Translucent Zirconia Veneers Case Study — Discolored Left Central Incisor Restored at 0.5 mm Facial

"a dark color left central incisor. The patient reported having that tooth endodontically treated many years ago due to trauma from an accident. The tooth color remains like that for many years." 

Medical and dental history:

• Medical history: uneventful
• Parafunction: no history of bruxism or clenching identified
• Local examination: no noticeable signs or symptoms; radiograph showed the previously endodontically treated tooth with no periapical abnormality
• Radiograph finding worth noting for later: open apex and an enlarged root canal, particularly in the cervical region, consistent with trauma during early tooth development

What the patient asked for. Not whitening of the whole arch. A single-unit solution for the one discolored tooth, matched to the untreated neighbours, with as little tooth preparation as possible.

1.2 What the clinical examination established

1.3 Shade — the two numbers that decide the case

In the report, shade was captured twice: once for the dark preparation and once for the adjacent natural teeth. That is the distinction the whole case turns on, because a 0.5 mm veneer sits on top of the first and has to read like the second.

Why this is captured in two separate frames: the target tells the lab what colour to build; the stump tells the lab how much of that colour it is being asked to carry across 0.5 mm of ceramic. A single "shade" field cannot answer both questions.

1.4 What was considered and set aside before zirconia

The report walks through the exclusion chain explicitly — this is the part most case write-ups leave out, and the one that proves the final material was chosen rather than defaulted to.

2. The Clinical Brief

This is the lab-facing requirement set as it is implied by the report's clinical plan, with the lab-side execution written against each item.

2.1 Preparation and margin

What the clinician did. Facial reduction uniformly to 0.5 mm. Incisal reduction of 2 mm. Cervical finish line placed slightly under the gingival margin. All corners rounded, preparation polished with fine diamond burs. Preparation confined within the enamel layer. (Anh et al., §4 Tooth preparation)

What the lab side must support. At that preparation window, finish-line position is a real variable. Independent in-vitro data on this restoration class puts fracture resistance at 539–661 N with an equigingival margin and 242–388 N with the margin in the incisal third, with physiological anterior loading at 190–290 N (Sci Rep 2025). The published case kept the margin at or just under the gingival margin — the strongest end of that range.

2.2 Shade and characterization

What the clinician asked for. A restoration that matches the adjacent natural teeth rather than a visibly lighter result.

What makes 0.5 mm the hard case. On a monolithic zirconia veneer this thin, shade is a function of thickness as much as of stain. Measured colour difference between 0.5 and 1.0 mm reaches ΔE00 ≈ 2.96 for zirconia, against 0.83 for lithium disilicate (Heliyon 2023). A zone that comes out thin is also a zone that reads a different colour, and stain cannot recover it because the problem is how much of the stump shows through, not what is painted on top. This is why thickness is verified after sintering rather than taken from the design file.

2.3 Form and dimensions

What the clinician planned. A conservative laminate veneer; shape referenced to the adjacent natural central and the lateral.

Lab-side input. The adjacent natural central was used as the primary form reference, with the veneer mirrored and corrected for the natural asymmetry between two central incisors rather than cloned straight. The incisal edge was taken from the contralateral tooth, projected digitally.

2.4 Occlusion

What the clinician recorded. No bruxism, no clenching, no excursive interference.

Lab-side action. No excursive contact designed into the restoration; anterior guidance left as it was found. For cases with parafunction reported, we add a note recommending a nightguard — zirconia holds up under occlusal load, but the opposing dentition is better protected when the surface facing it is polished rather than left glazed.

2.5 Bonding and intaglio

What the published case did. Before sintering, an opaque liquid — Prettau® Aquarell (Zirkonzahn, Italy) — was applied to the bonding surface of the milled veneer so the dark abutment could be masked while preserving outer translucency. The intaglio was then etched with a mixture of zirconia-etching acids — ZIRCOS-E (Eunjin Chemical, South Korea) — for 2 hours at room temperature and rinsed with distilled water. After annealing at 1150 °C for 1 hour and glaze firing at 900 °C for 10 minutes, the veneer was ready for cementation.

