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Table of Contents
Year : 2022  |  Volume : 5  |  Issue : 3  |  Page : 281-285

A comparative histological analysis of human pulp following direct pulp capping with propolis or biodentine

1 Lecturer in Oral and Dental Histology, Faculty of Dental Medicine for Girls, Al –Azhar University, Cairo, Egypt
2 Assistant Proffesor of Operative Dentistry, Faculty of Dental Medicine for Girls, Al –Azhar University, Cairo, Egypt
3 Lecturer of Orthodontic, Faculty of Dental Medicine for Girls, Al –Azhar University, Cairo, Egypt

Date of Submission26-Jun-2021
Date of Decision03-Mar-2022
Date of Acceptance18-Apr-2022
Date of Web Publication08-Jul-2022

Correspondence Address:
Nehad A Ahmad
Faculty of Dental Medicine for Girls, Al-Azhar University, Cairo
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jnsm.jnsm_74_21

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Introduction: Pulp exposure in permanent teeth conventionally has been treated with calcium hydroxide pulp capping. The purpose of this study was to evaluate the histological finding of healthy human pulp tissue after pulp capping using new materials, Biodentine (BD) and Propolis (Pr). Materials and Methods: Forty intact human premolars scheduled for extraction for orthodontic reasons were mechanically exposed. Teeth were divided into four groups of ten teeth each and capped with Pr and BD. The final restoration was done with glass ionomer restorative material. The teeth were then extracted on the 15th or the 45th day and subjected to processing for histological evaluation by an image analysis software. Results: Differences in inflammatory response and dentine bridge formation of the exposed pulp to the different materials. The BD group, at all evaluation periods, exhibited a thick newly formed reparative bridge of dentin that totally obliterating the site of exposure. At the exposure site, cell inclusions and mineralization, variable numbers of odontoblast-like cells, preserved pulp tissue, marked numerous collagen fibers, and blood vessels, were observed. On the other hand, the Pr group did not show any presence of dentin bridge or calcified material and intermediate to acute inflammation after the 15th day. On the 45th day, Pr showed an entire newly formed bridge of reparative dentin tissue, complete pulp degeneration with multiple edematous spaces, hyperemic blood vessels, vacuolated odontoblasts, extravasated red blood cells, multiple mineralized structures dispersed just underneath the dentin bridge and through the pulp tissue, and newly ill-defined odontoblasts. Conclusion: For pulp capping, BD has a better dentin bridge formation and pulp preservation than pr in the human teeth.

Keywords: Biodentine, dental pulp capping, propolis

How to cite this article:
Ahmad NA, Gad NA, Abdulmonaem MH. A comparative histological analysis of human pulp following direct pulp capping with propolis or biodentine. J Nat Sci Med 2022;5:281-5

How to cite this URL:
Ahmad NA, Gad NA, Abdulmonaem MH. A comparative histological analysis of human pulp following direct pulp capping with propolis or biodentine. J Nat Sci Med [serial online] 2022 [cited 2023 Feb 9];5:281-5. Available from: https://www.jnsmonline.org/text.asp?2022/5/3/281/350304

  Introduction Top

Maintenance of the vitality of dentino-pulpal organs is one of the basics of restorative and conservative dentistry. That is why conservative dentistry always recommends clinicians to try as much as possible to perform procedures that either keep the health and vitality of the dental pulp or grant a success and durability of exposed pulp healing.[1] Vital pulp therapy is described as a treatment that intends to maintain pulp tissue that was adversely affected but was not destroyed by caries or has been traumatized. Pulp capping is the most preservative and conservative procedure for the protection of the pulp from insult, and thus predisposes and results in healing.[2] Pulpal exposure, either iatrogenic or pathologic, requires direct pulp capping, which in turn, needs more invasive and costly treatment procedures. Many previous studies assessed the aspects that can enhance or compromise dental pulp healing.[3] In the past, eugenol and zinc oxide had the best outcomes after several comparative types of research on different capping materials. Then, calcium hydroxide (CaoH) was successfully applied due to its high biocompatibility.[4] Therefore, CaoH was considered the most convenient pulp capping agent for several decades. However, it has several disadvantages such as its high solubility, poor sealing ability to dentinal tubules in addition to the formation of multiple tunnel defects in the dentin bridge in close proximity to the material.[5] Such drawbacks necessitate the introduction of other materials with much lower side effects as mineral trioxide aggregate (MTA).[6] It can trigger a more rapid formation of dentine bridge which in turn is broader in thickness. Although, MTA has drawbacks such as poor handling properties, high cost, and longtime of setting.[7] Therefore, several materials have been developed to overcome the aforementioned disadvantages of both CaoH and MTA. A calcium silicate-based cement named Biodentine (BD) was introduced in 2011.[8],[9] BD possesses high levels of density, biocompatibility, stimulation of differentiation of undifferentiated pulp cells, and stimulation and promotion of dentine bridge formation. It also has fast setting time of about 12 min, in addition to its low porosity. In comparison to CaoH, BD had better mechanical and physical properties, higher sealing ability to dentine, higher density, and lower solubility.[10] Recently, a natural product, propolis (Pr) (Russian penicillin), was found to possess potent antibacterial, antiparasitic, antiviral, and anti-inflammatory properties.[11],[12] Flavonoids, phenolics, and various aromatic compounds are the main chemical constituents of Pr. In addition, Pr flavonoids have potent antimicrobial, antioxidant, and anti-inflammatory properties. It is also worthy mentioning that the production of prostaglandins, which play the key role in inflammatory response and their formation is much increased in inflamed tissue, is inhibited by Pr. It also supports the immune system by promoting phagocytic activities, stimulating cellular immunity, and augmenting healing effects. In addition, it contains elements such as iron and zinc, which are important for the synthesis of collagen.[13],[14] Hence, the purpose of this study was to evaluate the histological response of healthy pulp after pulp capping using either BD or Pr in the human teeth.

