Exposure to widespread lipophilic and bioaccumulative polychlorinated biphenyls (PCBs) induces diverse biochemical and toxicological responses in various organs, including the bone. The aim of this study was to evaluate the changes in growth rate, geometry, serum, and bone biochemical parameters and biomechanics of juvenile rat femur induced by lactational exposure to nonplanar PCB-155 and planar PCB-169 individually and in combination. Fifteen lactating Wistar rats were divided into four groups (PCB-169, PCB-155, PCB-155+169, and control), and PCBs were administered intraperitoneally at different time points after delivery. Femurs from 22-day-old offspring were analyzed by microCT, three-point bending test and inductively coupled plasma-mass spectrometry (ICP-MS) to obtain data on bone geometry, biomechanics and mineral composition. The serum levels of calcium, phosphate and alkaline phosphatase were also determined. Lactational exposure to planar PCB-169 resulted in shorter and thinner femurs, reduced endosteal and periosteal perimeters, smaller total cross-sectional and medullary areas, and lowered serum bone marker levels and calcium levels in the bone, while femur mechanical properties were not significantly altered. The changes observed in the combination exposure (PCB-155+169) group were similar to those observed in the PCB-169 group but were less pronounced. In summary, our results demonstrate that alterations in lactationally exposed offspring were primarily induced by planar PCB-169. The milder outcome in the combined group suggested that the PCB-169-mediated toxic effects on the bone might be reduced by a nonplanar PCB-155 congener. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1135-1146, 2017.

We report on a new approach to increase the fracture resistance of endodontically treated teeth. We propose a preparation of horizontal internal plateau (IP) in dentine and the use of retentive zirconia posts to achieve a more favourable load transmission. The aim of our work was to investigate the effect of the IP depth and the post diameter on the fracture resistance and the failure mode of maxillary central incisors. Seventy-two teeth were, divided into six groups of 12. IP 4 mm in diameter and 0, 1 or 2 mm in depth was prepared and zirconia posts of two diameters luted. Specimens were loaded until failure and fractures were classified as reparable or not. Two-way ANOVA, Tukey's HSD test and Poisson regression were used for statistical analysis (α = 0.05). Significantly improved fracture resistance and predominantly favourable failure modes were found when 2-mm deep IP is prepared.

This study was set up to explore the effects of the applied routes for fabricating cobalt-chromium (Co-Cr) dental frameworks on the metal-ceramic bond strength. Three groups (n = 12/group) of Co-Cr specimens (25×3×0.5) mm were fabricated by casting, milling, and by selective laser melting (SLM), and then airborne-particle abraded (110 μm Al2O3 particles). Dental porcelain was applied (8×3×1.1) mm onto the Co-Cr substrates, and the metal-ceramic bond strength was assessed by a three-point bend test according to the ISO 9693-1:2012 standard. Failure modes were determined using stereomicroscopy. Representative specimens from each group were used to assess the element distribution across the metal-ceramic interface, together with an inspection of its microstructure using a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Average profile roughness (Ra) values were obtained for each group of metal substrates. The metal-ceramic bond strength data and Ra data were statistically analyzed (one-way ANOVA, Tukey's HSD test, a = 0.05). The mean surface roughness was affected by the fabrication technology (p < 0.01), SLM Co-Cr demonstrating a significantly higher Ra value (1.78±0.20 μm), than cast and milled Co-Cr (1.21±0.07 μm and 1.05±0.11 μm respectively). However, the metal processing applied did not affect the metal-ceramic bond (p = 0.104). Differently processed metal-ceramic specimens showed a comparable distribution of elements on the interface, together with good wetting between the alloy and the porcelain. The porcelain bond strengths to cast, milled and SLM Co-Cr alloys are well above the minimum ISO 9693-1:2012 recommended value of 25 MPa for metal-ceramic systems, thus allowing the clinical application of SLM Co-Cr in porcelain-fused-to-metal prostheses.