Influence of different calcium chloride concentrations on the physicochemical properties of calcium silicate–based repair cements

DOI: https://doi.org/10.14436/2358-2545.16.1.e2626art2.oar

Submitted: 10/04/2026 | Revised and accepted: 22/04/2026

Contact address: Bruno Martini Guimarães — E-mail: bruno.guimaraes@unifal-mg.edu.br

How to cite: Malta MM, Antunes TBM, Pereira JS, Guimarães BM, Tartari T, Marciano MA. Influence of different calcium chloride concentrations on the physicochemical properties of calcium silicate–based repair cements. Dental Press Endod. 2026 Jan-Apr;16(1):e2626art2.oar.

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Marina Martelini MALTA — ORCID: 0009-0007-5509-033X

Thiago Bessa Marconato ANTUNES — ORCID: 0000-0001-6594-3948

Jennifer Santos PEREIRA — ORCID: 0000-0002-8763-3681

Bruno Martini GUIMARÃES — ORCID: 0000-0002-8604-4180

Talita TARTARI — ORCID: 0000-0003-4372-0158

Marina Angélica MARCIANO — ORCID: 0000-0001-6244-2531

1. State University of Campinas, School of Dentistry, Department of Restorative Dentistry (Piracicaba/SP, Brazil).

2. Federal University of Alfenas, School of Dentistry (Alfenas/MG, Brazil).

» The authors report no commercial, proprietary or financial interest in the products or companies described in this article.

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ABSTRACT

OBJECTIVES: Calcium chloride is a setting accelerator widely used in civil engineering. In parendodontic surgeries and root perforations, it may enhance cement hardening and reduce washout. Therefore, this study aimed to evaluate the influence of different calcium chloride (CaCl₂) concentrations on the physicochemical properties of the bioceramic cement CIMMO HP.

METHODS: CaCl₂ solutions were prepared at 10%, 15%, and 20% (n=6). For cement preparation, 0.43 g of CIMMO HP was mixed with 1.5 mL of each solution for 40 s. Setting time was assessed according to ISO 6876/2012 using metallic molds and a Gilmore needle applied at regular intervals until no surface indentation was observed. Solubility was determined by mass loss after 30 days of immersion in deionized water. pH was measured after 1, 7, 14, and 28 days. Data were analyzed by ANOVA and Tukey's test (p<0.05).

RESULTS: The 20% CaCl₂ group showed the shortest setting time (p<0.05), while the control had the longest (p<0.05). Solubility was higher in the 15% and 20% groups (p<0.05), whereas control and 10% showed lower values (p<0.05). All groups maintained alkaline pH, with no significant differences (p>0.05).

CONCLUSION: Calcium chloride effectively reduced the setting time of CIMMO HP; however, higher concentrations increased solubility. Thus, its use should be carefully optimized to improve handling without compromising material stability.

KEYWORDS: Dental cements. Calcium chloride. Chemical phenomena.

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INTRODUCTION

Mineral trioxide aggregate (MTA) is a calcium silicate–based cement, patented in 1995 by Professor Torabinejad,¹ composed of approximately 80% Portland cement, widely used in civil construction, and 20% bismuth oxide as a radiopacifier.² Initially, this material was indicated for retrograde filling in endodontic surgery; subsequently, its applications were expanded to include procedures such as pulp capping, pulpotomy, apexification, and the sealing of root perforations.²⁻⁶

MTA is a hydraulic cement highly tolerant to moisture from tissue fluids, as it requires the presence of water to initiate its setting reaction, which may take up to 28 days to be completed.⁴·⁷ The reaction between the powder and water initially results in the formation of a hydrated calcium silicate gel and calcium hydroxide, which, over time, transforms into a stable crystalline structure.⁸

Despite its favorable properties, conventional MTA presents clinical limitations, such as difficult handling, potential for tooth discoloration, and prolonged setting time.⁹ The extended setting time is considered a significant drawback¹⁰·¹¹ and is one of the reasons why, in certain clinical situations, the material is not used in a single-visit procedure.¹¹

