Disinfection effect on tear strength of hydrophilic PVS impression materials

Polyvinyl-siloxane impression materials(PVS) have applications in a variety of indirect procedures in prosthodontics and restorative dentistry. Favorable handling properties, excellent patient acceptance and good physical properties have resulted in their popularity in dentistry.

Objectives: The specific aim of this study was to determine the efficacy of three disinfecting solutions and two disinfecting methods, either spray or immersion, on newer generation hydrophilic vinyl-polysiloxane and polyether impression materials and to validate that the disinfecting methods provide no negative impact on the materials through an evaluation of the tear strength (TS). As an important physical property(TS) could serve as a predictor of clinical performance by PVS materials

Methods: Four types of PVS and one type of polyether impression materials were used: Examix(GC America), Genie(Schein), Take1(Kerr), Aquasil (Dentsply) and Impregum(3M ESPE). All materials were Type III light-body consistency (ISO4823:2000). Three Types of disinfectants were used: Ecotru(parachlorometaxylenol 0.20%), Prospray(O-Phenylphenol 0.28%,O-benzyl-p-chlorophenol 0.03%) and bleach(Sodium hyprocholrite 5.52% diluted 1:10 with distilled sterile water). Testing included both spray and immersion disinfection processes (10 minutes of exposure). 525 specimens were made in a stainless steel mold (2.5 x 7.5 x 0.1 cm) and TS determined using the trouser test(ISO 34-1:2004) at 50 ± 5 mm/min. Comparisons were made between TS of controls and that of disinfected groups of each impression materials using a pairwise t-test (α = 0.05)

Results: Aquasil Ecotru Spray(AES) showed a statistical decrease in TS (p=0.04), both Genie Prospray Spray(GPS) and Genie Ecotru Spray(GES) showed a near statistical decrease in TS (p = 0.06) while Impregum Bleach Immersion(IBI) increased with a (p = 0.09). No other statistical differences were noted.

Conclusions: Within the limitations of this in-vitro study, other than the (AES) group, no tested disinfectant or disinfecting method provided a statistically significant difference on the tear strength of the hydrophilic elastomeric impression materials.