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Year : 2005  |  Volume : 8  |  Issue : 2  |  Page : 7-11
Histological evaluation of calcium hydroxide and dentin bonding agent in direct pulp capping: - an in vivo study

Department of Conservative and Endodontics, SDMCDS, Dharwad, India

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Direct pulp capping remains an elusive dilemma in pulp therapy. The advent of new materials and the characterization of the role of bacteria in healing response have opened new avenues in direct pulp capping. In this study, four premolars indicated for orthodontic extraction were selected for pulp cupping. One group Bras capped with calcium hydroxide [DYCAL] and other group with dentin bonding agent [Prompt - L - Pop]. The teeth were extracted after one week and two weeks respectively and sectioned and observed . for histological response. Results showed that though both the groups showed odontoblastic activity and evidence of reparative dentin formation, The calcium hydroxide group showed better response. Mild inflammation was seen in both the groups. The results suggest that dentin bonding agents can be used as alternative direct pulp capping agents. However, further research is necessary.

How to cite this article:
Kilaru KR, Kidiyoor K H, Rao R N. Histological evaluation of calcium hydroxide and dentin bonding agent in direct pulp capping: - an in vivo study. J Conserv Dent 2005;8:7-11

How to cite this URL:
Kilaru KR, Kidiyoor K H, Rao R N. Histological evaluation of calcium hydroxide and dentin bonding agent in direct pulp capping: - an in vivo study. J Conserv Dent [serial online] 2005 [cited 2023 Sep 27];8:7-11. Available from:

   Introduction Top

Vital pulp therapy is one of the methods used to preserve vitality of pulp in conservative dentistry. Various materials such as calcium hydroxide and dentin bonding agents have been used. Calcium hydroxide has been the benchmark in direct pulp capping for numerous years now and is the standard against which newer materials are evaluated. The dual properties of high alkalinity and antibacterial action have made it the most popular and successful pulp capping agent [1] . However, Calcium hydroxide placed underneath restorations suffers from some inherent drawbacks like microleakage. Therefore, the need was felt to introduce dentin-bonding agents as an alternative to Calcium hydroxide [2] . There is little difference between both materials. -In the present study, we compared the efficacy of calcium hydroxide and dentin-bonding agents for direct pulp capping in an in vivo study using histological analysis.

   Materials and Methods Top

In the present in vivo study, two patients scheduled for orthodontic extraction of maxillary and mandibular premolars were selected. The patients were informed about the treatment plan and consent was obtained; the ethical committee approved the protocol.

The clinical procedure was as follows. In the first case mandibular second premolars (35 & 45) were selected to study the odontoblastic response to calcium hydroxide and dentin bonding agents. In the second case maxillary first premolar (14 & 24) were selected for the same. The teeth were anesthetized and access cavities were prepared on the occlusal surface using a No 301 air- turbine diamond bur under water spray coolant. After application of rubber dam, the pulp was exposed with an ISO 006 round bur with a diameter of 0.5 to 0.8mm, at low speed to limit the pulp injury as much as possible. The exposed pulp surfaces were rinsed with saline solution and dried, then treated with 0.5% Naocl (or) 3% H 2 O 2 for disinfection and to control bleeding [3] . After pulp exposure, one premolar in each case (35,14) was capped at the exposure site with calcium hydroxide cement (DYCAL). The cavity was then etched, dentin-bonding agent applied and restored with light cured composite. In the contra-lateral premolars (45, 24), the exposure site was capped with a single step self-etching primer and adhesive [Prompt - L - Pop] being careful not to increase the pressure on the pulp. The cavity was then restored with light cured composite. Extraction of teeth in first and second cases was scheduled after one and two weeks respectively, after confirmation of vitality of the teeth. After extraction, the teeth were immediately fixed in 10% buffered formalin and the roots of the teeth were cut with a diamond disc under heavy water spray. They were then decalcified using 20m1 of 5% nitric acid and 80m1 of 10% formalin. After decalcification, the specimens were processed and embedded in paraffin wax. Then, sections of about 4to5mm were obtained using semiautomatic soft tissue microtome. Staining procedure was performed using eosin and hematoxylin dye and the sections were observed under a Leitz Diaplan research microscope with the help of Wild MPS 48 camera at magnifications of 10x and 25x 3 .