Cementation itself used Single Bond Universal (3M) — a universal primer containing 10-MDP and silane — followed by RelyX Veneer LC (3M) light-cured veneer cement. On the tooth side, the abutment was prepared with fluoride-free pumice, etched with 37 % phosphoric acid for 15 seconds, rinsed, bonded with Single Bond Universal, air-dried and light-cured for ten seconds. The veneer was then seated, excess cement cleared, and each margin light-cured for 30 seconds.

【Our in-house workflow】 The acid-etch route the published case used (ZIRCOS-E mixed acid for 2 hours, then anneal at 1150 °C for 1 hour) is effective, but it is a long acid step and a second firing — not a routine production route for most laboratories. In our own workflow at Istar, routine intaglio preparation on monolithic translucent zirconia veneers runs as air-abrasion with 50 µm alumina at ~1.5 bar, 10 mm working distance, 10–20 s, ultrasonic clean, then a 10-MDP primer, with parameters and primer batch recorded on the case file. The underlying bonding chemistry is the same — micromechanical retention plus MDP coupling to the metal-oxide surface, as summarised in this adhesion review — but the production route is chosen for repeatability rather than peak theoretical bond strength.

Three things we do not do on a zirconia intaglio as part of our routine workflow, and the reason in each case:

• No hydrofluoric acid as a routine etchant. HF etches glass. Zirconia has no glass phase, so a routine HF step does nothing — the published case uses a specialist nitric-and-fluoride acid mixture, which is a different mechanism.
• No silane on its own. Silane couples to silica, and there is no silica in zirconia. In this case Single Bond Universal was used because it combines silane with 10-MDP; the active chemistry on zirconia is the MDP, not the silane.
• No phosphoric-acid cleaning of the intaglio. Residual phosphate competes with the MDP for the same binding sites on the zirconia surface, which is the opposite of what the primer is there to achieve.

2.6 Delivery and communication

What the published case needed. A conventional case: silicone impression, provisional restoration, milled zirconia, try-in, cementation, follow-up. No specific lab-timing information is reported.

【Our in-house workflow】 Standard lab time at Istar for a case of this class is 2–3 working days, and approving the CAD design before milling adds 1–2 days. Shade and form questions run through the case's WhatsApp group, with the case coordinator on the thread from intake to shipment. CAD can be sent for approval before milling on request, with production held until confirmed.

3. How a Case Like This Runs — Our In-House Workflow

Nine stages, all in-house at our Shenzhen and Huizhou facilities. Cases are not passed to a third-party laboratory. The published case was fabricated elsewhere; the steps below describe how Istar runs the same clinical objective in our own production.

Intake and evaluation → CAD design → 3D-printed working model → CAM milling → zirconia processing → characterization and firing → polishing → quality inspection → packing and shipment.

3.1 Intake and evaluation

【Our in-house workflow】 The stump shade and the target shade are logged as two separate fields on the case ticket, exactly as the published case recorded them in two separate figures. The facial thickness required to carry the masking is worked out before design starts. If 0.5 mm will not cover the recorded stump shade, that is said now rather than at try-in. Published masking data over a titanium abutment shows that at 0.8 mm only 3Y and 4Y material masks adequately; at 1.5 mm every generation masks; for severely discolored substrates no generation masks completely at any thickness (PubMed 36452362). The published case worked at 0.5 mm because the opacity was carried deliberately in an intaglio layer rather than left to the material body.

3.2 CAD design

【Our in-house workflow】 Three inputs drive the geometry: the adjacent natural teeth, the pre-op photographs, and any wax-up or provisional supplied. Soft-tissue items are resolved at this stage rather than with stain — an open contact gets the contact point moved slightly gingival with added proximal convexity; an asymmetric gingival margin is referenced against the contralateral side. Where a margin position does not sit well with the chosen material, the case coordinator raises it in the WhatsApp group with a proposed alternative and the case is held until it is resolved.

3.3 Milling and shrinkage compensation

【Our in-house workflow】 Every zirconia blank shrinks by a manufacturer-specified factor during sintering. We set that factor in the design software, run a reference test piece against each new batch, and recheck the compensation routinely. New-batch material is validated with a sample unit before it goes into production.

3.4 Zirconia processing — intent carried from the published case

The published case placed its opaque layer at the intaglio before sintering, which is the point at which it would locate masking without compromising the outer optical body. Our in-house workflow follows the same intent: internal effects first (chroma depth, incisal translucency), then characterization (mamelons, incisal halo, cervical saturation, mesiodistal micro-texture), then surface finish.

