Although further studies are necessary to corroborate these findings, both zirconia systems could be recommended for restoring posterior teeth on the basis of the fracture load values recorded in this experiment (>1000 N). The veneering procedure did not affect the overall load to fracture in any group.

The development of targeted nanocarriers able to be selectively internalized within tumor cells, and therefore to deliver anti-tumor drugs specifically to diseased cells, constitutes one of the most important goals in nano-oncology. Herein, the development of Janus mesoporous silica particles asymmetrically decorated with two targeting moieties, one of them selective for folate membrane cell receptors (folic acid) and the other one able to bind to mitochondria membrane (triphenylphosphine, TPP), is described in order to achieve sequential cell to organelle vectorization. The asymmetric decoration of each side of the particle allows fine control in the targeting attachment process in comparison with the use of symmetric nanocarriers. The presence of folic acid induces a higher increase in particle accumulation inside tumor cells, and once there, these nanocarriers are guided close to mitochondria by the action of the TPP moiety. This strategy can be applied for improving the therapeutic efficacy of current nanomedicines.

The purpose of this study was to evaluate and to compare the fracture load and the fracture pattern of monolithic and veneered zirconia posterior fixed dental prostheses (FDPs). Twenty standardized steel dies were prepared to receive posterior 3-unit FDPs. Specimens were randomly divided into 2 groups (n=10): (1) Lava Zirconia, and (2) Lava Plus. All FDPs were cemented using glass ionomer cement and subjected to thermal and mechanical cycling at 5-55ºC with a 30-s dwell time for 120,000 masticatory cycles. All specimens were subjected to a three-point bending test until fracture. Data were statistically analyzed using Student's t test, paired t-test and Weibull statistics (α=0.05). No differences were observed in fracture load between the groups. Veneering ceramic fractured before than framework in veneered zirconia group. The fracture pattern was different. The tested groups demonstrated clinically acceptable fracture load values. Monolithic zirconia solves the chipping problem.

The aim of this study was to investigate the load to fracture and fracture pattern of prosthetic frameworks for tooth-supported fixed partial dentures (FPDs) fabricated with different subtractive computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Thirty standardized specimens with two abutments were fabricated to receive three-unit posterior FDP frameworks with an intermediate pontic. Specimens were randomly divided into three groups (n = 10 each) according to the material: group 1 (MM)—milled metal; group 2 (L)—zirconia; and group 3 (P)—Polyetheretherketone (PEEK). The specimens were thermo-cycled and subjected to a three-point bending test until fracture using a universal testing machine (cross-head speed: 1 mm/min). Axial compressive loads were applied at the central fossa of the pontics. Data analysis was made using one-way analysis of variance, Tamhane post hoc test, and Weibull statistics (α = 0.05). Results: Significant differences were observed among the groups for the fracture load (p < 0.0001). MM frameworks showed the highest fracture load values. The PEEK group registered higher fracture load values than zirconia samples. The Weibull statistics corroborated these results. The fracture pattern was different among the groups. Conclusions: Milled metal provided the highest fracture load values, followed by PEEK, and zirconia. However, all tested groups demonstrated clinically acceptable fracture load values higher than 1000 N. PEEK might be considered a promising alternative for posterior FPDs.

Background In recent years there has been an improvement of zirconia ceramic materials to replace posterior missing teeth. To date little in vitro studies has been carried out on the fracture resistance of zirconia veneered posterior fixed dental prostheses. This study investigated the fracture resistance and the failure mode of 3-unit zirconia-based posterior fixed dental prostheses fabricated with two CAD/CAM systems. Material and Methods Twenty posterior fixed dental prostheses were studied. Samples were randomly divided into two groups (n=10 each) according to the zirconia ceramic analyzed: Lava and Procera. Specimens were loaded until fracture under static load. Data were analyzed using Wilcoxon´s rank sum test and Wilcoxon´s signed-rank test (P<0.05). Results Partial fracture of the veneering porcelain occurred in 100% of the samples. Within each group, significant differences were shown between the veneering and the framework fracture resistance (P=0.002). The failure occurred in the connector cervical area in 80% of the cases. Conclusions All fracture load values of the zirconia frameworks could be considered clinically acceptable. The connector area is the weak point of the restorations. Key words:Fixed dental prostheses, zirconium-dioxide, zirconia, fracture resistance, failure mode.

This systematic review aims to evaluate the different pretreatments of the zirconia surface and resin cement in order to determine a valid operative protocol for adhesive cementation. Methodologies conducted for this study followed the Prisma (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. An electronic search was performed in four databases. The established focus question was: “What type of surface conditioning method is the one that obtains the best adhesion values to zirconia over time by applying a resin cement?” Forty-five relevant papers were found to qualify for final inclusion. In total, 260 different surface pretreatment methods, mainly combinations of air-abrasion protocols and adhesive promoters, were investigated. Altogether, the use of two artificial aging methods, three types of cement and four testing methods was reported. The results showed that mechanicochemical surface pretreatments offered the best adhesive results. Self-adhesive cement and those containing 10-MDP obtained the best results in adhesion to zirconia. Artificial aging reduced adhesion, so storage in water for 30 days or thermocycling for 5000 cycles is recommended. A standardized adhesive protocol has not been established due to a lack of evidence

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Objectives To evaluate and to compare the clinical performance and survival rate of posterior monolithic and veneered zirconia fixed partial dentures (FPDs). Material and methods Sixty 3-unit posterior FPDs were included in the study. The patients were randomly distributed into two groups (n = 30 each) to receive either a monolithic (Zenostar T, Wieland Dental) or veneered zirconia (IPS e.max ZirCAD, Ivoclar Vivadent) FPD. Each patient received only 1 FPD. Tooth preparations were scanned (Trios 3, 3Shape), designed (Dental System 2016, 3 Shape), milled (Zenotec CAM 3.2, Wieland Dental), and cemented with a resin cement. Technical and biological outcomes and periodontal parameters were assessed. Data analysis was made using the Friedman and the Wilcoxon signed-rank tests with the Bonferroni correction and the Mann-Whitney U test. ResultsThe survival rate at 3 years was 100% for veneered and 90% for monolithic zirconia restorations. Three monolithic zirconia FPDs were lost because of biologic complications. The main complication in the veneered zirconia FPDs was the fracture of the veneering ceramic in 4 of the veneered zirconia FPDs. No fracture of the frameworks was observed in any of the groups. All restorations were assessed as satisfactory after 3 years. No differences in periodontal parameters were observed between the groups. Conclusions The results of this study suggest that monolithic zirconia and complete digital flow could be a viable alternative to veneered zirconia in the posterior regions. Clinical relevance The monolithic zirconia restorations with a digital workflow can be a viable alternative in posterior fixed partial dentures, with good periodontal outcomes. Clinical trial registration number ClinicalTrials.gov (Identifier NCT 04,879,498).