Cementing Dental Implant Bridge

There is a difference between cementation concepts of bridges and crowns on natural and implant abutments.The main difference is the spacing required between natural abutments and the metallic or ceramic materials used for implant abutments. Natural teeth with or without posts and cores have a greater "give". Genarally the space varies in reality from about 100 microns down to to about 30 microns. Any less than this would compromise the particle size of the luting agents. However it seems that metal- metal or metal-ceramic requires greter spacing because the abutments do not compress the same way as natural teeth. Subsequently implant bridges and crowns need this greater space to allow the luting agents a greater space to do their task in contributing to retention. Because metal-metal or metal-ceramic interfaces exhibit less flexure under function the fit must not be too intimate ie more passivity required to allow for complete seating with the luting agent of choice. It is also worthy to note that cementation of implant bridges places a greater dependency on the luting agent for resisting displacement of the restoration because of the lack of flexibility of the system to absorb forces in function. These recommendations are more consistently in line with non-biological industrial and engineering applications, threfore not as intuitive as our experieces in traditional dental applications. In my experience any bridges of more than 3-4 units ie 2-3 abutments, I usually design a combination of a screw retained element(s)along with cement retained units. This removes the variability of retention that is less than adequate or completly irretrievable. In summary my protocols generate greater passivity of fit on cemented units to allow the luting agent of chioce to contibute its retentive properties in non flex situations and also to allow for complete seating and in larger bridges of greater than 2-3 abutments to design in the comination of screw elements to insure retention and to have the option of predictable retrievability for whatever reasons future needs may present. In these cases nothing stronger than vaseline modified TEMP BOND or similar provisionl cement is required. Also to note is that concerns of the possibility of washout does not have the same implications as it does in tooth supported bridges and crowns. I hope that this information will be somewhat helpful in your dilemma. Regards, Dr. Michael Moscovitch

Well said!

Not sure if this is a forum for non-pro questions, but am hoping for some assistance. I had a dental/maxillary injury, and am in the final stages of restoration. My dentist has advised the use of permanent cement for my implant bridge, but wonder if I should be concerned about retrievability. I have implant abutments at 9, 10, and 12, with an ovate pontic at 11 (all one piece). My temporary includes these four teeth in one piece that fits over the three posts (because the bite angles and abutment placements aren't great, and the tempory bridge fits snug at this point with no cement). My permanent bridge will be one piece as well (four teeth), and is expensive as you can imagine. I have read the advantages and disadvantages of screw retention vs. temporary cement vs. permanent cement, and would be greatful for any suggestions that might help me talk more intelligently with my dentist about this issue. Thank you for any ideas you might have. Brief clinical history: 51 year old professional male in excellent health. Full evulsions of 9, 10, and 12, intrusion fracture of 11 and subsequent extraction of 11. Block bone graft above 9 and 10, gingival grafting around 9 and 10, implants placed at 9, 10, and 12 in 10/06, and abuttments and temporary bridge placed in June.