Restorative strategies for weakened roots: Systematic review and Meta-analysis of in vitro studies / Estratégias restauradoras para raízes fragilizadas: uma revisão sistemática e Meta-análise de estudos in vitro

This study evaluated fracture resistance values and failure mode of weakened roots restored with cast post and core, fiber post and anatomical posts. In vitro studies, published in English, Portuguese and Spanish, that evaluated weakened roots restored with at least two of mentioned strategies were searched for in three databases MEDLINE, PubMed and Scopus until June 2017; there was no restriction regarding the publication year. Fracture resistance values were obtained, and the following comparisons: cast post and core vs. fiber post and vs. anatomical post and fiber post vs. anatomical post were performed. Meta-analyses were conducted using the random effects model to calculate the combined effect of the difference between the averages. Six articles were included in the study. There was no significant difference between the fracture resistance values, but more catastrophic failures were observed on cast post and core, and the included studies presented a low risk of bias for the most domains. It was concluded that weakened roots restored with the searched strategies seem to have similar fracture strength, but fiber and anatomic post decreases the possibility of catastrophic failure. (AU)

Este estudo avaliou os valores de resistência à fratura e modo de falha de raízes fragilizadas restauradas com núcleos metálicos fundidos, pinos de fibra de vidro e pinos anatômicos. Foram pesquisados estudos in vitro, publicados em inglês, português e espanhol, que avaliaram raízes fragilizadas restauradas com pelo menos duas das estratégias citadas, em três diferentes bases de dados MEDLINE, PubMed e Scopus até junho de 2017; não houve restrição quanto ao ano de publicação. Os valores de resistência à fratura foram obtidos, e as seguintes comparações foram feitas: núcleo metálico fundido vs. pino de fibra de vidro e vs. pino anatômico e pino de fibra de vidro vs. pino anatômico. Meta-análises foram realizadas utilizando o modelo de efeitos randômicos para calcular o efeito combinado da diferença entre as médias. Seis artigos foram incluídos no estudo. Não houve diferença significativa entre os valores de resistência à fratura, mas foram observadas mais falhas catastróficas nos núcleos metálicos fundidos, e os estudos incluídos apresentaram um baixo risco de viés para a maioria dos domínios. Pode-se concluir que raízes fragilizadas, restauradas com as estratégias pesquisadas, parecem ter semelhante resistência à fratura, porém os pinos anatômicos e de fibra de vidro diminuem as possibilidades de falha catastrófica (AU)

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

Abstract Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

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.