XircOn Ultra is the toughest dental material in use for cosmetic, minimally invasive, and implant dentistry today. Higher than 3M Lava Ultimate, and higher than e.max, vita mark II and empress CAD, making XircOn Ultra the strongest esthetic ceramic material.

The higher compressive strength of XircOn Ultra is the result of special manufacturing processes used to bond the glass and polymer materials, including the use of a special sylanated glass ceramic which chemically bonds to the polymers, as compared to other hybrid or ceramic materials that form no such chemical bond.

Compressive strength, which best simulates chewing forces in the mouth, is measured by applying both upward and downward pressure on an object until it breaks. Unlike Flexural Strength, which simulates breaking a stick over your knee and is measured many different ways according to different international standards, compressive strength is measured only one way according to one ISO standard.

Compressive strength is measured according to International Standard ISO 4049 and ADA Specification 27. XircOn Ultra specimens were tested in a universal testing machine at a crosshead speed of 1mm/min. Data were obtained in KGF and transformed into MPa using the following formula:

RC = F x 9.807 / A
Where:
RC = compressive strength (MPa),
F = recorded force (kgf) multiplied by the constant 9.807(gravity), and
A = base area (7.06 mm2)

ISO testing of XircOn Ultra resulted in approximately 155 MPa to 205 MPa in Flexural strength depending on the testing methodology employed. Our published number of 175 MPa is based upon the 3-point bending testing using the most universally accepted international standards. All testing methods far exceed both FDA and European standards for dental ceramics. For a more useful strength comparison, XircOn Ultra recommends analyzing Compressive Strength, which better simulates the chewing stresses found in the mouth.

In order to be registered with the FDA, all dental material manufacturers must exceed 100 MPa in flexural strength, and they must exceed 50 MPa under European standards, and we believe that all materials meet this basic standard.

Three challenges exist in doing apples-to-apples comparison of flexural strength of competing materials.

The first challenge is that only XircOn Ultra, among all of the esthetic ceramics, is the only material manufactured in a large disc format, and is therefore one of the only materials which can be used off-the-shelf to make sample sizes as specified by most of the relevant ISO standards. All others must make special batches of material for testing or use smaller samples from chairside milling blocks, which some argue alters the results. Using the break-a-stick-over-your-knee example, you can imagine that it might be more difficult to break an 8 inch stick over your knee than it would to break a 24 inch stick.

The second challenge is that since the goal of testing is to demonstrate a 50 MPa or 100 MPa minimum requirement, regulatory authorities allow manufacturers to use one of many different generally accepted methods for measuring flexural strength, including standards found in ISO 10477, and ISO 6872, or ISO 4049, as published and changed over the years, and as altered based upon available sample sizes, and within those standards, manufacturers can elect to do any of the following tests:

- three-point bending test
- four-point bending test
- biaxial flexure test (piston-on-three-ball)
The third challenge is the basic question about whether flexural strength is the best possible measure of how “strong” a dental material is, especially for side-by-side comparisons. Flexural strength is measured by creating a span of unsupported material across an open space and applying downward force till it breaks. And while flexural strength may be an ideal test for construction materials, by contrast, dental restorations are usually supported by underlying teeth or implants, and so Compressive Strength is a far better measure of what actually happens in the mount.

In dentistry, hardness is what creates the clackiness found with most ceramic dentistry, as opposed to the soft and gentle bite characteristics of a XircOn Ultra restoration. Vickers Hardness is tested by striking specially shaped diamond anvil against the material and measuring the size of the indent created with varying force.

At less than 0.7 GPa (700 MPa), XircOn Ultra is the only esthetic material that is gentler than natural dentin.

XircOn Ultra, being at 10,000 MPa (or 10 GPa), is by far the most flexible dental ceramic in use today which makes the material ideal for implant dentistry where sensation and cushion afforded by the peridontal ligament is lost, and it allows the material to stand up better to the test of time where chewing forces eventually cause all-ceramics to weaken, chip, and crack.

The lower the number, the more the material flexes before it breaks. Unlike other hybrids, a unique chemical bond is formed inside the XircOn Ultra material matrix which allows the polymers to flex while not breaking apart from the ceramics.

A 3mm bar is created out of XircOn Ultra and bent. No other ceramic material used in dentistry can bend like XircOn Ultra without breaking. XircOn Ultra is the only dental ceramic which is actually more flexible than both dentin and enamel while providing strength characteristics which are significantly superior to both.

One of the unique properties of XircOn Ultra is that it is the only hybrid material approved today to be strong enough for use in creating bridges and full‐arch restorations. Simulations with three‐unit bridges were conducted in order to test the material in a more demanding stress and wear profile. This mastication simulation test conducted on XircOn Ultra nanoceramic hybrid dental restorative material involved 1.2 million simulated thermocycles at 70 Newtons of force.

Bond/adhesion testing was conducted on XircOn Ultra using a variety of CFI bonding techniques according to specifications found in ISO 10477.

XircOn Ultra was bonded to a nano-composite material and compared to a nano-composite and titanium reference bond.

The bond strength of nearly all XircOn Ultra specimens was stronger than the comparable titatium reference material. This bond strength remained excellent even at high temperatures. Sand blasting was determined to be the best surface conditioning method.

XircOn Ultra to composite bond strength was consistently greater than either composite to composite or composite to titanium bonds, in all temperatures and nearly all preparations.