## 1 Introduction  
In medicine, ultra-violet (UV) radiation is widely utilized in conjunction with various devices such as UV germicidal lamps and water purification as well as air and surface sterilization equipment. However, its use in dentistry is not as widely documented. In this field, UV light illumination is used mostly in the forensic identification of restorative materials, photo-polymerization of dental materials, and calculus detection in periodontal disease management. The recent plateau in the field of dental implantology has challenged many researchers to improve the implant success rate, which in turn has led to the identification of the ability of UV radiation to reverse titanium implant aging. Titanium implant aging, as a unique phenomenon, has been identified to reduce the osteoblastic activity essential for implant-bone integration [1,2]. The actual mechanism of aging in titanium is unknown. The surface of titanium is contaminated by various factors that can lead to aging. Thus, insights into how tissue integration between dental implants could be enhanced by understanding titanium aging and how this phenomenon can be reversed by photofunctionalization would be useful. The criteria for successful implant therapy lie on a direct functional and structural connection between the living bone and the surface of a load-carrying implant without intervening soft tissue layers [3]. The most common material used for implantology is titanium. One of the current problems in titanium implant therapy is incomplete integration, in which bone-implant contact (BIC) was reported to be only up to 65% in clinical practice. This value is far below the ideal 100% shown in animal studies [4, 5, 6]. As the greying population has become a global phenomenon, partial or full dentulism needing implant therapy has also increased. This poses challenges in oral rehabilitation as reduced bone density may decrease the survival rate and more so, the success of implant treatment. The incomplete bone formation around a dental implant is thought to be the result of low cellular attraction to the implant surface. The reduced bone volume, or bone density as seen in aged patients [7,8] may also compromised the BIC as the cellular interaction reduced as a result of cell senescence [9,10]. Bone formation around an endo-osseous titanium dental implant depends on the chemical, physical, and topographical characteristics of its surface [11, 12, 13]. Many researchers have shown that physicochemical properties such as hydrophilicity enhance cell adhesion and proliferation [14, 15, 16] because of the improvement in cell function by high surface wettability [17, 18, 19]. Therefore, current trends in clinical dental implant therapy include modifications of surface treatment to improve the surface properties and surface energy, which in turn increase the wettability of the implant. Considering the ability of titanium dental implants to undergo aging following manufacturing [1,20] renders a reduction in osteoblast cellular [21,22] activity during the healing process, especially in reduced bone density of the elderly [7,8], UV treatment of titanium has been introduced as a potential solution to reverse the aging process via removal of hydrocarbon contamination on the surface and promote cell-titanium implant interaction [23, 24, 25]. Given the optical properties of bulk titanium [26], UV irradiation of its surface could enhance its hydrophilicity [27], thereby increasing protein adsorption [28]. Previous review papers have comprehensively addressed issues on the longevity of the titanium surface to remain biologically active following manufacturing [1,2], overview of chairside surface modifications to improve the biofunctionality of dental implants [29], and effect of UV exposure in in vitro and in vivo studies [20,30] up to the time point the reviews were published.