In response to this limitation, the industry has developed alternatives with reduced setting time, such as Biodentine, a calcium silicate–based repair cement that incorporates calcium chloride in its liquid phase as a setting accelerator, reducing the setting time to approximately 9–12 minutes.¹² Calcium chloride is widely used in civil engineering due to its ability to accelerate the setting reaction of Portland cement.¹³

The incorporation of setting accelerators has gained clinical interest, as materials with faster hardening may minimize issues such as the "washout" effect, frequently observed in retrograde fillings during endodontic surgery and in extensive root perforations, where freshly placed cement, when in contact with fluids, may undergo early dissolution.¹⁴

Recently, the repair cements CIMMO HP and CIMMO HD have been introduced into the Brazilian market and have been widely used due to their cost-effectiveness. CIMMO HP is indicated for cases of incomplete root formation, revascularization, dental resorptions, retrograde filling in endodontic surgery, root canal obturation, and root perforations. CIMMO HD, in turn, is mainly indicated for root perforations, retrograde filling, and dental resorptions.

Considering that the addition of setting accelerators may influence properties such as pH and solubility, the present study aimed to evaluate the effect of different calcium chloride concentrations on the physicochemical properties of CIMMO HP, including setting time, pH, and solubility. Thus, it seeks to identify a concentration that may serve as a reference for optimizing bioceramic cements.

The hypothesis of this study is that higher calcium chloride concentrations reduce the setting time of calcium silicate–based cement.

MATERIAL AND METHODS

Calcium chloride (CaCl₂) powder (Dinâmica, Indaiatuba, SP, Brazil) solutions were prepared at concentrations of 10%, 15%, and 20% (w/v). For the 10% solution, 5 g of CaCl₂ were weighed using an analytical balance and dissolved in 50 mL of distilled water in a 100 mL beaker. Dissolution was performed under magnetic stirring (Fisatom 753A) at 1500 rpm for 5 minutes. For the 15% and 20% solutions, 7.5 g and 10 g of CaCl₂, respectively, were dissolved in 50 mL of distilled water following the same protocol.

For cement preparation, 0.43 g of CIMMO HP were mixed on a glass slab with 1.5 mL of the respective solution for each group. Mixing was performed for 40 seconds. A control group consisting of the cement mixed with water, without the addition of calcium chloride, was included in the study.

PHYSICOCHEMICAL TESTS

Sample size calculation

The sample size was estimated based on previous studies¹⁵·¹⁶. A power analysis was performed using G*Power 3.1,¹⁷ considering ANOVA for comparisons among multiple independent groups. A standard deviation of 0.44, a minimum detectable difference of 1.67, a statistical power of 80%, and a significance level of 5% were adopted. The calculation indicated a sample size of six specimens per group (n = 6).

Figure 1 illustrates the study groups and the tests performed.

Figure 1. Physicochemical tests performed and experimental groups of cements prepared with 10%, 15%, and 20% CaCl₂. Groups: CaCl₂ 10%, CaCl₂ 15%, CaCl₂ 20%. Tests: Setting time (n=6), Solubility (n=6), pH (n=6).

Setting time

After manipulation, the cements were placed into stainless steel rings (10 mm in diameter and 2 mm in height), positioned on a glass plate, in accordance with ISO 6876/2012, and maintained at 37°C and 95% relative humidity. A Gilmore needle (100 g with a cylindrical tip of 2 mm in diameter) was applied perpendicularly to the cement surface. The setting time was defined as the point at which no indentation was observed. Measurements were performed at 5-minute intervals.

Solubility

The methodology was based on Tanomaru et al.¹⁸ Freshly mixed cements were placed into resin rings (7.75 mm in diameter and 1.5 mm in height) fabricated by 3D printing (Anycubic Photon Mono 4K, Anycubic Technologies, Shenzhen, China) and positioned on a glass plate. A nylon thread was embedded in each specimen. A second glass plate, covered with a polyethylene film (50 μm), was pressed onto the cement and carefully removed to standardize the surface. Specimens were stored in an incubator for a period corresponding to 150% of the setting time at 37°C and 95% relative humidity.

