Summary: the six oral health problems you see every day in the chair are also six reasons a restoration lasts or fails early.
This article looks at each one from the laboratory side: what depends on design and fabrication, what the clinician needs to control before the impression, and what the lab needs to see on the prescription to get the case right the first time.
1. Secondary caries at the margin
Recurrent caries at the margin is one of the common reasons fixed restorations have to be remade.
On the lab side, three things add to that risk: open or overhanging margins that collect plaque, a finish line that is unclear on the model or scan so the technician has to guess, and a margin that was not polished. Our article on CAD/CAM accuracy, marginal fit and trueness explains how the lab controls fit.
What the lab needs: a clear finish line, not covered by tissue or blood; on a scan, a continuous margin with no holes in the data.
2. Gingival inflammation around restorations
Localized inflammation around a new restoration is often caused by the restoration’s shape rather than the patient’s hygiene: an over-contoured emergence profile, a misplaced contact point, or a pontic tissue surface that cannot be cleaned. That part is preventable in the lab. For full-arch work, see why the tissue surface of an FP1 prosthesis is polished.
3. Periodontal disease
On teeth with bone loss or mobility, restorations should follow periodontal stabilization. Inflamed tissue at the time of the impression shrinks after treatment and exposes the margin. For a bridge on compromised abutments, the lab needs to know in advance so pontic design, connector position and material can be planned accordingly.
What the lab needs: a note on the prescription about which abutments have bone loss or mobility, and whether the tissue has stabilized.
4. Post-cementation sensitivity
Sensitivity after cementation has three groups of causes: endodontic, occlusal, and dentin sensitivity related to the restoration. Only the third group is a reason to send the case back to the lab, together with photos and a description of when the pain occurs.
5. Tooth wear and bruxism
Flattened occlusal surfaces, V-shaped cervical wear and chipped old ceramics can all point to bruxism. That information changes material choice, thickness and occlusal design. See our full zirconia case for a bruxing patient. After treatment, many of these patients also need a jaw stabilization splint to protect the restorations.
6. Discolored teeth and dark preparations
Stained teeth, endodontically treated teeth and metal post-and-cores need a restoration that can mask the substrate. The preparation shade decides the material and the minimum thickness, and the lab cannot choose correctly from the target shade alone. See masking a dark A4 preparation to a bright 1M1 and minimum veneer thickness.
What the lab needs: the stump shade and a photo of the preparation next to the shade tab, as well as the target shade.
In short: what to include on the prescription
- Periodontal status of the abutments and the tissue at the time of the impression.
- Signs of bruxism or wear, if any.
- Stump shade and shade photos for anterior restorations.
- A clear finish line on the model or scan.
How to send a case step by step is on our ordering process page.
This article is written for dentists and dental technicians. Khai Nguyen Dental Lab fabricates restorations only on a clinician’s prescription and does not sell directly to patients.
