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Sealing the Screw Access Hole on Screw-Retained Implant Restorations
By Greggory Kinzer, D.D.S., M.S.D.
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When seating a screw-retained implant restoration there are many techniques and materials that can be used to seal the screw access hole. The most common material to use is direct composite, although there are some clinicians that have advocated pressing or milling a separate ceramic plug to cement over opening.
Prior to seating the restoration, it is advisable to treat the ceramic around the screw access hole outside the mouth to get it ready for bonding. Evaluate the ceramic interface carefully.
If the ceramic surrounding the screw hole looks like it is glazed, it is advisable to gently roughen the surface either with a diamond bur using slow speed or light air abrasion. Once prepared, the area can now be etched with HFl acid. The specific etching time is material dependent. If you are unsure about the material and/or etching time, please consult with your technician. After rinsing the etchant, I will place the restoration in distilled water and set it in the ultrasonic for five minutes.
I will always clean the abutment screw prior to seating the restoration. Although some implant systems use a “lab” screw and send a “new” screw for seating the restoration, most of the time the technician is using and handling the same screw we are going to put in the mouth.
Often the screw gets a build-up of debris on the threads that can affect the fit if it isn’t cleaned. Using an alcohol soaked 2x2 I will hold the screw threads tightly while turning it with the driver. It’s amazing how much debris you will often see removed from between the threads.
Once the restoration is seated and the screw properly torqued, it is advisable to place something over the screw itself. I generally use cotton pellets, but many materials will work (i.e. Teflon tape, Fermit and gutta-percha). Essentially, you just don’t want to have the composite directly on top of the screw head. After treating with the ceramic with silane (if appropriate) and placing/curing the adhesive, composite can be placed.
The type of composite used depends on the crown material and the depth of the access hole. If the crown is metal ceramic, I typically place an opaque composite up to the top of the metal to help mask the metal, followed by body/enamel materials. If I don’t have to mask any metal, I may still use an opaque composite; however, this usually depends on the depth access hole.
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