The prevalence of peri-implantitis has grown in the past few years and has become a major issue in implant dentistry. Long-term stable and healthy soft- and hard-tissue conditions should be achieved in combination with esthetically and functionally satisfying results. However, the rising number of placed implants in the past decades has come with an increase in the prevalence of peri-implantitis .
Peri-implantitis is defined as a pathological inflammation of the peri-implant soft and hard tissue leading to peri-implant bone loss. For pathogenesis, many different factors are discussed in the literature. Reviews have shown that oral hygiene, implant surgery factors such as implant position, soft- and hard-tissue amount and quality, prosthetic concepts and design, general medical history, and other factors have an impact on the establishment and progression of peri-implantitis .
Peri-implant soft tissue forms the first border of the peri-implant tissue to the oral cavity and therefore to the migration of microorganisms that can cause and accelerate peri-implant infections. Dental implants, unlike the natural teeth, do not possess a compact barrier against penetration properties of the oral cavity. Peri-implant soft tissue acts as a cuff-like barrier . In contrast to the periodontal attachment, there is no connective tissue fiber insertion into the implant surface. The peri-implant soft tissue possesses a lower number of blood vessels [4, 5] and cells but a higher amount of collagen [3, 6]. As a consequence of these anatomical differences, the peri-implant soft tissue has a decreased defending mechanism against microorganisms that in a pathological amount causes peri-implant infections.
A major etiological factor for peri-implantitis is the position of the implant in the surrounding bone . In addition to bone quality and vascularization, a sufficient amount of peri-implant bone is important for the long-term stability of the implant and a sufficient underlining to the peri-implant soft tissue . However, in most patients, the local bone amount is reduced due to atrophy, inflammatory processes, or resectional defects. Therefore, in the past few years, different techniques have been described to enlarge the local bone amount in prospective implant sites . Besides methods such as GBR or the sinus augmentation technique, different augmentation materials have been investigated and established in the daily clinical routine. Autologous bone in the context of hard tissue augmentations is still the gold standard due to its osteogenic capacity . To avoid the disadvantages that come with autologous bone transfer, such as a second surgical site and an increase in postoperative pain, biomaterial research has focused on the development of bone substitute materials that serve as scaffolds for the ingrowth of bone and its progenitor cells from the surrounding tissue .
The ability of bone substitute materials to form a sufficient and stable implantation bed has been proven in numerous clinical trials; however, it is still to a certain degree unclear if the different tissue reactions have an impact on the establishment of a peri-implant infection, especially when these biomaterials are used for augmentations around the implant shoulder. Due to the two-stage design of the implant, the implant shoulder presents a potential micro-gap between the abutment and the implant and a port of entry for microorganisms and peri-implant infections leading to a manifestation of peri-implantitis .
Regarding the stability of peri-implant hard and soft tissue, biological or anatomical factors are not the only elements that could be proven to have an impact. Technical factors such as the implant-abutment connection are also known to be key factors for long-term stable hard- and soft-tissue health . Regarding the implant-abutment connection, which seems to be the key issue, located on the interface between the implant, the peri-implant bone, the peri-implant soft tissue, and the oral cavity, different studies have shown that a Morse-tapered conical connection reduces the micro-movement and therefore the micro-motions, which results in a pump effect of sulcus fluid and microorganisms in the fragile peri-implant soft tissue [10, 12]. The conical connection leads to a kind of “cold welding” type of connection that seems to prevent bone loss compared to external implant-abutment connections [10, 12].
A further factor, which has been detected to improve peri-implant hard- and soft-tissue health and is related to a conical implant-abutment connection, is a “platform switching” design. By switching the platform between the implant and the abutment from the outside surface of the implant to the inside region and therefore in larger distance to the peri-implant hard and soft tissue, the colonization of microorganisms seems to be reduced. Furthermore, the conical connection in combination with a platform switching design decreases stress transferred onto the peri-implant bone. As a result, peri-implant bone loss is prevented and the peri-implant soft- and hard-tissue health can be preserved [11, 13].
The aim of the present retrospective investigation was to assess clinically and radiologically peri-implant tissue conditions and document peri-implant tissue stability in C-Tech implants when placed simultaneously with a GBR augmentation procedure after at least 3 years of loading.