Zirconia vs. E.max vs. PFM: Choosing a Crown Material

The short version

Most single-unit crowns ordered from labs today are one of four things: monolithic or multilayer zirconia, lithium disilicate (widely known by the brand name IPS e.max), porcelain-fused-to-metal (PFM), or full-cast gold. None of them is "best." Each one asks something different of your prep and gives back a different balance of strength and appearance.

This guide sets out the considerations a lab looks at when it reads your prescription. The clinical decision is always yours. What the lab needs is a clear statement of that decision, plus enough information to carry it out.

Zirconia

Zirconia is a polycrystalline ceramic. It is milled oversized from a pre-sintered blank and then sintered to full density, shrinking to its final size in the furnace.

Classic (high-strength) monolithic zirconia

• Strength: the highest flexural strength and fracture toughness of the all-ceramic options. It tolerates thin sections well, which makes it a common choice for molars and for patients with heavy function.
• Esthetics: fairly opaque. It masks dark stumps and metal cores well, but it can look flat or "chalky" in the esthetic zone.
• Reduction: the most conservative of the tooth-colored options. Manufacturers typically allow occlusal thickness in the range of about 0.5–1.0 mm, and chamfer or even feather-edge margins are acceptable.
• Cementation: can be cemented conventionally (resin-modified glass ionomer or self-adhesive resin cement) when the prep has adequate retention. When retention is short, an adhesive protocol is often used: air-abrade the intaglio, then apply an MDP-containing primer. Zirconia cannot be etched with hydrofluoric acid.
• Opposing wear: a well-polished monolithic zirconia surface is generally gentle on opposing enamel. Rough, unpolished or adjusted-but-not-repolished zirconia is not. After any chairside adjustment, polish it again.

High-translucency and multilayer zirconia

Newer zirconia formulations increase the cubic phase content to let more light through. Multilayer (gradient) blanks shift shade and translucency from the cervical area to the incisal edge inside one block, so a monolithic crown can show a more natural transition without layered porcelain.

The trade-off is that higher translucency generally comes with lower strength than classic zirconia. Labs tend to use the most translucent grades for anterior and premolar crowns, and stronger grades for posterior teeth and bridges. If you specifically want one or the other, say so on the prescription. "Zirconia" alone leaves the lab to choose.

Lithium disilicate (e.max)

• Strength: lower than zirconia, but well established for single crowns anywhere in the mouth when thickness requirements are met. Bridges are limited to short anterior and premolar spans.
• Esthetics: the best natural translucency and light transmission of the materials in this guide, which is why it is a favorite for anterior crowns, veneers and visible premolars.
• Reduction: needs more room than zirconia. Monolithic crowns typically call for about 1.5–2 mm occlusally and about 1–1.5 mm axially, with a rounded shoulder or heavy chamfer margin. Feather-edge margins are not suitable.
• Cementation: can be adhesively bonded (hydrofluoric acid etch, then silane, then resin cement), which adds support to the restoration and helps with short or tapered preps. For full-coverage crowns with good retention, the manufacturer also allows self-adhesive or conventional cementation.
• Stump shade matters: because the material is translucent, a dark stump, an amalgam core or a metal post can show through. The lab needs the stump shade to choose the right ingot opacity.

Porcelain-fused-to-metal (PFM)

• Strength: the metal substructure is very strong. The weak point is the veneering porcelain, which can chip, particularly under heavy or parafunctional loads.
• Esthetics: can be very good in the hands of a skilled ceramist, but the opaque layer limits translucency. If the gingiva recedes, a dark metal margin can show. A porcelain butt margin or collarless design helps at the cost of more lab work.
• Reduction: needs room for both metal and porcelain. That typically means about 1.5–2 mm occlusally and about 1.2–1.5 mm on facial surfaces that get porcelain, usually with a facial shoulder and a lingual chamfer.
• Cementation: conventional cements work well.
• Opposing wear: glazed feldspathic porcelain is more abrasive to opposing enamel than polished zirconia or gold. Some clinicians ask for metal occlusal surfaces on bruxers.

Full-cast gold

Full-cast gold (high-noble alloy) rarely gets mentioned in material debates, but it still has a place. It needs minimal reduction (roughly 1–1.5 mm occlusally), tolerates feather-edge margins, is cemented conventionally, and is among the kindest materials to opposing enamel. It also adapts very well at the margins. The obvious limit is appearance, so it is mostly considered for second molars and for patients who accept a metal restoration in exchange for longevity and minimal wear.

Side-by-side comparison

The values below are typical ranges from common manufacturer guidance. Always check the instructions for the specific material your lab uses.

Considerations by tooth position

• Anteriors: esthetics usually leads. Lithium disilicate or high-translucency multilayer zirconia are the typical candidates. If the stump is dark, discuss opacity with the lab rather than assuming the material will cover it.
• Premolars: the compromise zone. Upper premolars are often visible in a wide smile, while lowers carry more load. Either material can work when there is enough reduction.
• Molars: strength and thickness lead. Monolithic zirconia is the most common choice when clearance is tight, and gold is worth considering on second molars.
• Bridges: connector size drives the decision. Zirconia and PFM handle longer spans. Lithium disilicate is limited to short spans with generous connector height.

Bruxism and heavy function

For patients with visible wear facets, fractured restorations or a known clenching habit, many clinicians lean toward monolithic restorations (zirconia or gold) over layered porcelain. Layered surfaces are where chipping usually starts. A few practical points:

• Tell the lab the patient is a bruxer. It may change the zirconia grade, cusp anatomy (flatter, broader contacts) and how the occlusion is set.
• Ask for the occlusal surface to be polished, not just glazed. Glaze can wear off and leave a rough surface behind.
• Think about a night guard after seating, whichever material you choose.

What to tell the lab

Many remakes and phone calls about material come from a prescription that leaves room for interpretation. Include:

1. Material, specifically. "Monolithic zirconia, high-strength," "multilayer HT zirconia" or "lithium disilicate, bonded," not just "ceramic" or "white crown."
2. Shade and shade system. For example, A2 (VITA classical) or 2M2 (3D-Master). Note any cervical-to-incisal variation.
3. Stump shade for any translucent material, especially over discolored dentin, cores or posts.
4. Photos with a shade tab next to the adjacent tooth, for anterior and visible premolar cases.
5. Prep notes. Margin type, any area where you know reduction is tight, and what you want the lab to do if clearance is short: thin the crown, reduce the opposing tooth, or contact you first.
6. Function notes. Bruxism, what the opposing tooth is restored with, and your preferences for contacts and occlusion.

How this works on HERi2go

On HERi2go, the order form is generated automatically from the case you send from your scanner cloud. When the order is created, check that the material and shade match what you intend. Include stump shade and prep notes with the case, and use the case chat for anything that doesn't fit the form. The chat has built-in translation, so you can work with the partner lab in Korea in your own language. Unless the design is auto-approved because of a lab setting or a rush order, you approve the lab's CAD design before fabrication, so you can review the design files for crown thickness, contacts and emergence profile and ask for changes before anything is milled. See Dental Lab Turnaround Times for how that approval step fits into the schedule.

Quick checklist

• Match the material to the tooth position, the available reduction and the patient's function.
• Specify the zirconia type. "Zirconia" alone is not enough.
• Give stump shade for lithium disilicate and translucent zirconia.
• Flag bruxism, and ask for a polished occlusal surface on monolithic crowns.
• Tell the lab what to do if clearance is short.
• Check thickness and contacts at the design approval step before fabrication starts.