3.5 Sintering

【Our in-house workflow】 The temperature profile, ramp rate and hold time are fixed per material and logged per cycle. We do not shorten a cycle to save time — a shortened cycle does not merely weaken a unit, it changes its colour. The green unit sits on a heat-resistant low-deformation support so a thin incisal section does not bow under its own weight during the hold. After sintering, before any surface work, the restoration is seated on the working model and the fit verified; if it is off, we remill rather than grind to fit. The multilayer gradient and the nesting slice are recorded on the case file so a matching unit can be produced later.

3.6 Characterization and surface finish

Polish on the cervical and proximal surfaces. The surfaces that meet soft tissue and the adjacent tooth are polished to a high gloss rather than left glazed. Published wear data on opposing enamel puts polished zirconia at 57 µm of opposing wear against 78 µm for glazed, with volume loss of 0.21 against 1.18 mm³ and 0.33 against 0.68 mm³ in two configurations (research summary); the evidence is not unanimous but the direction favours polishing. If a restoration is adjusted chairside later, we ask for it to be polished back through the progressive sequence — surface roughness on zirconia multiplies wear on the opposing tooth.

3.7 Intaglio preparation

【Our in-house workflow】 As described in §2.5: air-abrasion with 50 µm alumina at ~1.5 bar, ultrasonic clean, 10-MDP primer; parameters and batch recorded on the case file.

3.8 Quality inspection

【Our in-house workflow】 Fit on the working model, margin seat, surface finish under inspection lighting, shade read against the submitted reference, dimensions against the design. Zirconia dust and resin exposure are controlled with dedicated extraction equipment in each department. Blanks and metal scrap go to a licensed recycling partner; non-recyclables go to a certified waste handler.

3.9 Packing and delivery

【Our in-house workflow】 Foam-cushioned packaging against transit damage. The case file travels with the restoration — material batch, nesting slice, sintering log, shade build steps, measured thickness — so a later matching unit can be produced from it.

4. Try-In, Patient Feedback and 24-Month Follow-Up

All findings in this section belong to the published report; nothing here is reconstructed and nothing is edited. Quotations are reproduced verbatim with attribution.

4.1 At cementation

The intaglio surface of the veneer was ultrasonically cleaned for 15 minutes, the universal primer applied for 20 seconds and air-dried for 5 seconds, and the cement applied to the bonding surface. On the tooth side, the abutment was etched with 37 % phosphoric acid for 15 seconds, rinsed, bonded, and light-cured for 10 seconds. The veneer was then seated, excess cement cleared, and each margin cured for 30 seconds. The marginal finish was polished and the occlusion checked for interferences (Anh et al., §8 Cementation).

Post-operative intraoral and extraoral photographs are included in the report as Fig. 5 and Fig. 6.

4.2 What the clinician reported

Marginal adaptation, shape and aesthetics were verified intraorally before final seating and confirmed satisfactory before cementation. Occlusion was checked after final polishing and no interferences were reported. (Anh et al., §8 Cementation.)

At follow-up, in the authors' own words:

"The patient returned for follow-up examinations 1 week, 1 year and 2 years later. No signs of dislodgement or marginal gaps were observed at the 2-year follow-up." — Anh et al., Medicine 2025, §8 Cementation

The 2-year follow-up intraoral photograph is reproduced as Fig. 7.

4.3 What the patient reported

The patient's own assessment at the end of treatment, reproduced verbatim:

"The patient's satisfaction was evaluated through an oral interview, and she was very satisfied with the result." — Anh et al., Medicine 2025, §8 Cementation

4.4 What the authors recorded as the limitation

The report is explicit about what this restoration type still does not do — and this is the part worth reading twice, because any case page that leaves it out is reading the material wrong. In the authors' own words:

"The limitation of using translucent zirconia in this case report is that, although it can improve the esthetic outcome compared to conventional zirconia, it still cannot fully replicate the natural translucency of teeth. The use of acid-etched zirconia veneers is a relatively new approach, and while laboratory results are promising, long-term clinical data remain limited. This case report demonstrated success after a 2-year follow-up, but longer observation periods and larger clinical studies would provide more robust guidance for clinical practice." — Anh et al., Medicine 2025, §9 Discussion

Two things worth stating alongside this quotation, for a reader deciding whether to send a case like this to a laboratory:

The single-unit position is the hardest optical case. A one-unit restoration beside an untouched natural neighbour has no adjacent restoration to blend into; it is the position in which the translucency gap between zirconia and a glass-ceramic is most likely to be read in strong directional light.

