Mistakes

Dental and Prosthetics Manufacturing Mistakes That Wreck Your Numbers

The specific errors that throw off dental lab yield, cost and turnaround numbers, each with the symptom, root cause, and a numeric fix.

The most expensive mistake in a digital dental lab hides in the slicer. Symptom: printed models measure fine to the eye but crowns seat with 80 to 150 micron marginal gaps and clinicians reject them. Root cause is almost always a scaling or shrinkage error, an STL imported in inches and auto scaled by 25.4, or resin cure compensation left at a printer default that does not match your resin lot. Fix it by printing a 20mm calibration cube every resin change and rejecting anything off by more than 50 microns. Only after geometry verifies does Dental Model Print Time give you a trustworthy schedule.

Under nested milling discs quietly bleed 30% of your material. Symptom: you pull 4 to 5 units from a 98mm zirconia disc while comparable labs get 7 to 9. Root cause is fixed rectangular nesting with no part rotation, oversized 4mm sprues, and generous safety margins that were never re tuned. The fix is true shape nesting with 2.5mm connector bars and tighter part spacing, targeting 65 to 75% area utilization. Run the layout through Batch Nesting Utilization and Milling Blank Yield before you commit the disc; recovering 2 to 3 units per disc on a 12 disc day is 24 to 36 extra units.

Remake rate reads clean while material spend runs hot. Symptom: your logged remake rate sits near 3% but consumables are 12% over plan. Root cause is remakes entered as brand new case numbers, so the denominator and numerator both drift and the Remake Rate calculator is fed garbage. Fix the data first: tag every remade unit to its original case ID and count reason codes. Honest crown and bridge remake rates land between 6 and 9%, and clear aligners closer to 2 to 4%. If your reported figure is half the industry floor, you are miscounting, not outperforming.

Promised turnaround slips because the buffer only counts machine time. Symptom: a 5 day quote consistently ships on day 8. Root cause is a lead time estimate built on mill and print hours while ignoring the 18 to 30 hour design queue, 6 to 8 hour sinter and glaze cycles, and QC holds. The fix is to load every queue stage into the Scan-to-Production Lead-Time Buffer and size it to the P90 case, not the average. A process that averages 3.2 days but has a P90 of 6 days needs a 6 day promise, or you miss one case in ten and burn the relationship.

Polishing and finishing labor gets guessed, then blows the quote. Symptom: cases look profitable on the estimate but technicians run 40% over their allotted minutes and overtime creeps in. Root cause is a blanket assumption like 4 minutes per unit carried over from monolithic glaze, when layered zirconia hand finishing genuinely takes 9 to 14 minutes and full contour PFM more. The fix is a 20 unit time study per appliance type feeding real minutes into Polishing Labor. If measured finishing is 11 minutes at a 45 dollar per hour loaded rate, that is 8.25 dollars a unit you were pretending did not exist.

Material cost per unit ignores everything that is not the blank. Symptom: you model aligner sheet at 0.90 dollars but invoices reconcile to 1.60. Root cause is counting only the thermoform sheet or the milled puck while ignoring 30 to 40% trim and web scrap, support resin, failed prints, and adhesive. The fix is a net to gross factor: if 35% of a sheet becomes scrap, divide usable cost by 0.65. Feed the gross figure into Material Cost per Appliance and cross check against Milling Blank Yield so scrap is never double counted or, worse, silently dropped from the quote.

The bottleneck is often after machining, in the pack out. Symptom: cases finish milling on schedule yet ship a day late in clusters. Root cause is a single autoclave with a 45 minute cycle while daily pouch demand spikes to 60 against a 40 pouch practical capacity, so sterilization becomes the constraint nobody scheduled around. The fix is to model peaks with Sterilization Packaging Workload, set an 11am machining cutoff for same day ship, and add a second cycle or chamber before volume grows. A 20 pouch daily overflow at even 8 dollars of expedited shipping is 160 dollars a day of avoidable cost.

Rush work goes out the door unpriced. Symptom: roughly 25% of cases get expedited but the average invoice never reflects it. Root cause is that rush status is a verbal agreement at the bench, never flagged in the case record, so overtime at 1.5x and 18 to 35 dollars of expedited air freight per case land in overhead instead of the price. The fix is a mandatory rush flag that routes through Custom Case Turnaround Cost and, for clear aligner runs, Aligner Build Cost, with a standing expedite surcharge. On 200 rush cases a month, capturing even 25 dollars each is 5,000 dollars you were absorbing.

Published 2026-07-02.