tradition meets integration
Implant assisted removable overdentures combines some of the stability of a fixed prosthesis with the retrievability of a removable denture. It involves two or more implants along with a removable appliance, and can be an upgrade from your traditional removable denture. The assistance of the implant fixtures provide added stability and can improve your chewing better than traditional dentures.
Implant Supported Fixed Dentures:
a prosthesis that is completely supported by the implants that retain it. 100% of the occlusal force is absorbed by the prosthesis, the implants supporting it and the bone supporting the implants.
Implant Assisted/Retained Removable Dentures:
a prosthesis that is retained by implant fixtures providing added stability, the support is shared amongst the implants and soft tissue of the jaw
Unlike an implant supported denture that supports 100% of the occlusal force from your bite, when you bite down while wearing an implant assisted denture, your gums will take most of the force. Although these replacement teeth will restore your ability to speak and eat normally, your bite won’t be as natural as with other denture options and it may not be as stable.
You will need to reline this type of denture occasionally because, as your bone and tissues change over time, the fixture will need to be adjusted to fit. However, these are the most affordable option out there for full-arch replacements.
styles of implant assisted overdentures
Locator Abutments/Attachments System
Locator abutments are individualized components that engage individual implants. With two or more implants , the stability of the denture is greatly improved
The abutment/attachment system is a two component system, the abutment which is tighten to the implant in the bone and the male component that is embedded in the denture. When the denture is seated properly, the male component housing a plastic clip will engage the female component in the mouth.
The plastic clips are available in various retention rates and will need to be changed from time to time as they begin to get distorted. The abutment in the mouth will also need to be managed from time to time and replaced as they too also wear down over time and lose their retention.
Cross sectional view of the locator abutment complex. The male housing is embedded in the denture, the abutment engages the implant in the bone and the two engage one another to help stabilize the denture.
Advantages:
financially less costly
easier home hygiene maintenance
easily repairable
Disadvantages:
prosthesis has a small degree of movement during fuction
the plastic male components will require replacement often
the female metal abutment will require replacement (commonly every two years)
Retention Bar Attachment System
As an alternative to the locator attachment system the connective bar design is indicated when implants may be off axis and are not parallel. The reason for an implant being placed off axis would be attributed to a lack of bone volume at the target area and the surgeon would aim for the placement of the implant to maximize the amount of bone surrounding the titanium implant. The bar will connect all the implants together, acting as a whole unit and increasing the stability as a whole.
There exist different types of bar designs with various attachments for retention, below are several examples:
Advantages:
the implants are splinted together strengthening the implants as a whole unit
a bar can correct for angled/off axis implants
the bar design can increase the degree of retention
has less rocking compared to the locator attachment system
Disadvantages:
added cost in addition to the denture
additional space for the bar is required when planning and designing the denture
additional visits required to plan and design the bar
Implant Assisted Removable Partial Dentures
Traditional removable partial dentures rely on the natural remaining teeth for retention and support. Often times the teeth supporting the denture need to be physically modified to support the partial denture frame. During function the selected teeth that support the partial denture do bear a larger functional load and thus the forces on those teeth over time can have compromising effects.
The use of implants to assist in the retention and support can alleviate the forces acting on these teeth, increasing their longevity and foundational stability. In addition to this, the metal clasp that normally provide retention for the denture can also be eliminated therefore improving the esthetics. The attachment system customarily associated with removable partial dentures us the locator attachment system, but variations in design will be determined by the edentulous space.
Advantages:
unaesthetic clasp and unpleasant retention wires can be eliminated in the esthetic zone
implants share the occlusal force responsibility and reduces the forces acting on the existing teeth
Disadvantages:
added cost in addition to the removable partial
the attachment system will need ongoing maintenance/replacement of parts