The influence of laser frequency and groove distance on cell adhesion, cell viability, and antibacterial characteristics of Ti-6Al-4V dental implants treated by modern fiber engraving laser.

Objective: Micro-nano scale surface modification of Ti-6Al-4V was investigated through the fascinated modern fiber engraving laser method. The process was performed at a high laser speed of 2000mm/s, under different laser frequencies (20-160kHz) and groove distances (0.5-50μm).
Methods: Topographic evaluations such as Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FE-SEM) were used to identify the quality and regularity of patterns. The proliferation of human osteoblast-like osteosarcoma cells (MG63) was analyzed by MTT assay for up to 72h. Also, the plate counting method was used to quantify the viability potential of the modified surface against Escherichia coli bacteria.
Results: The cellular viability of the sample modified at the laser frequency of 20kHz and grooving distance of 50μm increased up to 35 and 10% compared to the non-treated and control samples, respectively. In the case of the surface modification at lower grooving distances range between 0.5-50μm, the maximum laser frequency (160kHz) applied leads to lower pulse's energies and less bacterial adhesion. Otherwise, at groove distances more than 50μm, the minimum laser frequency (20kHz) applied reduces the laser pulse overlaps, increases the cell adhesion and antibacterial properties.
Significance: Surface modification by the fiber engraving laser process significantly enhances the cell adhesion on the surface. As a result of such roughness and cell adhesion enhancement, the surface toxicity feature diminished, and its antibacterial properties improved.
(Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)