The effect of sandblasting distances on the shear bond strength of a self-etch and total-etch adhesive system to cervical dentin in the gingival wall of Class II restorations

Abstract

Background: This study aimed to examine the effect of sandblasting on the shear bond strength (SBS) of two adhesive systems on cervical dentin in the gingival wall of Class II restorations at two different distances.

Materials and methods: In this in vitro study, 88 intact premolars were used. After creating a natural smear layer, samples were divided into self-etch (CLEARFIL LINER BOND F) and total-etch (Adper Single Bond 2) groups (n = 44). Each group was subdivided into subgroups (n = 22) for sandblasting at 5 mm or 10 mm, with the contralateral half as control. Following sandblasting (50-μm particles, 2 bar, 2 s), the resin composite was bonded to the dentin surface, with the SBS of the samples measured using a universal testing machine. The samples were examined using a scanning electron microscope (SEM) and analyzed by an energy dispersive X-Ray (EDX). The results were analyzed using three-way repeated measures analysis of variance and Chi-square tests (α = 0.05).

Results: Sandblasting significantly reduced the SBS in both adhesive groups (P < 0.001). However, the adhesive system and distance did not significantly affect the bond strength (P > 0.05). The SEM images displayed the formation of irregularities in the smear layer, and EDX analysis revealed the presence of residual alumina particles on the blasted dentin samples.

Conclusion: Cervical dentine sandblasting reduced the adhesive SBS regardless of the 5- or 10-mm distance or the adhesive system used. Thus, sandblasting is not recommended as a method of dentin preparation before restoring cervical lesions.

Keywords: Air abrasion; dental; dental bonding; dental cavity preparation; dental restoration; permanent.

Figure 1

Shear bond strength (MPa) of the experimental and control groups of the study and according to the adhesive used and sandblast distance (mm)

Figure 2

Frequency distribution (%) of fracture type on the control side of the study groups (color figure)

Figure 3

Frequency distributions (%) of fracture type on the sandblasted side of the study groups (color figure)

Figure 4

Image of two sandblasted groups in different magnifications: (a) sandblasted at a distance of 5 mm with ×300; (b) sandblasted at a distance of 10 mm with ×300; (c) control surface with ×300; (d) sandblasting at a distance of 5 mm with ×5000, The white arrow points to microcracks in the underlying dentin structure; (e) sandblasting at a distance of 10 mm with ×5000; (f) control surface with ×5000

Figure 5

SEM image of the samples from the lateral view with ×1000: (a) sandblasted group from a distance of 5 mm with H-acid etch surface preparation; (b) nonsandblasted group from a distance of 5 mm with acid etch surface preparation; (c) sandblast group from a distance of 5 mm with acid primer surface preparation (white arrow); (d) non-sandblast group from a distance of 5 mm with acid primer surface preparation; (e) sandblast group from a distance of 10 mm with acid etch surface preparation; (f) non-sandblast group from a distance of 10 mm with acid etch surface preparation; (g) sandblast group from a distance of 10 mm with acidic primer surface preparation, Sandblasting particle penetration (white arrow); (h) nonsandblast group from a distance of 10 mm with acid primer surface preparation, Penetration depth 2 µ (white arrow)

Figure 6

Energy dispersive X-ray (EDX) diagram of experimental (a and b) and control group (c): (a) EDX diagram of 5 mm sandblasted group; (b) EDX diagram of 10-mm sandblasted group; (c) EDX diagram of control group

Figure 7

SEM image of extra samples (control group) from the surface view at ×1000: (a) control group with acid etch surface preparation, scattered smear layer, and some extent of smear plugs (white arrow); (b) control group with acid primer surface preparation, closure of the dentinal tubules (white arrow)

Figure 8

SEM image of extra samples (experimental group) from the surface view: (a) sandblasted group from a distance of 5 mm with acid etch preparation; (b) sandblasted group from a distance of 5 mm with acidic primer preparation; (c) sandblasted group from a distance of 10 mm with acid etch preparation, microcracks (white arrow); (d) sandblasted group from a distance of 10 mm with acidic primer preparation

Figure 9

EDX diagram of the extra samples (sandblasting groups): (a) self-etch group at 5 mm distance; (b) total-etch group at 5 mm distance; (c); self-etch group at 10 mm distance (d) total-etch group at 10 mm distance