Dental implants have been undergoing a constant flux in terms of ideas and advances to increase implant bioactivity and bone-implant interfacial strength. PEEK has been a prime synthetic competitive candidate among load-bearing dental/orthopedic applications to replace metallic implants [
9]. Upon comparison with traditional metal implants, there is less risk of stress shielding caused by material stiffness mismatch between the implant and biological tissue. This is attributed to the similarity of PEEK elastic modulus to that of human bone. Additionally, PEEK is inherently radio-lucent, allowing greater post-operative perceptibility of the surrounding tissue. Its privilege characteristics of heat resistance and chemical compatibility with various sterilization techniques coupled with low-cost molding techniques mark PEEK as a practical and economical material for biomedical device manufacturing [
32]. On the other hand, multiple researchers have been investigated to increase the bioactivity of PEEK [
33]. Physical or chemical surfaces modification strategies were reported to increase surface energies and encourage binding of biological molecules [
34,
35]. Osseointegration is the crucial success goal of implants that depends on topographical and physicochemical properties [
36]. Multiple studies have demonstrated that, implant surface properties could be considered the significant key to control the amount and quality of cells adhered to the implant resulting in enhancing implant osseointegration. Consequently, surface chemistry and topography are the most influential properties for cell adhesion. Surface chemistry controlling the implant wettability hence becomes a deciding factor for the protein adsorption and cell adhesion [
37]. On the other hand, the implant surface topography and roughness have been heightened during the last four decades to continuously improve the long-term success [
14]. Laser modification approach emphasizes on improving the implant osseointegration through generating a nano-scale topographical surface pattern. Accordingly, laser modification could be considered a promising scheme due to their high resolution, high operating speed, low cost and keeping the bulk properties unaltered. Also, laser enhances the implant surface wettability that plays a key role in determining proteins adsorption and cell adhesion on the implant surfaces resulting in improved peri-implant osseointegration [
20,
38]. Moreover, it was confirmed by Zheng et al. [
39] that the improvement of biocompatibility of the laser textured PEEK surfaces attributed to the formation of polar groups. Another efficacious issue for improving implant osseointegration is the ultraviolet irradiation. It was recognized that ultraviolet irradiation causes removal of implant surface hydrocarbons leading to increased protein binding force, promoting osteoblastic activity and promoting cell attachment and proliferation resulting in enhanced peri-implant bone healing [
24]. One of the great challenges is the development of bioactive proteins, which are being used to improve the healing process. Healing is a complex process, which involves cellular organization, chemical signals and the extracellular matrix for tissue repair [
40]. Platelet rich fibrin (PRF) consists of an autologous leukocyte-platelet-rich fibrin matrix that could serve as a vehicle in carrying cells involved in tissue regeneration and appears to have a continued release of growth factors in a period between 1 and 4 weeks, hence stimulating the wound healing process in a significant amount of time [
26,
41]. Concerning previous prospective, this current study could be considered an innovative trial to improve the bioactivity of PEEK implant surfaces. In this recognition, Nd:YAG laser was the optimum engineering approach to basically adjust the PEEK implant surfaces topography to the nano-scale. Moreover, two different modification techniques either UV or PRF were carefully picked in combination with the nano-topographical engineered PEEK surfaces. Both laboratory and animal testing model assessments were conducted to evaluate the biological responses and osseointegration of bioactive engineered PEEK surfaces. The atomic force microscope was used to determine the surface roughness parameter (Ra) in nanometer resulted in a mean value equal to 125.179 nm (SD = 0.41). This result indicates that application of the Nd:YAG laser leads to successful engineering of the PEEK surfaces topography to the nano-scale. A comparable study conducted a comprehensive survey at three different laser wavelengths:
λ = 1064, 532 and 355 nm to compare their effect on the roughness and contact angle of PEEK substrates, properties directly related to the cell viability on implants. It was found that the 355-nm laser radiation produced a slight surface melting with the formation of some polar groups [carboxyl (O–C = O) and peroxide (O–O)] on the PEEK surfaces resulting in a potential promotion of cell adhesion onto laser-treated PEEK. A similar effect was observed by exposing PEEK to Q-switched Nd:YAG laser radiation (
