Zirconia And Prosthetic Finishing
What This Process Needs To Solve
A milled zirconia crown comes off the machine with a surface that no patient would accept, and the finishing step decides both how it looks and how the opposing tooth wears against it. Unlike metal, zirconia cannot be brought back by polishing compound alone — it has to be cut back to shape first, then brought to gloss, and the two steps need different diamond.
We supply micron powder from W1 to W30 for prosthetic finishing, loose or formulated as a paste, with low iron content specified for any grade that touches a visible surface.
Why iron content decides whether the crown discolours
Zirconia is white and stays white only if nothing diffuses into it during finishing. Iron is the problem element: a powder carrying iron residue leaves it in the surface layer, and it does not show up under the chair light — it shows up weeks later as a grey or yellow shadow, after the crown is cemented and the case is closed. That is why prosthetic work is specified on magnetic content and non-diamond residue rather than on hardness, and why we report both per lot.
Shape first, gloss second
The milling step leaves a surface that is geometrically correct but too rough at the margin. The first finishing grade has to remove material without chipping the margin — a coarse particle at a thin margin is where a crown fails. Polycrystalline powder is used at the finish because it breaks down during use and produces a finer surface at the same nominal size, which is what takes the surface from matte to glossy in one step instead of two.
What we hold on the batch
Top cut is controlled tighter than the standard grade window, because the margin of a crown is a thin edge where a single oversize grain shows. We report D90 and the maximum particle on the batch certificate for every prosthetic grade.
Where It Goes Wrong
- Grey shadow on a white crown. Iron residue in the powder, visible only after cementing.
- Chipped margin. One coarse particle at a thin edge, usually at the first finishing grade.
- Surface stays matte after the final step. Monocrystalline used where polycrystalline is needed.
- Paste dries before the case is finished. Carrier viscosity, not the powder.
Recommended Grade By Finishing Step
Prosthetic finishing is specified by step and by whether the surface is visible, not by the restoration type.
| Step | Recommended grade | Micron size | Why this grade |
|---|---|---|---|
| Shape correction after millingMargin and occlusion | |||
| Occlusal adjustment | HDY monocrystalline | W15 – W30 | Removes stock without loading, holds size through the pass |
| Margin refinement | HDY, tight top cut | W7 – W15 | Oversize control protects a thin edge |
| Bringing to glossVisible surfaces | |||
| Pre-polish | HDYS agglomerated or HDY | W3 – W7 | Uniform scratch pattern before the final step |
| Final gloss | HDYM fine micron | W1 – W3 | Reaches a clinical gloss without a second pass |
| Paste supplyClinic and lab | |||
| Finishing paste | HDY, low iron, carrier matched | W1 – W14 | Carrier has to hold the powder on a vertical surface |
Factory Direct Since 1990
Zhecheng Hongxiang Superhard Material Co., Ltd. is an integrated manufacturer and exporter of synthetic diamond powders since 1990, located in the Diamond Capital of China.
- Own manufacturing base in Zhengzhou, Henan — powder, coating and grading on one site.
- In-house particle size and SEM inspection on every batch before packing.
- Export packing with neutral or custom label, plus sample quantities for process trials.
What To Include
Describe your workpiece, process and target result. We will match the diamond grade from the existing product range.