What is TLZ?
TLZ is our all-zirconia, monolithic crown or bridge restoration. TLZ is guaranteed against breakage for the life of the patient. Tested at a flexural strength of 850 MPa, our High-Translucency, monolithic formula is stronger than nearly all other restorations on the market. A unique fabrication process makes TLZ beautiful, lifelike and a high recommendation from ROE.
TLZ is appropriate for posterior restorations, is completed in just 6 laboratory days and is guaranteed to satisfy.
When you need the strongest restoration available, ask for TLZ!
Crowns for LifeTM
Limited Lifetime Warranty Statement
Crowns for LifeTM applies to ROE Dental Laboratory’s TLZ all zirconia crowns. TLZ is an acronym for Translithic Zirconia, the material used to fabricate TLZ crowns. This is a warranty against breakage resulting from normal mastication. This is not a warranty against shade change, wear, or replacement required from additional dental procedures. This limited warranty covers replacement of the TLZ crown only, and not any costs associated with removal or replacement. Replacement with an alternate restorative material may result in additional costs.
How is it designed for dental?
Zirconia, which is unearthed as zirconium dioxide, is a white crystalline oxide that exists in three phases, cubic, tetragonal, and monoclinic, depending on temperature and pressure formation. In dentistry we concern ourselves with the latter two. Zirconia in the pure tetragonal phase is unstable. In order to create the milling blocks used in our machines, dental manufacturers add yittria, creating yittria-stabilized tetragonal polycrystals (Y-TZP)2. In this state zirconia is extremely hard and possesses a unique characteristic called transformation toughening. When tensile stress is introduced from crack propagation, the tetragonal formation morphs into monoclinc, increasing the volume 3 to 5%, and subsequently transforms the stress from tensile to compressive. This self-healing mechanism makes zirconia the ideal material for the oral environment.
In-operatory adjustment of zirconia As mentioned above, micro crack propagation is prevented while the monoclinic transformation occurs, thereby increasing surface tension and tensile strength (i.e., - theoretically, grinding can increase the strength of Y-TZP zirconia). But before grinding-away on your crowns, you should observe certain criteria. The severity of grinding and the rise in temperature will affect the volume percentage of toughening. We recommend using fine-grade burs and copious amounts of water coolant to decrease heat generation. Researchers have studied the quality of diamond particles impregnated in dental burs, the hardness of the binding material, and the precision and centricity of the shafts, and have found that no one manufacturer has a superior product. All manufacturers agree that hydration and very light-to-no pressure is the best technique – let the bur do the work and avoid dull tools. Also, the inside of a coping or monolithic restoration must be left untouched. It is recommended that if internal adjustments are needed for seating, the preparation should be adjusted.
Wear to opposing A common question that arises about our TLZ allzirconia restorations concerns the wear effects they have on opposing dentition. There are many documented studies measuring the wear of zirconia against fluorapatite, porcelain, gold, lithium dicilicate, lucite etc. These invitro studies can be summarized by focusing on particle size and finished surfaces. Zirconia is comprised of ultra-fine particles that do not become saw-tooth when roughened, unlike standard porcelains used in dental restorations. This characteristic evidently leads to low-wear of opposing enamel. A Study in J Adv Prosthodont 2010;2:111-5 showed that wear to the antagonist teeth is much less than that of feldspathic porcelains. Moreover, the study agrees with many other studies we’ve reviewed, zirconia shows very low wear when highly polished.
Rella Christiansan’s TRAC Research group has released preliminary results of a 7-year full-contour zirconia wear study which supports both of these claims. The study seeks to measure the amount of wear zirconia and other monolithic restorations exhibit invivo. After one year, the “very promising” results show that zirconia “mimics” natural dentition.
Currently many other companies are completing invivo wear studies. We will keep you informed as further studies are published.
Use primers when mechanical retention is minimal. They generate a sound bond between the restoration and the cementation material Monobond
IvocleanTM & MonobondTM Plus - Ivoclar Vivadent
Monobond Plus - Ivoclar Vivadent
ZPrime - Bisco
Scotchbond - 3M
SS White® The Great White® Z
Komet USA LD0540 Zirc / emax Adjustment Kit
Brassler USA KO196
D2740 Crown - Porcelain/Ceramic Substrate
D6245 Pontic Porcelain/Ceramic
D6740 Abutment Crown Porcelain/CeramicC
TLZ Crowns following High Explosive's Test