Search

In the current study, we evaluate the equivalent stiffness of peritubular reinforcement effect (PRE) of porous dentine optimized by the thickness of peritubular dentine (PTD). Few studies to date have evaluated or quantitated the effect of PRE on composite dentine. The miscrostructure of porous dentine is captured by scanning electron microscope images, and then finite element modeling is used to quantitate the deformation and stiffness of the porous dentine structure. By optimizing the radius of PTD and dentine tubule (DT), the proposed FE model is able to demonstrate the effect of peritubular reinforcement on porous dentine stiffness. It is concluded that the dentinal equivalent stiffness is reduced and degraded with the increase of the radius of DT (i.e., porosity) in the certain ratio value of Ep/Ei and certain radius of PTD, where Ep is the PTD modulus and Ei is the intertubular dentine modulus. So in order to ensure the whole dentinal equivalent stiffness is not loss, the porosity should get some value while the Ep/Ei is certain. Thus, PTD prevents the stress concentration around DTs and reduces the risk of DTs failure. Mechanically, the overall role of PTD appears to enhance the stiffness of the dentine composite structure. These results provide some new and significant insights into the biological evolution of the optimal design for the porous dentine microstructure. These findings on the biological microstructure design of dentine materials are applicable to other engineering structural designs aimed at increasing the overall structural strength. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to analyze the clinicopathological features and prognosis of esophageal signet ring cell (SRC) carcinoma in China. Methods: Patients with poorly differentiated adenocarcinoma were identified in two hospitals from January 2006 to June 2016. The patients were divided into three groups according to component of SRCs: SRC≥50% group, SRC < 50% group and non-SRC poorly differentiated adenocarcinoma group. Results: Fifty-seven patients had carcinoma (SRC≥50%), and 79 patients had tumors containing <50% SRCs, and 535 patients was in non-SRC poorly differentiated adenocarcinoma group. There were no significant differences among the three groups in clinicopathological characteristics. Patients in SRC≥50% group had a lower overall survival rate (at 3-year 37.6%versus71.1%; at 5-year 0% versus 43.3%; p<0.001) compared with the control group. Even survival outcome of patients in SRC < 50%was inferior to that of in control group (at 3-year 53.0%versus71.1%; at 5-year 25.9% versus 43.3%; p<0.001). Female sex, large tumor size and increasing TNM stage were independent prognostic factors for SRC ≥50% esophageal carcinoma patients. Conclusions: The incidence of esophageal SRC carcinoma is relatively rare and the worst outcome is observed in the SRC≥ 50% group. It is necessary to explore new therapeutic modalities to achieve further improvements in the clinical outcome of these patients. [ABSTRACT FROM AUTHOR]

During eating, the teeth usually endure the sharply temperature changes because of different foods. It is of importance to investigate the heat transfer and heat dissipation behavior of the dentino–enamel junction (DEJ) of human tooth since dentine and enamel have different thermophysical properties. The spatial and temporal temperature distributions on the enamel, dentine, and pulpal chamber of both the human tooth and its discontinuous boundaries, were measured using infrared thermography using a stepped temperature increase on the outer boundary of enamel crowns. The thermal diffusivities for enamel and dentine were deduced from the time dependent temperature change at the enamel and dentine layers. The thermal conductivities for enamel and dentine were calculated to be 0.81 Wm-1K-1 and 0.48 Wm-1K-1 respectively. The observed temperature discontinuities across the interfaces between enamel, dentine and pulp-chamber layers were due to the difference of thermal conductivities at interfaces rather than to the phase transformation. The temperature gradient distributes continuously across the enamel and dentine layers and their junction below a temperature of 42°C, whilst a negative thermal resistance is observed at interfaces above 42°C. These results suggest that the microstructure of the dentin-enamel junction (DEJ) junction play an important role in tooth heat transfer and protects the pulp from heat damage. [ABSTRACT FROM AUTHOR]