• Users Online: 610
  • Home
  • Print this page
  • Email this page

 Table of Contents  
Year : 2023  |  Volume : 13  |  Issue : 1  |  Page : 29-32

Light-cured calcium hydroxide cements release of calcium ions using argon based induction coupled mass spectroscopy - an in vitro study

1 Department of Conservative Dentistry and Endodontics, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat, India
2 Department of Conservative Dentistry and Endodontics, Ahmedabad Dental College and Hospital, Ahmedabad, Gujarat, India

Date of Submission13-Jun-2021
Date of Decision09-Jul-2021
Date of Acceptance28-Oct-2021
Date of Web Publication12-May-2022

Correspondence Address:
Sidharth S Menon
Department of Conservative Dentistry and Endodontics, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2045-9912.344976

Rights and Permissions

Calcium ion-releasing ability of different calcium hydroxide-based pulp capping materials was comparatively evaluated in this study. Different brands of cements were taken from different manufacturers and categorized into three groups. Three different brands of Ca(OH)2 cements (Dycal, TheraCal, and Cal LC) were taken prepared by mixing and curing the cements as per the manufacturer’s instructions. Consequently, ion release was measured after 7, 14, and 21 days by argon-based induction coupled plasma mass spectroscopy test. Within the limitations of this study, light-cured Ca(OH)2 cements released a higher amount of calcium ions compared with self-cured Ca(OH)2 cements. Theracal was found to be the highest light-cured calcium ion releasing materials throughout the period of 21 days. In conclusion, further clinical studies are warranted to substantiate the findings of this study.

Keywords: calcium ion; indirect pulp capping; TheraCal; Ca(OH)2; Dycal; Cal LC; vital pulp therapy; pulp

How to cite this article:
Menon SS, Sanghvi Z, Chokshi S, Patel P, Trivedi P, Patel N. Light-cured calcium hydroxide cements release of calcium ions using argon based induction coupled mass spectroscopy - an in vitro study. Med Gas Res 2023;13:29-32

How to cite this URL:
Menon SS, Sanghvi Z, Chokshi S, Patel P, Trivedi P, Patel N. Light-cured calcium hydroxide cements release of calcium ions using argon based induction coupled mass spectroscopy - an in vitro study. Med Gas Res [serial online] 2023 [cited 2022 Aug 17];13:29-32. Available from: https://www.medgasres.com/text.asp?2023/13/1/29/344976

  Introduction Top

Vital pulp therapy has been the mainstay of restorative dentistry since time immemorial and has reiterated its significance with duly fulfilling esthetic, functional and psychological needs of the patients. Different strategies have been used for vital pulp therapy, namely indirect or direct pulp capping and pulpotomy with the former being the minimally invasive and most viable option. With the advent of new bioactive materials and biomimetic approach towards dentistry pulp capping procedure has reclaimed its significance like never before and has shown tremendous potential with respect to preservation and protection of pulp vitality respectively. The protective biomaterials should have specific properties such as biocompatibility, biointeractivity (biologically relevant ions releasing), and bioactivity (apatite forming ability) to activate the pulp cells and the formation of reparative dentin.[1] Calcium hydroxide has been the longest in service pulp capping agent with successful treatment outcomes along with extensive follow-ups supporting its usage. The primary action of any pulp capping agent is to achieve antibacterial effect and reparative dentin formation which determines the success of the procedure. Calcium hydroxide achieves its pulp capping actions dominantly by elution of calcium ions.[2],[3],[4] However, the mechanism of how calcium ions are released remains elusive.

Numerous studies have proposed that elution components from pulp capping agents, especially calcium ions, play a definitive role in reparative dentin formation via osteoblast differentiation, modulation of osteopontin and bone morphogenetic protein 2 levels[6] and the documented antibacterial efficacy,[7] which makes this ion become an indispensable entity for pulp capping procedures. Also the release of calcium ions and the fast formation of apatite may well explain the role of pulp capping agents as a scaffold to induce new dentin bridge formation and clinical healing.[4] Traditional self-cured Ca(OH)2 cement (Dycal, Dentsply Caulk, Milford, DE, USA) is soluble, raises alkalinity, and forms a necrotic layer at the material-pulp interface. It also has greater chances of microleakage and clinical setting of this material in the presence of blood and oral fluids raising valid questions regarding its efficient usage.[1] Light-cured Ca(OH)2 cements on the other hand impart friendly benefits for practitioners. Newer light-cured agents containing calcium trisilicate compounds have been shown to release calcium ions.[1] There is an increasing need for current pulp capping material to be evaluated on its calcium releasing ability for positive and consistent clinical outcomes.

