Penetration of different impression materials into exposed dentinal tubules during the impression procedure

Adhesive restorations have been shown to guarantee excellent performance and longevity, although this comes with some disadvantages. Among these, the vulnerability of dentine to different agents has been widely evaluated. The aim of this study was to evaluate the possible penetration of impression materials into freshly cut dentine. Dentine from 27 teeth was impressed with polyether (Impregum Penta L) (nine teeth) and with polyvinyl siloxane (Aquasil Ultra LV) (nine teeth). The surface of nine teeth after the impressions were used as the control. Specifically, the extroflections caused by the imprinting of the dentinal tubules on the impression material, the so-called impression tags, were measured. Furthermore, the presence of the material inside the tubules was examined. Scanning electron microscopy analysis showed material tags for all of the experimental groups. The mean lengths (±SD) were 22.6 (±11.0) μm for polyether, 21.8 (±12.8) μm for polyvinyl siloxane and 11.3 (±7.0) μm for the tooth control, with mean diameters (±SD) of 2.8 (±0.5), 2.4 (±0.7) and 3.1 (0.7) μm, respectively. Fractal analysis showed fractal dimensions of 1.78 (±0.03), 1.77 (±0.03) and 1.71 (±0.03), respectively. These data demonstrated that the impression materials can remain inside the dentinal tubules, which can adversely affect the adhesive procedures.