Study on the adverse effect of acid-corrosion on the dentin in terms of degradation of fracture resistance.

Human dentin is known for its hierarchical structure through long-term evolution. Dental caries, embodied by dentin demineralization, is ascribed to a different reaction between peritubular dentin (PTD) and intertubular dentin (ITD) to acid dissolution. This study sheds light on the adverse effect of acid on dentin in terms of degradation of its fracture toughness (FT) due to the acid dissolution-induced corrosion of PTD. A scanning electronic microscope (SEM) is utilized to visualize the difference between normal and acid-treated dentin subjected to the same loading method in terms of crack propagation performance. 3D simulative representative volume elements (RVEs) are developed to analyze the effect of PTD missing on the performance of dentin fracture resistance (FR). The results indicate PTD plays a significant role in enhancing dentin FR capability and thus reveals the importance of structural integrity for dentin.

Atomic force microscopy-based assessment of multimechanical cellular properties for classification of graded bladder cancer cells and cancer early diagnosis using machine learning analysis.

Cellular mechanical properties (CMPs) have been frequently reported as biomarkers for cell cancerization to assist objective cytology, compared to the current subjective method dependent on cytomorphology. However, single or dual CMPs cannot always successfully distinguish every kind of malignant cell from its benign counterpart. In this work, we extract 4 CMPs of four different graded bladder cancer (BC) cell lines by AFM (atomic force microscopy)-based nanoindentation to generate a CMP database, which is used to train a cancerization-grade classifier by machine learning. The classifier is tested on 4 categories of BC cells at different cancer grades. The classification shows split-independent robustness and an accuracy of 91.25% with an AUC-ROC (ROC stands for receiver operating characteristic, and ROC curve is a graphical plot which illustrates the performance of a binary classifier system as its discrimination threshold is varied) value of 97.98%. Finally, we also compare our proposed method with traditional invasive diagnosis and noninvasive cancer diagnosis relying on cytomorphology, in terms of accuracy, sensitivity and specificity. Unlike former studies focusing on the discrimination between normal and cancerous cells, our study fulfills the classification of 4 graded cell lines at different cancerization stages, and thus provides a potential method for early detection of cancerization. STATEMENT OF SIGNIFICANCE: We measured four cellular mechanical properties (CMPs) of 4 graded bladder cancer (BC) cell lines using AFM (atomic force microscopy). We found that single or dual CMPs cannot fulfill the task of BC cell classification. Instead, we employ MLA (Machine Learning Algorithm)-based analysis whose inputs are BC CMPs. Compared with traditional cytomorphology-based prognoses, the non-invasive method proposed in this study has higher accuracy but with many fewer cellular properties as inputs. The proposed non-invasive prognosis is characterized with high sensitivity and specificity, and thus provides a potential tumor-grading means to identify cancer cells with different metastatic potential. Moreover, our study proposes an objective grading method based on quantitative characteristics desirable for avoiding misdiagnosis induced by ambiguous subjectivity.