Osteoblast integration of dental implant materials after challenge by sub-gingival pathogens: a co-culture study in vitro

Abstract

Sub-gingival anaerobic pathogens can colonize an implant surface to compromise osseointegration of dental implants once the soft tissue seal around the neck of an implant is broken. In vitro evaluations of implant materials are usually done in monoculture studies involving either tissue integration or bacterial colonization. Co-culture models, in which tissue cells and bacteria battle simultaneously for estate on an implant surface, have been demonstrated to provide a better in vitro mimic of the clinical situation. Here we aim to compare the surface coverage by U2OS osteoblasts cells prior to and after challenge by two anaerobic sub-gingival pathogens in a co-culture model on differently modified titanium (Ti), titanium-zirconium (TiZr) alloys and zirconia surfaces. Monoculture studies with either U2OS osteoblasts or bacteria were also carried out and indicated significant differences in biofilm formation between the implant materials, but interactions with U2OS osteoblasts were favourable on all materials. Adhering U2OS osteoblasts cells, however, were significantly more displaced from differently modified Ti surfaces by challenging sub-gingival pathogens than from TiZr alloys and zirconia variants. Combined with previous work employing a co-culture model consisting of human gingival fibroblasts and supra-gingival oral bacteria, results point to a different material selection to stimulate the formation of a soft tissue seal as compared to preservation of osseointegration under the unsterile conditions of the oral cavity.

Surface characterization of titanium implant healing abutments before and after placement

“…However, the integrity of this soft tissue seal is also vulnerable to bacteria, especially immediately post‐surgery . A study by Zhao and colleagues and others presented the idea of a “race‐for‐the‐surface” between bacterial cells and mammalian gingival cells as a defining factor in the establishment of this soft tissue seal, and overall soft‐tissue health . Although this phenomenon has been primarily emphasized when considering soft‐tissue attachment implants, the race‐for‐the‐surface can occur on any component of the implant system that is simultaneously exposed to bacteria and cells .…”

“…33 A study by Zhao and colleagues and others presented the idea of a "race-for-the-surface" between bacterial cells and mammalian gingival cells as a defining factor in the establishment of this soft tissue seal, and overall soft-tissue health. 33,[37][38][39][40] Although this phenomenon has been primarily emphasized when considering soft-tissue attachment implants, the race-forthe-surface can occur on any component of the implant system that is simultaneously exposed to bacteria and cells. 39,41,42 Therefore, in order to understand the conditions in which this soft tissue health is compromised, components associated with early stage healing of gingiva need to be better investigated.…”

Competitive colonization of prosthetic surfaces bystaphylococcus aureusand human cells

“…However, the influence of the critical initial event of perioperative bacterial contamination on the subsequent race for the surface, including adhesion, spread and growth of human cells on the surface of the biomaterial, has not received enough attention, a point of concern which is the inspiration for our work. Simultaneous bacterial adhesion, biofilm formation and tissue integration has been poorly studied despite the fact that co‐culture models have been demonstrated to provide a better in vitro mimic of the clinical situation …”

Evaluation of oral microbial corrosion on the surface degradation of dental implant materials

“…The incorporation of Zr into the native oxide layer increases its passivity, resulting in significantly lower amounts of metal ion release as compared with pure Ti when immersed in acidic media simulating the oral environment . Despite its improved corrosion behavior, TiZr is similar to Ti substrates in terms of initial bacterial attachment and biofilm formation and therefore may be prone to the bacteria‐induced corrosion exhibited by pure Ti surfaces …”