So the above-mentioned factors and respective reasoning formed the basis of our study. Hence, the aim of the study was to compare the calcium release of two light-cured Ca(OH)2 cements (Cal LC and Theracal) and self-cured cements Ca(OH)2 (Dycal).

  Materials and Methods Top

Mold preparation

Cylindrical molds measuring 3 mm in diameter and 1.5 mm in height dimension of polyvinylchloride were prepared for the study. The specimens were made by mixing and curing three batches of Ca(OH)2 cement. They were then filled in standard mold (polyvinylchloride) sizes of 3 × 1.5 mm2. The specimens were prepared by mixing and curing three Ca(OH)2 cements (Self-cured Ca(OH)–Dycal (Dentsply Caulk, Milford, DE, USA) Theracal (BISCO, Chicago, IL, USA) light-cured Ca(OH)2 and light-cured Ca(OH)2-Cal LC (Prevest Denpro Ltd., New Delhi, India) according to manufacturer’s instructions and were filled in molds of standardized dimensions and each group contained 10 specimens.

Specimen preparation

For Group I specimen in this group was by mixing in equal proportion of base i.e. titanium dioxide and barium sulfate in glycol disalicylate and catalyst (i.e. 1:1), i.e. calcium hydroxide, zinc oxide and zinc stearate in ethyl toluene sulphonamide to a condensable consistency with plastic spatula on oil impervious paper-pad. For Group II (calcium trisilicate) and Group III (urethane dimethacrylate, triethylene glycol dimethacrylate, silanated barium glass, amorphous fumed silica, barium sulfate, calcium hydroxide), they were prepared by dispensing the cement from the syringe and bulk light cured with the light-emitting diode probe vertically placed as close as possible to the specimen for 20 seconds as recommended by the manufacturer, the different cement pastes were placed into the plastic molds (3 mm in diameter and 1.5 mm in height). Each mold was placed on the bottom part of a standard test tube, which was filled with de-ionized water. The water was collected for analysis according to the predetermined periods. Each filled mold was placed on the bottom of the standard test tube which was filled with 15 mL of de-ionized water at 37°C. The stored water was collected for Ca analysis and replaced after 7, 14, and 21 days respectively.


After each time interval 5 mL of calcium sample from each group was carried for analysis and quantification by argon-based induction coupled plasma mass spectroscopy (A600, Shimadzu, Osaka, Japan) test and the values calibrated in the designated parts per million (ppm) units.

In the present study, a simulated intrapulpal pressure of 0.29 kPa was produced by the addition of 0.1 mL HNO3 within a test tube of 15 mL deionized water (3 cm H2O) to achieve calcium quantization up to two decimal places before the analysis respectively.

Statistical analysis

Calcium ion release at various time durations from all the groups was measured and mean along with standard deviation was calculated. These values were compared using two-way repeated analysis of variance and Tukey’s post hoc test under SPSS20 (IBM, Armonk, NY, USA).

  Results Top

The results of our study showed that all the materials we evaluated are calcium ion releasing. Light cured Ca(OH)2 cements were proved to release significantly more calcium ions during all the test periods when compared with Dycal group [Table 1].
Table 1: Calcium ion release (part per million) of three groups

Click here to view

  Discussion Top

To improve the handling properties of conventional calcium hydroxide cements, resin-based cements containing calcium hydroxide were developed. These materials are light-cured, highly resistant to etchants, present superior physical properties, and handling characteristics.[8] So, two such materials namely Cal LC (Prevest Denpro) and Theracal (Bisco) were the experimental groups in this study respectively where Cal LC is a light-cured radiopaque calcium hydroxide paste which is composed of urethane dimethacrylate, triethylene glycol dimethacrylate, silanated barium glass, amorphous fumed-silica, barium sulfate and calcium hydroxide, and Theracal LC is a unique light-cured, radiopaque, dentin adhering liner and base material containing calcium hydroxide and calcium hydroxyapatite in a urethane dimethacrylate base. It is a highly filled resin with minimal shrinkage and water absorption unlike conventional Ca(OH)2 cements making it more compatible as a part of routine dental practices.

