Four Things I Think About When Planning For Implant Assisted RPDs
Implant Assisted RPD can be a great option for patients with multiple missing teeth on limited budget. However, when planning for these type of cases, there are many things to consider….sometimes the benefits of RPD with clasps don’t always work the same way mechanically with attachments on implants…And the fact that teeth can move with periodontal ligament and the implants don’t move can make things work a little differently when you combine tooth supported clasps with attachments on implants. Added to that is another layer of consideration with tissue resiliency and different manufacturing methods incorporating certain amount of processing errors for the metal framework and the acrylic fabrication.
Over the years, when I am planning for implant assisted RPDs, there are certain steps I take to keep me out of trouble. Today, I want to share these tips and hope to help you deliver a favourable outcome for your implant assisted RPDs.
1/Think about your Path of Insertion During Pre-surgical planning
Whenever possible, I like to plan ahead the proposed path of insertion for the partial denture. If anatomically feasible, I like to plan the implants along the same path of insertion. Sometimes the morphology of the bone does not allow this to happen. But if possible, I want to find a path of insertion that is not too far off from the proposed implant angulation. By keeping this path of insertion in mind, I have better prosthetic options to ensure the implant assisted RPD will work favourably with the implants.
2/Tooth preparation with the implant angulation in mind
When I am doing tooth preparation for an implant assisted RPD, I like to place an impression coping on the implants while I prepare the guideplanes and modify height of contours. By doing so, I am constantly looking at the implants angulation to ensure my proposed path of insertion is as parallel to the implants as possible.
3/Fixture Level Impression to keep restorative options open
I don’t like to finalize the type of abutments to be used for the attachments at the beginning. I like to keep my options flexible. As a result, I like to take a fixture level impression at the time of final impression. This master cast will allow me to select any abutments I like when the case is properly mounted and when you have an undistorted view of the available prosthetic space. Sometimes what you thought would be suitable may not work and by having a fixture level impression, I have the option to change my mind. This is important to me.
4/Attachment Pick up Flexibility
If you are working with an attachment with housing, the housing can be incorporated into the denture in many ways. The housing can be picked up by the acrylic. It can be casted to the metal framework. Or it can be laser welded to the metal framework. I like to keep my housing separate from the metal framework if possible. I will want the housing to be connected to the acrylic. If at the insertion appointment, I find the attachments to be not engaging to the abutments, I can remove the housing from the acrylic and have the flexibility to pick up the attachments intra-orally.
With attachments, if they are off they are off. There is no room for forgiveness as implants do not move. To design an implant assisted RPD with the flexibility for acrylic chairside pick up is an important strategy for me to counteract any possible processing error.
With that being said, in my experience, I rarely have to pick up attachments chairside when I have a very accurate model to work with.
I hope by incorporating these tips, you will find success and joy in delivering implant assisted RPDs and help improve the quality of life of your patients.
Thanks for reading.
