## 1 Introduction  
Dental implants have become an integral part of restorative dental care and the number of implants being placed is steadily increasing. As the use of dental implants increases, it is likely that the complications will also increase if the current systems are not optimized. It has been reported that every fifth inserted implant eventually develops peri-implantitis after masticatory loading for a mean period of time of from 3.4 to 11 years [1, 2]. Biological complications involve the mucosa and bone surrounding the dental implant [3, 4]. Peri-implant bone complications often involve a loss of bone vertical height and volume. Peri-implant bone loss is of great importance as it has been established as one of the main criteria of implant success [5]. This crestal bone loss seems to be related to the location of the microgap that created between the implant-abutment interface [6]. Decreased peri-implant bone loss was observed previously when utilizing different approaches related to the connection geometry of the dental implant-abutment interface, such as platform-switching [7]. [PERSON] and [PERSON] have defined platform-switching as \"a protocol that includes smaller diameter restorative components that have been placed onto larger diameter implant restorative platforms--the outer edge of the implant-abutment interface is horizontally repositioned inwardly and away from the outer edge of the implant platform\" [7]. The exact aetiology behind this enhanced peri-implant bone response has not been confirmed. Recent studies demonstrated higher levels of metal ions being released through accelerated corrosion from the platform-matched compared to platform-switched implant-abutment couplings (IAC), suggesting that this difference in the amount of corrosion products may be a factor [8; 9]. The role of implant corrosion products in peri-prosthetic osteolysis has been extensively discussed in the orthopedic literature, which demonstrated that metal ions/particles in tissues can influence various metabolic pathways leading to cytokine release and interference with the function of various cells, such as osteoblasts, macrophages and fibroblasts, thereby disrupting bone homeostasis and contributing to the development of osteolysis [10; 11; 12]. The topic of degradation products released from dental implants and their association with peri-implant bone loss has received close attention in recent years [13; 14; 15; 16; 17; 18; 19]. In fact, the earlier work of the current research group [8; 9; 20] provided some indirect evidence of the possible role of corrosion products in the mediation of crestal bone loss around dental implants. Additionally, this glimpse of the immunological response pattern to the corrosion products that were released, observed in the previous research [20], suggests that there are immunological aspects of peri-implant bone loss, supporting the theory of foreign body response (FBR) to the dental implants introduced by [PERSON] and colleagues [13; 14]. This FBR to the implant can be aggravated by various factors related to the implant hardware, patient characteristics or surgical hazards. Regarding implant-related factors, ions and particles released from the implant/prostheses combinations due to corrosion have been suggested to initiate a disbalanced FBR. In fact, the role of peri-implant titanium particles, micromotion and biocorrosion as risk indicators for peri-implantitis has been highlighted but requires further research [21]. Although titanium (Ti) shows a high corrosion resistance, obtained through the formation of a passive oxide layer, certain environmental conditions, such as those experienced in the oral cavity, can breach this protective oxide layer and cause corrosion [22]. [PERSON] and [PERSON] have stated that, even under passive conditions in which metal oxide film breakdown is not observed, metals and alloys will release ions into the surrounding tissue at a finite rate [23], affecting the mechanical integrity of the implant and the health of the surrounding tissue [22].