Theracal being the current material has its considerable bioactivity connected with the presence of silanol groups and resin groups that are able to promote the formation of calcium phosphate deposits. In this study, light cured Ca(OH)2 materials showed high biointeractivity (ion release) and bioactivity with high open pore volume (i.e., porosity). The internal network of high open pore volume provides a large surface area for the leaching process.[9] The high amount of calcium ions released from TheraCal can be related to the presence of a calcium silicate component in a hydrophilic monomer, making it uniquely stable and durable. The faster hydration reaction of TheraCal LCs resulted in low solubility and high calcium release during the early few hours.[9]

Mineralized tissue formation due to contact of Ca(OH)2 and connective tissue has been observed from the 7th to the 10th day after application.1 The complete antibacterial activity takes place in 7 days by Ca(OH)2, and the slight inflammation induced by Ca(OH)2 is resolved in 14 days.[4] Even though the recommended application period for the Ca(OH)2 is 4–5 weeks, it is reported that 4–5 weeks of Ca(OH)2 application causes necrosis of the normal cells. Thus, the time period of 7, 14, and 21 days for calcium ion release measurement in this study allows to gauge the action of Ca(OH)2 emulating its usage in clinical setting.

Specimens of 3 × 1.5 mm were used in the present study to simplify the process and avoid the washing-out of the test material during immersion in deionized water and for exposing the entire surface to light-emitting diode curing tip.[1],[10] Also the normal tip of light-emitting diode curing unit is 15 mm and cures to the depth of 2 mm effectively1 thus justifying the chosen dimensions for the study.

Deionized water at neutral pH was chosen for specimen immersion to obtain accurate measurements of ion release without ion contamination from the immersion liquid.[10] Since the study evaluates the calcium ion release a neutral liquid medium was deemed necessary and replaced distilled water which was the choice of medium in previous studies.

Different methods are available for evaluating calcium ion release they are ethylenediaminetetraacetic acid titration method, induction coupled plasma-mass spectrophotometry, atomic absorption spectrophotometry, and potentiometer. Ethylenediaminetetraacetic acid titration method is both technique and operator sensitive with risk of over and under-estimation of calcium ion with high interferences.[11] Induction coupled plasma-mass spectrophotometry has matrix effects and high cost of instrumentation as its disadvantage[12] and potentiometer does not show the same capacity of calcium ion detection as spectrophotometer.[13] Argon based Induction coupled plasma mass spectroscopy testis a holistic method used to measure the release of calcium ions, i.e., argon gas used to detect the ionized elements released in an atomized liquid medium providing linear correlation with actual calcium concentration and real-time values. This method allows reproducibility along with continuous monitoring.[14],[15],[16] Hence, was elected as the testing method for this study.

The findings of calcium ion release in our study were not comparable to recent studies because the experimental protocols were different and justified by the respective methodology chosen by the authors of their studies,[9],[10],[11],[17],[18],[19],[20] which signified that cements containing resin components need to be cured and this causes a reduction in the release of calcium ions and also attributed calcium ion release to the additional hydroxyapatite crystals in the tooth itself rather than the pulp capping agent through their respective potentiometric and randomized control histological analysis which was in contrast to the results of our study.

The results of this study showed that the resin portion in the light cured Ca(OH)2 cement (containing hydrophobic and hydrophilic monomers) can promote calcium and OH ion release within the wet area on the tooth pulp and/or dentin and favored the interaction with the hydrophilic tooth dentin.[9],[10],[19],[21],[22],[23],[24]

In the present study, a simulated intrapulpal pressure of 0.29 kPa produced by the water in the cylindrical containers (3 cmH2O) was used. Normal pulp has a pressure of 1.5 Pa (15 cmH2O) and inflamed pulp of 3.5 Pa (36 cmH2O).[25],[26],[27] A bare minimum pressure was chosen to prevent dissolution of the released ions and ease out their measurement by the ion-selective probes. A minimum intrapulpal pressure allows the movement of ions towards the pulp via dentinal tubules, whereas the ionic elution from the materials is eventually reduced respectively.

Both the control and experimental groups tested for the study were found to be calcium ion releasing. Light-cured Ca(OH)2 cements released more calcium ions than the Dycal whereas the Theracal group showed significant higher values throughout the 21 days study period and in all time periods respectively.

