Difficult impression appointment revisited

Following up on the difficult impression appointment from a previous post:

https://dental-tidbits.blogspot.com/2021/04/difficult-impression-appointment.html

The aim of preparation is to convert a difficult task to an easier one. The impression that I sent off that day turned out the be absolute rubbish and completely inappropriate for the final impression. 

I could approach the case with a clear head and cleaned the old impression off the tray and placed adhesive long before the appointment. This way there was enough time for the solvent to evaporate and the adhesive to be effective. 

I used light body PVS in every single cavity to block it out. I thought this would be difficult to handle but it was quite simple and if excess bled out of the cavity I could push it back in with an instrument. I had to change tips half way through because I was too slow in the placement and the material had early set half way through the blocking out. One thing I would change is to dry the teeth thoroughly before placement as they had saliva in them and the PVS didn't stick as well as it should have. It was a testament to the undercuts on these teeth that I had difficulty removing the PVS from the cavities. Use a probe to pierce the material and push it out the buccal or lingual aspect into the waiting suction. A single undercut in an impression will be fine as the material may flex around it or the material may tear off leaving the rest of the impression untouched. However, multiple undercuts around the arch will be too retentive and will overcome the adhesion between the tray and the impression material and debonding will occur.

I took the impression in alginate and it went without a hitch. Snap removal was essential to avoid distortion. There will be some difficulty as the patient wants to keep the canines now with a partial denture rather than an immediate full denture and I had blocked out the undercuts between the canines and premolars so the demarcation between the teeth is indistinct and so the adaptation of the denture to the canines will be impossible to get right. I plan to correct this in the reline.