Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin: microcomputed tomography and scanning electron microscopy analysis

Abstract

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm(3), (0.053±0.002) mm(3), (0.003 6±0.001) mm(3) and (0.005 9±0.002) mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

Figure 1

Photomicrograph of apical root showing root end filling material adaptation to root dentin and the gutta-percha canal filling in sagittal view. (a) WMTA, white-colored mineral trioxide aggregate; (b) EWMTA, etched white-colored mineral trioxide aggregate; (c) GMTA, gray-colored mineral trioxide aggregate; (d) EGMTA, etched gray-colored mineral trioxide aggregate.

Figure 2

Reconstructed axial section images (at 0.5 mm each) showing absence of voids following treatment. (a–c) Treated with WMTA; (d–f) treated with EWMTA. Arrow indicates complete seal with no gap. WMTA, white-colored mineral trioxide aggregate; EWMTA, etched white-colored mineral trioxide aggregate.

Figure 3

Reconstructed axial section images (at 0.5 mm each). (a–c) GMTA group, showing presence of voids and incomplete adaptation of root-end filling material to dentin walls (solid arrow). (d–f) EGMTA group, showing absence of voids. GMTA, gray-colored mineral trioxide aggregate; EGMTA, etched gray-colored mineral trioxide aggregate.

Figure 4

SEM photomicrographs at the root apex in axial view, showing marginal adaptation and interface between each material tested and dentin walls. (a) EWMTA, etched white-colored mineral trioxide aggregate; (b) WMTA, white-colored mineral trioxide aggregate; (c) GMTA, gray-colored mineral trioxide aggregate; (d) EGMTA, etched gray-colored mineral trioxide aggregate. Solid arrow indicate the retrograde material; open arrow to the root dentin; triangle to the gap. SEM, scanning electron microscopy.

Figure 5

SEM photomicrographs in sagittal view, showing retrofilling material/dentin interface. (a, b) WMTA, gray without etch; (c, d) EWMTA, gray with etch. D, dentin; MTA, mineral trioxide aggregate; WMTA, white-colored mineral trioxide aggregate; EWMTA, etched white-colored mineral trioxide aggregate; SEM, scanning electron microscopy.

Figure 6

SEM photomicrographs in sagittal view, showing retrofilling material/dentin interface. (a, b) GMTA, white without etch; (c) EGMTA, white with etch. D, dentin; GA, gutta percha; MTA, mineral trioxide aggregate; GMTA, grey-colored mineral trioxide aggregate; EGMTA, etched gray-colored mineral trioxide aggregate; SEM, scanning electron microscopy.