TLZ is our zll-zirconia, monolithic crown or bridge restoration. TLZ is also our Crowns For Life restoration, meaning it 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 oppropriate for posterior restorations, is completed in just 6 laboratory days and is guaranteed to satisfy. We offer a 5 year guarantee.
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
tinsile 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 fi ne-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 fi nished 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.
Currently many companies are completing invivo
wear studies. We will keep you informed as further
studies are published.
ROE Recommendation
Posterior crowns
Flexural Strength
850 mpa
Preparation
Conventional C&B(chamfer)
RECOMMENDED BUR KITS FOR ADJUSTING ZIRCONIA:
SS White® The Great White® Z
Komet USA LD0540 Zirc / emax Adjustment Kit
Brassler USA KO196
