In simple terms, success can be described as the following:
(1) biological stability (ie, no loss of hard and soft tissue because of infections or overloading);
(2) mechanical stability (ie, no fracture, loosening, or damaging of the prosthetic components, including implants and implant-abutment joints); and
(3) hygienic ability (ie, the implant borne reconstruction must be designed so that it can be easily cleaned by the patient).
Moser and Nentwig1 developed the Ankylos implant (Figure 1A) in 1985.
(1) it should be universally applicable as either a delayed or an immediate implant prosthesis;
(2) it should exhibit maximum primary stability even in poorly structured bone;
(3) it should allow for optimum load distribution for permanent bone stability during functional loading;
(4) it should facilitate soft-tissue stability because of the "gap-free," bacteria-proof tapered abutment connection with maximum mechanical stability;
(5) it should provide for simple prosthetic restoration options, including a combination of implants with remaining natural teeth; and
(6) it should be an economical restorative treatment option for the replacement of all missing natural teeth.
The endosseous part features a special thread design with the thread depth increasing toward the apex.
The varying thread design distributes the chewing forces toward the flexible spongy bone while providing simultaneous load relief at the cervical (crestal bone) region.1,2
The reason for this design is that the relatively elastic spongy bone, which contacts about 90% of the implant body, decreases in volume in the cervical direction and becomes less elastic because of the cortical supporting shell, whose rigidity is approximately 10 times higher than the spongy bone.
After being osseointegrated and clinically loaded, the implant causes an increase in tension peaks in the very tiny cortical layer, which can lead to subsequent cervical bone loss.3
This irregular surface of a small (3.5 × 11 mm) Ankylos implant provides the same surface area as that of a natural molar tooth.
the dimension of the abutment should be smaller than the diameter of the implant body ("platform switching") to get the optimal effect of the barrier and protection function of the peri-implant soft tissue.
The tapered implant–abutment connection (Figures 1A, 4A, and 5) was used in the design of the Ankylos implant because it offers the following technical advantages:
(1) in contrast to hexagonal or tube-in-tube connections, the tapered connection technology ensures the best possible load transfer;
(2) a precisely manufactured tapered connection can be gap free and therefore bacteria-proof (Figure 4A); and
(3) the Ankylos tapered connection is rotationally stable, requires a comparatively low torque (15 N/cm), and offers the greatest possible security against screws loosening and breaking.
SURGICAL PROCEDURE DEPENDING ON THE BONE QUALITY
These include
(1) pilot drilling;
(2) drilling to the diameter and length planned;
(3) conical reaming; and
(4) final thread tapping.
A conical reamer, which corresponds to every available implant size, can also be used as a tool to check for the correct implant position and orientation.
The reamer functions as a cutting instrument when rotated clockwise and as a condensing instrument when rotated counter-clockwise.
This provides for another condensation procedure in poorly structured bone.
The average loading period was 56.8 months. Postoperative follow-ups were made once a year by a standardized protocol. The results were classified by prosthetic application in the Table.
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