Introduction to Overdentures
Anchoring an overlay denture to retained roots enhances denture stability and provides numerous functional advantages. Due to compromised periodontal support, resilient designs, such as the Locator®, are more commonly used. Bars splint two or more natural abutments or implants. Attachment function can be rigid or resilient, depending on the bar chosen and on the case design. Because of this they are most often used when bone support is very limited. The following are general guidelines that may be used to help you to decide on which attachment might be best for a particular situation. They are based on our 30 years of experience with dental attachments, but the final choice must be based on the particular dentist's philosophy, education, and experience. In most cases teeth to retain overdentures are reduced, approximately to the height of the gingival tissue. The endodontic procedures are completed and any periodontal problems are resolved before the prosthetics begin. If the bone loss is 50% or greater, then the prognosis for these roots is relatively poor, extraction of these teeth and placing implants may be the best choice. If the bone loss is in the 50% or less category, Locator®, radicular studs, or bars can be used. Your choice will depend on your philosophy. For many years the conventional wisdom was, splinting abutments with bars made them stronger. Studies done at UCLA and other places have contradictated this opinion. The more recent body of information would tend to indicate that there is less force to the roots or implants from a resilient free standing attachment than when they are connected with a bar.

How to Select a Partial Denture Attachment:

The choice in partial denture attachments is between Non-resilient and Resilient. Non-resilient (rigid) attachments are highly stable connectors with very slight movement in function. Some may be used for segmenting fixed partial dentures to simplify future case conversion to a removable restoration. In distal extension partial denture cases, occlusal forces are directed relatively evenly to both the abutment teeth and the edentulous ridge. Therefore, rigid attachments are kinder to the edentulous ridge than are resilient attachments. When abutment teeth are stable, rigid attachments are often the connectors of choice.

Resilient attachments are stress directing attachments for Kennedy Class I and II cases which place occlusal load on both abutment teeth and the edentulous ridge. The ridge is more heavily loaded than when using rigid attachments, while the abutment teeth are more lightly loaded.

 The following are general guidelines that may be used to help you to decide on which attachment might be best for a particular situation. They are based on 30 years of experience we have with dental attachments, but the final choice must be based on the particular dentist's philosophy, education, and experience. Based on your answers to the following question you will choose either Non-Resilient Attachments or Resilient Attachments.

1.  Bone Support Around the Abutments - If the bone support is good (0-20% bone loss), or if abutments can be made strong by splinting, non-resilient attachments are the connectors of choice. If the bone support is fair (20%-40% bone loss), the choice will most often be resilient attachments. If the bone loss is 40% or greater, more than likely the abutments need to be reduced to the height of the gingival tissue and the roots used to retain an overdenture.
2. The Condition of The Ridge - If the edentulous ridge has little loss of bone, either resilient or non-resilient attachments could be used. But, if the ridge is significantly resorbed, non-resilient attachments would most likely be indicated.
3. Is the opposing arch non-resilient (rigid) or resilient? Two resilient prostheses should generally not oppose each other, as two mobile occlusal planes will impair chewing efficiency.