In 2023, the U.S. digital dentistry market is valued at $1.26 billion and projected to be valued at $1.78 billion by 2030. Concurrently, the value of zirconia CAD/CAM materials market in 2022 has been calculated at almost $300 million (and projected to hit $510 million by 2030). This means zirconia alone represents nearly 24% of the U.S. digital dentistry market, and growing.
First introduced in 2010, the use of zirconia for C&B restorations had a rocky start, mostly due to esthetic concerns. As material innovations advanced and esthetics improved, this material is growing again in popularity… and quickly, due to its strength durability and now, esthetics. This, however, brings with it a new set of challenges.
In a 2023 article in Dental Economics, Dr. Gordon Christensen points out that tens of thousands of dentists a year are reporting that their zirconia crowns are prematurely failing. In many cases, they simply separate from the preparation. Christensen points out several factors at play in these cases, including:
While each of these issues deserves its own individual investigation, we will focus primarily on the last one and the role of cement in the placement of a zirconia crown.
Practitioners will often opt for the use of a bonded-in resin cement when attaching their crowns to a preparation. The reasoning is sound: these cements feature industry-topping bond strengths – a logical choice when a common issue is the crown separating from the preparation. Counterintuitively, research from the Technologies in Restoratives and Caries Research wing of the Clinician’s Report Foundation found that the highest rate of failure in zirconia crowns due to cement issues came from self-adhesive resin cements at 5%, and the second-highest rate of failure came from bonded-in resin cements at 4%. This is attributable to two primary factors: 1) the inflexibility of resin cements as time and wear and physical forces play on the crown, and 2) the general intolerance to moisture of these types of cements, which require total isolation during application—a relatively difficult task.
The study found that the lowest rate of failure came with the use of RMGI cements, at only 1%. RMGI cements are both more flexible than resin cements and they do not require total isolation. In other words, they are a much more forgiving material.
RMGI cements, too, are not perfect. Bond strength is traditionally lower than resin cements and in terms of practitioner preference, they are much less convenient to use—or were originally—and have required the hand mixing of a powder and a liquid.
Over the years and in an effort to meet clinician demand for greater convenience, dental materials manufacturers developed paste-to-paste RMGI cements packaged in syringes that would efficiently mix the material via mixing tip. This led to greater precision, accuracy, consistency and convenience with RMGI cements, but had one major drawback: lower bond strength.
The Major Exception
One RMGI cement that has shown to be an exception to the rule: VOCO’s Meron Plus QM. Its predecessor, Meron Plus (a powder/liquid RMGI cement) and Meron AC (in an application capsule) has a shear bond strength to dentin of 8 MPa. Meron Plus QM actually gained bond strength when designed for a paste/paste formulation: 11.3 MPa to dentin.
The science of this is fascinating and Gregor Connell, VOCO’s Director of Clinical Education, covers it in detail in his whitepaper “Resin Modified Glass Ionomer Update: The Marriage of Strength and Convenience.”
Meron Plus QM consequently becomes an viable option for the cementation of zirconia crowns & bridges. The added convenience of a 5-second tack cure for easy clean-up and a QuickMix syringe makes it the ideal RMGI cement for this large and growing segment of the digital dentistry market. Many high-profile dentists have found it to be crucial to their practices and procedures. Dr. Chad DuPlantis, in a 2019 article in Oral Health, writes:
“The traditional formulations of GI cements were a powder/liquid mix which was rather technique sensitive. More recently, however, manufacturers have worked on improving the physical properties to the paste-paste syringe-based RMGI cement options. This recent innovation of paste-to-paste RMGI cements (Meron Plus QM, VOCO) also features added resin, which slightly decreases the fluoride release. The additional resin in the newer formulation also leads to a higher bond strength than other cements with lithium disilicate restorations. The newer delivery systems are also advantageous in that they clean up easier as compared to the previous versions. RMGI cements were one of the first cements that had demonstrated positive performance in many of the desired characteristics.”
As zirconia continues to grow in popularity, more and more clinicians are searching for ways to ensure the success of their restorations. One way to help is with a good RMGI cement. VOCO’s Meron Plus QM has the variety of qualities that practitioners look for and patients appreciate—even if they don’t know quite how or why their restorations work.
To learn more about Meron Plus QM, click here. Or if you are interested in buying, take advantage of a 2+1 promotion by clicking the button below.