Investigating the race for the surface and skin integration in clinically retrieved abutments with two-photon microscopy

Abstract

Bone conduction hearing implants can rehabilitate some types of hearing loss. A hydroxyapatite (HA)-coated skin-penetrating abutment was developed to allow for soft tissue preservation and increased skin-abutment adherence. Inflammation is thought to relate to bacterial infection of pockets around the abutment. Upon integration, the host's ability to cover the abutment surface ("race for the surface"), and thus control and prevent competitive bacteria from colonizing it, is improved. However, the attachment mechanisms behind it are not clear. In this study, we applied two-photon microscopy to visualize tissue attachment on abutments retrieved from patients. Skin integration markers were validated and applied to four HA-coated abutments. Evidence of skin integration was found, including the presence of hemidesmosomes, a basement membrane, dermal collagen and vascularization. Cases with clinical signs of severe inflammation and evident biofilm formation showed limited skin integration based on these indicators, confirming the applicability of the "race for the surface" model.

Clinical Outcomes of Soft Tissue Preservation Surgery With Hydroxyapatite-Coated Abutments Compared to Traditional Percutaneous Bone Conduction Hearing Implant Surgery—A Pragmatic Multi-Center Randomized Controlled Trial

“…As previous investigations have suggested, soft tissue-abutment integration is possible in animals (34,35). Recently, it has been shown to be clinically possible in humans (32,36) using this HA-coated abutment. It was hypothesized that the combination of skin preservation and tissue integration could improve the subjective benefit of the treatment, by improving the cosmetic aspects and reducing post-operative complications without compromising long-term clinical outcomes.…”

The clinical outcome and microbiological profile of bone-anchored hearing systems (BAHS) with different abutment topographies: a prospective pilot study

“…To achieve a successful soft-tissue integration, fibroblasts must win the ‘race for the surface’ against microorganisms on the implant surface [ 10 , 30 ]. Against the assumption that a tight structural barrier is a prerequisite, are the recent findings that tissue-integrating hydroxyapatite-coated abutments were still at risk for infection [ 14 , 31 ].…”

“…Nevertheless, colonisation per se does not necessarily imply infection, although it represents the first step of microbial infection by the accession and establishment of pathogens to the site [ 44 ]. Therefore, while colonisation is the presence of bacteria on a body surface without causing disease, infection is the invasion of host tissues by microorganisms resulting in disease [ 31 ]. The remaining question is which is the minimal infectious dose and the pathogen.…”

Multiview deconvolution approximation multiphoton microscopy of tissues and zebrafish larvae

“…Moreover it has the unique advantage of inducing Second Harmonic Generation (SHG) signal in the proteins collagen, myosin, and tubulin 19 . These advantages allow imaging thick tissue sections 20 or small organisms 21 , detection of multiple signals simultaneously 22 , imaging of stained structures but also detection of inherent autofluorescence signal and SHG 23 , with reduced overall photobleaching.…”