## 1 Introduction  
The osseointegration of dental implants is fundamental to the clinical success of this reconstructive therapy aiming to replace tooth loss [1; 2]. The process of osseointegration basically follows the conserved sequence of bone regeneration, but it is the topography and roughness of the dental implant that dictates how fast bone forms on the surface. The surface topography and roughness of dental implants affect the in vitro attachment, proliferation, and differentiation of osteogenic cells [3]. Furthermore, in vivo research suggests that surface treatment can support the osseointegration of dental implants [4; 5; 6]. Methods to improve the surface characteristics of dental implants have extensively been explored, with sandblasting followed by acid etching being commonly used in clinical routine [7]. However, changes in nanotopography have a multifaceted impact, not only modifying surface roughness but also influencing the physical, chemical, and biological properties [1; 8]. Surface roughness plays a fundamental role in determining cell behavior, where an optimal range of roughness facilitates cell growth and proliferation. At the same time, cellular deformability plays a substantial role in shaping its response to surface roughness [9]. Using the cell lines HeLa and MDA MB 231, a moderate surface energy and intermediate roughness ratio were favorable for cell adhesion, growth, and proliferation [9]. Furthermore, advancing the osteophilic properties of dental implant surfaces further is helpful in complex clinical scenarios, including immediate post-tooth extraction implants and cases involving patients with weakened bone or impaired wound healing abilities [10; 11; 12; 13; 14]. Here, laser and coating with hydroxyapatite nanoparticles seems to be a promising approach to modify and ideally improve the osteeconductive capacity of dental implants. The laser treatment of implant surfaces is a promising approach to support early osseointegration [5]. Surface modifications include the creation of a nanostructured surface with enhanced roughness [15]. Laser treatment can further improve the resistance to corrosion and wear, eliminate contaminants, reduce infection risk, and improve the biocompatibility of the implant [16]. Laser can thicken the oxide layer on the titanium surface [17]. As a consequence, the laser treatment of implants enhances their removal torque, indicating a stronger bond between implant and bone [18; 19]. Hydroxyapatite (HA) coating is another strategy used for enhancing the osseointegration of dental implants [4]. Nanoparticles composed of calcium phosphate exhibit physical properties and porosity resembling human bone [20; 21]. Thus, HA is used as a bone substitute [21] and for coating dental implants [22]. One novel approach is to combine the laser treatment and HA coating of dental implants. Combining laser treatment with HA coating is a promising strategy to enhance the osteophilic properties of dental implants [23]. These implants show increased bone-to-implant contact and faster osseointegration, especially during the first two months after implant placement [4]. Implants treated with laser followed by phosphate deposition showed increased surface roughness, improved surface chemistry, and enhanced biocompatibility for bone cells [24; 25]. The use of laser for surface treatment with subsequent phosphate deposition can support the performance of dental implants [1; 26]. Cells exposed to rough biomaterials firmly attach and interact with the material, in addition to their high proliferation rates [24]. However, HA nanoparticles can induce inflammation by triggering the activation of monocytes and neutrophils [27]. There is thus a demand for a bioassay to simulate the impact of laser treatment and the HA coating of implant surfaces on the cellular response. In vitro, HA particles can stimulate the release of cytokines, including interleukin-6 (IL6) [28]. HA has the potential to be a contributing factor to implant-associated inflammation [27; 29].