Screw-retained restorations.
Screw retention buys retrievability: the restoration can be removed and replaced without destroying it. For anything likely to need maintenance over its life, that is the governing advantage.
What retrievability is worth
Implant restorations need maintenance more often than tooth-borne ones. Screws loosen, components wear, peri-implant tissue needs managing, ceramic chips, and prostheses need modifying as the rest of the mouth changes.
A screw-retained restoration is removed, dealt with and replaced. A cemented one is cut off and remade.
That difference compounds with the number of units involved, which is why screw retention is generally preferred on multi-unit and full-arch work.
Access channel position decides feasibility
The channel emerges wherever the implant axis points. In an anterior implant angled facially, that is the incisal edge or the facial surface — aesthetically unacceptable and structurally weakening. In a posterior tooth, a channel through a functional cusp tip removes material where load concentrates.
Assess the angulation before deciding on retention. It is the single question that determines whether screw retention is available at all.
Where it is unfavourable, an angulated screw channel corrects a useful range — typically up to around twenty-five degrees — and has made screw retention viable in many cases that previously required cement.
Angulated channels need the right driver
These systems use a system-specific driver, and it is not unusual for a practice to receive a restoration it cannot seat because the driver was not on hand.
If that route is chosen, confirm the driver is available at the practice before the case is made. It is a small check that prevents a wasted appointment.
Preload and torque
Tightening the screw stretches it slightly, and that elastic stretch is what clamps the joint. Preload is lost through settling as microscopic surface irregularities flatten under initial load, which is why retorquing after a short interval is common practice.
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.
Use a calibrated driver and the manufacturer's stated torque. A screw that loosens more than once is reporting a mechanical problem rather than needing a third tightening.
Sealing the access channel
The channel is filled after torquing — commonly PTFE tape or a similar material over the screw head, then composite over that. The tape allows the composite to be removed cleanly if the restoration needs retrieving.
Filling the channel with composite directly onto the screw head makes retrieval considerably harder and partially defeats the reason for choosing screw retention.
Record the channel position in the notes. Finding it later under composite is easier when someone wrote down where it was.
Multi-unit and full-arch considerations
The advantage of retrievability grows with the number of units. A full-arch prosthesis will need maintenance across its life — component replacement, repair, hygiene access, adaptation as the rest of the mouth changes — and a cemented one cannot be removed to do any of it.
Splinted screw-retained units also have to seat passively along a common path, which is what non-engaging components are for.
For anything beyond a single unit, screw retention should be the default and cement retention the exception with a stated reason.
What to send
System, product line, platform and connection. Confirmation that screw retention is intended, and whether an angulated channel is needed. The antagonist and any concern about where the channel will emerge.
If you are unsure whether the angulation permits screw retention, say so and let the laboratory assess before components are ordered.
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