Assessment of Preference of Mixing Techniques for Impression Materials

Introduction: The effect of mixing techniques on the quality of final impressions has been shown in previous studies. Compared to the hand-mixing technique, the auto-mixing and the electronic-mixing techniques enhance the quality of impressions. Objectives: The objective of this study was to compare 30 dental undergraduate students preferences regarding the quality, quantity and duration of mixing (1)medium body polyether impression material and (2)putty viscosity silicone impression material using the electronic (Pentamix 3) mixing unit compared to the hand mixing technique; and (3)light body vinyl poly siloxanes (VPS) impression material using the auto-mix system (Garant) compared to a light body condensation-silicone mixed with the hand- mixing technique. Methods: Participants rated their level of preference using a scale from 1 to 5 for ease of mixing, control of loading, quality of mixing, level of cleanliness, accuracy of dosage, homogeneity, absence of voids or defects, amount of wasted material, effort to manipulate and overall rating. The duration of mixing and tray loading or injection of the material were also measured. Results: Comparisons 1 and 3 demonstrated a statistically significant difference (p<0.05) on the overall satisfaction of the participants regarding the mixing technique used. There was a great variability on the amount of material dispensed and there was a significantly (p<0.05) higher quantity of material wasted when the hand-mix technique was used. For all three comparisons there was a statistical significantly (p<0.05) longer period of time used to manipulate materials manually compared to the electronic and automix techniques. Conclusions: Under the limitations of this study it can be concluded that the electronic and the automix techniques are easier methods for mixing impression materials. Furthermore the electronic and automix techniques seem to minimize the waste of material in addition to provide a faster mixing. (This study was partially supported by 3MESPE, Seefeld, Germany)