## 1 Introduction  
Recently, rehabilitation of masticatory function using dental implants has become a treatment option [1]. One of the most important considerations for the success of dental implants is the occurrence of osseoeintegration [2, 3]. Ossoeintegration can be influenced by numerous factors. [PERSON] et al. reported that osseoeintegration can be affected by design of the implant, chemical composition, topography of the surface, and materials such as shape, length, and diameter [4]. [PERSON] et al. stated that the mechanical stability and loading conditions can affect osseoeintegration [5]. [PERSON] et al. stressed that the status of the host bone bed and its intrinsic healing potential should also be considered as important factors for successful osseoeintegration [6].  
Primary stability, which means mechanical engagement with cortical bones, and secondary stability, which means deposition of new bone that reaches the peak point at 8 weeks and stabilizes at 12 weeks, act as factors in osseoeintegration [7, 8, 9, 10]. Stability dip, the cross point between primary stability and secondary stability at four weeks of implant placement, should also be considered, and how stability is endured affects osseointegration [11].  
To achieve successful osseointegration, osteoblasts must contact the implant surface well [12], a process that varies depending on implant surface treatment and roughness of the implant surface [13]. The debate continues over smooth and rough surfaces, that is, between the sandblast large grit acid etching (SLA) method and other methods such as resorbable blast media, acid etching, anodizing, plasma spray, and hydroxyapatite coating [14; 15]. One clinical issue is how to reprocess implant surfaces treated with SLA [16]. Over time, the newly fabricated titanium surface becomes hydrophobic due to hydrocarbon adherence and surface charge changes, which has been known to degrade its biochemical ability [17; 18]. To solve this problem, ultraviolet (UV) irradiation on titanium surfaces was developed to remove hydrocarbons and restore reduced biochemical capabilities [18; 19].  
One of the main clinical issues has been securing stability of inserted implants, which may be affected by bone-implant contact [8; 20]. Many studies were conducted to quantify implant stability [21]. Perio test values (PTVs) using Periotest(r) (Medizintechnik Gulden, Modautal, Germany), implant stability quotients (ISQs) using Ossetl(r) (Ossetl AB, Gothenburg, Sweden) and implant stability tests (ISTs) using Anycheck(r) (Neobiotech, Seoul, Korea) have been used [12; 22]. Unlike the above products, Anycheck(r) has an all-in-one design, which makes it easy to manipulate and allow multiple implants to be measured quickly at the same time. In addition, healing abutments can be retained without removal, which may minimize crestal bone loss [23].  
According to a series of papers, a statistically significant relationship exists between UV irradiation and osseointegration [17; 18; 19]. UV treatment can produce photofunctionalization on aged titanium surface, turning it into a bioactive and osteoconductive surface, which can significantly increase and improve osseointegration by removing the hydrocarbons from their contaminated surfaces [17; 18; 19]. However, since the above claims were obtained in vitro, how UV photofunctionalization contributes to osseointegration in vivo is still unknown.  
Therefore, the aims of this study were, first, to evaluate the difference of implant stability between UV-irradiated and non-irradiated groups and, second, to measure the differences in bone-to-implant contact (BIC) values histologically and statistically after 4 and 12 weeks of implantation in canine models.