Comparing the Dimensional stability of One-Step, Two Step and a modified Two Step Putty/Light Body Addition Silicone Impression Techniques at different time intervals of impression pouring- An In-Vitro Study

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Dr. Ankit Sharma, Dr Sarang Sharma, Dr Manish Kumar, Dr Nitin Rastogi, Dr Noor Addeen Abo Arsheed, Dr Chetan Sharma,


Introduction: Dimensional accuracy of an impression is a decisive factor for the success of fixed prosthodontic treatment, and the impression technique and the pouring of the impression at the convenience of operator is a critical factor affecting this accuracy.

Aim and Objective: The purpose of this in-vitro study was to evaluate the dimensional stability of the one-step, two-step putty/light-body, and a modified two-step impression technique poured at different time intervals.

Material and Method: A stainless steel master model with two abutments simulating full crown preparation was fabricated, and 30 impressions were made by using addition silicone impression material for each technique. Six impressions of each technique were poured at five different time intervals i.e. 15 minutes, 75 minutes, 24 hours, 48 hours and 7 days respectively. The data so collected was subjected to one-way ANOVA and Holm-Sidak multiple comparison tests.

Results: Significant difference was found between one-step & two-step and one-step & modified two-step impression techniques at all the time intervals considered (p<0.05). However, there was no significant difference between two-step and modified two-step impression technique at all the time intervals considered (p>0.05).

Conclusion: The casts made by using two-step and modified two-step impression techniques had clinically insignificant deviations from the master model even up to 7 days of delayed pouring. However, the casts made by using one-step impression technique had clinically significant deviations from the master model after 24 hours of delayed pouring.

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