This is the same material that is used to provide tooth-colored fillings, and in its simplest form is used for just that. Older generation composite resins can discolor over time, seriously compromising an otherwise good looking tooth, replacing the filling with a newer material can really make a difference to the appearance with almost no extra loss of tooth structure.
In certain situations and when more destructive procedures are not appropriate composite resin can be used:
To close gaps between teeth
Provide full surface coverage (veneering)
Build up worn down teeth
Creating a natural pleasing smile can sometimes be achieved by simple adjustment of the existing tooth structure - rounding off sharp edges, shortening teeth that are too long or polishing the front surface so that light reflects differently, all to achieve the predetermined symmetry and proportion.