Flow Profile of Regular and Fast-Setting Elastomeric Impression Materials Using a Shark Fin Testing Device NATHANIEL C. LAWSON, MS*, DENIZ CAKIR, DDS, MS † , LANCE RAMP, DMD, PhD ‡ , JOHN O. BURGESS, DDS, MS § ABSTRACT Statement of the Problem: Light-bodied impression materials with high flow over time are needed to capture preparation margins, particularly with impressions of multiple preparations. Purpose: The flow of five different impression materials (three vinyl polysiloxane, one polyether, and one hybrid) of two setting times (fast and regular) was compared over 30-second intervals. Materials and Methods: Flow was measured using a shark fin testing apparatus (3M ESPE, Seefeld, Germany). A weighted metal caste was suspended above a cup of impression material.The caste was dropped into the impression material, which displaced the material and caused it to flow into a triangular notch within the caste, creating a “shark fin.”The test was repeated for each specimen at 30-second increments.These shark fin molds were kept in an incubator to allow setting of the impression materials. After complete setting, the height of the “shark fin” was measured.The data were analyzed using separate two-way analysis of variance and Tukey’s HSD post hoc analyses to determine significant intergroup differences (p = 0.05). Results: Shark fin values differed significantly among materials and at each time interval (p = 0.05). Polyether impression materials produced the greatest flow when compared with the vinyl polysiloxane and hybrid materials. Conclusion: Based on the limitations of this study and the materials used, polyether impression material had a better flow profile compared with the vinyl polysiloxane and hybrid materials. CLINICAL SIGNIFICANCE An impression material must be selected based on the consistency and flow properties of the material, its setting time, anatomic aspects of the preparation, and speed of the operator. Impressions with deep subgingival margins and/or multiple preparations may be better captured with a polyether impression material. (J Esthet Restor Dent 23:171–178, 2011) INTRODUCTION I mpression material must have low viscosity to accurately record impression details such as the interproximal spaces, deep restorative preparations, and gingival crevices. Low viscosity allows better flow of the material, which is important for accurately capturing fine details of the preparation. 1 Vinyl polysiloxane impression materials are the most widely used materials for final impressions. 2 These materials are *DMD/PhD student, Department of Prosthodontics, University of Alabama at Birmingham, Birmingham, AL, USA † Instructor, Department of Prosthodontics, University of Alabama at Birmingham, Birmingham, AL, USA ‡ Associate professor, Department of Prosthodontics, University of Alabama at Birmingham, Birmingham, AL, USA § Assistant dean for clinical research, Department of Prosthodontics, University of Alabama at Birmingham, Birmingham, AL, USA ORIGINAL ARTICLE © 2011 Wiley Periodicals, Inc. DOI 10.1111/j.1708-8240.2010.00396.x Journal of Esthetic and Restorative Dentistry Vol 23 • No 3 • 171–176 • 2011 171