All-on-4: Provisional Bridge or Immediate Definitive? Strategy and Timeline

All-on-4 is a multi-stage protocol — not because the lab requires it, but because tissue and bone need time. Below, we describe the logic of the timeline from the perspective of a laboratory that fabricates both provisional and definitive bridges.

Why a Provisional Bridge?

A provisional bridge in All-on-4 serves three functions simultaneously: it protects implants from occlusal forces, shapes the emergence profile for the final restoration, and allows the patient to return to daily function.

Without a provisional phase, you risk an unstable emergence profile, an unknown occlusal reference point, and final aesthetics that cannot be predicted at the planning stage.

All-on-4 Timeline

Week 0 — Surgery

Placement of 4 implants (two straight, two posterior angled at 30–45°). Within 24–48 hours — placement of a provisional PMMA bridge.

Weeks 1–12 — Remodeling and Integration

The implant achieves secondary stability (bone remodeling). Soft tissue forms around the provisional bridge. During this time, occlusal and aesthetic corrections are possible.

Week 10–12 — Verification

Assessment of integration (clinically and radiographically), emergence profile, and provisional occlusion. If results are satisfactory — planning of the final restoration.

Week 12–16 — Final Restoration

Impression or scan taken for the final restoration. In the laboratory: monolithic zirconia or metal-ceramic. Turnaround time at deltalabs.: 3–5 business days from scan receipt.

Comparison: Provisional vs. Definitive Bridge

Feature	Provisional (PMMA)	Definitive (Zirconia/Metal)
Material	PMMA (acrylic)	Monolithic zirconia or metal-ceramic
Fabrication Time	1–3 days	3–5 business days
Occlusal Adjustments	Easy (grinding)	Limited
Strength	Lower	High (zirconia: 1000+ MPa)
Esthetics	Functional	Definitive
Material Cost	Low	Higher
Purpose	Tissue shaping and occlusion verification	Final rehabilitation

When Can the Transition to the Definitive Restoration Be Accelerated?

For implants with high primary stability (ISQ ≥70) and straightforward occlusal cases, the definitive restoration may be possible earlier than 12 weeks. However, the standard for complex cases — bone resorption, augmentation — is 12–16 weeks.

Do not shorten the provisional phase if: augmentation or bone grafting was performed, the patient smokes, there is immunosuppression, or occlusion requires significant adjustment.

Can the definitive bridge be placed immediately after surgery?

Technically possible for implants with immediate loading (ISQ ≥70). In practice, it's risky — without a provisional phase, you lack occlusal verification and a formed emergence profile.

How long will a provisional bridge last in use?

PMMA is a temporary material. With normal occlusal forces, it lasts 3–6 months. With bruxism, it can be shorter — the patient should use a nightguard.

How much does a provisional bridge cost vs. a definitive one?

A provisional PMMA bridge costs significantly less than a definitive zirconia one. At deltalabs., prices are available in our price list — the difference is due to milling time and the base material cost.

Can a provisional bridge be "recycled" as a definitive one?

No. PMMA is too soft, absorbs stains, and does not meet the strength requirements for a definitive restoration. The definitive restoration must be made from a new material.