Discrimination of cancerous and healthy colon tissues: A new laser-based method.

BACKGROUND: Femtosecond (fs) Laser Ionisation Mass Spectrometry (fs-LIMS) on colon tissues are described and investigated using ionization/fragmentation processes in details to present a new application in this study. Linear Time of Flight (L-TOF) mass analyzer was utilized to investigate paraffin-embedded human tissue in this study. The effect of fs laser intensity on the spectral characteristics was investigated and interpreted due to mass spectra obtained using 800 nm wavelength with 90 fs pulses at 1 kHz repetition rate. OBJECTIVES: Mass spectra of tissues were recorded from L-TOF system and then analyzed by performing a statistical approach called Principal Component Analysis (PCA). The fs-LIMS method applied is proposed as a new and pioneering technology to analyze tissues using L-TOF system, as a human free fast and reliable intra-operative cancer diagnosis method for guiding surgeon to clean the edges of cancerous tissues to be applied during the surgical operation, for pathological examinations. Fs-LIMS provides some unique diagnosis opportunities to investigate biochemical characteristics of cancerous tissues leading to obtain sensitive, fast, and reliable results. The analysis of tissue is based on distribution of molecular ion (m/z) peaks in low mass region (

Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement.

Yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90°, 75°, 60°, 45°). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1 mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45° angle which resulted in significantly higher SBS (18.2 ± 1.43 MPa) than other groups (at 90° angulation (10.79 ± 1.8 MPa), at 75° (13.48 ± 1.2 MPa) and at 60° (15.85 ± 0.81 MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.