Screw-retained implant restorations have become the default choice for many labs — fewer cement complications, retrievable prosthetics, and predictable torque control. But the lab workflow has more steps than most shortcuts suggest. This guide walks through the full process from model transfer to final screw tightening, with practical notes on analog selection, screw channel planning, and torque specs.
What You Need Before Starting
Item — Role in Workflow
Transfer coping / impression post — Captures intraoral implant position
Implant analog — Replicates implant geometry inside the working model
Abutment (straight or angled) — Connects model position to final prosthesis
Retaining screw (Rosen / ASC / standard) — Locks prosthesis to abutment or multi-unit
Torque wrench (10–35 Ncm) — Delivers controlled preload to screw threads
Lab-use only. All components on this list are non-sterile and not for intraoral placement. MOQ 50 pcs per batch.
Screw-Retained Implant Model Setup
Step 1 — Model Transfer with Implant Analog
After the clinician sends the impression, seat the transfer coping and place the implant analog into the coping inside the working cast. Confirm three things:
1.Hex orientation — match the anti-rotate index to the platform geometry. Reversed hex = misfit crown.
2.Seating depth — analog shoulder should sit flush against the model surface. Gaps cause vertical dimension errors.
3.Platform compatibility — confirm the analog matches the implant system in use (internal hex, conical connection, tri-channel, etc.)
Common mistakes: forcing the analog without checking hex alignment, using worn transfer copings that no longer lock, and mixing analog platforms between brands. A precision-milled analog with ±0.01 mm tolerance eliminates most seating issues. Order in batches of 50 pcs to keep consistent platform geometry across all models.
This analog ensures accurate screw-retained implant model work.
Step 2 — CAD Design and Screw Access Planning
Once the model is scanned or poured, open your CAD software (Exocad, 3Shape, DentalCAD). The critical decision here is the screw access channel angle.
Straight channel — works when the implant long axis aligns with the restoration access. Simpler milling, lower cost.
Angled screw channel (ASC) — required when anterior inclination, limited interocclusal space, or esthetic constraints block straight access. Typical angles: 17°, 25°, 30°.
In Exocad, set the channel path before designing the coping geometry. If you design the crown first and back-fit the channel, you risk thin walls at the access hole. Plan the channel, then build the anatomy around it.
For ASC cases, use a compatible angled screw channel component designed for multi-unit abutment access. Available in batches of 50 pcs.
Screw-Retained Implant Abutment Selection
Choose between:
1.Straight abutment — Implant axis is favorable; standard crown height
2.Angled abutment (15°–25°) — Correcting up to 25° divergence from ideal path
3.Custom milled Ti abutment — Complex emergence profile, soft tissue support
CNC mill from medical-grade titanium alloy (Ti-6Al-4V). Tolerance target: ±0.01 mm. For labs without in-house milling, outsource to a CNC service with Exocad-ready output (STL / PLY / OBJ, 48 h turnaround). Minimum order 50 pcs per design.
Screw-Retained Implant Screw & Torque
Step 1 — Screw Selection and Torque
For any screw-retained implant case, select Rosen or ASC screws.The retaining screw is the only mechanical link holding the prosthesis to the implant. Selection depends on the connection type:
Conical connection (tapered interface) — use a Rosen screw with conical head. The taper mates with the internal conical seat of the abutment, providing frictional retention plus screw preload.
Multi-unit / ASC platform — use an angled screw channel screw designed for the specific angle path.
Internal hex / external hex — verify thread pitch (0.5 mm vs 0.8 mm) before ordering.
Lab assembly torque reference:
Connection Type — Torque Range
Conical (Rosen-type) — 30–38 Ncm
Multi-unit abutment — 30–38 Ncm
Straight abutment screw — 40-58 Ncm
All screws supplied in batches of 50 pcs. Mixed-platform kits available on request.
Step 2 — Try-in and Final Delivery
This screw-retained implant workflow ensures passive fit.Before the prosthesis leaves the lab:
1.Seat the screw-retained crown or bridge on the model with the analog in place. Confirm passive fit — no rocking, no gaps at margin.
2.Check screw access clearance with the final screw. The screw head should sit below the occlusal surface.
3.Verify screw engagement by hand-threading first. If resistance occurs before full seating, stop — do not force.
At delivery, the clinician tightens to the manufacturer’s specified torque. Label each case with the screw type used and the torque applied during try-in.
FAQ
Q1.What is the difference between an implant analog and an abutment in the lab workflow?
A1：The analog stays in the working model to replicate implant geometry. The abutment is the clinical connector that goes into the patient’s mouth. The analog enables accurate model design; the abutment enables prosthesis retention. Both are required in a screw-retained workflow.
Q2：What is the minimum order quantity for implant analogs and screws?
A2：MOQ is 50 pcs per batch. This ensures CNC milling efficiency and consistent platform geometry across your lab’s working models. Mixed-platform kits available on request.
Q3：What torque should I use for a Rosen screw during lab try-in?
A3：Lab verification torque for conical connection screws typically ranges 25–35 Ncm. This is for try-in seating only — final torque is the clinician’s responsibility per the implant system protocol.
Q4：Do you provide Exocad design files with screw-retained cases?
A4：Yes. STL, PLY, and OBJ formats are available with our CNC milling service. Files are Exocad-compatible and delivered within 48 hours for standard cases. MOQ 50 pcs per design.
Q5：Are these screws and analogs sterile?
A5：No. All parts supplied are non-sterile, lab-use only. Not intended for intraoral placement or human implantation.
Learn more about implant connections via Straumann resources.