Clinical reports have indicated that there occurs many bubbles on the surface of the gypsum model because of the hydrogen release from the addition silicon impression materials. Recently the products containing hydrogen absorber have been being
developed but not perfect yet. In this study, 4 type III dental stones(New Fujirock ; G.C., New Plastone : G.C., MG dental stone ; Maruishi, Suprastone : Kerr) was poured into the impression of detail-reproducing test block taken using
addition-type
silicones(Correct VPS ; J/P, Exafine ; G.C., Express ; 3M, Extrude; Kerr, Provil; Bayer, Reprosil; Dentsply) with the intervals of 0, 15, 30, 45, 60, 90, and 120 minutes. Gypsum model was removed from the impressions and the number of bubbles on
the
surface of casts was counted after 30 min. Ordinal numbers were given to the ranges of the number of bubbles like this, Score 0, 0, 1; 1~10, 2; 11~30, 3; 31~60. 4;61~100, 5; 101~200, 6; 201~40, 7; 401 or more
There was no bubble in Correct VPS impression poured immediately in MG dental stone and Extrude impression poured immediately in New Fujirock, New Plastone, and MG dental stone. Significant bubbles were appeared in Provil until 15 minutes (Score
1~3),
Reprosil until 30 minutes(Score 1~2), and Express until 45 minutes(Score 1~2) in all gypsum models(p<0.05). Express impression poured in Suprastone(Score 2) and New Platone(Score 4) had bubbles until 120 minutes(p<0.05). On the basis of this
study
it
can be concluded that not only hydrogen release but also compatibility with gypsum should be considered when using addition silicones.
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