Composite Veneers
Write a short note on composite veneer materials.
Answer:
They are also known as prosthodontic veneer composites or composites for dental indirect restorations.
- The resin may be used as a veneer, i.e. a tooth-colored layer used to hide the underlying metal for crowns and field partial dentures.
- Early materials were heat-cured poly (methyl methacrylate) improved by filers and cross-linking agents.
- Recent veneer materials are hybrid, micro, or nanofiller-reinforced resins such as Bis-GMA, urethane methacrylate or 4,8-di (methacrylic methylene), tricyclo (5.2.1.02,6)decane.
Some are further reinforced.
- The newer resins have superior physical properties and are polymerized by light or heat and pressure.
- Resins are mechanically bonded to the metal using wire loops or retention beads.
- Recent improvements include micromechanical retention created by acid-etching the base alloy and the use of chemical bonding systems such as 4-META, phosphorylated methacrylate, epoxy resin, or silicon dioxide that is flame sprayed to the metal surface followed by the application of a silane coupling agent (silicoating).
Indications of Veneer materials:
- Inlays
- Onlays
- Veneers
- Anterior crowns (metal free)
- As veneer over metal-supported crowns and FPDs.
Advantages of Veneer materials:
- Fabricate easily
- Can be repaired intraorally
- Opposite teeth undergo less wearing.
Disadvantages of Veneer materials:
- Microleakage of oral fluids and staining under the veneers due to thermal cycling and water sorption.
- Surface staining and intrinsic discoloration.
- Susceptibility to toothbrush wear
- Cannot be used in crowns serving as abutments for removable partial dentures.
- Not as durable as ceramics and PFM.
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