λ = 1064 nm) [
42]. The potentiality of this approach to enhance the biological response of biomaterials was mostly studied in metals and mainly titanium alloys [
43‐
45]. Biomimetic–bioactivity test for the present study using SBF is considered a reliable method to evaluate their bone bonding ability [
28]. The XRD patterns of the studied groups either the control laser engineered nano-topographical PEEK surfaces or laser engineered PEEK surfaces modified with UV or PRF have shown the distinctive peaks of PEEK substrates, in addition to the significant peaks of some calcium phosphate minerals with the detection of the characteristic peaks of hydroxyapatite. These XRD results confirmed the formation of different apatite minerals including hydroxyapatite on the nano-topographical engineered PEEK surfaces of the three studied groups, and so verifying the in vitro bioactivity of these engineered PEEK surfaces. Besides, SEM images demonstrated accumulations of the apatite minerals on the nano-topographical engineered PEEK surfaces of the three studied groups with a significant difference directly related to the amount of dispersed minerals, where few crystals were observed on the control PEEK surfaces, while many aggregations were noted all over the laser/UV engineered PEEK surfaces with obviously great coverage for the laser/PRF engineered surfaces. Theses surface morphological observations indicated the recognizable bioactivity enhancement of the engineered PEEK surfaces that could be predicted in an ascending pattern from the control group to the laser/UV engineered group to the highest bioactivity for the laser/PRF engineered surfaces. Martin et al. [
46] conducted a study to evaluate PEEK used as an implant material after surface modification by electron beam deposition of titanium using SBF to evaluate their bioactivity. The study concluded that PEEK modified by electron beam deposition of titanium had improved bioactivity when compared to unmodified PEEK. Histological findings of the decalcified bone sections demonstrated significant osseointegration features for the three studied groups. Meanwhile, the control nano-topographical engineered PEEK surfaces showed less bonded bone segments at the bone-implant interface in association with an interrupted cementing line configuration. On the other hand, the laser engineered PEEK surfaces in combination with UV or PRF showed more bone bonding areas with a continuous cementing line configuration along the bone-implant interface coupled with prominent bone maturity. Also, it was noted that, the laser engineered PEEK surfaces combined with PRF exhibited superior osseointegration features compared with the laser engineered PEEK surfaces modified with UV. Likewise, histomorphometric outcomes represented by the calculated BIC% for each implant revealed a significant increase in the BIC% mean value among the three studied groups. The least mean value of BIC% was recorded for the control nano-topographical engineered PEEK surface 56.43 (0.97), then significantly increased for the laser/UV engineered PEEK surfaces 77.30 (0.78) to the highest statistically significant mean value for the laser/PRF engineered PEEK surfaces 84.80 (1.29). (< 0.0001). These histological observations and BIC% validated the ability of the nano-topographical engineered PEEK implant surfaces of the three studied groups to interact with the biological bone tissues stimulating the peri-implant bone healing, hence improving their osseointegration. Accordingly, it could be indicated that the bioactivity of PEEK implant surfaces was successfully improved either for the control nano-topographical engineered PEEK implants or laser engineered PEEK implant surfaces in combination with UV and PRF. Furthermore, laser engineered PEEK implant surfaces in combination with PRF could be considered the most bioactive implants comparing to the other two studied groups. It is commendably stated that these histological results were comparable with the SEM observations of apatite minerals formation that were displayed from the in vitro biomimetic–bioactivity test for the studied groups. Guo et al. [
47] focused their attention on the roughness effect on the biological activity and osteogenic efficiency of laser-treated surfaces. Femtosecond laser irradiation was used to modify the surface of PEEK implants (with and without the reinforcement of nano-SiO
2 particles). It concluded that the femtosecond laser surface modification has a significant effect on the PEEK micromorphology and its composite, significantly improving their biological activity.
