Influence of Dentine Pre-Treatment by Sandblasting with Aluminum Oxide in Adhesive Restorations. An In Vitro Study

Abstract

Dentine pretreatment through sandblasting procedures has been widely studied but no curve test results are currently available. Thus, the aim herein was to in vitro compare the adhesive strength in sandblasted or not samples using a universal testing machine. Thirty -two bovine teeth were divided into two groups, namely test (n = 16 bars), sandblasting with aluminum oxide particles (50 µm) was performed before the adhesion procedures), and control (n = 16 bars), where no sandblasting procedure was performed. A bi-material curve test was used to evaluate the characteristics of the dentine pretreatment in terms of tensile stress and fracture strength. A scanning electron microscope (SEM) was used to analyze the fracture topography in the composite, bonding, dentin, and at the relative interfaces. The results demonstrated a statistically significant difference between the two groups in terms of tensile stress at maximum load showing values of 84.300 ± 51.342 MPa and 35.071 ± 16.609 MPa, respectively for test and control groups (p = 0.033). Moreover, a fracture strength test showed values of 18.543 ± 8.145 MPa for test and 8.186 ± 2.833 MPa for control group (p = 0.008). In conclusion, the sandblasting treatment of the dentine significantly influenced the mechanical resistance of the adhesion in this in vitro study.

Keywords: adhesive dentistry; dentine pretreatment; fracture resistance; in vitro study; sandblasting procedure; tensile stress test.

Figure 1

Sample preparation: (a) Detail of the crown’s cross section Shift reagent stained. Please note that this staining bonds the organic component highlighting the areas made up of dentin; (b) Dentine bars, size 2 × 2 × 8mm. (c) Sample mounted on the traction machine.

Figure 2

Notches creation: (a) The red arrows indicate the pre-crack areas; (b) Comparison between Conventional Test and bi-material Curved Test. In Curved Test, notches (created both on the dentine and composite sides) will be the pre-cracks from which the two fracture lines originate.

Figure 3

The graph shows the values of the two groups at Breaking Stress and at Maximum Load Stress.

Figure 4

Scanning electron microscope (SEM) of Group 1 (Test) and Group 2 (Control): (a) SEM image of Group 1 at 80 × magnification. The fracture involved dentin with several direction changes; (b) SEM image of Group 2 at 80 × magnification. The fracture involved both dentin and the composite with direction changes; (c) Detail of Group 1 (interface) at 500 × magnification; (d) Detail of Group 2 at 500 × magnification.

Figure 5

Scanning electron microscope images: (a) of Group 1 at 1.00K × magnification. At the interface there are no detachments; (b) SEM image of adhesive part, in detail observe the Hackle lines; (c) SEM image of Group 2 at 1.00K × magnification; it is shown a clear failure at the interface between dentin and adhesive; (d) 1.00K × magnification of both composite and dentin. sides.