Disa Dental - Disa Journal

GENERAL INFORMATION ABOUT ZIRCONIA

WHAT IS ZIRCONIA?

Zirconia (ZrSiO4) is a mineral belonging to the mineral class of Silicates, discovered in 1789 by M.H. Klaproth.
Zirconium dioxide (ZrO2) is a compound of the element zirconium occurring in nature and has already been used for 10-15 years in the prosthetic dentistry. It is partially stabilized by yttrium and enriched with aluminium. This results into positive characteristics such as high bending strength (>1400 MPa*), hardness (1200 HV*) and a Weibull module of 15,84*.
(* Values of Zirkonzahn ICE Zirconia Translucent)

WHERE IS IT USED?

In addition to its high resistance Zirconia is fully biocompatible. That is why it is increasingly used in the medical field (auditory, finger and hip prostheses) and in dentistry (pins, crowns and bridges restorations, implants). In industry it has already been used for more than 40 years. The white basic colour of Zirconia, the possibility of colouring in dentin colours and its biotechnological characteristics enable the production of biocompatible, high-quality and esthetical dental and implant reconstructions.

WHICH INDICATIONS AND/OR CONTRA-INDICATIONS ARE THERE?

All indications in the fixed and removable range.
Contra-indications in the case of too small vertical dimension.

Range of applications

IS ZIRCONIA RADIOACTIVE?

Everything is radioactive! The human body has 6000 Bq. One gram Zirconium dioxide has approx. 0.4 Bq. A crown weighs approx. 1 gr.,
metal ceramic can have up to 2 Bq/gr.

ARE REMOVABLE DENTAL PROSTHESES POSSIBLE?

Yes, if certain physical laws of the construction technology for Zirconia are taken into account and the dental technician masters the manufacturing technology.

WHY CAN BRIDGES BREAK?

Bridges can break if fundamental errors are made in the frame structure manufacturing. There is a Zirkonzahn calculation tool for dimensioning bridge structures. This program can be used free of charge under www.zirkonzahn.com.

HOW DOES THE AGING PROCESS OF ZIRCONIA AND THE INVOLVED LOSS OF STRENGTH COMPARE WITH THE USUAL METAL CERAMICS?

All frame structure materials age, including metals. The bending strength before aging of metal is approx. 500 MPa, of ICE Zirconia approx. 1400 MPa. With a theoretical, but so far not proven loss of strength of 30% still remain 980 MPa in respect to Zirconia.

AESTHETICS COMPARISON ZIRCONIA/METAL CERAMICS

ICE Zirkon frame structures are translucent and therefore aesthetically superior in comparison with opaque metal frame structures.

HOW DOES THE DURABILITY OF ZIRCONIA FRAME STRUCTURES INCLUDING VENEERING COMPARE WITH PORCELAIN-FUSED-TO-METAL CROWNS?

When the framework design is correct in terms of dimension and precision there are no disadvantages compared with
porcelain-fused-to-metal crown technology.

100% Prettau® Zirconia versus metal-ceramic – The Hammer test!

HOW DO THE COSTS COMPARE WITH METAL CERAMICS?

Regarding the material use Zirconia is equivalent or just slightly more expensive than metal ceramic.

IS FULL ZIRCONIA POSSIBLE?

Experts among the dental technicians are able to realize conventionally precious metal-based dental prosthesis constructions in zirconia.
In this connection Zirkonzahn has developed the high translucent Prettau^® Zirconia and a colouring technology especially coordinated with it. Thus, aesthetically appealing full Zirconia restorations can be manufactured.

PRETTAU^® ZIRCONIA

WHAT IS THE USE OF PRETTAU^® ZIRCONIA?

Prettau^® Zirconia is highly translucent and it is used for manufacturing esthetic full Zirconia works in connection with a specially developed colouring technology, in particular within the field of implants, and is also to prevent ceramic chipping.

IS PRETTAU^® ZIRCONIA TOO HARD AND ABRASIVE?

