Every adhesive step is only as good as the field it is performed in. Choosing and placing isolation takes a few minutes and decides the outcome of the hour that follows.

What contamination does to a bond

Saliva, blood and crevicular fluid each leave a film on the prepared surface that an adhesive cannot penetrate. A bond made over such a film looks complete at the chair and fails at the margin months later.

The measured drop in bond strength after salivary contamination is large enough that no adhesive system claims immunity to it.1

Preparation

Before the first adhesive step

  • Choose the method for the case

    A rubber dam for posterior bonding and multiple restorations; a retraction cord and cotton rolls for a single anterior margin close to the gingiva.

  • Place it before etching

    Isolation placed after the etchant has been applied protects nothing.

  • Check the seal

    A dam that leaks at one tooth is a dam that leaks.

  • Keep the field visible

    Position the light and the suction before the adhesive, not during it.

A rubber dam isolating two posterior teeth
A rubber dam isolating the two teeth to be restored, with the margins visible.
Clinical tip

When a margin sits below the gingiva, a retraction cord placed before the dam often makes the difference between a visible margin and a guess.2

When the dam is not an option

Some patients cannot tolerate a dam, and some teeth cannot hold a clamp. The alternatives are not equal, but they are not nothing: cotton rolls changed often, a dry-field device, a saliva ejector positioned by an assistant, and a shorter working time.

Document the method chosen. A later failure is easier to understand when the record says how the field was kept dry.

Key takeaway

Isolation is part of the adhesive protocol, not a step before it.

Plan it with the case, place it before the etch, and keep it until the last layer is cured.

Further reading

References

  1. Hitmi L, Attal JP, Degrange M. Influence of the time-point of salivary contamination on dentin shear bond strength of 3 dentin adhesive systems. Journal of Adhesive Dentistry. 1999;1(3):219–232.
  2. Wang Y, Li C, Yuan H, et al. Rubber dam isolation for restorative treatment in dental patients. Cochrane Database of Systematic Reviews. 2016;9:CD009858.