Furthermore studies are needed to study the mechanism of the relationship between eluted media and odontoblast differentiation[28],[29],[30] and toxicity of these materials at histological and cellular levels which ultimately determine the quality of dentin bridge formation in the presence of biological fluids glorifying the true status of these ions in pulp capping agents which may unravel its yet to explore potential and utilization of those findings to achieve the best of clinical outcomes and tissue healing feasible respectively.

Within the limitations of the present study, it can be concluded that:

  1. All light cured Ca(OH)2 cements released calcium ions in comparison to conventional Ca(OH)2 cements despite addition of resin monomers and inherent shrinkage associated with it.
  2. Also the calcium ion release of light-cured Ca(OH)2 cements was found to be higher in all time periods of study than self-cured Ca(OH)2
  3. Among Theracal and Cal LC, Theracal significantly released higher calcium ions with respect to entire time period considered for the study which is credited to scaffold action (calcium trisilicate component) and faster hydration reaction rates.

However, further clinical trials are warranted to confirm these findings and the superiority of light-cured over conventional self-curing Ca(OH)2 based pulp capping materials.


We thank Gujarat Labotatory, Ahmedabad, Gujarat, India for the data analysis of the specimens.

Author contributions

All the authors has substantially contributed to the design and conduct of the study, manuscript preparation, analysis, and reporting of this study and approved the final manuscript for publication.

Conflicts of interest


Open access statement

This is an open access journal, and articles are distributed under the terms of the Creative Commons AttributionNonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

