Multi-Unit Abutments: When and How To Use Them

Written by Andrew Sedler

Dentists learn applications where multi-unit abutments are beneficial, indications for the application of multi-unit abutments, and more.

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Multi-Unit Abutments at Burbank Dental Lab

When restoring a full arch, screw-retained implant prosthetic case, even a minimal disparity in the draw of the implant interface access causes restorative challenges. The use of multi-unit abutments can overcome restorative challenges and is highly recommended (if not required) when creating a full arch screw-retained implant restoration. Multi-unit abutments (MUA), are designed with a range of angle correction and are available for virtually all implant platforms. Multi-unit abutments provide a passive draw and positive uniform seat for all abutment sites.

What You Will Learn In This Article

  • Applications where multi-units abutments are beneficial
  • Indications for the application of multi-unit abutments
  • Prosthetic restorations that benefit from the use of multi-unit abutments
  • The steps to use for successful use of multi-unit abutments

Indications for the Usage of Multi-Unit Abutments

Multi-Unit abutments are intended to be connectors between the dental implants and multiple implant screw-retained restorations. (Figure 1)

  • There are usually 3-4 angle correction options to choose from, ranging from straight - 0º to 45º.  Make your selection at conversion appointment or at the initial prosthetic impression appointment. Also be aware that as the restorative process unfolds,  you may have to consider changing one or more of the angulations in order to best support the final prosthetic.

The critical point here is that when you place your multi-unit impression coping, and screw on to the abutments before initial impression, the pins should all be close to parallel. They do not have to be precisely parallel but close by eye. That is the point and benefit of using multi-units - they are forgiving.

Multi-Unit Abutment - One

Multi-unit abutments can also correct for implant height disparities. The prosthesis seats more solidly and predictably if you use multi-unit abutments to not only correct for angulation but also for height. Multi-unit abutments can accommodate for height differences because they come in a selection of height profiles. Your goal is to use low profile multi-unit abutments in implants placed higher relative to the occlusal plane of the tissue, and use taller profile multi-unit abutments when the implants are places deeper into the bone. The goal is to have all of the multi-unit abutments seating at about tissue level, and relatively even with each other.

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Prosthetic Restorations That Benefit From Multi-Unit Abutments

Implant retained bars at Burbank Dental Lab

Implant retained bars such as Hader and Locator bars.

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Hybrid denture prosthetics

Including Burbank Dental Lab's- SmartComposite Hybrid, and Zir-Max.M Smart Zirconia Hybrid.

Zygomatic Implant Applications - Dr. Joel Defrancq

Zygomatic implant applications

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Multi-unit abutments are mandatory when converting a denture to implant-retained at surgery.

Procedures and Steps For Using Multi-Unit Cases

Many clinicians place multi-unit abutments at the surgery appointment and convert a denture into an implant-retained prosthetic. This is always best done by placing appropriate multi-unit abutments and adapting the denture to the multi-unit abutments. However, if you choose not to immediate-load the implants, it is always best to seat the multi-unit abutments before the initial impression as you begin the restorative process. If you begin the impression process with multi-units placed and take your impressions at the multi-level rather than implant level, it saves you steps later and enhances the accuracy of the final prosthetic’s fit.

Multi-Unit Abutment Placement and Impression Techniques

Abutment placement instructions

  • Step 1

    Remove the healing abutment

  • Step 2

    Select the best height and adulation and place the MUAs with appropriate manufacturer’s tool, and tighten until resistance is felt.

    Multi-unit with ti cylinders

    Figure 5

  • Step 1

    Connect the open tray impression coping to the multi-unit abutment.

  • Step 2

    Inject a heavy body impression material (polyether material or polyvinylsiloxane) around the impression coping. Fill the tray with impression material and record the impression.

  • Step 3

    After setting, unscrew the impression coping and remove the impression.

  • Step 4

    Attach an abutment replica multi-unit to each impression coping.

  • Step 5

    Send the impression to Burbank Dental Lab.

Advantages to beginning your restorative process with the foundation of multi-unit abutments in the mouth

  • 1

    You can determine the angulation correction needed yourself in the patient’s mouth rather than on a model in the lab.

  • 2

    You are able to evaluate the vertical clearance that you have available. This allows you to evaluate the prosthetic options early in the process.

  • 3

    The lab can predictably place multi-unit analogs in the model, which will simplify lab procedures and facilitate more predictable results.

    Burbank Dental Lab - Fig. 6

    Figure 6

Burbank Dental Lab

3 Issues To Be Aware of When Restoring Using Multi-Unit Abutments

  • 1

    Be aware when adding an additional micro-gap.

  • 2

    The average cost will increase approximately $245 per implant site.

  • 3

    Multi-unit abutments will add an additional screw connection with the potential to loosen.

The advantages of using multi-unit abutments far outweighs any of the concerns mentioned regarding the above issues. You will have a much easier and more predictable seating of the final restoration. You will also create reduced stress translated into the restorative system due to the passive nature of the seating process of multi-unit abutments. Additionally, each time the patient has a recall appointment, it will be much easier to remove and replace the prosthesis.

Our team at Burbank Dental Lab is always available to case plan any case with you, and your benefit will be especially seen when undertaking edentulous cases as have been discussed in this article.
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Fabrication
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Burbank Dental Lab has three new state-of-the-art Carbon M2 printers. We are very excited about the options that these cutting-edge printers will allow us to offer our dental clients. Here are some of the advantages that these printers will begin to deliver to you and your dental practice.

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