Articles - Forum Implantologicum

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Feature Article

May 27, 2018 // 16 min read

Different Implant-Abutment Interfaces – Overview and Clinical Implications

Abstract

The clinician is confronted with the availability of a huge number of dental implants and components today. As a consequence, the choice for the ideal implant and abutment type in each individual situation is quite complex. The goal of implant treatment is to achieve long-term stable implants and restorations which are functionally and esthetically appealing, exhibit healthy peri-implant conditions and create high patient satisfaction. For the survival of implants and prostheses, both the biomechanical stability of the implant components and the biologic response of the surrounding tissues are of relevance. Knowledge of biomechanical and biological principles leads to an understanding of the existing implant types and their range of indications, which facilitates the decision-making process for the clinician. Furthermore, the consequences of implant placement at, below or above the bone crest on the bone reaction are reflected for each implant type.

Three levels of significance in implant dentistry are highlighted using basic and recent scientific evidence - the bony part, the interface area between implant and abutment, and the transmucosal part. Key issues such as the formation of a biologic width, the platform switching concept, the influence of microgaps, microleakage and micromovements, and the pros and cons of internal and external implant-abutment connections are discussed. In addition, a short overview on abutments and few condensed clinical recommendations are given.

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Introduction

Replacing missing teeth with dental implants is a well-proven and successful treatment option today for partially and fully edentulous patients (Figs 1 – 2). The survival rates for single tooth implants were found to be 95% at 10 years (Jung et al. 2012). Inserted implants are continuously exposed to chewing forces of between 383 and 678 N for women and 512 and 1019 M for men (Raadsheer et al. 2004; Cosme et al. 2005; Ikebe et al. 2005). This load is transferred via the implant-abutment connection to the bone. Biomechanical studies found the load concentration to be located predominantly in the area of the implant-abutment interface. This zone can affect both the peri-implant bone and the surrounding soft tissues.

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Fig. 1a: Patient is edentulous in the maxilla and wearing a conventional denture

Fig. 1b: Six implants were placed according to the diagnostics and a fixed implant-supported prosthesis (FDP) was inserted

Fig. 1c: The patient’s smile with the conventional denture

Fig. 1d: The patient’s smile on the day of insertion of the FDP

Fig. 1a Fig. 1b Fig. 1c Fig. 1d

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Fig. 2a: Patient with multiple anodontia in the maxilla

Fig. 2b: Situation after orthodontic treatment and insertion of implants. All the teeth were prepared in a minimally invasive way using preparation guides to raise the bite as well as for esthetic reasons

Fig. 2c: Rehabilitation of the maxilla with single implant crowns and cemented all-ceramic crowns

Fig. 2a Fig. 2b Fig. 2c

Overload can also lead to elastic deformation at the implant-abutment level and cause technical complications. For the survival of implants and prosthodontics, both biomechanical stability of the implant components and biologic response of the surrounding tissues are of relevance.

Peri-implant bone levels and their stability over time are crucial to the long-term performance of implants (Albrektsson et al. 1986). Several studies concluded that peri-implant bone loss is a biologic reaction to the implant associated with the creation of the interface between implant and abutment. This interface creates a microgap for bacteria. Other factors contribute to the peri-implant bone reaction, including the surgical intervention, the implant (e.g. design, surface, position, angulation, insertion depth, loading type), the prosthesis (e.g. design, abutments) and the patient (e.g. general health, smoking, hygiene, history of periodontitis, parafunctions) (Doornewaard et al. 2017; Zembic et al. 2010).