After this period, the specimens were removed from the molds and their initial mass was measured using an analytical balance (Ohaus Adventurer AR2140, SP, Brazil). Each sample was then individually immersed in plastic containers with 7.5 mL of deionized water and stored for 30 days. Subsequently, the specimens were placed in a vacuum desiccator for 24 hours at 37°C for dehydration, and the final mass was recorded.

Measurement of pH

The pH of the cements was evaluated after 1, 7, 14, and 28 days of immersion. Samples were prepared in polyethylene tubes (10 x 1.6 mm) and immersed in containers with 10 mL of deionized water, then stored at 37°C and 95% relative humidity. Measurements were performed using a previously calibrated digital pH meter (Digimed, São Paulo, Brazil). The mean pH values were recorded for each group at each time point.

Statistical analysis

Data were initially subjected to the Shapiro-Wilk test for normality and Levene's test for homogeneity of variances. One-way ANOVA was then performed, followed by Tukey's post-hoc test for multiple comparisons. The significance level was set at 5% (p < 0.05).

RESULTS

Table 1 presents the results for setting time and solubility.

Table 1. Mean and standard deviation of setting time and solubility of the cements at different calcium chloride concentrations.

Groups	Setting time (min)	Solubility (%)
Control	33 ± 2.74ᴬ	2.0 ± 1.12ᴬ
10%	28 ± 1.37ᴮ	5.31 ± 3.6ᴮ
15%	29 ± 0.55ᴮ	5.10 ± 2.31ᴮ
20%	23 ± 1.72ᶜ	5.72 ± 1.67ᴮ

Different uppercase letters indicate statistically significant differences in setting time and solubility among groups (p < 0.05).

Setting time

The control group, without a setting accelerator, showed a significantly longer setting time than the other groups (p < 0.05). No significant difference was observed between the 10% and 15% calcium chloride groups (p > 0.05). The cement containing 20% calcium chloride exhibited the shortest setting time (p < 0.05).

Solubility

The control group and the 10% calcium chloride group showed the lowest solubility values, with no significant difference between them (p > 0.05). In contrast, the 15% and 20% calcium chloride groups exhibited significantly higher solubility values (p < 0.05), with no difference between them (p > 0.05).

Results for pH

Table 2 shows the pH results for all groups. The pH remained alkaline and above 11 at all evaluated time points for all groups, with a slight decrease from day 1 to day 28 (p < 0.05).

Table 2. Mean ± standard deviation of pH values of cement groups immersed in distilled water for 1, 7, 14, and 28 days.

CaCl₂ concentration	1 day	7 days	14 days	28 days
Controle	11.68 ± 0.05ᴬᵃ	11.51 ± 0.05ᴬᵇ	11.42 ± 0.03ᴬᵇ	11.38 ± 0.02ᴬᵇ
10%	11.65 ± 0.13ᴬᵃ	11.58 ± 0.11ᴬᵃ	11.19 ± 0.20ᴮᵇ	11.41 ± 0.14ᴬᶜ
15%	11.73 ± 0.06ᴬᵃ	11.64 ± 0.12ᴬᵃᵇ	11.43 ± 0.02ᴬᶜ	11.54 ± 0.05ᴬᵇᶜ
20%	11.71 ± 0.03ᴬᵃ	11.60 ± 0.06ᴬᵃᵇ	11.41 ± 0.02ᴬᶜ	11.52 ± 0.04ᴬᵇᶜ

Different uppercase letters indicate statistically significant differences in pH among groups within the same time period (p < 0.05).

Different lowercase letters indicate statistically significant differences among time periods within the same group (p < 0.05).

DISCUSSION

Setting time is one of the most relevant properties of calcium silicate–based cements, as it can directly influence their stability in clinical situations such as root perforations and retrograde fillings in apical surgery. In this context, calcium chloride has been used as a setting accelerator, contributing to reduced hardening time and minimizing the washout effect. However, the optimal concentration capable of improving this property without compromising other material characteristics has not yet been well established. Therefore, the present study evaluated different calcium chloride concentrations on the setting time and solubility of the cement. The results demonstrated that increasing the concentration influenced both properties, leading to the rejection of the null hypothesis.

