Screwmentation Implant Case- Improved By Thomas W. Mitchell, DDS, FAGD

Introduction: 

Many of us love the screwmentation procedure for implant supported crowns due to the ease of adjustment and the retrievablility. There can be a problem with the procedure that I've previously shown. Because implant abutments are round and we must provide room for cement, most crowns will rotate ever so slightly on the abutment. This is especially true for zirconia crowns. If you bond the crown to the abutment outside the mouth, as I've previously shown, it's possible to get the crown slightly rotated on the abutment, and the bonded unit will not fit back on the implant. Ask me how I know! My good friend Alan Wolfson (AlanW) told me about this last year, but since I have so much crap after my name I didn't listen to him. Now I know so I'm telling you. After attaching the abutment to the implant, torqueing it down almost to final force, and adjusting the crown's proximal and occlusal contacts, bond or cement the crown to the abutment in the mouth. Allow plenty of time for the cement to cure as, unlike teeth, abutments are cold so the cements set slower. Then remove the bonded unit, clean off the excess, and proceed to final torque and filling the screw access.

Thomas W. Mitchell, DDS, FAGD
Screwmentation allows us to have a screw retained implant supported crown for ease of retrievability, and to adjust the contacts/occlusion with the abutment on the implant, vs having the crown already bonded to the abutment and needing to screw/unscrew the unit multiple times during adjusting procedures.
Thomas W. Mitchell, DDS, FAGD
#14 Astra EV implant torqued to 20 ncm's. Final torque will be 25 ncm's.
Thomas W. Mitchell, DDS, FAGD
After normal crown contact/occlusion adjustment procedures, fill the screw access with Teflon tape
Thomas W. Mitchell, DDS, FAGD
Then place a ring of cement on the crown and seat it on the abutment. Allow plenty of time for the cement to cure since the abutment is colder than a tooth, which increases the setting time. This is WO Anchor by Apex Dental Materials. This is a dual cure resin cement. I've had problems using Rely X Luting with this procedure as it won't set due to the coldness of the abutment. I allow 10 minutes for the cement to set.
Thomas W. Mitchell, DDS, FAGD
Then remove the unit and clean off the excess cement.
Thomas W. Mitchell, DDS, FAGD
This is the other side. Excess cement, if not removed, will cause peri-implantitis.
Thomas W. Mitchell, DDS, FAGD
Nice and clean and ready to be torqued back on to 25 ncm's.
Thomas W. Mitchell, DDS, FAGD
Then place Teflon tape to protect the screw head.
Thomas W. Mitchell, DDS, FAGD
I mask out the darkness of the screw access hole first with white opaque flowable. This is WO Titan flowable, bonded to the crown using Interface and Surpass 2 (primer) from Apex Dental Materials.
Thomas W. Mitchell, DDS, FAGD
Then composite to complete the screw access filling. This is Exquisite Restoration shade A2. My 87 yo patient insists that her restoration be a bleach shade. This is OM2.
Thomas W. Mitchell, DDS, FAGD
One other problem can occur. This is another case from the same day. All these implants now have a conical connection/Morse Taper for the abutments. These abutments are on the implant, even partially torqued, long enough for some "cold welding" to occur. The only way I could get this one off the implant was with the famous "Richwell Crown Remover".

Conclusion: 

So an improved procedure, at least for me. Thanks to Alan for the help. Bonding it clinically prevents getting the crown slightly out of alignment on the implant. If that happens then you have to send it back to the lab and they put it in a low temp oven to break down the cement. Then you get to start over. Hope this helps.

Case by: 

Thomas W. Mitchell, DDS, FAGD