Objective: This study was to compare 30 graduate students in prosthodontics and operative dentistry with regard to mixing impression materials. Variables investigated included the quality, quantity and duration of mixing, amount of wasted material, and preferences of the professors.
Method: Evaluation was divided into 3 groups. The first group compared medium-body polyether impression material (Impregum Soft, 3MESPE) mixed by hand and with an electronic mixer (Pentamix3). The second group compared putty-viscosity c-silicone impression material (Speedex, Coltene) mixed by hand and a vinyl poly siloxane impression material (VPS) (ExpressXT PuttyPenta, 3MESPE) with an electronic mixer (Pentamix3). The third group compared light-body VPS (ExpressXT, 3MESPE) mixed with the auto-mix system (Garant) and a light-body condensation-silicone material (Speedex, Coltene) mixed by hand. The mixing process for each participant was timed and the amount of wasted material was measured. Participants completed a survey at the conclusion of the mixing exercises regarding preferences. Mean values were compared within participant groups with paired t test (a=.05).
Result: Overall preference of the electronic and auto-mixing techniques were statistically significantly higher than hand-mixing technique (p<.05). There was a great variability on the amount of material dispensed. There was a statistically significantly higher amount of material wasted when the hand-mix technique was used (p<.05). For all three comparisons there was a statistical significantly longer period of time used to manipulate materials manually compared with the electronic and automix techniques.
Conclusion: Under the limitations of this study it can be concluded that the electronic and the automix techniques are preferred methods for mixing impression materials. Furthermore the electronic and automix techniques seem to minimize the waste of material in addition to providing a faster mixing. (This study was supported by 3MESPE, Seefeld, Germany)
Keywords: Dental materials, Impression materials, Mixing technique and Prosthodontics