Intracellular nutrient metabolism, particularly the metabolism of essential amino acids (EAAs), is crucial for cellular functions, including energy production and redox homeostasis. An EAA deficiency can lead to cellular dysfunction and oxidative stress. This study explores the mechanisms underlying cellular responses to EAA starvation, focusing on ROS-induced DNA damage and apoptosis. MC3T3-E1 cells were subjected to EAA starvation, and various assays were conducted to assess cell proliferation, survival, DNA damage, and apoptosis. The antioxidant N-acetylcysteine (NAC) was employed to block ROS formation and mitigate cellular damage. Gene expression and Western blot analyses were performed to elucidate molecular pathways. EAA starvation-induced ROS generation, DNA damage, and apoptosis in MC3T3-E1 cells. NAC administration effectively reduced DNA damage and apoptosis, highlighting the pivotal role of ROS in mediating these cellular responses during EAA deficiency. This study demonstrates that EAA starvation triggers ROS-mediated DNA damage and apoptosis, offering insights into the intricate interplay between nutrient deficiency, oxidative stress, and programmed cell death. NAC emerges as a potential therapeutic intervention to counteract these adverse effects.

The purpose of this study was to clarify the physical durability of a diamond-like carbon (DLC) thin film coated on pure titanium. The titanium surface of the abutment does not have sufficient toughness to prevent an increase in surface roughness or damage when the implant is scaled using a professional mechanical implement. The scaling process used for the removal of the dental plaque adhered to the abutment surface could increase the potential for the deposition of oral microorganisms and the accumulation of plaque, which increase the risk of peri-implantitis. A DLC thin film is biocompatible material that is known for its toughness, including extreme hardness, high abrasion resistance, chemical inertness, and high corrosion resistance. Protecting the abutment surface with the application of a DLC might prevent plaque adhesion due to its non-stick property. There was little change in the surface roughness of titanium samples to which DLC surface protection had been applied when the surface of the sample was scratched with a stainless steel scalar more than a thousand times. When cleaning the surface of pure titanium samples, the surface roughness significantly increased. DLC thin films are effective for the prevention the surface roughness of pure titanium implants from being increased when the conventional cleaning of the surface of the implant is performed.

This study investigated antibacterial dentures fabricated by peening titanium apatite onto a polymethyl methacrylate (PMMA) denture base resin using a peening device. The effects of different peening mass flow rates and total peening masses on the deposition and antibacterial properties of titanium apatite were investigated. Titanium apatite was peened onto PMMA specimens at mass flow rates of 1, 2, and 5 g/s, with total peening masses of 5, 10, and 15 g. The surface morphology, elemental distribution, and mass changes were analyzed before and after peening and after immersion and water rinsing. The antibacterial activity against Staphylococcus aureus was evaluated using a crystal violet assay. The results showed that reducing the peening mass flow rate increased the amount of titanium apatite transferred and enhanced the antibacterial properties, with the highest deposition achieved at 1 g/s. Varying the total peening mass did not significantly affect the deposition pattern or antibacterial activity. The arithmetic mean roughness of the denture base remained unchanged after peening, indicating its clinical applicability. In conclusion, peening titanium apatite onto PMMA at a lower mass flow rate enabled stronger bonding and incorporation of antibacterial properties, potentially contributing to the development of novel antibacterial denture base materials.