en Periodontology Periodontology Original article Original article <div style="text-align: justify;"><strong>Background and Aim:</strong> The present study introduces photofunctionalization as a technique for tackling biological aging and increasing the bioactivity of titanium. This <ins cite="mailto:Tahereh%20Bitaraf" datetime="2019-07-15T03:30">in</ins>-<ins cite="mailto:Tahereh%20Bitaraf" datetime="2019-07-15T03:30">vitro </ins>study evaluated the effects of ultraviolet (UVC) light treatment of titanium surfaces with different time-related changes on the behavior and function of human mesenchymal stem cells (MSCs).<br> <strong>Materials and Methods: </strong>MSCs were cultured on nine untreated titanium surfaces (four-week-old surfaces; group 1), nine fresh UVC-treated surfaces (immediately after UV treatment; group 2), and nine three-day-old UVC-treated surfaces (group 3). Cellular proliferation and attachment were measured by MTT. Alkaline phosphatase (ALP) was assessed by total protein extraction, and the enzyme activity was evaluated using a special ALP kit. <ins cite="mailto:Tahereh%20Bitaraf" datetime="2019-07-15T03:45">One-way analysis of variance (ANOVA) and </ins>p<ins cite="mailto:Tahereh%20Bitaraf" datetime="2019-07-15T03:45">ost-hoc Tukey</ins>&rsquo;s <ins cite="mailto:Tahereh%20Bitaraf" datetime="2019-07-15T03:45">test were used to examine the effect of UVC on titanium surfaces.</ins><br> <strong>Results: </strong>The mean attachment of MSCs to titanium disks in groups 1 to 3 was 0.118&plusmn;0.003, 0.103&plusmn;0.007, and 0.155&plusmn;0.009, respectively. The mean proliferation of MSCs in groups 1 to 3 was 0.229&plusmn;0.004, 0.189&plusmn;0.023, and 0.298&plusmn;0.020, respectively. The proliferation and attachment in group 3 were significantly higher compared to other groups (P<0.05). Speeds of MSCs growth in groups 1 to 3 were 94%, 81%, and 92%, respectively. The ALP activity of MSCs in groups 1 to 3 was 0.153&plusmn;0.003, 0.187&plusmn;0.003, and 0.161&plusmn;0.003, respectively. The ALP activity in group 2 was significantly higher compared to other groups (P<0.05).<br> <strong>Conclusion: </strong>UVC pretreatment of titanium surfaces increases the ALP activity. However, cellular attachment and proliferation were not increased in the present study due to the high probability of laboratory error.</div> Ultraviolet Rays, Cell Adhesion, Cell Proliferation, Mesenchymal Stem Cells, Photochemistry, Titanium, Radiation Effects 7 11 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-708-1&slc_lang=en&sid=1 MR Shbahangfar Drshabahangfar@gmil.com 10031947532846009714 10031947532846009714 No Assistant professor, Periodontology Dept, Dental Faculty,Tehran Medical Sciences E Jafari 10031947532846009715 10031947532846009715 No Dentist A Tarashohi 10031947532846009716 10031947532846009716 No Dentist P Olyaee 10031947532846009717 10031947532846009717 No Dentist T Bitaraf taherehbitaraf@yahoo.com 10031947532846009718 10031947532846009718 Yes Assistant professor, Dental Implant Research Center, Dental Faculty, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran