The ankylos endosseous dental implant: assessment of stability up to 18 months with the Periotest.

Osseointegration is an ongoing histometric process that may vary during clinical function. The implant must be stable at uncovering, which reflects the status of bone-implant interface. The physiology of bone healing associated with endosseous implants suggests that this process occurs between 8 and 12 months, and Periotest values (PTVs) tend to reflect changes in the stability of the bone-implant interface. Stability generally increases gradually from the time of uncovering to an optimal PTV that occurs at a point close to 12 months. This stable interface must remain intact for long-term clinical survival. Rapid development of this optimal PTV is highly desirable in order to prevent premature overloading of the bone-implant interface. The Ankylos implant is a new screw-type implant design in which the thread pitch and length vary to maximize trabecular bone contact. The purpose of this report is to evaluate to 18 months the stability (PTVs) of this implant design. More than 457 implants were placed and followed for a period of 18 months by the multicentered, multidisciplinary Ankylos Implant Clinical Research Group (AICRG). Implant stability (PTVs) was assessed using the Periotest at abutment connection and at 3, 6, 9, 12, and 18 months after uncovering. The Periotest values for all implants rapidly reached an optimal status between uncovering (-3.1 PTVs) and 3 months (-3.4 PTVs). This rapid increase in stability has not previously been reported for other implant designs. The mandibular arch was more negative (-3.8 PTVs) at uncovering as compared with the PTVs for the maxillary arch (-1.7 PTVs). Negative PTVs were recorded (1) as length and diameter increased, (2) as bone density increased, (3) in certain jaw regions, (4) as the number of implants/case increased, and (5) for implants stabile at placement. The Ankylos screw implant design produced rapid stabilization 3 months after uncovering.