   Discussion Top

Vital pulp therapy has once again come and prominence due to the latest innovations in the field of material science as well as preservation of pulp vitality. There is a constant endeavor to develop materials that will make vital pulp therapy more predictable and successful. For a long time calcium hydroxide has been the material of choice but newer concepts and research has prompted the use of materials like dentin bonding agents and mineral trioxide aggregate (MTA) [4],[5]

Traditionally, calcium hydroxide, by virtue of its dual properties of high alkalinity and antibacterial action, has been the most popular and successful pulp-capping agent. Calcium hydroxide with an alkaline pH of 11 to 12 is known to stimulate the activation of the alkaline phosphatase enzyme as well as the differentiation of undifferentiated mesenchymal cells of the pulp into odontoblast like cells [1] . Also, with the dissolution of calcium hydroxide into calcium and hydroxyl ions, calcium ions have mitogenic potential to improve migration, differentiation and mineralization. Hydroxyl ions induce high level of alkalinity for the division of cells, to act against inflammation and to play a role in the formation of reparative dentinal bridge. This makes calcium hydroxide a successful and predictable pulp-capping agent. [1],[2],[3]

However, it has certain inherent disadvantages like the high alkalinity that can elicit an intense inflammatory response, its gradual dissolution which can lead to the formation of tunnel defects and the etching procedure associated with resin-bonded restorations which might interfere with the chemistry of calcium hydroxide. Thus alternative materials were introduced to overcome these drawbacks [1],[3],[4] .

According to Brannstrom et al, success in direct pulp capping depends on prevention of microleakage [10] . Hence, the agents that seal and bond to the tooth structure started receiving more attention especially with the evolution of dentin bonding agents.

Dentin bonding agents are low viscosity resins that form micro- mechanical bonding to the tooth structure by penetrating the demineralized collagen meshwork and forming hybrid zones. This is to provide microleakage resistant barrier. Therefore, in line with Brannstrom's theory, dentin­bonding agents were proposed as pulp capping materials. However, they do suffer from certain drawbacks. The etching creates osmotic shrinkage of the odontoblasts. Also, organic solvents like ethanol or acetone can destroy odontoblastic processes. It has also been postulated that the unpolymerized part of resin is toxic to pulpal cells. The longevity of the bond and resistance to microleakage is not established [3],[4],[6],[7],[8].

Here we have used a sixth generation bonding agent [Prompt- L -Pop] which has the advantage of single step application with no separate etching, priming and bonding required. It eliminates the need for rinsing and drying of the cavity. In total etch system using phosphoric acid, the formation of a hybrid layer follows the demineralization of the dentine, in self- etching systems the demineralization and hybridization occur simultaneously. Additionally, as etch and rinse systems require a drying step after washing off the phosphoric acid, they come with the possibility of over drying and the consequent collapse of the collagen fibre network, which may prevent penetration of the adhesive. This cannot occur with the self- etch systems which do not require drying, as the acidic solution in not washed off. The effect of incorporation of the smear layer on the strength of the adhesive layer is not known [9] .

Therefore, in our study an effort was made to compare the potential of dentin bonding agents versus calcium hydroxide as direct pulp capping agents. The observations from the histological specimens obtained after one and two-week intervals yielded some interesting facts.

Firstly, the pulp capped with calcium hydroxide showed increased odontoblastic activity as well as evidence of reparative dentin formation at one and two weeks.

The pulp capped with dentin bonding agents showed odontoblastic activity and evidence of reparative dentin formation, to a lesser extent than the calcium hydroxide group {Preben H.B et al (2003) studied human pulp reactions to direct capping with dentin adhesives and calcium hydroxide cement and anticipated the use of dental adhesives as pulp capping agent [2]}. Mild Inflammatory cells were detected in both the groups. Antonio Scarano et al (2003) evaluated the effect of dentin bonding agents + calcium hydroxide on the cellular events that occur on the direct pulp exposures and reported that neither of the material used was toxic or biologically incompatible [3] .

