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Distributed fibre optic sensors (DFOS) are popular for structural health monitoring applications in large engineering infrastructure because of their ability to provide spatial strain measurements continuously along their lengths. Curved paths, particularly semicircular paths, are quite common for optical fibre placement in large structures in addition to straight paths. Optical fibre sensors embedded in a curved path configuration typically measure a component of strain, which often cannot be validated using traditional approaches. Thus, for most applications, strain measured along curved paths is ignored as there is no proper validation tool to ensure the accuracy of the measured strains. To overcome this, an analytical strain transformation equation has been developed and is presented here. This equation transforms the horizontal and vertical strain components obtained along a curved semicircular path into a strain component, which acts tangentially as it travels along the curved fibre path. This approach is validated numerically and experimentally for a DFOS installed on a steel specimen with straight and curved paths. Under tensile and flexural loading scenarios, the horizontal and vertical strain components were obtained numerically using finite element analysis and experimentally using strain rosettes and then, substituted into the proposed strain transformation equation for deriving the transformed strain values. Subsequently, the derived strain values obtained from the proposed transformation equation were validated by comparing them with the experimentally measured DFOS strains in the curved region. Additionally, this study has also shown that a localised damage to the DFOS coating will not impact the functionality of the sensor at the remaining locations along its length. In summary, this paper presents a valid strain transformation equation, which can be used for transforming the numerical simulation results into the DFOS measurements along a semicircular path. This would allow for a larger scope of spatial strains measurements, which would otherwise be ignored in practice.

Objective: To evaluate an association between bone levels of inflammation/oxidative stress mediators and postoperative discomfort after third molar conventional or piezosurgery., Material and Methods: Twenty-six subjects with bilaterally impacted mandibular third molars, who underwent either piezo or conventional surgery, were included in a split-mouth design study. MicroRNA-21 (miR-21) expression, interleukin-1 beta (IL-1β), and vascular endothelial growth factor (VEGF) proteins, as well as superoxide dismutase (SOD) activity in alveolar bone, were evaluated. Pain intensity, the first pain appearance, analgesic first use and total dose taken, trismus, and swelling were clinically recorded., Results: MiR-21 expression was higher while VEGF protein was lower in piezosurgery vs. conventional groups. The differences in IL-1β protein and SOD activity were not significant between groups. The pain intensity on the first day was significantly decreased in piezosurgery group. The first pain appearance and the first analgesic taken were reported sooner in conventional vs. piezosurgical group. Significantly pronounced trismus on the third day following conventional surgery was found. In conventional group, significantly increased trismus was observed on the third compared to the first postoperative day. MiR-21 showed significant correlation with the first pain appearance., Conclusion: Delayed onset of less pronounced postoperative pain after piezosurgical vs. conventional extraction of impacted lower third molar was significantly associated with expression of bone miR-21., Clinical Relevance: Alveolar bone miR-21 may reflect surgical stress and is associated with third molar postoperative pain onset.

Introduction: Age-related changes of dental pulp tissue and atherosclerosis of carotid arteries as its feeding arteries could influence the functionality of pulpal circulation. The objective of our study was to evaluate the effect of aging (physiological process) and carotid bifurcation atherosclerosis (pathologic process) on the pulpal microcirculatory system using multifractal analysis of the laser Doppler flowmetry signal., Methods: Three groups of 10 subjects were enrolled in the study: the young group (healthy subjects, 20-25 years), the middle-aged group (healthy subjects, 50-60 years), and the clinical group (subjects with carotid bifurcation atherosclerosis, 50-60 years). Pulpal blood flow (PBF) signals recorded by laser Doppler flowmetry were assessed by multifractal analysis that estimates Hölder exponents of the signal. PBF levels, the average mean values, and the range of Hölder exponents were obtained., Results: PBF levels were significantly higher in the young group compared with the middle-aged and clinical groups, and the difference between the middle-aged and clinical groups was not statistically significant. The range of the Hölder exponents was narrower in the middle-aged and clinical groups than in the young group and narrower in the clinical group than in the middle-aged group. The average mean value of Hölder exponents was significantly higher in the young group than in the middle-aged and clinical groups, whereas there was no significant difference between the middle-aged and clinical groups., Conclusions: Our study investigating the multifractality of the PBF signal showed that the aging process and carotid atherosclerosis could affect the complex structure of PBF oscillations and contribute to a better understanding of pulpal hemodynamics., (Copyright © 2020 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)