a dry, clean operating field
improved access and visibility
protection of the patient and the operator
potentially improved properties of dental materials
5 × 5 inch (12.5 × 12.5 cm) sheet
6 × 6 inch (15 × 15 cm) sheets
thin (0.006 inch [0.15 mm])
medium (0.008 inch [0.2 mm])
heavy (0.010 inch [0.25 mm])
extra heavy (0.012 inch [0.30 mm])
Light and dark dam materials are available, and darker colors are generally preferred for contrast.
Shade selection also should occur prior to placement of a rubber dam, because a desiccated tooth appears whiter than a moist or wet tooth.
Rubber dam material has a shiny side and a dull side. Because the dull side is less light reflective, it is generally placed facing the occlusal side of the isolated teeth
A thicker dam is more effective in retracting tissue and more resistant to tearing
The thinner material has the advantage of passing through the contacts easier, which is particularly helpful when contacts are tight.
Sturdevant's Art and Science of Operative Dentistry