IADR Abstract Archives

Impression Material Tear Strength Before and After Recommended Setting Time

Impression Material Tear Strength Before and After Recommended Setting Time

Clinically, if impression materials are removed from the mouth prior to the manufacturer's recommended setting time, thin portions of the impression might be susceptible to tearing.

OBJECTIVES: This study measures the tear strength of two light-bodied polyvinyl siloxane materials (Aquasil Ultra and Imprint 3) and a polyether material (Impregum) before, during, and after the recommended setting time. 

METHODS: Tear strength specimens (n=6) were prepared using a notched plexiglass mold to produce samples with a 0.1mm film thickness. Impression material was injected into the mold, and after a 1minute working time, the mold was placed in a 35±1C water bath.  Specimens set for 3 additional minutes and were then loaded in tension until failure at 500mm/min using an Instron testing device. The test was repeated after waiting additional 30second intervals in the water bath.  The maximum tensile force and the surface area across which it was applied were used to measure the tear strength of each specimen.  Data were analyzed with ANOVA and Tukey/Kramer tests (alpha=0.05).

RESULTS:   A two-way ANOVA showed significant differences between materials and setting times.  The Tukey/Kramer test showed that: Aquasil Ultra had no significant differences in tear strength before and after the recommended set time and Imprint 3 and Impregum had significantly lower tear strength before the recommended set time and significantly higher tear strength after the recommended set time. 

Total Set Time (min:sec)

Aquasil Ultra

Imprint 3

Impregum

4:00

5.53±1.11

3.14±0.94

1.08±0.30

4:30

6.51±1.57

*5.97±0.91

*1.52±0.13

5:00

*7.07±0.98

6.36±0.79

1.84±0.11

5:30

8.35±1.73

7.76±1.06

1.93±0.14

*indicates recommended set time

CONCLUSION: Our study shows that some elastomeric impression materials have a lower tear strength before the recommended setting time and increased strength after this time.  Clinicians should leave impression materials in the oral cavity for the recommended setting time at minimum.

Supported in part by T32DE017607


AADR/CADR Annual Meeting
2010 AADR/CADR Annual Meeting (Washington, D.C.)
Washington, D.C.
2010
240
Dental Materials 7: Polymer-based Materials-Physical Properties and Performance
  • Lawson, Nathaniel  ( University of Alabama at Birmingham, Birmingham, AL, USA )
  • Ramp, Lance C.  ( University of Alabama at Birmingham, Birmingham, AL, USA )
  • Cakir, Deniz  ( University of Alabama at Birmingham, Birmingham, AL, USA )
  • Beck, Preston  ( University of Alabama at Birmingham, Birmingham, AL, USA )
  • Burgess, John  ( University of Alabama at Birmingham, Birmingham, AL, USA )
    • Poster Session
    Impression Materials
    03/04/2010