Treatment plan

Overdentures can be divided in to two types. Type "A" is abutment retained, where the abutment and attachment (Locator or ball type) are machined as one piece and screwed directly in to the implant. The ball type abutment can often be utilized either with a o-ring type set up to allow some resiliency of the denture or fairly rigid with a metal housing and replaceable nylon liners. Many implant companies offer one piece implants where the implant and attachment are a single unit. A minimum of two implants should be inserted quite parallel to each other in the symphesis for the ball type set up to work successfully. Locator attachments are a little more forgiving, allowing for 20 degree divergence, Locators are very rigid compared to the o-ring attachment.
The type "B"  overdenture consists of a bar screwed on to the implants and the denture is retained with attachments to the bar. The bar can be designed as a hader bar, dolder bar or various attachments (Locator, ball type, Bredent, ERA, Swinglock, Swisslock) incorporated on to the bar. Two implants need to be placed at a minimum, although three or more implants should be placed. Just in case one implant fails, the bar is not a total loss and can often be modified to suit the new situation. Overdenture bars can be manufactured through a CAD CAM system in titanium or waxed up and cast at the laboratory. A bar type overdenture design affords better stress distribution to the implants versus a abutment borne overdenture

First visit

Assess medical history and perform thorough medical and oral exam to discover contra indications like diabetes, Bisphosphonates (Fosamax) regimen, severe parafunction or a smoking habit of the patient will help in identifying good treatment candidates. Discuss treatment goal with patient. Take full arch impression of both arches. Send impression to the laboratory and request a base plate and wax rim with uniform diameter metal beads incorporated in the base plate for the arch to be treated. Make appointment for next visit.

Second visit

Establish CR with base plate and wax rim and take pano with base plate and wax rim in patient mouth. Discuss financial arrangements with the patient. Send panograph to oral surgeon and a request to send you a surgical report once the implants are placed, indicating the brand of implant, number and diameter. Send CR record to the laboratory to have models mounted. Arrange initial appoint for patient with surgeon while the patient is in your office.
Post visit work up: measure inter arch space available on mounted model and determine if a bar retained or abutment retained denture can be done

Third visit

Pre patient appointment work up: Read surgical report to determine what brand of implant, number of implants and diameter was placed during surgery. Decide if a direct impression (open tray) or indirect impression (closed tray) should be taken. Order appropriate impression copings and have torque driver or hand screw driver on hand.
Remove healing abutments. Take full arch fixture level impression and full arch opposing impression. Screw healing abutments back on to implants. Send to lab to pour models and fabricate new base plate and wax rim. Have laboratory also fabricate verification jig with metal temp abutments.

Fourth visit

Remove healing abutments. Screw in verification jig with only one screw through one terminal abutment. Take x-ray to verify proper seating of the seating jig on all implants. In case the seating jig does not seat, cut seating jig in to segments and fasten each abutment with a screw. Use GC pattern resin or light cure seating jig back together. Screw healing abutments back on to implants. Establish CR and send wax rim, base plate, models and seating jig back to lab to mount models, set up teeth in wax, reposition analogs on model and manufacture bar.

Fifth visit

Remove healing abutments. Try in teeth in wax and bar. To check proper fit of the bar, screw down bar with only one screw through a terminal abutment. Take x-ray to verify proper seating of all abutments on to the implants with only one screw. Take new bite over wax try in and have lab process denture over bar. Screw healing abutments back on to implants.

Sixth visit

Remove healing abutments and hand tighten bar with only one screw. Take x-ray to verify seating of all abutments. Use torque wrench to tighten screws to manufacturers recommended torque. Seat denture over bar and verify proper seating and adjust bite as needed.