First impressions count: how to take a primary impression

An impression can be loosely defined as a mark that has been impressed onto a surface. This relatively broad definition reminds us of the versatility with which impressions are used within dentistry. It is often helpful to categorise impression types by clinical stage, as outlined in Table 1.

Clinical stages of impressions

The primary impression is arguably one of the most critical procedures within clinical dentistry. While it does not require the same level of technical skill as many other clinical procedures, the primary impression will often underpin a series of subsequent technical and clinical stages—many of which can be made more efficient and effective if appropriate time and effort has been dedicated at the beginning. This article does not consider primary impressions for completely edentulous arches.