UCLA Type Implants: Crowns Have Less of a Tendency to Loosen?

Dr. E. asks:
The first implants I learned how to restore were the UCLA type implants where the crown was screwed directly into the implant fixture. The screw used for this was I think bigger and wider than the screw used to torque down an abutment. I have not used them in a while. I switched to using an abutment and crown configuration where I torque down the abutment and cement the crown. I have had a few abutment screws loosen up. I do not remember having this problem when I used the UCLA type crown. Is this the case – are the screws for the UCLA type crowns bigger and wider than the screws used to torque down abutments? Do UCLA type crowns have less of a tendency to loosen?

2 Responses to UCLA Type Implants: Crowns Have Less of a Tendency to Loosen?

1. Carlos Boudet, DDS says:

   April 1, 2010 at 8:28 pm

   Your question is similar to one posted recently.
   The problem of screw loosening was seen more commonly in years past when external hex connections were widely used.
   With the advent of a great number of implant systems that use an internal connection, the propensity for screw loosening has diminished tremendously.
   If you still have problems with screw loosening in your cement retained restorations, you may have to look at several things:
   Your implant system (internal vs external connection)
   Your occlusion (lateral forces, no posterior support, etc…)
   your torquing parameters
   I would be interested to know the system you use.
   I would dare to say that the great majority of dentists restoring implants use cement retained crowns rather than screw retained crowns for their day to day typical cases.
2. keith goldstein says:

   July 24, 2010 at 1:22 am

   it could also be the screw that was used
   was this a gold screw
   did the screw you received with the other abutments a titanium one
   this can matter
   also if they sent you a lab screw that is not designed as a permanent screw that can also be a reason