Balancing microbial and mammalian cell functions on calcium ion‐modified implant surfaces

Abstract

Implant integration is a complex process mediated by the interaction of the implant surface with the surrounding ions, proteins, bacteria, and tissue cells. Although most implants achieve long-term bone-tissue integration, preventing pervasive implant-centered infections demands further advances, particularly in surfaces design. In this work, we analyzed classical microrough implant surfaces (only acid etched, AE; sandblasted then acid etching, SB 1 AE) and a new calcium-ion-modified implant surface (AE 1 Ca) in terms of soft-and hard-tissue integration, bacterial adhesion, and biofilm formation. We cultured on the surfaces primary oral cells from gingiva and alveolar bone, and three representative bacterial strains of the oral cavity, emulating oral conditions of natural saliva and blood plasma. With respect to gingiva and bone cells and in the presence of platelets and plasma proteins, AE 1 Ca surfaces yielded in average 86% higher adhesion, 44% more proliferation, and triggered 246% more synthesis of extracellular matrix biomolecules than AE-unmodified controls. Concomitantly, AE 1 Ca surfaces regardless of conditioning with saliva and/or blood plasma showed significantly less bacterial adhesion (67% reduction in average) and biofilm formation (40% reduction in average) than unmodified surfaces. These results highlight the importance of a calcium-rich hydrated interface to favor mammalian cell functions over microbial colonization at implant surfaces.

Relevance of Topographic Parameters on the Adhesion and Proliferation of Human Gingival Fibroblasts and Oral Bacterial Strains

“…Protocol of saliva preparation for experiments was done in accordance with Sánchez et al [32]. Then aliquots of 10.0 mL were treated as described [33]. Previous to bacterial tests, a set of samples of each of the different surfaces analyzed was conditioned in natural saliva.…”

“…Gingival fibroblasts were maintained as stated previously [33] but here cells between the fourth and the fifth passage were used in the experiments.…”

“…The adhesion and proliferation experiments were carried out as described in [33] but here we investigated also 30, 60, and 90 min of adhesion.…”

“…Bacterial adhesion experiments were carried out following the experimental procedures previously described [33]. In short, we used a modified robbins device to keep in contact for 60 min the titanium samples with a bacterial suspension (3 x 10 8 bacteria mL −1 ) collected in their exponential phase of growth, under laminar flow conditions (2 mL min −1 ) Then, the bacterial flow was carefully stopped, the samples removed, and the retained bacteria quantified.…”

“…For the biofilm formation assays, the previously described protocol was followed [33]. In short, biofilm production of bacteria adhered to the surfaces was allowed for 24 h at 37°C using BHI as culture media.…”