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Taking a good impression

The single biggest driver of a good result, and how to get it right, zones, principles, and the errors to avoid.

If there is one stage that determines the quality of a finished finger prosthesis, it is the impression. Capture it well and everything that follows, the fit, the proportion, the realism, has the foundation it needs. Capture it poorly and no amount of skill downstream fully recovers it. This guide covers what a reliable impression requires.

Why the impression matters most

The impression is the single biggest driver of the final result. It records the shape, contour and seating of the residual finger, everything the device is built around. A small error here is baked into every later step, so the time spent getting it right is the highest-value time in the whole process.

Capture all four zones

A complete impression captures four distinct zones, each doing a different job:

  • Residuum tip and contour, how the device caps the finger and how natural the end appears.
  • Surrounding tissue, so the device blends with the hand rather than sitting on top of it.
  • Transition edge, where silicone will meet skin; the make-or-break detail for realism.
  • Base and seating margin, which determines retention, how the device stays on.

The key principles

Four principles separate a reliable impression from an unreliable one:

  • Neutral position. Capture the hand relaxed and naturally positioned, never clenched or splayed, so the device suits how the hand actually rests.
  • No compression. Support without pressing. Pressure during set records a distorted, smaller residuum, the most common and most avoidable error.
  • Full set. Allow the material to set completely before removal; early removal springs the impression out of shape.
  • Inspect before finishing. Check for voids and distortion while the patient is still present, so you can recapture there and then if needed.
Want the full method? The complete impression technique is covered in the BioDigit clinician training. See the training →

The most common error

If you take one thing from this guide: the most common, most avoidable error is compression during set. Steadying the residuum with pressure feels natural, but it bakes a fault into every later step by recording a smaller, distorted shape. Support the hand from positions that do not load the impression surface, and if in any doubt, recapture before the patient leaves. A few extra minutes at this stage saves a remake later.

Where this sits in the process

The impression is one part of a method that also covers measurement, colour matching, acceptance and fitting. The BioDigit training teaches the full method for each, and the Fitting Guide and Chairside Checklist serve as references at the bench. This article is an overview; the training is where the technique is taught in full.

A note on scope

Technique aside, suitability and clinical decisions remain yours, governed by your registration and judgement. The method concerns how to capture and build the device well; whether and when to proceed is your call as the treating clinician.

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