Replacement of lost teeth using oral implants is an accepted treatment modality with well documented, high long-term success rates of up to 90 % at 10-year follow up. Conventional dental implant strategies that work successfully in delayed implantology have serious limitations regarding functionality and esthetic outcome in immediate implantology. Although, Implant indication expands nowadays. The major advantages of immediate implant placement are the reduction in treatment time with fewer surgical interventions leading to an improved quality of life and overall cost reduction, and most important socket preservation due to early functional load.
The main reasons for these shortcomings are based on the fact that currently available dental implants are cylindrical and made of titanium. Actually, they resemble the natural root neither in form nor in color. The lack of the correct fit in most instances has to be compensated by multiple complex additional treatments such as bone augmentation, guided tissue regeneration as well as gum pasty. So that, these procedures are time consuming, costly and not fully predictable.
The natural extraction socket represents the ideal anatomy and starting point for a root formed implant. The anatomic bone situation is ideal for the absorption of the load of a root analogue implant.
In addition, the cylindrical implants do not fit at all, that leads to a horizontal and vertical atrophy. In many cases the atrophied bone especially in the presence of thin soft tissue does not show esthetic approach because of the grayish gingiva or even visible implant shoulders. These complications may occur within days after implantation or after years in the context of old age involution. A correction of this failure requires a number of invasive procedures as Guided tissue regeneration, which are questionable outcome, therefore it is advisable to use root colored implants.
Display of different dental implant forms clearly indicates that Osseo integration does not primarily depend on the form of the implant. In addition to surface treatment of implant, it is important to prepare the implant site in an atraumatic way in order to achieve a perfect bone to implant contact.
There is absolutely no logical reason at all not to use the already existing intact tooth socket as implant site and to adapt the implant to the tooth socket instead of the vice versa approach including drilling, bone trauma, bone loss and additional bone augmentations.
All attempts in the long history of dental science to fix homologue, heterologous or allogeneic root analogue implants into a fresh extraction socket failed due to the conical root form, rejection and lack of preciseness and were therefore not established. With the implementation of the modern CAD/CAM technology it became easily possible to manufacture an exact copy of the dental root.
Is there any difference in Osseo integration?
It is not only to reconstruct the anatomy of the individual tooth, but it is possible to consider the underlying bone quantity and quality. This way the surface of the implant can be modified accordingly. Macro-retentions (protrusions) are a condition for the safe fixation of a root-formed and therefore conical implant in the bone. Macro-retentions have to be firmly limited to spongy bone, since only spongy bone can absorb pressure without fracture at a remote site. Micro fractures cannot be avoided, but in contrast to fractures of cortical bone fractures in spongy bone remain limited with reduced damage and quick regeneration due to the excellent blood supply always present in spongy bone.
Another reason for the high regenerative potential of spongy bone lies in its extensive vascularization. Retentions in the area of the thin cortical bone leads irrevocable to fractures, sometimes at remote sites, with subsequent bone recession. In order to be on the safe side and avoid fracture of the thin cortical bone at any cost, the implant is reduced at the buccal and lingual face by approximately 0.1–0.2mm. The principle of differentiated Osseo integration therefore dictates the innovative implant design. In areas without macro retentions no fracture or impression induced resorption takes place and primary Osseo integration occurs without delay. Only by consideration of these different healing modalities Osseo integration can be accomplished in conical or root-analogue formed implants.
What are the advantages of the novel implant?
No bone drilling and drilling guides are necessary. Associated risks are avoided. No bone drilling equals no operative trauma, no bone loss, no damage to neighboring structures including dental roots, mandible nerve, or maxillary sinus. The exact fit of the implant leads to an optimized implant-bone contact surface and thus maximal primary stability with shorter healing periods, because there are no gaps between the implant and the bone. Additionally, surgical interventions like bone augmentation, guided bone or tissue regeneration are not required.
The exclusive use of root colored Zirconia leads reproducibly and predictably to satisfying esthetic results.
Thanks for Professor Alfred Kocher and Dr. Wolfgang Pirker for their support to accomplish this review (Pirker, W. and Kocher, A. (2009), True anatomical zirconia implants for molar replacement: a case report from an ongoing clinical study with a 2-year follow-up. Oral Surgery, 2: 144–148).