In dentistry abrasion (Latin: abrasio = to scratch off) means the loss of tooth substance due to friction. Enamel and dentin are part of the so-called ‘hard’ tooth structure. Abrasion in this context translates into wear or attrition.
As we know from nature, elephants starve to death at the age of 50 - 60 years because their dentition at that stage is too abraded to
process food.

Sintered Prettau^® Zirconia, owing to its own special material composition, displays incredible density and smoothness. Therefore the material does not cause any wear on natural dentition.

I illustrate this phenomenon by practical example: Rub wood against a smooth glass pane and nothing will happen but, rub wood against wood and it will splinter. As two materials of the same kind meet (tooth against tooth) natural dentition will inevitably wear also. However, when natural tooth meets smooth zirconia (like wood against glass) no abrasion occurs. The abrasive nature of any material is determined by its degree of surface polish and inherent density. The ”softer” enamel will glide over polished, much harder zirconia without wear.

By contrast veneer porcelain (or even metal) will cause wear on natural dentition due to its highly porous structure which acts like sandpaper. Veneer porcelain is 1000 times more abrasive compared to polished Prettau^® Zirconia.

Our experiences with zirconia vindicate our view: Zirconia causes practically no abrasion to natural dentition.

In the past we have observed the facts in our own environment and currently they are being tested scientifically in several universities. In general terms we can say this: The harder and smoother a material the less the wear it causes under friction. Wear results in abrasion.

PROCESSING OF ZIRCONIA

MUST ZIRCONIA BE GROUND WITH WATER COOLING (E.G. CORRECTION WHEN TRYING ON THE FRAME STRUCTURE)?

Water cooling is recommended, but not mandatory.

HOW DOES THE BONDING BETWEEN CERAMIC AND ZIRCONIA DEVELOP?

Mechanical retention. Compressive stress and surface fusion.

BY WHAT MEANS CAN ZIRCONIA WORK BE CEMENTED?

Phosphate cement or glass ionomer cement.

ARE EDGE EXTENSIONS POSSIBLE AFTER TRYING-IN?

Edge extensions after trying-in the frame structure are possible by using ceramic shoulders. However it is better to try in the frame-work before milling.

ZIRCONIA FRAME STRUCTURES ARE ALWAYS FRICTION-FREE AND ALWAYS FALL FROM THE MOUTH OF THE PATIENT WHEN TRYING-IN.

Friction is technically feasible, but not recommended. It would be better to thinly coat the frame structures with Vaseline before trying-in.

THE CROWN EDGES ON ZIRCONIA OBJECTS ARE TOO THICK.

This is not a material problem, but a processing error. After milling and before sintering the ICE Zirconia blank, the crown edges must be manually and thinly prepared by the technician.

HOW WELL DOES ZIRCONIA FIT?

If the processing is correct, precise fittings in the hundredth range are standard with the Zirkonzahn system. The marginal integrity amounts to 20 μm as with gold work.

WHAT HAPPENS WHEN GRINDING OFF AND/OR CORRECTION GRINDING OF ZIRCONIA TAKES PLACE?

There are no problems, if it is ground off under water cooling and any resulting sharp edges are rounded off.

IS THE TANGENTIAL PREPARATION OFFICIALLY SAFE ENOUGH FOR ZIRCONIA WORKS?

There are no objections on the part of Zirkonzahn against tangential preparations when the frame design is appropriate.

IS A ZIRCONIA CROWN STABLE ENOUGH OR POSSIBLY UNUSABLE AFTER TREPANATION?

Using water cooling and with appropriate tools no structural frame damage should occur.

WHICH DRILLING TOOLS ARE RECOMMENDED FOR TREPANATION OF ZIRCONIA CROWNS?

Zirconia diamond burs are recommended.

GENERAL INFORMATION ABOUT ZIRCONIA

PRETTAU® ZIRCONIA

PROCESSING OF ZIRCONIA

PRETTAU^® ZIRCONIA