Transcription
Michael J. Maginnis, D.D.S., M.S.Board Certified Specialist in RemovableProsthodontics7742 Office Park Blvd, Suite A-1, Baton Rouge, LA 70809(225) 201-1000The Implant OverdentureTo paraphrase the real estate industry: “Locator, Locator, Locator”.There’s nothing like them, and I’ve tried them all, from cast barswith Hader or Ackermann clips, ball overdenture abutment heads,Dalla Bonas and o-rings. Locators are simple, effective, and veryretentive.However, one important point needs to be wellunderstood: If you can’t make a good denture without implants, youshouldn’t be making a denture with implants.No implant will ever replace sound, prosthodontic principles. All dentures need toadequately cover the supporting tissues and have a functional centric occlusion at acomfortable vertical dimension of occlusion.With that being said, two osseointegrated implants placed inthe anterior maxilla or mandible in approximately theposition of the missing cuspids can be restored with Locatorabutments to provide the patient with excellent retention andstability.The Locator abutments are gold in color and arereferred to as the “female” portion of the system.The “males” are the colored nylon inserts that offerretention values of 1.5, 3, and 4.5 lbs. A metalhousing embedded in the denture base retains themales. The abutments are manufactured by ZestAnchors (www.zestanchors.com) for 50 differentimplant companies and their various implantdesigns. You should have no trouble finding aLocator to fit whatever implant you are attempting to restore. Abutment heads areavailable in tissue collar heights of 0mm to 6mm and the collar need only just clearthe gingival crest. The end result is a very low profile abutment (plus malecomponents) of 2.5 mm for non-hexed implants and 3.25mm for externally hexedimplants. This compares very favorably to the 4.5mm to 7mm range of othercurrently available implant abutments.
How many do you need? As far as I’m concerned, two are plenty. Beyond that, youget into broken fingernails. These attachments can be too retentive.To place abutments and seat and remove maleattachments, use the gold colored Female TriangularSeating Tool pictured at left along with the MaleSeating and Removal Tool.After seating andtightening the abutment, use a torque wrench set to 20N/cm or insert the shank of a straight handpiece burinto the hole in the side of the Triangular Seating Tooland turn an additional 45 degrees (1/8 to 1/4 turn).Direct or indirect, how do you want to attach the male housings to the denture?With the indirect method, you’ll need to transfer the abutment’s position to themaster cast using an impression post or impression coping and a very stiffimpression material. At the same time and with the same impression material thefinal impression for the denture base is made. Consistently achieving good resultsfor both procedures can be difficult to accomplish. For this reason, I would suggestconcentrating on making the best impression for the denture base and using thedirect method for attaching the males to the finished denture at the time of delivery.After the finished denture has been tried in and adjusted for a comfortable fit andgood function, cold-cure acrylic can be used to secure the male housings to thedenture base. Light-cured resins are difficult to fully cure beneath a denture andwhen fully cured, too brittle, thus allowing the male housings to break free. A fastsetting, cold-cure, pink repair resin is the ideal material of choice.The silver male housings come from the manufacturer with ablack processing male inserted within the housing. Theprocessing male is designed to provide a slight amount ofvertical travel to accommodate the compression of soft tissueunder the denture base. For any procedure that involvesresetting or replacing a male housing (i.e. reline/rebase), a black processing malemust be used in all Locator male housings in the denture .extra black males can beordered from the supplier.Along with the male housing, comes a white washer or“skirt” that prevents the cold-cure resin from entering thegingival crevice during the bonding procedure. Slip the ring
over the abutment head and snap the male into place. Thehousings are now ready to be attached to the denture. Toallow for this, room must be made within the denture base sothat the male housings do not contact any part of the denturewhen it is fully seated.Use GC Fit Checker to make certain that a sufficient amountof acrylic has been removed from the denture base. Nocontact between the denture base and the metal housingshould show in the white silicone paste.The amount of Fit Checker used to fill the hole will give an indication as to theamount of acrylic resin that will be needed to bond the malehousing to the denture base.Use a 701 straight handpiece bur to punch a vent hole in theexternal surface of the denture base toallow for escape of excess acrylic. Wetthe base acrylic with monomer andinject enough pink cold-cure repair resin to just under fillthe hole. Seat the denture over the dry male housings and guide the patient intocentric occlusion.Once the acrylic has set, and the denture has been removedfrom the mouth, use the Male Seating and Removal Tool toremove the black processing male from its housing.Remove any excess acrylic from theintaglio surface of the denture and from the exterior of thevent hole.Small bulges of acrylic may need to be added to the exteriorsurface of the denture facial to the location of the malehousings to assist the patient in removal of the prosthesis.What color male is placed into the metalhousing depends on how much retention you need. I always startwith blue, the lightest, and it generally proves to be adequate. If you have anunusually long denture anteriorly-posteriorly, additional retention may be neededin the form of a pink or clear male. The same is true if the abutments are closertogether than the cuspid position.Excessively angled abutments may require the use of extendedrange males. These are nylon inserts in which the centernipple of nylon has been removed. The green male has 3 to 4 lbs. of retention, theorange male 2 lbs., the red male has 1.5 lbs., and the gray male 1 lb.
Use the Male Seating and Removal Tool to snap the nylon insertsinto the male housing and deliver the denture. These attachmentshave proven to be so dependable and low-maintenance that Iroutinely replace o-ring abutments with Locator abutments in oneshort visit as shown below:The Locator abutments can also be used in a variety of partial dentureconfigurations, often negating the need for precision attachments.Instead of having to restore the terminal abutments with precision attachmentcrowns, Locator abutments placed to their distal will suffice for the necessaryretention of a claspless partial denture:As pictured below, Locator abutments can provide increased retention and anteriorsupport in the difficult to restore Class IV partial denture.The possibilities are infinite and only limited by your imagination and the patient’sbone.Maginnis the Dentist
The Implant Overdenture . re without implants, you . To paraphrase the real estate industry: “Locator, Locator, Locator”. There’s nothing like them, and I’ve tried them all, from cast bars with Hader or Ackermann clips, ball overdenture abutment heads, Dalla Bonas and o-r
