished). Initial colors of the specimens were evaluated with a digital spectrophotometer and the CIEL*a*b* color system. The specimens were stored in wine (37°C) for 12 months, and the color measurements were reassessed after 4, 6, and 12 months of storage. Scanning electron microscopy (SEM) analysis was performed at the end. Data were analyzed using ANOVA and Tukey's test (α = 5%). The presence of SBMP resulted in lower overall color change of the RC as compared with the control. The non-polished specimens exhibited a significantly higher color change than the polished specimens. SEM images corroborated the previous findings. In summary, the use of modeling liquid between layers of RC shows potential for application to reduce or delay the staining process of RC over time. Moreover, polishing is essential to provide increased color stability of the RC restoration.