Comparing effectiveness of mineral trioxide aggregate, bioceramic putty and tannic acid in maintaining pulp vitality after experimental pulpotomy in rats

Abstract

This study aimed to evaluate and compare the effectiveness of mineral trioxide aggregate (MTA), bioceramic putty (BP) and tannic acid (TA) for experimental pulpotomy. Our in-vivo experimental study involved sample of 45 rats that were randomly divided into 4 groups: Group 1 (subdivided into negative (1-A) and positive (1-B) subgroups), Group 2 (MTA treated), Group 3 (BP treated) and Group 4 (TA treated). 4 weeks post pulpotomy, specimens were analyzed histologically, immunohistochemically using dentin sialoprotein marker, and histomorphometrically by assessing the thickness of newly formed dentin bridge. Group 1-B showed pulp necrosis without hard tissue formation. Group 2 showed moderate dentin formation while group 3 presented a thick layer of calcific barrier. Group 4 showed dentin bridge formation, however, irregular pulp calcifications and radicular pulp necrosis were seen. The thickness of newly formed dentin bridge showed a significant difference between group 1-B and group 2, 3 &4. Significant difference was found between group 2&3 and group 3&4. Dentin sialoprotein immunohistochemical expression was negative in group 1-B, mild in group 2, strong in group 3 and moderate in group 4. MTA and BP proved to be effective pulpotomy agents with BP being superior. For TA, further studies are required to explain the recorded unfavorable effects in some specimens.

Fig. 1

Photo micrographs demonstrating light microscopic evaluation of study groups. (A) Group 1-A showing normal pulp zones with distinct regularly arranged odontoblastic layer (OB) separated from tubular dentin (TD) by a well-defined predentin layer (PD). The pulpal capillaries (CAP) demonstrated no congestion. (B) Group 1-B showing huge areas of dead pulp tissue (black asterisk) with a moderate to severe inflammatory reaction in the radicular pulp (red asterisk). OD: old dentin. C& D: Group 2; (C) Showing formation of a thick layer of tubular dentin (TD) as well as areas of osteodentin (OsD). No definite odontoblastic zone (OB) or predentin layer was detected. Moderate pulpal capillary congestion (arrows) was seen. (D) Another specimen showed formation of a thinner layer of atubular dentin (AD) and indefinite pulp zones (asterisk). (E) Group 3 showing a thick layer of newly formed calcific barrier in the form of a layer of atubular dentin (AD) followed by tubular dentin (TD). Distinctive pulp zones with mild inflammatory infiltration and moderate capillary congestion (red asterisk) were seen. PD: predentin, black asterisk: distinct odontoblast-like cells, green asterisk: remaining BP material. F& G: group 4; (F) Showing dentin bridge formation (atubular dentin (AD) followed by osteodentin (OsD)). Irregular pulp calcifications were seen (arrows). No definite pulp zones could be detected. Green asterisk: remaining TA material. (G) In one specimen, radicular dentin resorption (arrows) and pulp necrosis (red asterisk) were seen. (H&E stain, original magnification ×400).

Fig. 2

Photomicrographs displaying immunolocalization of dentin sialoprotein (DSP) in different study groups. (A) Group 1-A showing positive expression of DSP within the matrix of predentin layer (PD, black arrows) together with nuclear immunostaining within the odontoblast cells (white arrows). (B) Group 1-B shows negative immunohistochemical expression of DSP. (C): Group 2 shows positive mild expression of DSP within some areas of the newly formed osteodentin (OsD, black arrows). (D,E): Group 3 illustrating strong DSP reaction within the dentin-pulp complex. It involves predentin layer (PD) (black arrows) and odontoblast-like cells (white arrows). (F): Group 4 depicts moderate immunostaining only in discrete areas within the newly formed osteodentin layer (black arrows) together with some stromal cells (black arrowhead) (dentin sialoprotein immunostaining counterstain with Mayer’s hematoxylin., original magnification ×400).

Fig. 3

Showing statistical analysis of the thickness of newly formed dentin bridge between different groups using ANOVA and Tukey-test.