**3.3. Cytotoxicity analysis**

The results presented in **Figure 7** indicate that the austenitic ISO 5832-1 SS exhibited cytotoxic behavior similar to the negative control, that is, it shows no cytotoxicity. This is indicated by the cell viability curve for the laser-treated samples above the level IC50% of cytotoxicity. **Table 4** shows the pH of the extracts at a concentration of 100%.

The cytotoxicity of the ISO 5832-1 stainless steel was evaluated in the present study according to ISO 10993-5 [30]. The absence of cytotoxicity is desired for stainless steels for medical and dental applications [31]. The slight decrease in the cell viability for the laser-treated samples

Evaluation of the Biotribological Behavior and Cytotoxicity of Laser-Textured ISO 5832-1… http://dx.doi.org/10.5772/intechopen.73140 73

**Figure 7.** Cell viability as a function of the extract concentration of the laser-textured and untreated samples.


**Table 4.** Values of pH for the extracts at a concentration of 100%.

The friction coefficient values for the untreated specimen showed a rapid increase in the beginning of the test (running-in), and practically stabilized around values close to μ = 0.5 as the surface becomes less rough. In the case of the laser-textured samples, the friction coefficient decreases up to 100 s, reaching a stabilization period up to the end of the test. For sample 2, the friction coefficient initially presented gradual increase up to 500 s reaching 0.35 and then drops to less than 0.2 at the end of the test. Sample 3 showed a tendency of continuous increment of the friction coefficient with time. For sample 4, in turn, it remained practically

**Figure 6.** Variation of friction coefficient as a function of the test time for the laser-textured and -untreated specimens.

The effect of the variation of the coefficient of friction as a function of the test time was studied by Huang et al. [29]. They verified some tribological properties of Ti-6Al-4 V alloys with and without coating ("laser clad"), for a period of 3500 s in different rotation frequencies, and at the end of the tests, they verified that the coefficient of friction for the coatings was always

The results presented in **Figure 7** indicate that the austenitic ISO 5832-1 SS exhibited cytotoxic behavior similar to the negative control, that is, it shows no cytotoxicity. This is indicated by the cell viability curve for the laser-treated samples above the level IC50% of cytotoxicity.

The cytotoxicity of the ISO 5832-1 stainless steel was evaluated in the present study according to ISO 10993-5 [30]. The absence of cytotoxicity is desired for stainless steels for medical and dental applications [31]. The slight decrease in the cell viability for the laser-treated samples

constant and at lower than that of the other conditions.

**Table 4** shows the pH of the extracts at a concentration of 100%.

inferior to the substrate.

72 Lubrication - Tribology, Lubricants and Additives

**3.3. Cytotoxicity analysis**

is explained by its susceptibility to localized corrosion [5, 6, 32, 33]. According to Pieretti and Costa [5], the laser process affects the corrosion resistance of the laser-treated stainless steel biomaterials, producing a less protective passive film with areas prone to its breakdown, although the samples are not considered cytotoxic.

Studies on the biomaterials tribological behavior are important because they reveal unique aspects about the surface wear mechanisms [34]. The knowledge of wear response contributes to the understanding of other surface phenomena, which can occur simultaneously and potentiate one another, such as the phenomenon of corrosion.

The occurrence of both concomitantly can lead to acceleration of particle detachment, including nonmetallic inclusions that may be housed under biomaterial surface [35], and these may come into contact with the bloodstream and lodge in any part of the human body causing, many times, harm to the patients.
