5 Year Clinical Evaluation of CONELOG® Screw-Line Implants With 7 mm Length: a Prospective Randomized Double-blinded Clinical Study

In order to avoid sinus augmentation in the upper jaw and a vertical augmentation in the lower jaw, various manufacturers offer short implants of 6-8mm length. The prevention of augmentative measures, especially in the mandible, is a fundamental component of the minimization of invasiveness while at the same time improving the functional capability. The benefit lies in the possibility to place implants without prior bone augmentation even in difficult anatomical conditions. This significantly reduces the invasiveness which on the one hand allows a higher number of patients to be treated with implants (especially morbid patients and anxiety patients) and on the other hand makes the treatment more predictable, with less risk, cost-efficient and considerably faster. Moreover, new scientific insights are gained in the area of short implants.

As with all implants, the risks associated with the study consist of intraoperative complications (e.g. damage of adjacent structures), failure of the implant (e.g. impairment of wound healing, fracture of the implant body), the abutment or abutment screw (e.g. loosening, fracture), or the crown on the abutment (veneer fracture, scaffold fracture).

The objective is to determine whether implants with the Conelog® connection and a length of 7mm are suitable for splinted/non-splinted monolithic lithium disilicate crowns cemented on individualized titanium abutments in the chewing centre of the mandible. The main indication for short implants is severe atrophy of the jaw, which creates a longer distance from the implant shoulder to the occlusal plane. An unfavourable crown-to-implant ratio means higher stress on the screws, the implant-abutment surface and possibly on the osseointegration of the implants. This raises the question whether splinted crowns have a positive effect on implant survival compared to non-splinted crowns.

The two 7mm Conelog ® implants are either used in the area of the second premolar and the first molar or the first and second molars of the mandible. The diameter of the implant depends on the width of the alveolar bone and ranges from 3.8 to 4.3 mm.

In case of a bilateral free-end situation, both quadrants are treated as part of the study, and both treatment variants are applied by using splinted crowns on one side and individual crowns on the other (split mouth design).