ddmt

Silicates

late 1800s and used extensively until 1970. Had highsolubilitytooraluids, easytodiscolor,and increases in opacity during staining and dehydration.

Acrylic Polymers

introduced in 1945 and were of moderate usage in the 1960s. Had improved resistance to solubility and no problem with dehydration, although staining remained a problem. The undesirable qualities of unlled acrylics were: a. large dimensional change on setting and with temperature, resulting in percolation of saliva at margins

Dimethacrylate polymers with inorganic reinforcing agents (llers) aka Composites

introduced in 1960 and still in use.

Ionomer Restoratives

introduced in 1972 and have been primarily indicated for restoration of cervically eroded areas

1. Pressure / Bulk-pack / Compression Technique

2. Non-pressure Technique (Bead Technique) / Brush Technique

3. Flow Technique

Methods of mixing and packing resin in the prepared cavity:

Percolation

Premature removal of Mylar matrix

Marginal leakage – may be due to:

70 80%

The inorganic fillers _____ of the resin.

Organic matrix

the most common are based on dimethacrylate identied as BIS-GMA (bisphenol glycidyl methacrylate) or urethane dimethacrylate (UDMA). BIS-GMA is a very viscous liquid and low molecular weight monomers (dimethacrylates) are added to control the consistency of the composite paste.

Inorganic Fillers

a) give higher strength

b) lower the coecient of thermal expansion

Coupling agents

s–To provide a good bond between the inorganic llers and the polymer matrix, manufacturers treat the surface oft he llers. T