  Materials and Methods Top

Ethical approval

The protocol of this study was approved by the Ethical Committee at the Faculty of Dental Medicine for Girls, Al-Azhar University, Cairo, Egypt: Code: REC-PD-22-02.

Patients selection

The current study used forty healthy human premolars. Teeth were scheduled for extractions due to orthodontic reasons. They were selected from patients ranging from 15 to 25-year-old. All teeth were examined both clinically and radiographically to ascertain that the teeth are free from caries, trauma, and periapical and periodontal lesions. The status of the pulp was assessed by using thermal (hot and cold) and electrical pulp tests following isolation using rubber dam and local anesthetic procedure.

Cavity preparation

Class I cavity preparation was done. Cavities were prepared using sterile carbide fissure bur of diameter 0.8 mm (mm). Another round sterile carbide bur of 1.2 mm diameter was used to drill an exposure of about 1.2 mm at the center of the cavity pulpal floor. Bleeding at the exposure site was controlled by saline irrigation and sterile cotton pellet pressure. Then, the exposure site was sterilized using 5.2% of NaOCl solution. The cotton pellets were renewed till the complete hemostasis was established and the exposure site was dried by the use of a sterile dry pellet of cotton.

Classification of teeth

Forty teeth were used in this study were divided into four equal groups (I, II, III, and IV) n = 10.

Pulp capping procedure

In Group I and II, the exposed pulps were capped with BD. Both BD powder and liquid were mixed according to the manufacturer's recommendations in an automatic mixer (amalgamator) for 30 s. The putty-like mixture was dispensed on a mixing pad and applied to the cavity by an amalgam carrier. In Group III and IV, 100% Pr powder (Ecuadorian Rainforest LLC, USA) was mixed with 70% ethyl alcohol to a thick consistency on a paper pad with the aid of plastic spatulas. The mixture was carried to the exposure site in a metal carrier.

The remained cavity of all experimental teeth and whole cavities of the control teeth were filled with resin-modified glass ionomer (GC Corporation, Tokyo, Japan). Patients belonging to Groups I and III were asked about the presence of postoperative sensitivity or pain over 15 days, while patients belonging to Groups II and IV were asked the same over 45 days. Specimens from Groups I and III were extracted after 15 days, whereas teeth from Groups II to IV were extracted after 45 days under local anesthesia.

Histopathological evaluation

The teeth were fixed in 10% buffered formalin solution with a ratio of 1:50. After 2 weeks of fixation, the samples were decalcified using 17% ethylene diamine tetraacetic acid solution with pH = 7. The teeth were allowed to decalcify for 8 h (8.00 am to 4.00 pm). The decalcification solution was discarded at the end of the day; teeth were thoroughly washed with running tap water and were placed in formalin overnight. The teeth were removed from formalin, thoroughly washed and placed in the respective decalcification solution at 8.00 am the following day. The procedure was repeated routinely every day until the teeth were completely decalcified. After decalcification, the samples were dehydrated as usual and embedded in paraffin blocks. The blocks were sectioned in a buccolingual plane at 6-μm thickness. Sections were stained using hematoxylin and eosin (H and E) for histopathologic evaluation. The stained sections were evaluated using a light microscope. A digital camera was used to take photomicrographs. The used camera was attached to the light microscope by a C mount. The histopathological changes including the formation of dentine bridges, odontoblastic layers architecture in addition to the signs of inflammation, were evaluated.

