Light body or wash impression materials are often employed to record sub-gingival tooth margins. Thin portions of these impression materials are very thin and susceptible to tearing upon removal from the mouth. Marginal tearing jeopardizes impression accuracy that is critical for restorative dentistry. Resistance to marginal tearing is affected by tear strength of impression materials. Objective: This study measures the tear strength of eleven elastomeric impression materials and a polyether material (Impregum/3M ESPE) 90 seconds after the recommended mouth removal time. Methods: Tear strength specimens (101.6mm X19.05mm X2.7mm; n=40) were prepared using Boghosian axial-notched molds to produce samples with two film thicknesses of approximately 0.50mm and 0.30mm. Impression material was injected into the mold, and after 20 seconds, the mold was placed in a water bath (35±1°C). The specimens were removed from the water at the manufacturers' recommended mouth removal time (MRT), 90 seconds after which, they were demolded and loaded in tension until failure at 500mm/min using Instron (Model#3366). The maximum tensile force and surface area across which it was applied were used to calculate the tear strength. Data were analyzed using ANOVA and Tukey/Kramer tests(α=0.05). Results: Within the limitations of the study, statistically significant differences were observed between competitive materials and Aquasil Ultra Cordless Tissue Managing Wash Impression Material showed higher tear strengths among the tested materials.
Impression Materials
| Tear Strength (MPa/Mean±SD) | |
0.50mm
| 0.30mm
| |
Aquasil Ultra Cordless TMIM Wash-Multi (Tissue Managing Impression Material)/DENTSPLY
| 3.73±0.37
| 3.49±0.32 |
Aquasil XLV/DENTSPLY
| 2.94±0.27
| 2.68±0.23 |
Imprint4 Ultralight/3MESPE | 1.88±0.13
| 1.52±0.22 |
Imprint4 Lightbody/3MESPE | 2.47±0.22
| 2.04±0.27 |
Imprint3 Light body/3M ESPE
| 2.93±0.24
| 3.02±0.15 |
Take1 Advanced Light/KERR
| 1.88±0.25
| 1.64±0.22 |
Flexitime Correct Flow/Heraeus-Kulzer | 1.82±0.22
| 1.73±0.14 |
Impregum Soft Lightbody/3M ESPE | 1.20±0.15
| 1.26±0.16 |
Genie Extralight body/SULTAN | 2.52±0.25
| 2.40±0.30 |
Exa'lence Lightbody Fast-set/GC-AMERICA | 2.22±0.22
| 2.26±0.22 |
TMIM Tray/DENTSPLY(Control)
| 3.69±0.43
| 3.53±0.37 |
Conclusion: Early higher tear strength is very important consideration for clinicians while selecting impression materials.