Eliminating Porcelain Layered On Zirconia Bond Failure

Zirconia layered with aesthetic porcelain will easily delaminate from the zirconia framework due to unrestricted reaction layers being formed during the layering cycle

The Fig.2 slide is layered porcelain over the sandblasted zirconia framework.

The step process is to sandblast the surface /clean it with steam or ultrasonic. Then layer & fire the overlying porcelain.

Unbonded zirconia and lithium silicate surfaces oxidize and form a reaction layer between the layer of Aesthetic porcelain & the zirconia

Reaction Layers are from 10 to 40 microns This layer enables

Fig. 2 is a zirconia frame with zirconia layered porcelain

Fig.5 is Lithium disilicate layered on pressed Lithium disilicate

Every UNbonded porcelain layered unit we tested failed from partial delamination to catastrophic failure, Usually from occlusal impact or repeated cyclic stress. 

The use of bonding porcelain is paramount to eliminating interface bond failures. Not all bonders are designed to provide a seamless bonded interface

Criteria for a superior seamless bond

Spectrafire SP bonder eliminates the need to fire the bonding layer before layering porcelain.c.

Saving up to 90 minutes of lost labor time waiting on firing and cooling time to achieve bonding.

1- The CTE (coefficient of thermal expansion between the two materials must be within 1.5 digits + or – of the host substrate.

2- The bonding layer thickness needs to be evenly over the entire interface surface .

Uneven bonding layer application affects the layering porcelain value and puddles create dark areas from the interface.

3- The bonding ceramic needs a recrystallization range of 740°c up through 925°c

The bonder must have a low wetting angle (20° at low temps 740°c) Up through 925°c

(using a High firing body porcelain does not have a wetting angle that provides a deep adhesion to the ceramic framework surface )

4- The bonder ceramic must also s form cohesion with the layering porcelain at the temperatures that are ideal for the layering porcelain

CTC (Coefficient of Thermal Conductivity)

The cooling of the zirconia substrate in relation to the CTC of the layering porcelain is significant

The CTC of Yz is 2.7 to 3 3 / the overlay porcelains are 5 to 9  ( gold is 16 )

Primary entry / Exit Parameters

Entry time into the oven and cooling set by the volume of the frame

Entry Guidelines

Use an Entry time of 5 minutes for normal crown size, cooling time 4 minutes

Use an entry time of 5 minutes for larger units (implant molars) with 6 minutes cooling

Use an entry time of 10 minutes for All On Four and heavy volume units. Use a  minimum of 20 minutes of cooling.

Ignoring these guidelines leads to catastrophic framework fracturing  

Conventional Zirconia Bonding Step Process

1- Sandblast surface to be layered with porcelain with alumnus Oxide preferably 100/ 110 micron Al203

2- Ultrasonic clean the framework

3- Brush on bonding layer & fire this cycle takes 40 to 90 minutes from start to finish before you can layer the aesthetic facial porcelain.

4- Proceed to Layer porcelain on the fired bonded surface

SP No Fire Bonding Step Process

1- Sandblast with alumnus Oxide the surface to receive the layering porcelain

2- Ultrasonic clean the framework

3- Use a quick ? second duration spray using the SP No fire Bonder from Spectrafire.com

4- You can skip the separate bond firing - Sp No fire Bonder sets in the air to a firm skin that does not move under the wet layers of porcelain. You saving up to 90 minutes of lost production time. 

Features: SP No Fire Bonder

I. Universal bonder for Zirconia & Lithium disilicate & Lithium silicate

II. Perfectly matched CTE for Zirconia/lithium silicate, lithium disilicate interface bonding.

III. SP Bonder dries to a firm skin shell in seconds.

IV.Recrystallizes from 740°c to 925°c 

V. SP NO Fire eliminates the lost production time of separately firing the bonder first   

VI. Economical with up to 240 sprays per can 

VII. @95.00 per canister ( you get approx, 240 sprays cost 0.39 cents

VIII. 90 minutes of lab production time @ 8.00 hour is up to 27.00 per case lost productivity.

SP NoFire Bonder is available through Spectrafire, com or direct 877-989-2248

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