Mix quality and dispensing rate for two automatic mixing units

Objectives: Dental professionals expect an automatic mixing unit to quickly deliver an impression material to either a tray or an intraoral syringe. Speed is important as impression materials have a finite working time. The counterbalance to speed is the homogeneity of the mix of the base and catalyst paste. A homogenous mix is critical in ensuring consistent, high quality impressions. The objective of this study is to compare the mixing quality of Pentamix™2 to that of the new Pentamix™3 which offers a dispensing rate 2 times faster than that of its predecessor and mixes either VPS or polyether impression materials.

Methods: Five samples of polyether impression material (3M ESPE, Impregum™ Penta™ Medium Body) were mixed with Pentamix™ 2 (3M ESPE; P2) and with the Pentamix™ 3 (3M ESPE; P3). After the material had polymerized, the distribution of the two different colored paste components (catalyst and base) was measured with a spectrometer (Ocean Optics, S2000) and a lens system enabling a spacial resolution of 0.1mm. The samples were moved in the focus of the lens on a zigzag course in an area of 2x8mm by two linear axis. During this movement, the a-value of the Lab color system was recorded by a data logger (113 values in ~6.5 minutes per run, per sample). The standard deviation of the a-value of each sample was used as the measurement of mix quality.

Results: The mean and standard deviations (in brackets) for color values by device was: P2: 0.24 (0.060), P3: 0.24 (0.042). Two Sample T-Test and CI showed that the standard deviation of the color values of the samples mixed with P3 do not differ from the ones mixed with P2 (P-value 0.963).

Conclusion: P3 enables a dispensing rate 2 times faster than that of P2 with the same high quality material mix.