Cement vs Screw Retention.
This is the most consequential design decision in implant restorative work, and it is frequently made by habit rather than by case.
The core trade-off
Screw retention gives retrievability. The restoration can be removed and replaced without destroying it, which matters for maintenance, for managing peri-implant problems, for repairing porcelain, and for anything that goes wrong over a restoration's life.
Cement retention gives an uninterrupted occlusal surface, tolerates implant angulation that would place a screw channel unfavourably, and can compensate for a degree of positional discrepancy in multi-unit work because the cement layer absorbs it.
Everything else in this decision is elaboration on those two positions.
Residual cement is a genuine clinical problem
Excess cement extruded below the tissue at seating is very difficult to detect and very difficult to remove. It is not radiopaque in all formulations, it is not visible, and it does not announce itself.
The association between residual cement and peri-implant inflammation is well established, and cases have been reported where removing retained cement resolved peri-implantitis that had been treated unsuccessfully by other means.
The risk scales directly with margin depth. A cement margin at or above the tissue can be cleaned reliably. A margin two or three millimetres subgingival cannot, whatever technique is used. This single fact drives most of the contemporary preference for screw retention or for custom abutments with shallow margins.
When screw retention is difficult
The access channel has to emerge somewhere. In an anterior implant angled facially, that somewhere is the incisal edge or the facial surface, which is aesthetically unacceptable and structurally weakening. In a posterior tooth, a channel through a functional cusp tip removes material where load concentrates.
Angulated screw channel systems address a useful range of this, typically correcting up to around twenty-five degrees, and they have made screw retention viable in many cases that would previously have required cement. They require a system-specific driver, which needs to be on hand at delivery.
Screw loosening is the other consideration. It is largely a function of preload, of connection design and of whether the restoration is loaded off-axis — and it is manageable and correctable, which is precisely the advantage retrievability confers.
The hybrid that resolves most cases
A screw-retained abutment is placed and torqued to the implant, and the crown is then cemented onto that abutment. Because the abutment can be designed with its margin at or slightly above the tissue, cement excess is visible and removable.
The crown can also be cemented extraorally onto a replica of the abutment, with excess cleaned and the assembly then delivered as a single screw-retained unit. That approach removes residual cement risk almost entirely while keeping an uninterrupted occlusal surface.
The cost is an additional component and additional laboratory work, and the requirement for sufficient interocclusal space to accommodate both abutment and crown. Where space allows, it is frequently the best answer available.
Cement choice when cementing
If a restoration is being cemented, the cement should be one that can be found and removed. Radiopaque formulations allow retained excess to be identified radiographically. Cements that clean up cleanly at the rubbery stage are easier to manage than those that set hard quickly.
Definitive resin cements maximize retention and minimize retrievability, which on an implant is often the wrong priority. Many clinicians deliberately use a weaker cement so the restoration can be removed if needed, accepting the possibility of decementation as the lesser problem.
Whichever is used, seat with minimal cement in the restoration, vent the excess, and check radiographically afterwards where the margin is subgingival.
Screw mechanics, briefly
Tightening an abutment screw stretches it slightly, and that elastic stretch — preload — is what holds the joint together. The screw is effectively a spring clamping the components against each other.
Preload is lost through settling, where microscopic surface irregularities flatten under initial load, and through any force that separates the joint. This is why retorquing after a short interval is common practice: the first tightening settles the interface, and the second restores the preload that settling consumed.
It is also why torque values matter and why a calibrated driver is worth having. Under-torquing leaves insufficient preload and the screw loosens. Over-torquing can take the screw past its elastic limit, at which point it no longer springs back and may fracture — usually at the least convenient moment.
What happens when a screw fractures
A fractured abutment screw is retrievable in most cases, with the right instruments and patience, but it is an unwelcome appointment and occasionally it is not retrievable at all.
The circumstances that produce it are predictable: repeated loosening that was retightened rather than investigated, off-axis loading from a cantilever or an offset occlusal table, an ill-fitting component that never seated properly, or a non-passive multi-unit framework.
A screw that loosens more than once is reporting a mechanical problem. Retightening it a third time without asking why treats the symptom, and the fracture that follows is foreseeable.
A decision framework
Start with retrievability: does this case have a meaningful likelihood of needing maintenance, revision or repair? Multi-unit work, patients with peri-implant risk factors, and anything provisional all say yes.
Then check the angulation: would a screw channel emerge acceptably, with or without an angulated system? Then check the space: is there room for a screw-retained abutment plus crown if the hybrid approach is preferred? Then check the margin depth a cemented option would require.
In most cases that sequence resolves it. Where it does not, the case is worth a conversation before components are ordered rather than after.
In short
- Screw retention buys retrievability; cement buys access and angulation tolerance
- Residual subgingival cement is strongly associated with peri-implant inflammation
- Cement margin depth is the variable that matters most — keep it shallow
- Angulated screw channels correct a useful range but need a specific driver
- Screw-retained abutment plus extraorally cemented crown resolves most cases
More on implant
Discuss a case
Where a case sits between options, a short conversation before preparation is usually quicker than resolving it afterwards.