Page 28 - COS-FOD2015

Compend. Oral Sci:vol1(4);2015;21-31

Five impressions were made from the alumi- Prior to casting in Type IV die stone ((Velmix,
num master block using automixed polyvi- Kerr Italy Spa, Scafati, Italy), the impression

nylsiloxane impression material, light- and was dried using compressed air and left to
heavy-bodied (Examix™ NDS Injection Type stand at room temperature (23±1)ºC for 1 hour.
and Heavy Body, GC America Inc., Illinois, A non-perforated circular perspex tubing was
USA) in a customised tray made from perforat- then attached to the impression and the die
stone was mixed under vacuum according to
perforated circular perpex tubing. For each im-
the manufacturer’s instructions. The die stone
pression the light-bodied material was syringed
was then allowed to set for 1 hour at room tem-
into the grooves from one end to the other us-
perature. Each of the 5 impressions was
ing an intraoral tip. The material was pushed
poured 7 times until 35 die stones were ob-
ahead of the syringe tip to ensure no entrap-
tained. These die stones were randomly divided
ment of air until all the grooves and shoulder
into 5 groups (A, B,C, D and E) and later act as
areas were covered. The heavy bodied material
the master dies for making the impression us-
was then loaded into the tray. A polythene
ing all the test materials described in Table 1.
sheet was placed on top of the tray and dead
weights of 1,500 g (ISO 4823:2000) were
placed for 5 seconds and impression material

was allowed to set for 5 minutes.

Table 1. Impression materials used in this study

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