## 4 Discussion
### Future Trends  
Common surface modifications change the chemical and mechanical properties of miniscrews. However, roughening of the miniscrew surface poses a disadvantage both in terms of the risk of contamination and the difficulty of preventing bacterial colonization [58]. Poor oral hygiene leads to the accumulation of anaerobic bacteria around the miniscrew, resulting in the activation of immune cells such as neutrophils and macrophages that migrate to the implant site. This activation causes the release of proinflammatory cytokines such as IL-1B, IL-6, and TNF-\(\alpha\)[59]. Studies on surface modifications of titanium implants have developed over the years. With advances in surface modification technologies, there has been a transition from traditional bioinert surfaces to biocompatible surfaces, and then to bioactive surfaces. As a satisfactory standard could not be reached with bioactive and bioinert coatings, recent studies have applied biomimetic coatings that simulate body fluids. These fourth-generation surface treatments are shedding light on future research [60]. Biomimetic calcium phosphate (BioCaP) coatings have been developed under physiological conditions (37\({}^{\circ}\)C temperature and pH 7.4) under which bioactive agents such as bone morphogenetic protein-2 (BMP-2) can be deposited on the surface [61; 62]. [PERSON] et al. used histomorphometric analyses to evaluate osteoconductivity by applying BioCaP (amorphous or crystalline) coatings with or without bovine serum albumin (BSA) on miniscrews [63]. Based on their results, the authors concluded that crystalline BioCaP coating is an effective method to accelerate osseointegration and increase the success rate of orthodontic miniscrews [63]. [PERSON] et al. aimed to improve the biocompatibility of stainless-steel miniscrews with the two-phase BioCaP coating they developed [64]. In their study, titanium discs were immersed in biomimetic modified Tyrode (BMT) solution for 24 h and stainless-steel discs were immersed in the same solution for 0, 12, 24, 36, or 48 h. The discs were then immersed in a supersaturated calcium phosphate solution for 48 h to form a crystal layer, and BSA was also added to this layer as a model protein during biomimetic mineralization. Their results demonstrated improved roughness and wettability of the smooth stainless-steel surface. Longer BMT coating time was also associated with increased cell seeding efficiency, cell proliferation, and cell spreading area on the surface. They concluded that the two-phase BioCaP application could improve the surface properties of stainless-steel miniscrews [64]. [PERSON] et al. aimed to create a polyethylene glycol (PEG) layer, using plasma coating to create a bacteriostatic effect on the surface of titanium miniscrews [65]. To achieve this layer, they activated the surfaces of titanium miniscrews with argon plasma and then with PEG plasma at different powers (100, 150, and 200 W) for 30 and 60 min. The PEG-coated samples showed more than 80% biocompatibility for fibroblast and osteoblastic cells. The miniscrews treated with only argon plasma activation showed an increase in bacterial colonization. The authors concluded that PEG significantly inhibits bacterial affinity due to its chemical configuration [65]. [PERSON] et al. also examined the effects of the antimicrobial photosonodynamic treatment (aPSDT) ofzinc oxide (ZnO) nanoparticle-coated miniscrews on anaerobic bacteria [66]. The study compared uncoated miniscrews treated with phosphate-buffered saline (PBS) or 0.2% chlorhexidine (CHX) with ZnO nanoparticle-coated miniscrews treated with PBS, light-emitting diode (LED) (aPDT), ultrasound (aSDT), or both LED and ultrasound (aPSDT). They reported that ZnO nanoparticle-coated miniscrews with surface aPSDT had the greatest antimicrobial effect against periopathogenic biofilm. Gene expression levels of proinflammatory cytokines such as IL-1\(\beta\), IL-6, and TNF-\(\alpha\) were also significantly lower in this group [66].