  Results Top

Biodentine group

  • Dentin bridge formation: At all evaluation periods, the newly formed reparative dentin bridge closed the exposure site. Its thickness was thin after 15 days [Figure 1]a and thick after 1 month [Figure 2]a
  • A continuous reparative dentin was also observed with a variable thickness along the lateral wall of the pulp. A line of demarcation was seen between the primary and the reparative dentin; in addition, a layer of predentin was observed [Figure 1]b and [Figure 2]b. In [Figure 2]c, globular calcification was observed in predentin layer, dentinal tubules with normal appearance were observed
  • Pulp tissue: In Group I and II a preserved pulp tissue with mild inflammation as well as marked numerous collagen fibers were observed [Figure 1]b and [Figure 2]b, [Figure 2]c
  • Odontoblasts: After 15 days, some cells in the odontoblastic layer exhibited fatty degeneration [Figure 1]b. After 45 days, a newly formed continuous odontoblastic layer was seen in most spacemen. On the other hand, some of the cells in the odontoblastic layer were vacuolated along the lateral wall [Figure 2]b and [Figure 2]c.
Figure 1: (a and b) A photomicrograph of pulp capped with biodentin for 15 days showing: (a) Exposure area with capping material (M), dentin bridge (black arrow) (H and E, ×40). (b) Fatty degeneration of some odontoblastic cells (blue arrows), numerous collagen fibers (C), dilated vacant blood vessel (V), blood vessel with extravasated red blood cells (green arrow), inflammatory cell infiltration (white arrows), blood vessel engorged with blood (yellow arrows), predentin (black arrow), RD, primary dentin (D) and line of demarcation between primary and reparative dentin (red arrow) (H and E, ×40). RD: Reparative dentition

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Figure 2: A photomicrograph of the Biodentin group after 45 days showing: (a) The exposure site with the capping material (M) and a newly formed dentin bridge completely (D) closing the exposure site (H and E, × 40). (b) Fatty degeneration of odontoblastic layer cells (black arrows), intact odontoblastic layer cells outlined the pulp tissue on the other side (green arrow) edematous area (E), predentin (black arrow), RD, primary dentin (D) and line of demarcation between primary and reparative dentin (red arrow) (H and E, ×40). (c) Vacuolization of odontoblastic layer cells (black arrows), thick collagen fibers (white arrows), retained odontoblast (blue arrows), fibroblast and undifferentiation mesenchymal cells (thick yellow arrows), inflammatory cell infiltration (thin yellow arrows), edematous area (E), globular calcification in predentin layer (green arrows) and dentinal tubules (red arrows) (H and E, ×200). RD: Reparative dentition

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Propolis group

  • Dentin bridge formation: No dentine bridge formed after 15 days [Figure 3]a. After 45 days, a newly formed reparative dentin bridge was seen and in near vicinity to the exposure site
  • Reparative dentin and predentin layer were also seen in the lateral root canal walls [Figure 4]a
  • Pulp tissue: it maintained its normal structure, especially after 45 days, loose connective tissue with numerous hyperemic blood vessels
  • Inflammatory cells: scarce-to-mild inflammatory cells were found in scattered patterns in the pulp [Figure 3]b and [Figure 4]b, [Figure 4]c
  • Odontoblasts: Continuous intact odontoblastic layer cells outlining the pulp tissue were seen after 15 days [Figure 3]a. After 45 days, a mature long odontoblastic layer was seen along the lateral surface of the dentin [Figure 4]a and [Figure 4]b.
Figure 3: A Photomicrograph of pulp capped with propolis for 15 days showing: (a) The exposure area with capping material (M), no formed dentine bridge (H and E, ×40). (b) odontoblastic layer cells (black arrow), inflammatory cells (yellow arrow), many dilated vacant blood vessels (v) extravasated red blood cells (blue arrow), blood vessels engorged with red blood cells (green arrow) and tissue edematous (E) (H and E, ×40)

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Figure 4: A photomicrograph of pulp capped with propolis for 45 days showing (a) the exposure area with capping material (M), a newly formed dentin bridge (D) (H and E, ×40). (b) Intact odontoblastic layer cells (black arrow), chronic inflammatory reaction (white arrow), thick bundles of collagen fibers (yellow arrow), predentin (green arrow), and dentin (*) (H and E, ×100). (c) Vacuolization of odontoblastic layer cells (black arrows), retained odontoblast (yellow arrows), thick bundles of collagen fiber (blue arrows), and chronic inflammatory cells (green arrows) (H and E, × 200)

