Overdentures.
An overdenture sits over retained roots or implants rather than on bare ridge. It preserves bone, improves retention and stability, and asks for more vertical space than a conventional denture. Tick Over Denture on the Rx.
Why retain roots
Alveolar bone resorbs when teeth are lost, and continues resorbing for as long as the patient is edentulous. Retained roots preserve the bone around them, which maintains ridge form and gives the prosthesis something to sit against.
Retained roots also preserve periodontal proprioception, which improves the patient's control of the prosthesis and their sense of bite force in a way a fully mucosa-borne denture does not.
Even roots retained without attachments — simply decoronated, sealed and covered — deliver much of the bone preservation benefit.
Attachments
Where retention is wanted, attachments can be placed in the retained roots or on implants: studs, magnets, bars or locator-style components depending on the case.
Each has consequences for maintenance. Retentive inserts wear and need replacing periodically, which the patient should be told about at the outset rather than discovering at a review appointment.
Bars splint multiple abutments and distribute load, at the cost of more vertical space and more demanding hygiene access beneath.
Space is the constraint
This is the recurring problem with overdentures. The prosthesis has to accommodate the attachment, the housing that engages it, adequate acrylic thickness over both, and the denture teeth — all within the interocclusal space available.
Where space is inadequate, the base fractures around the attachment housing, or the teeth have to be set too far from ideal position, or the prosthesis becomes unacceptably bulky.
Measure it at the planning stage. Once roots are prepared or implants placed, the remedies are limited.
Records
As for a complete denture — custom tray, border-moulded definitive impression, bite block for jaw relation, set-up try-in — with the attachment positions captured accurately.
For implant overdentures, the component detail matters as it does in any implant case: system, product line, platform and connection. None of it can be inferred from an impression.
Maintenance expectations
Overdentures need more maintenance than conventional dentures, not less. Retentive components wear, attachments loosen, and the tissue and bone beneath continue to change.
Retained roots need caries prevention — they are frequently in patients with a caries history, covered by a prosthesis, and root caries under an overdenture is a common reason for eventual failure. Fluoride application and review matter.
Say all of this before treatment. It is part of the plan rather than an unwelcome discovery later.
Preparing retained roots
Roots retained for an overdenture are decoronated to a low, rounded, dome shape and sealed — usually endodontically treated and restored with a well-adapted restoration at the canal orifice.
The contour matters. A root left too tall interferes with the prosthesis and concentrates load; one with sharp margins irritates the tissue and complicates the fit surface. A low dome distributes load and is easier to keep clean.
Where attachments are being placed, the root has to be prepared to accept them and the preparation depth planned so the attachment sits within the available space rather than proud of it.
Implant overdentures specifically
Two implants in the mandibular canine regions supporting an overdenture is among the best-evidenced treatments in removable prosthodontics, and the improvement in retention and patient satisfaction over a conventional lower denture is substantial.
The prosthesis remains largely tissue-supported in that configuration — the implants provide retention rather than support — so the definitive impression still has to capture the denture-bearing area properly.
Component detail is essential on the prescription: system, product line, platform, connection and the attachment being used.
What to put on the prescription
Tick Over Denture and the stage under Procedure. Mark the retained roots or implants on the design chart and state the attachment system precisely.
Give the teeth shade and mould, and note the interocclusal space available if it is limited. That single figure changes what can be made.
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Digital scans and conventional impressions are both accepted. Cases move by UPS and Purolator, and Fairmont works with practices throughout British Columbia and across Canada.