  References Top

Chaudhari W, Jain R, Jadhav S, Hegde V, Dixit M. Calcium ion release from four different light-cured calcium hydroxide cements. Endodontology. 2016;28:114-118.  Back to cited text no. 1
Schröder U. Effects of calcium hydroxide-containing pulp-capping agents on pulp cell migration, proliferation, and differentiation. J Dent Res. 1985;64 Spec No:541-548.  Back to cited text no. 2
Fitzgerald M, Chiego DJ, Jr., Heys DR. Autoradiographic analysis of odontoblast replacement following pulp exposure in primate teeth. Arch Oral Biol. 1990;35:707-715.  Back to cited text no. 3
Gandolfi MG, Siboni F, Botero T, Bossu M, Riccitiello F, Pratiù C. Calcium silicate and calcium hydroxide materials for pulp capping: biointeractivity, porosity, solubility and bioactivity of current formulations. J Appl Biomater Funct Mater. 2015;13:43-60.  Back to cited text no. 4
Kitasako Y, Ikeda M, Tagami J. Pulpal responses to bacterial contamination following dentin bridging beneath hard-setting calcium hydroxide and self-etching adhesive resin system. Dent Traumatol. 2008;24:201-206.  Back to cited text no. 5
Rashid F, Shiba H, Mizuno N, et al. The effect of extracellular calcium ion on gene expression of bone-related proteins in human pulp cells. J Endod 2003;29:104-107.  Back to cited text no. 6
Komabayashi T, D’Souza R N, Dechow PC, Safavi KE, Spångberg LS. Particle size and shape of calcium hydroxide. J Endod. 2009;35:284-287.  Back to cited text no. 7
Cox CF, Sübay RK, Ostro E, Suzuki S, Suzuki SH. Tunnel defects in dentin bridges: their formation following direct pulp capping. Oper Dent. 1996;21:4-11.  Back to cited text no. 8
Gandolfi MG, Siboni F, Prati C. Chemical-physical properties of TheraCal, a novel light-curable MTA-like material for pulp capping. Int Endod J. 2012;45:571-579.  Back to cited text no. 9
Shubich I, Miklos FL, Rapp R, Draus FJ. Release of calcium ions from pulp-capping materials. J Endod. 1978;4:242-244.  Back to cited text no. 10
Jeya Gopika G, Ramarao S, Usha C, John BM, Vezhavendhan N. Histological evaluation of human pulp capped with light-cured calcium based cements: a randomized controlled clinical trial. Int J Sci Rep. 2017;3:120-127.  Back to cited text no. 11
Nuttall KL, Gordon WH, Ash KO. Inductively coupled plasma mass spectrometry for trace element analysis in the clinical laboratory. Ann Clin Lab Sci. 1995;25:264-271.  Back to cited text no. 12
Duarte MA, Martins CS, de Oliveira Cardoso Demarchi AC, de Godoy LF, Kuga MC, Yamashita JC. Calcium and hydroxide release from different pulp-capping materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;104:e66-69.  Back to cited text no. 13
Sawhney S, Vivekananda Pai AR. Comparative evaluation of the calcium release from mineral trioxide aggregate and its mixture with glass ionomer cement in different proportions and time intervals - an in vitro study. Saudi Dent J. 2015;27:215-219.  Back to cited text no. 14
Frau I, Wylie S, Cullen J, Korostynska O, Byrne P, Mason A. Microwaves and functional materials: a novel method to continuously detect metal ions in water. In: Mukhopadhyay SC, Jayasundera KP, Postolache OA, eds. Modern Sensing Technologies: Springer International Publishing; 2019.  Back to cited text no. 15
Maeno S, Niki Y, Matsumoto H, et al. The effect of calcium ion concentration on osteoblast viability, proliferation and differentiation in monolayer and 3D culture. Biomaterials. 2005;26:4847-4855.  Back to cited text no. 16
Aureli F, Ciprotti M, D’Amato M, et al. Determination of total silicon and SiO(2) particles using an ICP-MS based analytical platform for toxicokinetic studies of synthetic amorphous silica. Nanomaterials (Basel). 2020;10:888.  Back to cited text no. 17
Clapham DE. Calcium signaling. Cell. 1995;80:259-268.  Back to cited text no. 18
Tronstad L, Andreasen JO, Hasselgren G, Kristerson L, Riis I. pH changes in dental tissues after root canal filling with calcium hydroxide. J Endod. 1981;7:17-21.  Back to cited text no. 19
Hosoya N, Takahashi G, Arai T, Nakamura J. Calcium concentration and pH of the periapical environment after applying calcium hydroxide into root canals in vitro. J Endod. 2001;27:343-346.  Back to cited text no. 20
Nekoofar MH, Adusei G, Sheykhrezae MS, Hayes SJ, Bryant ST, Dummer PM. The effect of condensation pressure on selected physical properties of mineral trioxide aggregate. Int Endod J. 2007;40:453-461.  Back to cited text no. 21
Arandi NZ. Calcium hydroxide liners: a literature review. Clin Cosmet Investig Dent. 2017;9:67-72.  Back to cited text no. 22
Arandi NZ, Rabi T. Cavity bases revisited. Clin Cosmet Investig Dent. 2020;12:305-312.  Back to cited text no. 23
Schenkel AB, Veitz-Keenan A. Dental cavity liners for Class I and Class II resin-based composite restorations. Cochrane Database Syst Rev. 2019;3:CD010526.  Back to cited text no. 24
Gandolfi MG. A new method for evaluating the diffusion of Ca(2+) and OH(-) ions through coronal dentin into the pulp. Iran Endod J. 2012;7:189-197.  Back to cited text no. 25
Kurun Aksoy M, Tulga Oz F, Orhan K. Evaluation of calcium (Ca2+) and hydroxide (OH-) ion diffusion rates of indirect pulp capping materials. Int J Artif Organs. 2017;40:641-646.  Back to cited text no. 26
Negm AM, Hassanien EE, Abu-Seida AM, Nagy MM. Biological evaluation of a new pulp capping material developed from Portland cement. Exp Toxicol Pathol. 2017;69:115-122.  Back to cited text no. 27
Park SM, Rhee WR, Park KM, et al. Calcium silicate-based bio-compatible light-curable dental material for dental pulpal complex. Nanomaterials (Basel). 2021;11:596.  Back to cited text no. 28
Pedano MS, Li X, Yoshihara K, Landuyt KV, Van Meerbeek B. Cytotoxicity and bioactivity of dental pulp-capping agents towards human tooth-pulp cells: a systematic review of in-vitro studies and meta-analysis of randomized and controlled clinical trials. Materials (Basel). 2020;13:2670.  Back to cited text no. 29
Jun SK, Cha JR, Knowles JC, Kim HW, Lee JH, Lee HH. Development of Bis-GMA-free biopolymer to avoid estrogenicity. Dent Mater. 2020;36:157-166.  Back to cited text no. 30


  [Table 1]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  In this article
Materials and Me...
Article Tables

 Article Access Statistics
    PDF Downloaded18    
    Comments [Add]    

Recommend this journal