All-on-X Case Planning Protocol: What the Lab Sees Before You Drill

Every All-on-X case that lands at our lab arrives with a story. Some arrive with a CBCT, a desired tooth position, a verified vertical, and a clinician who already knows where the AP spread sits. Those cases finish on time. Others arrive with an intraoral scan and a hope. Those cases finish eventually, sometimes after two provisional revisions and a remount appointment nobody scheduled for.

The difference is not surgical skill. The difference is what got decided before the first osteotomy. Below is the planning sequence we run on every full-arch case that comes through Dani Dental, written for the restorative dentist, the prosthodontist, and the oral surgeon who wants the lab in the conversation early.

1. Decide the final prosthetic before you plan the implants

This is the one that gets reversed most often, and it is the single biggest predictor of remake risk. If the surgical team places implants based on bone, and the restorative team then tries to design a prosthesis around the placement, the case becomes a compromise from day one. Cantilever lengths run long. Screw access ports erupt through incisal edges. Pink porcelain shows when the patient smiles wide.

Reverse it. Pick the prosthetic first. Monolithic zirconia hybrid? Titanium bar with individual ceramic crowns? PMMA long-term provisional that converts to final at month six? Each of those answers changes the AP spread you need, the restorative space you need, and the screw channel angulation you can tolerate. Tell the lab which prosthetic type at the planning meeting, not after the implants are osseointegrated.

For reference, a monolithic zirconia full arch needs 15mm of restorative space from the implant platform to the opposing occlusion. A titanium bar with individual ceramic crowns needs 17mm. If your CBCT shows 12mm and the patient does not want alveoloplasty, the prosthetic decision is already made for you, and it is not zirconia.

2. Verify the vertical dimension twice, then verify it again

Full-arch cases fail at vertical more often than they fail at fit. The patient arrives wearing a denture that has been over-closed for six years. The clinician scans, the lab designs, and the provisional goes in at the new corrected vertical. The patient complains the bite feels strange for three weeks, then comes back at week four saying their TMJ is sore.

We ask for two vertical records on every All-on-X case. One taken at the planning visit with the existing prosthesis or bite rims, and a second taken at the provisional try-in before the surgical guide is fabricated. If those two records disagree by more than 2mm, we stop the workflow and call. The technician on the case calls the office directly, not a sales rep, not a routing line. The clinician and the lab decide together which vertical the final case will be built to.

This one phone call has saved more cases than any single piece of CAD software we own.

3. The AP spread conversation belongs in the planning meeting

Anteroposterior spread is the distance from a line connecting the most distal implants to the most anterior implant. Multiply that number by 1.5, and you have your maximum safe cantilever length. This is not new information. What is new is how often we receive cases where nobody calculated it before the implants were placed.

For a mandibular All-on-4 case with implants at the lateral incisor and second premolar positions, AP spread typically runs 10 to 12mm. That gives you a 15 to 18mm cantilever budget per side, which covers a first molar but not a second. If the patient is a heavy bruxer or has a Class III tendency, knock 20% off that number before you cantilever anything.

Maxillary cases get more forgiving AP spreads when implants extend distal to the sinuses, but those cases also carry more restorative space variability. Discuss the AP spread at the planning meeting. Build the surgical guide around the prosthetic envelope. Do not let the lab discover the AP spread at the design stage.

4. Shade and tooth selection happen at the wax try-in, not the final

We see this pattern on roughly one case in five that comes in without a structured try-in protocol. The clinician approves a digital tooth setup based on a flat screen rendering. The provisional is milled. The patient sees the provisional in the mirror and asks why the centrals look wider than her old denture. The case goes back to design.

A physical try-in at the PMMA stage costs the lab a day of milling and the clinician one appointment. A redesign at the zirconia stage costs the lab a week of CAD and the clinician a delayed delivery. We strongly recommend a PMMA try-in on every All-on-X case where the patient has esthetic expectations, and we recommend the patient bring a spouse, an adult child, or a close friend to that appointment. Outside eyes catch midline issues that the patient and clinician have already normalized.

5. Plan the screw access channels in CAD, not at delivery

Angled screw channels are not new, but they are still underused on cases that would benefit from them. If the planned implant position puts the screw access through the cingulum of a maxillary central, that case needs an angled channel at the design phase. Discovering it at the try-in means redesigning the abutment library and re-milling.

We flag screw channel positioning at the design review and send a screenshot to the clinician for approval before milling begins. This is a five-minute conversation that prevents a five-day delay.

6. Document the conversion plan before surgery

If the case is going from extraction to immediate provisional in one visit, the conversion plan needs to be documented before the patient walks in the door. Which teeth are coming out, in which order. Whether the existing denture is being relined as the conversion prosthesis or whether a pre-fabricated PMMA shell is being modified chairside. Who is responsible for the verification jig.

We ship every conversion case with the technician's direct phone number printed on the shipping manifest. If something is off at the chair, the clinician calls the technician on the case, not a service rep. This is not a marketing line. It is how we keep conversion appointments from running into the next patient's chair time.

Where the lab fits in

None of these protocols require a specific lab partner to execute. They require a lab that picks up the phone, looks at the CBCT before milling starts, and tells you when something in the plan does not add up. That is the model we run. Cases that come in with a complete planning packet finish in 16 to 18 weeks on average. Cases that arrive incomplete take longer, because we stop and ask before we cut.

If you want to talk through a case in planning, the technician who would handle the work is the person who picks up. That part has not changed in three generations.