Threaded versus porous‐surfaced designs for implant stabilization in bone‐endodontic implant model

Abstract

An endodontic implant model system was used to compare the effect of implant design on stabilization in bone. Specifically a porous-surfaced design was compared to conventional threaded and smooth-tapered endodontic implant designs. All implants were placed in immediate function thereby assessing the effect of early limited movement on the fixation achieved. A total of eighty-three endodontic implants were inserted in the mandibles of six adult mongrel dogs. Animals were sacrificed immediately after implantation and after 3, 6, and 12 months. Implants were evaluated by clinical and radiographic examination and after animal sacrifice by pull-out tests of the implant from the tissues, SEM examination of the pulled-out implants and, finally, histology. The pull-out test results indicated increasing shear strength with implantation time for the porous-surfaced implants in contrast to the gradual loss of fixation for the threaded implants and the continuous low shear strength for the smooth implants. Histological studies and SEM examination indicated the reason for these changes. Smooth implants became encapsulated by fibrous connective tissue from early post-implantation time periods. Threaded implants, although initially mechanically interlocked with bone, developed a fibrous connective tissue capsule that gradually thickened with time until, by 6 months, little mechanical interlock of bone and implant was present. It was assumed that this fibrous capsule thickening was caused by implant movement. The porous-surfaced implants, however, became stabilized by bone ingrowth and showed more extensive bone formation within the surface pores with time. It is concluded that for implants that are made functional immediately after implantation, as in this study, porous-surfaced implants can become strongly fixed by bone ingrowth, in contrast to conventional threaded or smooth-surfaced designs, thus presenting a more favourable long term prognosis.

Application of the finite element method in dental implant research

“…Clinical, radiographic and histological examinations of the Endopore design, have demonstrated that shorter implants, shorter initial healing periods and simpler surgical techniques can be obtained. 89 These results have been demonstrated to be consistent in a clinical setting, where success rates exceed 96%.…”

Clinical and radiographic evaluation of NobelActiveTM dental implants

“…Small amounts of micromotion did not prevent bone ingrowth into porous Vitallium staples in the dog model (Cameron et al 1972), however, micromotion due to the application of up to 200 pounds of force resulted in fibrous tissue integration instead of bone infiltrating the staple (Cameron et al 1973). Maniatopoulos et al (1986), using the dog model, inserted endodontic implants into bone through the interradicular bridge of the molars and the endodontic canal of the incisors, using three different implant designs: screws, smooth tapered implants, and porous cylinders. Masticatory forces applied to the implants through the periodontal ligament resulted in implant micromotion.…”

Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

“…However, attributable in part to PEEK's relatively inert and hydrophobic surface, recent evidence has demonstrated that smooth PEEK can exhibit poor osseointegration [9,25] and fibrous capsule formation around the implant [23,34]. Lack of bone-implant contact can induce micromotion and inflammation that leads to fibrous layer thickening, osteolysis, and implant loosening [2,13,29,37,48]. Previous studies [1,4,15,16,18,36] have shown that surface modifications such as plasma treatments, coatings, and composites can improve PEEK implant integration, yet many suffer practical limitations such as delamination, instability, and mechanical property tradeoffs.…”