Although calcium chloride has been widely used as a setting accelerator for over a century, its mechanism of action is not yet fully understood. Nevertheless, there is general consensus that CaCl₂ acts as a catalyst for the early hydration of calcium silicates, particularly tricalcium silicate (C3S) and dicalcium silicate (C2S). This effect is associated with the formation of a more porous and permeable calcium silicate hydrate (C–S–H) gel, which facilitates ion diffusion and accelerates the hydration process of cement particles. Consequently, a three-dimensional network responsible for material hardening is formed more rapidly, resulting in reduced setting time.¹⁹

Calcium chloride should preferably be incorporated into the liquid phase to ensure complete dissolution and homogeneous distribution within the material. For this reason, in the present study, CaCl₂ was added to the mixing liquid. Its incorporation as a powder may result in undissolved particles, compromising mixture uniformity and, consequently, the final properties of the cement. In conventional applications, particularly in civil engineering, CaCl₂ content is typically limited to no more than 2% by mass of the cementitious material, as higher concentrations may lead to undesirable effects, such as increased shrinkage, alterations in mechanical strength, and potential durability issues.

Although the CaCl₂ concentrations used in this study exceeded those typically recommended for civil engineering applications (≤2% by cement mass), higher levels were intentionally employed to investigate their effects on the physicochemical properties of the material within a dental context, where clinical conditions and material requirements differ substantially.²⁰

In endodontics, calcium chloride is present in commercial calcium silicate-based cements, such as BioRoot RCS and Biodentine, although its concentration is not disclosed by manufacturers. Several studies have incorporated CaCl₂ into experimental calcium silicate–based cements at concentrations of 15%,²¹ 10%,²¹⁻²³ 5%,¹¹·²⁴⁻²⁶ 3%²⁴ and 2%.²⁷ In the present study, a progressive reduction in setting time was observed with increasing CaCl₂ concentration, with the most pronounced effect at 20%. These findings are consistent with previous reports demonstrating a reduction in setting time following CaCl₂ addition.²³·²⁵·²⁷

The addition of calcium chloride increased cement solubility in a concentration-dependent manner. This behavior may be associated with microstructural changes, such as increased porosity and enhanced leaching of soluble components. These modifications may also promote water loss over time, contributing to drying shrinkage. Indeed, setting accelerators such as CaCl₂ have been reported to increase drying shrinkage and reduce mechanical strength in cementitious materials, which may compromise dimensional stability at higher concentrations.²⁰·²⁷

However, different findings were reported by Bortoluzzi et al.,²³ who observed a reduction in solubility with the addition of 10% CaCl₂ to Portland cement, which was attributed to a possible decrease in porosity. This discrepancy may be related to methodological differences between studies. Regarding pH, the present study did not show significant changes with increasing CaCl₂ concentration, in contrast to Bortoluzzi et al.,²³ who reported higher pH values at early time points followed by stabilization over time.

CONCLUSION

The addition of 20% calcium chloride resulted in the greatest reduction in the setting time of calcium silicate–based cements. However, increasing concentrations were associated with higher solubility, with no significant effect on pH values.

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Authors' contributions

Marina Martelini Malta (MMA) | Thiago Bessa Marconato Antunes (TBMA) | Jennifer Santos Pereira (JSP) | Bruno Martini Guimarães (BMG) | Talita Tartari (TT) | Marina Angélica Marciano (MAM)

Conception or design of the study: TBMA, MAM

Data acquisition, analysis or interpretation: TBMA, MMM, JSP, TT, BMG, MAM

Writing the article: MMM, TBMA, JSP

Critical revision of the article: BMG, TT, MAM, MMM, TBMA, JSP

Final approval of the article: BMG, TT, MAM, MMM, TBMA, JSP

Overall responsibility: MAM

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