One case followed for 2 years is not a survival rate. Cohort-level figures put ultra-thin monolithic zirconia restorations at 99.5 % survival at 2 years across 201 units (PubMed 39523553). That is context, not a prediction for any individual restoration.

4.5 Follow-up timeline

5. The Decisions That Shaped This Case

Five questions decided how this case went. They are also the five we work through on any translucent zirconia veneers case we take on:

Answer those five before preparation and there are no surprises at try-in. Where a case cannot be resolved along them — a severely discoloured stump, an incisal that has to match a glass-ceramic optically, uncontrolled parafunction — we say so before the tooth is cut.

6. Sending Us a Case Like This

In the order we read it:

1. Photographs — frontal smile, rest-lip, lateral, intraoral close-up, and two shade frames: natural tooth with a shade tab in the same frame, and prepared stump with a shade tab in the same frame.
2. Scan or impression with a bite registration. Either is fine. A buccal photograph of the preparation helps.
3. Occlusal notes — anterior guidance, any lateral interference, parafunction history.
4. Any reference the patient has given you — an older photograph, a provisional, a diagnostic wax-up, a DSD plan — and where it came from.
5. Your preference on the intaglio — shipped abraded and primed by us, or sintered and finished with the intaglio left for chairside bonding.

We reply with a written feasibility note before the tooth is prepared: the masking judgement against your stump shade, the generation and layer strategy we would use, the margin and finish-line call, the measured-thickness window we would hold, and the lab-time estimate.

7. FAQ

Can a dark stump be masked at 0.5 mm? Often, yes — and the Anh et al. 2025 case on this page is one example. It depends on how many shade steps separate the stump from your target, which generation of zirconia is used, and whether an intaglio opacity layer is applied. For severely discoloured stumps, no zirconia generation masks completely at any thickness (PubMed 36452362). We tell you before the preparation.

What do you need from me to start? The two shade frames above are the ones that matter — the stump shade frame and the target shade frame. Everything else helps, but those two are what let us answer the thickness question.

How do zirconia veneers compare with lithium disilicate veneers? Lithium disilicate reads higher on translucency at the same thickness — about 22 against 15 in TP00 at 0.5 mm (Heliyon 2023). Zirconia holds up better under heavier function and against a hard opposing surface. Where masking a dark stump through a thin facial is the leading constraint, translucent zirconia with intaglio-side opacity — as in Anh et al. — is usually the workable answer.

Can translucent zirconia veneers be bonded reliably? Yes, with the right intaglio preparation. The published case used an acid etch (ZIRCOS-E, 2 h) + annealing + a 10-MDP universal primer (Single Bond Universal) + resin cement, and the restoration was in place with no dislodgement at 2 years. Our in-house routine route uses air-abrasion + 10-MDP for repeatability. Full protocol in this adhesion review.

Where should the finish line sit? Equigingival to just-sub-gingival within enamel is a conservative default on a thin veneer for the strength it holds back. An incisal-third margin is not off-limits, but published fracture resistance for it is lower — 242–388 N against 539–661 N for an equigingival margin, with physiological anterior loading at 190–290 N (Sci Rep 2025).

What is the turnaround at Istar? 2–3 working days of lab time for a standard case. Adding design approval before milling takes 1–2 more.

Can you see the design before you mill it? Yes. Ask at submission and we will send the CAD and hold the mill until you confirm.

Do you outsource? No. CAD, model printing, milling, zirconia processing, characterization, polishing, QC and packing all run inside our Shenzhen and Huizhou facilities.

Can we visit the factory or audit by video? Yes. Both facilities are open to visits, and video audits can be scheduled.

8. Send the Case

Send the case conditions and we will return a feasibility note before you prepare. Include the two shade frames, a scan or impression, and your occlusion notes. We will come back with the masking judgement, the generation and layer strategy, the margin call, the thickness window we would hold, and the lab time.