Implant Restorations: Cemented vs. Screw-Retained
Most of us are familiar with the Pro’s and Con’s of cementing restorations on dental implants versus retaining them with screw fixation. Cemented restorations are technically easier and within the comfort zone of all dentist’s, while screw-retained restorations are retrievable. At face value, it appeared that all things being equal, these retention options were, well, equal. However, a few years ago, clinical research showed that platform switching, i.e. placing an abutment on the implant in which the neck of the abutment is narrower than the platform of the implant, allowed for a better soft tissue seal around the abutment and was more resistant to food and bacteria being able to breach that seal and reach the bone level. While this is still considered to be true, we are seeing many dental implants beginning to show peri-implantitis years after the fixture was placed.
What might account for this? Well, one thought is that even a small amount of dental cement (in cemented restorations) could migrate apical to the crown into the “undercut” area of the platform switching abutment and be beyond the dentist’s ability to access it to clean it out. Conversely, the possibility of food debris getting into this same location could cause the same problems over time. When this happens, an implant requires guided bone regenerative procedures, which are not always predictable, or in many cases the implant must be removed,
With this in mind, the pendulum is starting to shift towards screw-retention. This allows a dentist to remove a crown periodically to evaluate tissue and patient hygiene and also allows for a surgeon to perform a more predictable guided regenerative procedure if needed. Additionally, if an implant crown becomes damaged, it can easily be removed without risking damage to the abutment and a new crown fabricated.
Time and experience are still our teachers when it comes to the practice of dentistry!