Understanding stock and custom abutments.

Introduction:

Abutments are the components that connect the dental implant to the final prosthesis, be it a crown, bridge, or denture. They play a pivotal role in transferring occlusal forces from the prosthesis to the implant and subsequently to the bone. The choice between stock (prefabricated) and custom (patient-specific) abutments is crucial, influencing the aesthetic, functional, and biological outcomes of implant restorations.

1. Stock (Prefabricated) Abutments:

Definition: Stock abutments are mass-produced in various shapes, sizes, and angulations to fit a wide range of clinical scenarios.

Advantages:

  • Cost-Effective: Generally, stock abutments are less expensive than custom abutments.
  • Immediate Availability: They are readily available, making them a convenient choice for clinicians.
  • Proven Track Record: Many stock abutments have a long history of use with well-documented success rates.

Disadvantages:

  • Limited Customization: Their prefabricated nature might not cater to all clinical scenarios, especially those requiring unique angulations or emergence profiles.
  • Potential Aesthetic Limitations: In the aesthetic zone, stock abutments might not always provide the most natural-looking emergence profile or gingival contour.Reference: Bidra AS, Rungruanganunt P. Clinical outcomes of implant abutments in the anterior region: a systematic review. J Esthet Restor Dent. 2013;25(3):159-76.

2. Custom (Patient-Specific) Abutments:

Definition: Custom abutments are designed and fabricated specifically for an individual patient, based on detailed impressions or digital scans of the implant position and surrounding soft and hard tissues.

Advantages:

  • Precise Fit: They offer a precise fit, tailored to the patient’s unique anatomy and implant position.
  • Optimal Aesthetics: Custom abutments allow for a more natural emergence profile and gingival contour, especially crucial in the aesthetic zone.
  • Versatility: They can cater to challenging clinical scenarios, such as implants placed at non-ideal angulations or in areas with limited space.

Disadvantages:

  • Cost: Custom abutments are generally more expensive than stock abutments.
  • Fabrication Time: They require additional time for design and fabrication, potentially extending the treatment timeline.Reference: Priest G. Virtual-designed and computer-milled implant abutments. J Oral Maxillofac Surg. 2005;63(9 Suppl 2):22-32.

3. Biological Considerations:

  • Gingival Health: The design and fit of the abutment influence the health of the surrounding gingiva. Custom abutments, with their patient-specific design, might offer better gingival contours, promoting optimal soft tissue health.
  • Bacterial Seal: The connection between the implant and the abutment should be tight to prevent bacterial ingress, which can lead to peri-implantitis. Both stock and custom abutments, when properly selected and fitted, can offer a good bacterial seal.Reference: Linkevicius T, Apse P. Influence of abutment material on stability of peri-implant tissues: a systematic review. Int J Oral Maxillofac Implants. 2008;23(3):449-56.

Angled Abutments: If the implant position is unfavourable for a straight abutment, angled abutments can be utilised. These allow the screw hole to be positioned away from the aesthetic area or into the occlusal area. The use of a dynamic or angled screw is used and this therefore requires a specific driver, these are related to the type of screw used. The end of the driver is usually elliptical which allows it to engage in the screw head and the final torque setting is usually lower than that of straight access screws.

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