Impression defects at margins (drag, voids, pulls)
What it is
A conventional elastomeric impression (or the light-body "wash" around the prep) that shows marginal voids/bubbles, tears, or drag/pull lines near the finish line — so the exact margin is not accurately recorded and the crown risks being fabricated with an inaccurate fit. Impression defects (especially voids/bubbles) are commonly reported findings across impression techniques.
Why it happens
• Fluid contamination at the margin (blood/saliva/crevicular fluid) preventing material from flowing and reproducing fine detail → voids/incomplete margin reproduction • Tray movement during polymerization (or repositioning after seating) → characteristic drags/pulls in VPS materials; VPS flow decreases quickly after mixing, so movement during early setting is a frequent cause • Working time exceeded / delayed seating → flowability is already impaired when the tray is inserted, increasing the risk of pulls and incomplete margin reproduction • Technique issues in putty-wash / dual viscosity procedures (air entrapment while syringing, poor wash adaptation, inadequate sulcular access) → bubbles/voids and marginal defects
The full clinical mistake entry includes
- How to avoid it — the prevention protocol
- The clinical tip experienced clinicians use
- The documented reference behind the mistake
More clinical mistakes
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