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  Discussion Top

Preservation of pulp vitality is the prime requisite for vital pulp therapy, especially direct pulp capping procedure that aims at maintaining a healthy and vital pulp via stimulation of the formation of a protective barrier triggered after the placement of a certain type of dental biomaterial that is known as a pulp capping agent.[15] For several decades, the pulp capping agents that were mostly used over the exposure site was conventional or resin-modified CaoH-/oxide-based materials. A treatment modality that was preferred by most of the clinicians as a result of the continuous leaching of calcium ions that aids in the formation of dentine bridge at the exposure site. However, the use of such materials did not last more due to the adverse effects that were discovered as a result of its usage such as the presence of tunnels in the dentine barrier, extensive dentine formation obliterating the pulp chamber, high solubility in oral fluids, lack of adhesion, and degradation after acid etching.[16] A variety of materials, as a result of these limitations, have recently been proposed, such as BD, which is commonly used as pulp capping materials. Recently, a natural product, Pr has shown to possess potent antimicrobial and anti-inflammatory properties which inhibit the creation of prostaglandins.[17] Furthermore, it contains elements, such as iron and zinc, which are essential for the synthesis of collagen.[18] The clinical criterion is insufficient for an evaluation of the long-term prognosis for teeth treated by pulp capping. It is impossible to clinically diagnose teeth, in which healing is complicated by inflammation. Therefore, a critical evaluation of the results of pulp capping can only be made histologically.[17] This study revealed a histopathological analysis of the human pulp response to direct capping with Biodentine and Pr. In the current study, BD cement induced early reparative dentinogenesis because of the physicochemical properties of these materials that enhance the mineralization process. The thickness of the dentin bridge was thin after 15 days and become thick after 45 days. In the BD group, the dentin bridge with normal pulp was observed in all teeth after 45 days. In most teeth of the BD group, odontoblasts were arranged just below the dentin bridge with some structural changes. These cells were not true odontoblasts but odontoblast-like cells having an elongated shape and palisade orientation. These findings are consistent with other studies.[18],[19],[20] Odontoblast-like cells produce an extracellular matrix that becomes a complete dentin bridge after mineralization. The thickness of the dentin bridge and the pulp preservation depends on the amount of odontoblast-like cells. With increased layers of these cells, the thickness of the dentin bridge is increasing, and the pulp remains vital.[21] This encouraging therapeutic action of BD cement might be attributed to a considerable release of transforming growth factor β1 in the pulp cells that stimulates the odontoblasts to increase their activity and enhances the reparative dentinogenesis. Similar findings were reported in several previous studies.[22],[23],[24] In the present study, specimens capped with Pr exhibited less inflammation on both the 15th and 45th days. This could be related to the anti-inflammatory property of Pr. Flavonoids and caffeic acid present in Pr are known to play an important role in reducing the inflammatory response by inhibiting the lipoxygenase pathway of arachidonic acid. Flavonoids and caffeic acid also aid the immune system by promoting phagocytic activities and stimulating cellular immunity. The stimulation of various enzyme systems, cell metabolism, circulation, and collagen formation could contribute to the hard tissue bridge formation by Pr. These effects have been shown to be the result of the presence of arginine, Vitamin C, provitamin A, B complex, and trace minerals such as copper, iron, zinc, and bioflavonoids.[25] All these factors assist in faster healing of the wound. In addition to its wound healing ability, Pr is a good antimicrobial agent. It breaks down the bacterial cell walls and cytoplasm and prevents bacterial cell division.[26] While in the Pr group, presenting layer, reparative dentin, and new odontoblasts were recorded. These findings were considered an improvement in the pulp healing process. Finally, the results of this biological study are in concurrence with the chemical–physical and mechanical properties of the BD and tech biosealer capping (TBC).[27] The main limitations of this study were the small sample size used and the relatively short time of evaluation. Therefore, this study suggests more extended investigations on a large sample size to address the specifications and influences of the TBC on the dental pulp cells and their reparative capability to form the dentin bridge. Under the circumstances of this study, BD has a better therapeutic outcome than the Pr after the pulp capping procedure. Therefore, further studies are recommended to evaluate.

  Conclusion Top

The BD has a better early dentin bridge formation and pulp preservation than Pr after direct pulp capping. The late response of pulp to Pr as a pulp capping agent was comparable to BD in human teeth.

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Conflicts of interest

There are no conflicts of interest.

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