Mechanical Properties of Monophase Impression Materials

Objective: The purpose was to compare mechanical properties of the monophase consistency of several addition silicone (AS), polyether (PE) and hybrid (H) elastomeric impression materials. Methods: Pants tear energy (Webber RL, Ryge G: J Biomed Mater Res 1968; 2:281-296), strain in compression (ISO 4823) and elastic recovery (ISO 4823) were determined. Split pant tear specimens were 0.85 mm in thickness. All specimens were prepared in aluminum molds pre-heated to 37°C and cured until the end of the specified setting time in a water bath at 37°C. Specimens were tested (Instron 5866) at 5 minutes after the start of mixing. Data were analyzed by one-way ANOVA and Fisher's PLSD test at the 0.05 level of significance. Results: Means of tear energy (J/m²), strain in compression (%), and elastic recovery (%) with standard deviations in parentheses (n=8) are listed. There were no statistical differences among the materials with the same superscripted letters (p=0.05).

Material	Tear Energy, J/m2	Strain in Compression, %	Elastic Recovery, %
AS - Aquasil Ultra Monophase fast set	1380 (70)	3.78 (0.26)	99.37 (0.12)
PE - Impregum Soft	1000 (50)	2.70 (0.19)b	98.29 (0.06)e
PE - Impregum Penta Soft Quick Step	910 (80)	2.80 (0.15)bc	98.35 (0.10)e
PE - P2 Polyether Magnum 360 Monophase	720 (30)a	4.19 (0.14)d	98.73 (0.10)
AS - Exafast NDS Monophase	700 (120)a	2.91 (0.09)c	99.66 (0.01)g
AS - Affinis Monobody	700 (70)a	3.43 (0.05)	99.55 (0.05)f
AS - Flexitime Magnum 360 Mono Phase	660 (50)a	2.46 (0.03)	99.58 (0.02)fg
H -Senn Monophase Type	440 (45)	4.20 (0.12)d	99.13 (0.09)
Fisher's PLSD Interval (p=0.05)	70	0.19	0.10

Conclusions: An addition silicone and two polyether impression materials had significantly better tear energy than the other products tested. Elastic recovery was high for all materials with highest values for addition silicones. Supported in part by 3M ESPE.