Tensile Strength of Novel Experimental Hydrophilic Vinyl Polysiloxane Impression Materials Compared to Control and Commercial VPS Impression Materials

Shahab Ud Din; Nouman Noor; Sadaf Humayoun; Sadia Khalid; Sandra Parker; Mangala Patel

Shahab Ud Din Department of Oral Growth and Development (Dental Physical Sciences Unit), Bart’s and The London School of Medicine and Dentistry, QueenMary, University of London, UK
Nouman Noor Rawal Institute of Health Sciences (RIHS), Islamabad
Sadaf Humayoun Rawal Institute of Health Sciences (RIHS), Islamabad, Pakistan
Sadia Khalid Dentistry and Allied Disciplines, Shaheed Zulfiqar Ali Bhutto Medical University (SZABMU), Pakistan Institute of Medical Sciences (PIMS), Islamabad
Sandra Parker Department of Oral Growth and Development (Dental Physical Sciences Unit), Bart’s and The London School of Medicine and Dentistry, QueenMary, University of London, UK
Mangala Patel Department of Oral Growth and Development (Dental Physical Sciences Unit), Bart’s and The London School of Medicine and Dentistry, QueenMary, University of London, UK

Keywords: Impression materials, vinyl polysiloxane (VPS), Tensile strength

Abstract

Objective: To measure the tensile strength of novel experimental hydrophilic (medium bodied) vinyl polysiloxane impression materials developed from ab initio in comparison to control and commercial vinyl polysiloxane impression materials. Materials and Methods: This experimental study was conducted at the Department of Oral Growth and Development, Bart’s and The London School of Medicine and Dentistry, Queen Mary, University of London, UK from 1st Oct 2010 to 28th February 2014. Five novel experimental (medium bodied) VPS impression materials (Exp-I, II, III, IV and V) were developed and evaluated for their effect as crosslinking agent and surfactant on the tensile strength and percent elongation-at-break in comparison to control and three commonly used commercial (medium bodied) VPS impression materials (Aquasil Ultra Monophase, Elite HD Monophase, Extrude. These properties were evaluated using Tenius Olsen (mechanical testing machine).
Results: Aquasil Ultra Monophase (Aq M) had a significantly higher Ultimate Tensile Strength (UTS) compared to all commercial and Experimental VPS. Although Exp-III showed the lowest UTS among all the materials but this was only significant for Aq M. On comparing Exp-I (control) with Exp-II, after adding TFDMSOS into Exp-II there was a slight, but not significant, increase in UTS. After adding the surfactant to hydrophilic Exp-III, IV and V, the UTS decreased slightly, but not significantly, compared to Exp-II. After addition of cross-linking agent (TFDMSOS) there was a significant increase in elongation-at-break of Exp-II compared to the control (Exp-I), which was further significantly increased after incorporating the surfactant (Rhodasurf CET-2) in the Exp hydrophilic VPS formulations (Exp-III, IV and V). Elongationat-break was significantly increased after incorporating the surfactant (Rhodasurf CET-2) in the Exp hydrophilic VPS formulations (Exp-III, IV and V) compared to Exp-II.
Conclusion: All Exp VPS had significantly higher % elongation-at-break (more than double) than commercial VPS. Percentage elongation-at-break further increased significantly after adding Rhodasurf CET-2 (Surfactant).