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Why biology must not be ‘plan B’ for dental implants

by: Prof. B. Touati

Dental professionals must change their thinking when considering soft tissue adhesion around implants and certain involved components such as healing abutments.

A real biologically driven approach is needed to obtain soft tissue health and stability, and this starts with the primary closure of the tissue wound resulting from implant placement. The junctional epithelium is part of the body’s “first line of defense”; the first protective barrier to external environment infections. Because implants pierce the body shell, the interface between mucosa and the implant-abutment complex is indispensable to protect against microbial invasion.

Repeated disconnections/reconnections of healing abutments often creates a bleeding wound with torn epithelial and connective tissue cells. This may trigger the apical migration of epithelial cells of the junctional epithelium, which, thanks to hemidesmosomes and adhesive glycoproteins, will ultimately stabilize and adhere to the first immobile biocompatible material – the implant neck or abutment. The consequence is the creation of a pocket with instable soft tissues, especially in patients with thin or moderate biotypes.

Connective tissue adhering to the implant abutment surface

Connective tissue adhering to the implant abutment surface. Image © Schüpbach Ltd

When disconnecting a transmucosal component, such as a “healing” abutment, a bleeding site should be classified as a wound. If it doesn’t bleed, then it is a pocket. The latter is more likely to allow bacteria to access the implant platform and threads, therefore being a potential cause of a crestal bone loss. To support the health of the peri-implant mucosa, the transmucosal component that is connected at the day of surgery should ideally never be removed.

After primary closure of the tissue wound, an undisturbed biologic space and uninterrupted cell adhesion must be ensured, to help protect against the incidence of mucositis, which bears to risk to develop into peri-implantitis. One solution is to place the final abutment only once. Or to add restorative flexibility – to place one base, one time. This is designed to allow undisrupted epithelial adhesion at the mucosa/abutment interface, which helps to isolate the body from the external environment.

This procedure is a paradigm shift.

Because the abutments of two-piece implant systems are located where a sound mucosal barrier should adhere for the long term, it is logical with bone-level implants to conceive of two-piece abutments:

  1. A sterile base with a prosthetic post that is never disturbed, and
  2. A screw-retained restorative crown.

In addition, transmucosal surfaces of final screw-retained crowns should always be decontaminated before placement to offer a pristine surface for the adhesion epithelial and connective tissue of the peri-implant mucosal barrier.

Tissue-level implants allow adequate mucosal adhesion but are far from ideal prosthetically and esthetically. Alternatively, when using bone-level implants one would be wise to respect a new paradigm when it comes to abutments. The On1 concept is designed to be an easy, practical, and biologically relevant solution for both the surgeon and the restorative dentist, and especially aims to promote soft tissue health and stability.

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