The Use of 810 and 1064 nm Lasers on Dental Implants: In Vitro Analysis of Temperature, Surface Alterations, and Biological Behavior in Human Gingival Fibroblasts.

Objective: The primary objective of this study was to evaluate the safety of 810 and 1064 nm laser treatment on dental implants. Background: Peri-implantitis is a challenge for clinicians and researchers. Methods: A pig mandible model was used to evaluate temperature increases during laser irradiation. Surface alterations on processed pure titanium discs were analyzed via scanning electron microscopy and measurement of surface contact angles. Processed titanium discs were cocultured in vitro with human gingival fibroblasts; subsequently, cell proliferation was measured. Results: The maximum temperature and time to reach each threshold were comparable. No surface alterations were detected after 810 nm laser irradiation, whereas surface cracks were observed after 1064 nm laser irradiation under the parameter setting of 31.84 W/cm2. Compared with unaltered processed pure titanium discs, the proliferation of human gingival fibroblasts was significantly greater on altered processed pure titanium discs. Conclusions: The use of either 810 or 1064 nm laser treatments may increase the risk of thermal damage in terms of increased temperature if the parameter setting is not warranted. In addition, the use of 1064 nm laser treatment could lead to changes in pure titanium discs that do not negatively affect cell proliferation. Further investigations of laser-assisted therapy are necessary to improve guidelines concerning the treatment of peri-implantitis. Clinical trial registration number: 2021-P2-098-01.

New methods for inducing the differentiation of amniotic-derived mesenchymal stem cells into motor neuron precursor cells.

Our study investigates the differentiation of amniotic-derived mesenchymal stem cells (ADMSCs) into motor neuron (MN) precursor cells induced by a combination of extracellular matrix (ECM) and multi-cell factors. Membrane-like ECM was made by an enzymatic and chemical extraction method and exhibited good biological compatibility. Cells in the experimental group (EG) were treated with ECM and multi-cell factors in a multi-step induction process, while the control group (CG) was treated similarly, except without ECM. In the EG, after induction, the cells formed processes that connected with neighboring cells to form a net that had directionality. In these cells, neuron-specific enolase (NSE) and synaptophysin (SYN) expression levels increased and glial fibrillary acidic protein (GFAP) expression decreased. The SYN expression in the EG cells was higher compared with those in the CG. In the CG, NSE expression increased, while the expression of Nestin and SYN did not change. These were several changes in the levels of other genes: ADMSCs at passage 1 expressed Nanog, SOX2, octamer-binding transcription factor 4 (OCT4) and Nestin. In the EG, at the beginning of induction, the expression of Nanog decreased and that of SOX2 and Nestin increased. After 2 days, the cells expressed Nestin, OCT4 and SYNIII, and after 3 days, they expressed Olig2, OCT4, Nestin, SYNII and Islet1 (ISL1). Finally, at day 6, the cells expressed Nestin, SYNI, SYNIII, ISL-1, homeobox 9 (Hb9) and oligodendrocyte lineage transcription factor 2 (Olig2). In the CG, the cells never expressed SYNI, SYNII or Hb9. Our studies therefore demonstrate that the extracted ECM was capable of promoting the maturation of synapses. Human ADMSCs are composed of multiple cell subsets, including neural progenitor cells. The multi-step induction method used in this study causes human ADMSCs to differentiate into MN precursor cells.