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1. BONDING TO UNCONVENTIONAL
SURFACES
Crowns and restorations:
Amalgam / Cast metal
Porcelain
Acrylic
Gold
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2. AMALGAM / CAST METAL CROWNS
1. Modification of metal surface –
• Sandblasting
• Diamond-bur roughening
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3. 2. Use of intermediate resins that improve bond
strength
Ex. All-Bond 2, Enhance, Metal Primer
 All-Bond 2 – 3rd generation DBA
 10% phosphoric acid for conditioning
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4. 1. Primer A + Primer B – mix
2. Apply to enamel till acetone evaporates
3. Air-dry for 10 secs
4. Primer B – metal primer
 Further and more research
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5. 3. New adhesive resins that bond chemically to
precious and non-precious metals
Ex. 4 – META - Superbond C & B,
 Molecule orients towards O / OH group in
metal – HYDROGEN BOND
 Bond strength to amalgam less than that
with other sandblasted metals
 Setting time – 10 mins
 Better – Orthomite Super Bond, MCP Bond
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6. 10 – MDP bis-GMA resins - Panavia EX
 Phosphate ester group
 Oxides of metal – Ni, Cr, Co, Sn
 Anaerobic environment – Oxyguard gel
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7. Procedure:
1. Sandblast - 50 microns Al2O3 for 3 secs
2. Etch with 37% phosphoric acid - 15–30 secs
Large restorations – coat of Metal Primer for 30
secs
3. Sealant
4. Bond with adhesive resin
5. Should not occlude with antagonist
Repolish with rubber cups after debonding.
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8. PORCELAIN
 Adult patients
 Feldspathic porcelain (10-20% Al2O3), high
aluminous porcelains, glass ceramics
 Conventional acid etch ineffective
 Technique –
1. Roughening of surface with burs/green
stones
2. Porcelain primer
3. Highly filled adhesive
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9. WOOD et al (1986)
 Bond strength equal/greater than to enamel
surface with this technique
 Damage to porcelain surface
ZACHRISSON et al (1993)
 Unacceptably high failure rates
 Lab tests – high bond strength
 In vitro – continuously increasing force
 In vivo – traumatic incidents, repeated stress
– propagation of micro cracks
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10. Instead of silane – PORCELAIN ETCHANTS
1. 9.6% Hydrofluoric acid gel – 2-4 mins
2. Equivalent etch by – 1.23% APF for 10 mins
3. 4% APF – 2 mins
 Microporosities for mechanical interlock
 Frosted appearance like enamel
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11. Procedure:
1. Isolate
2. Deglaze - sandblasting 50 microns Al2O3 –3 secs
• Intraoral sandblasting – Microetcher
• High-speed evacuater
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12. 3. 9.6% HF gel - 2 mins
Strong acid – careful isolation
- remove gel with cotton first
- copious rinsing
- high-volume suction
- immediate drying
4. Bond with highly filled BisGMA resin
5. Use of silane optional
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13. COMPOSITES
Old composites –
 Decrease in free MMA groups
 Exposed filler particles from silane leached
out
1. Superficial layer abraded with diamond or
carbide bur
2. 37% phosphoric acid
3. Silanation
4. Bonding
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14. ACRYLIC
 Temporary restorations
1. Wet surface with MMA for 3 mins
2. Bonding – unfilled resin or composite
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15. GOLD
 Not in much use
1. Sandblasting
2. Electrolytic tin plating – chemical and
mechanical bonding to resin
3. Gallium-tin solution (Adlloy)
4. Metal primers
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16.  Bond strength not enough to withstand
occlusal forces
 VTD adhesive monomer (triazine-dithiol), 4-
META
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