I'm not a materials scientist. I'm the person who orders materials, schedules the dental lab milling, and occasionally explains to a dentist why a crown didn't seat. I've been doing that for six years, and in that time I've personally made—and documented—22 significant mistakes. Roughly $14,000 ended up in the scrap pan.
This article is a side-by-side comparison of lithium disilicate ingots and zirconia CAD/CAM blocks. It's not a datasheet summary. It's what I learned after choosing the wrong material, plus the workflow rules I wish someone had given me in 2019.
First, let's define what we're actually comparing
In our lab, a lithium disilicate ingot is a pressed material: you invest a wax pattern, burn it out, and press the glass-ceramic into the mold. It's our go-to when translucency is the whole point. We also mill lithium disilicate blocks on some cases, but the ingot path is where most of my pressing-related mistakes happened.
When we say zirconia CAD/CAM blocks, we almost always mean sinterable dental zirconia blocks. They arrive soft, almost chalk-like, get milled in an enlarged form, and then go through a sintering furnace. Depending on the brand, that firing causes roughly 20% linear shrinkage. The CAM software needs to compensate for that before milling. Getting that part wrong is exactly how I wasted thousands of dollars.
Comparison #1: Strength and case indications
Let's state the obvious: zirconia is stronger. The manufacturer values I checked in January 2025 commonly list pressed lithium disilicate around 400 MPa flexural strength, while zirconia CAD/CAM blocks after sintering are typically in the 1,000–1,400 MPa range depending on the formula. Those numbers don't tell the whole clinical story, but they explain why I plan zirconia when the span is long or the connector area is thin.
My lesson came in 2019, my first year handling production. A dentist wanted a four-unit posterior bridge and asked for lithium disilicate because he didn't want metal. I knew the published indication didn't cover a four-unit bridge with two pontics, but I pressed it anyway. It fractured at the connector eleven months later. The remake cost us about $890 in materials plus one week of delay. I wanted to blame the ingot. The real problem was that I selected a material outside its indication range.
That mistake became rule #1: for multi-unit posterior spans, we reach for zirconia. Lithium disilicate is excellent for the cases it was designed for. But strength isn't a feeling—it's a limit.
Comparison #2: Esthetics, where strong isn't the point
Zirconia has come a long way. High-translucency zirconia can look genuinely good. But “more translucent” is not the same as “lithium disilicate.” When anterior teeth are placed side by side, the light behavior is different. A monolithic zirconia crown can still look flat at the incisal edge, especially when I have to keep it thick enough for strength.
In 2021, we milled two upper central incisor crowns in zirconia because the patient was a bruxer. The dentist chose zirconia for strength, and the shade match was fine. At the try-in, though, everyone in the room could see something was off. The patient looked in the mirror and asked why the two front teeth didn't pick up light like the teeth next to them. We remade both in pressed lithium disilicate. They didn't break—they just looked like teeth.
Esthetics conclusion: if the case is a maxillary anterior crown and light transmission matters, my first choice is lithium disilicate. If we use zirconia instead, I warn the dentist about the visual trade-off or plan for a cutback design. Strength was never the issue in that case. Appearance was.
Comparison #3: What happens after milling? The part comparison charts miss
Here's the part that surprised me. When I reviewed our redo costs over the past 18 months, we wasted more dollars on zirconia blocks than on lithium disilicate ingots. Not because zirconia is a bad material. Because the extra processing steps give you more chances to ruin something expensive.
In September 2022, we switched to a new brand of sinterable dental zirconia blocks for a seven-unit bridge. On paper, the block looked identical to our previous one. But different manufacturers state different sintering compensation factors. I left the old material profile in the CAM software. After sintering, the framework was about half a millimeter off and didn't seat on two abutments. That mistake cost us roughly $2,100 after remake time and rescheduling.
That's when I learned the workflow truth: milling is the easy part. The hard part is everything between milling and the final try-in. A lithium disilicate press failure usually shows up right after divesting, before you invest hours in finishing. A zirconia sintering error might not show until the furnace cycle is done, the model is burned, and the dentist is calling. By then, you can't just add material to the inside of a crown.
So when people ask me which process is simpler, I tell them the truth: pressing lithium disilicate has more manual steps, but zirconia has bigger hidden failure costs when something goes wrong.
The factor that overrides both: garbage in, garbage out
One more thing changed my opinion more than any material test. A ceramic restoration cannot be better than the model or scan it was made from. It doesn't matter if you chose the perfect lithium disilicate ingot or the best zirconia block—if the margin is wrong on the die, the restoration is wrong.
We still receive Impregum impressions from offices that haven't moved to digital scanning. Honestly, a well-taken Impregum impression can be excellent. Polyether is dimensionally stable, and when the dentist keeps the field dry and lets it set completely, the poured die is crisp. The problem is that a slightly distorted impression can still look acceptable. The CAD/CAM process will accurately mill a crown for the wrong model.
That's why our lab checks the model before we mill anything. The material choice matters. But the impression quality matters earlier.
Which should you pick? My scenario-based advice
- Single anterior crown where esthetics is the main reason for the restoration: pressed lithium disilicate ingot, or a milled lithium disilicate block if you don't run a pressing line.
- Posterior crown in a heavy bruxer or a multi-unit bridge: sinterable dental zirconia blocks, processed exactly according to the sintering profile.
- A lab that only does dental lab milling with no pressing furnace: you can mill lithium disilicate blocks and zirconia blocks, but you still need the correct furnace cycle for both.
- A chairside CEREC workflow: same logic in smaller format—lithium disilicate block for anterior single units, zirconia CEREC blocks for posterior work. Make sure the block is approved for that furnace and that the walls aren't milled too thin.
- If the case starts with a physical impression: check the die before committing expensive raw material. Impregum and other quality impression materials can produce excellent casts, but only if the impression itself is clean and complete.
Bottom line
Five years ago, I thought “zirconia for posterior, lithium disilicate for anterior” was the whole answer. It was a useful starting point, but it's no longer enough. Today's zirconia blocks are more translucent, and lithium disilicate formulations keep pushing into stronger territory. The decision now depends on the specific case, the restoration design, and the process discipline in your lab.
The fundamentals haven't changed: choose the material inside its indication, verify your CAM settings, start from an accurate impression or scan, and don't trust a sintering profile just because it was already in the software.
I still keep both materials in stock. I just stopped pretending one was universally better than the other.
