When and How to Use Multi-Unit Abutments
It is not uncommon to run into challenges when restoring a full arch, screw-retained implant prosthetic case. However, the use of multi-unit abutments can overcome these challenges. 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.
TABLE OF CONTENTS
- Indications for the application of multi-unit abutments
Indications for the Usage of Multi-Unit Abutments
When implant angulation is required.
- Multi-Unit abutments are intended to be connectors between the dental implants and multiple implant screw-retained restorations.
- Make your selection of angle correction options ranging from straight – 0º to 45º at the conversion appointment or at the initial prosthetic impression appointment.
- 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.
- 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.
When implant height disparities is needed.
- 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.
Prosthetic Restorations That Benefit From Multi-Unit Abutments
Implant retained bars
Hybrid denture prosthetics
Zygomatic implant applications
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.
Open tray – MUA level impression instructions
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 Iverson Dental Labs