The observations of our study point to the fact that while calcium hydroxide is a reliable material in pulp capping, dentin-bonding agents also appear to show promising results in this therapeutic modality. The evidence of reparative dentin formation and odontoblastic activity along with minimal inflammation indicates good response of the pulp to the dentin-bonding agent. Clinically, both the cases were asymptommatic with no post­operative discomfort.

Due to the short duration of study, the advent of newer materials in the market and procedural difficulties in in-vivo studies, further research is recommended on the use of dentin bonding agents as pulp capping materials.


At one-week, calcium hydroxide exhibited increased odontoblastic activity and evidence of reparative dentin formation. Mild Inflammatory cells were detected.

At one-week, dentin bonding agent exhibited lesser odontoblastic activity compared to calcium hydroxide group and reduced evidence of reparative dentin formation. Mild Inflammatory cells were detected.

At two weeks, calcium hydroxide showed numerous odontoblasts visible with increased activity of reparative dentin formation. Mild Inflammatory cells were detected.

At Two weeks, dentin bonding agent showed odontoblastic activity and evidence of reparative dentin formation to a lesser extent. Mild Inflammatory cells were detected

   Conclusion Top

The potential advantage of direct pulp capping with dentin bonding agents is that they provide improved seal of the exposure periphery for prevention of reinfection. Long term clinical trials are necessary before this treatment can be recommended but the initial results appear to be very promising.

Acknowledgements: -

My sincere thanks to the Departments of Orthodontia and Oral Pathology for help in the study by providing patients, tissue processing, slide preparation and photographs.

[Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6],[Figure 7],[Figure 8]

   References Top

1.Harold R. Stanley, Gainesville."Pulp capping: Conserving the dental pulp- can it be done? Is it worth it?" Ooo - 68: 628-639 - ,4989.  Back to cited text no. 1    
2.Preben Horsted-Bindslev, Valdas Vilkinis. "Direct capping of human pulp with a dentin bonding system or with calcium hydroxide cement." Ooo - 96: 591-600; 2003.  Back to cited text no. 2    
3.Antonio Scarano, Licia Manzon and Domencico Tripodi. "Direct capping with four different materials in humans: Histological analysis of odontoblast activity." Journal of Endodontics - Vol.29, No.11: 729-734; 2003.  Back to cited text no. 3    
4.Ay Segul Olmez, Nurhan Oztas and Feridun Barak "A histopathologic study of direct pulp capping with adhesive resins." 000 - 86:98-103; 1998.  Back to cited text no. 4    
5.Mercedes S.Dominguez, David E Witherspoon, James L."Histological and scanning electron microscopy assessment of various vital pulp­therapy materials." Journal of Endodontics - 29:324-333; 2003.  Back to cited text no. 5    
6.Y. Kitasako S. Inokoshi. "Short term reaction of exposed monkey pulp beneath adhesive resins." Operative dentistry - 23: 308 - 317; 1998.  Back to cited text no. 6    
7.Gary Unterbrink. "Direct pulp capping with a dentinal adhesive resin system: A pilot study." Quintessence international - vol 26: 765-770; 1995.  Back to cited text no. 7    
8.Y. Tsuneda T. Hayakawa. "A histopathological study of direct pulp capping with adhesive resins." Operative dentistry - 20: 223-229; 1995.  Back to cited text no. 8    
9.F.J. Trevor Burke."What's new in dentin bonding? Self-etch adhesives." Dental update - 31:580-589; 2004.  Back to cited text no. 9    
10.Martin Brannstrom . Dentin and Pulp in restorative dentistry.  Back to cited text no. 10    

Correspondence Address:
Krishna Rao Kilaru
Department of Conservative and Endodontics, SDMCDS, Dharwad
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-0707.42598

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]


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