## 4 Discussion  
A perfectly clean titanium surface is considered to comprise only titanium and oxygen, which creates a titanium oxide surface. However, such pure surfaces are not available even in the laboratory, as it only a short period of atmospheric exposure is required for the surface to be contaminated with a monolayer of hydrocarbons and inorganic impurities. In a study conducted by [PERSON] et al. [5], lower carbon pollution was observed on surfaces that had been isolated from the surrounding environment during production compared with those that had not. It is known that the higher the deposit of hydrocarbon compounds, the lower the hydrophilicity and the greater the angle of contact of the water. Usually, to measure this effect on hydrophilicity, the contact angle of a drop of liquid on the surface being studied is measured, and digital images of the same are analyzed. The importance of good wettability and a low contact angle is to ensure rapid protein absorption and good cell adhesion to hinder bacterial colonization. Osteoblasts grown on hydrophilic surfaces produce more markers of differentiation by creating an osteogenic microenvironment, potentially contributing to faster and improved osseointegration. In general, the information provided by implant manufacturers only refers to the maximum sterilization length, which is usually 5 years. However, the need for clinics to have a wide assortment of material available means that they must have an ample supply of stored implants. Due to these circumstances, it is unlikely that dental implants can be used within 4 weeks of manufacturing, implying that most implants will have already undergone a process of ageing prior to insertion. Different methods have been proposed to preserve the surface of titanium under the best biocompatibility conditions, including packaging in ultravacuum conditions (ultrahigh vacuum), immersion in isotonic solutions, irradiation with ultraviolet C light, the use of cold plasma, and medical ozone. Whereas the first two methods attempt to keep the implant surface intact, the others focus on restoring the surface of titanium oxide, freeing it from impurities. Perhaps the most viable and economical solution against the inevitable biological ageing of titanium is exposure to UV radiation just before use in a procedure known as photofunctionalization [6]. The underlying mechanism of photofunctionalization appears to be based on the creation of amphiphilic molecules, also called amphipathic molecules. These are molecules  
Figure 7: Box plot of angles obtained with an 85 W lamp at different irradiation times, including the control. The graphs show the lower (Q1), mean (Q2), and upper (Q3) quartiles. that have one hydrophilic (water soluble) end and another hydrophobic end (rejects water). It was stated that modifying the electrostatic properties of the titanium surface plays a decisive role in its bioactivity. The change in surface energy is responsible for this modification. It was also mentioned that this fundamental change is caused by the formation of spaces between the oxygen atoms that allow the adhesion of OH hydroxyl radicals. Other authors attributed this effect to the energy of UVC beam photons, which induces the formation of hydroxyl radicals and hydrogen dissociation. Finally, there are authors who attributed this effect to the rupture of the C=O bonds, removing surface contaminants and regenerating a clean surface that would leave the penta-coordinated titanium (Ti5c) exposed. Regardless of the exact mechanism, photofunctionalization creates homogeneous conditions for all implants regardless of the date of manufacture, offering the clinician the opportunity to accurately compare individual results. In this way, differences in the osseointegration of products from the same manufacturer can also be eliminated. This effect has been observed at various UV wavelengths, including ultraviolet A (UVA), ultraviolet B (UVB), and even in combinations of both ultraviolet C light (UVC), which is commonly used due to its higher power.