Learn Orthodontics

Impression taking - Common problems

There are lots of possible errors when taking impressions. You need to assess your impressions as to whether they are suitable for the purpose or not. Impressions for study models must be high quality, showing ALL the teeth and the full depth of the sucli.

Alginate too stiff

Impression is difficult to seat and impression has a 'lumpy' appearance (arrowed)


Alignate too runny

This results in excess material running down the patient's throat

upper imp 2upper imp 4

Tray too small

Tray shows through alginate on both sides (arrowed)

bad 2

Alginate tearing away from tray

This can result in a distorted impression when cast

bad 6

Tray too far forward

bad 7a