In vivo animal study on sheep demonstrated a superior bonding strength of the bone/implant interface during implantation of laser textured treated PEEK implants and concluded enhanced fusion and higher deposition of mineralized matrix observation after 6 months of implantation [
48]. Current health-related research is following biomimetic approaches in learning how to engineer new biocompatible materials with nanostructured features [
38]. From this prospective, laser nano-topographical engineering approach of PEEK implant surfaces creates a unique bioactive implant surface with nanostructures that mimic the natural environment of cells henceforth able to biologically interact with cells at a molecular level to effectively control the processes of tissue regeneration, such as cell adhesion, proliferation or differentiation and subsequently improved peri-implant bone healing. Although both laser engineered PEEK implants modified with UV or PRF demonstrated improvement of the PEEK implant bioactivity represented by superior osseointegration features and BIC% mean values of 77.30 (0.78) and 84.80 (1.29) respectively, but the laser engineered PEEK implants in combination with UV recorded significantly less BIC% than the laser engineered PEEK implants modified with PRF which recorded the significantly highest BIC%. This could be attributed to the fact that the effect of the UV irradiation could be supplementary to the Nd:YAG laser nano-topographical engineering of PEEK surfaces, because this laser modification approach could be suggested unaccompanied for improving the implant surface wettability [
20,
38]. In this sense, modification of the laser engineered PEEK implant surfaces with UV irradiation has been successfully improving bioactivity and osseointegration through the creation of the biomimetic nanostructure implant surfaces in association with modification of the implants surface energy. Similar results of recent studies support the UV irradiation to improve implant surfaces wettability and bioactivity [
21‐
25]. AL Qahtani et al. [
37] conducted a study to evaluate the change in the surface wettability of titanium dental implants after UV radiation. The study concluded that UV radiation of different implant surfaces improved their wettability which would lead to improved biological response and improved bone forming capabilities. Regarding the Nd:YAG laser nano-topographical engineered PEEK implant surfaces in combination with PRF, it was reported that the PRF could be considered a source of growth factors involved in osteoblast adhesion, improving subsequent bone healing [
27]. From this point, it could be supposed that this enhancement of the implant surfaces bioactivity might be due to a compound modification scheme including Nd:YAG laser resulting in an engineered biomimetic nano-topographical bioactive implant surface in association with alteration of the implant surface energy by increasing the surface wettability, as well as the bioactive protein PRF coat that allows another modification to the implant surfaces by alteration of their chemistry. Therefore, this compound unique scheme for PEEK implant surfaces modification creates an engineered biomimetic/bioactive implant surfaces through topographical, physical and chemical modifications; thereby, the laser/PRF engineered PEEK implant surfaces achieved the superior significant bioactivity and peri-implant bone healing. Different studies discussed the effect of platelet rich plasma (PRP) and platelet rich fibrin (PRF) in dentistry to enhance osseointegration and peri-implant bone healing. Meanwhile, the potential of these studies recognizes titanium and even zirconia implants [
26,
29,
31]. AL Qahtani et al. [
37] conducted a study to evaluate the change in the surface wettability of dental implants after UV radiation. The study concluded that UV radiation of different implant surfaces improved their wettability which would lead to improved biological response and improved bone forming capabilities. Regarding PEEK implants, there has been a lot of focus on nano-scale coating of PEEK with bioactive apatite and production of bioactive PEEK nanocomposites to enhance their biological responses [
49]. To the best of our knowledge, no other studies compared the
in vitro and
in vivo bioactivity of PEEK implants following similar design as this present study to improve PEEK implant bioactivity resulting in the production of a simple nano-topographical, biomimetic, bioactive engineered PEEK implant system.