Key Takeaways
- TheraCal LC is formulated without HEMA, ethanol, or MDP — components known to cause pulpal irritation or harm — by design.
- TheraCal LC turns alkaline immediately upon exposure to moisture, reaching a pH of approximately 10–11, creating an environment that supports pulpal healing.1,2
- Biocompatibility concerns in practice most often come from application errors, not the material itself. Following the instructions for use — visibly moist dentin, layers ≤1mm, light cure for 20 seconds — is essential.
Learn more about TheraCal LC and download the full product profile: bisco.com/theracal-lc/
If you've come across studies or forum discussions suggesting TheraCal LC shows cytotoxic behavior, you're not alone — and the concern is worth taking seriously. Resin-modified materials as a group have faced criticism for potential cytotoxicity, and clinicians managing direct pulp capping cases have every reason to scrutinize what they're placing near exposed pulpal tissue.
BISCO has spent over four decades building chemistry designed for clinical outcomes, and TheraCal LC is no exception. The material was engineered specifically to address the limitations of traditional liners such as calcium hydroxide, glass ionomers, MTA, and resin-modified glass ionomers (RMGIs) - including the very biocompatibility concerns that have followed resin-modified materials for years.
Here's a structured look at what the science actually shows, question by question.
Q: I've heard TheraCal LC is cytotoxic — is that true?
This is probably the most common concern, and it deserves a direct answer.
TheraCal LC has been specifically evaluated through published in vitro studies. An independent in vitro study using human dental pulp stem cells reported cell viability greater than 80% following exposure to material extracts, further supporting a lack of cytotoxic effects in a pulp-relevant cell model.3 Multiple additional published studies confirm biocompatibility when TheraCal LC is used according to its instructions for use (IFU).4
TheraCal LC has been evaluated for biocompatibility following the ISO 10993-1 (Biological evaluation of medical devices) and ISO 7405 (Evaluation of biocompatibility of medical devices used in dentistry) within an ISO 14971 (application of risk management to medical devices) based risk management process.
The critical nuance here is application compliance. As the BISCO product team notes, TheraCal LC needs to be fully polymerized. Layers must not exceed 1mm in depth, and the material must be light-cured for a full 20 seconds. When those steps are followed, the data consistently prove that TheraCal LC is safe for it's intended use. Concerns in clinical practice most often trace back to application errors, not the material itself.
Q: If it's resin-based, doesn't it contain HEMA?
This is a fair assumption — HEMA is present in many resin-modified glass ionomers and some adhesives, and its association with pulpal inflammation and cytotoxicity is well-documented in the literature.5–9 The assumption that TheraCal LC carries the same chemistry is understandable. But it's not accurate.
TheraCal LC does not cntain HEMA. This was a deliberate formulation decision. The material was also developed without ethanol, another known pulpal irritant, and without MDP, which carries an acidic pH that can be damaging to exposed pulpal tissue.
This is what sets TheraCal LC apart from the RMGI class at a chemistry level. RMGIs have been shown in multiple studies to be cytotoxic to the pulpal complex, and that toxicity is frequently attributed to HEMA.5–9 TheraCal LC was engineered around those findings — not in spite of them.
It is worth noting that All-Bond Universal, used later in the restorative workflow, does contain MDP, but it is applied after TheraCal LC has been light cured and is not placed on the pulp directly. The formulation decision that matters here is what goes on the pulp, and TheraCal LC was designed with pulp compatibility as a priority.
Q: Shouldn't a material touching the pulp be non-acidic?
Yes, and TheraCal LC delivers on this. Research confirms that an acidic environment (pH < 7) is harmful to exposed pulpal tissue.10 The question for any liner placed near the pulp is not just whether it avoids acidity at placement, but whether it maintains a favorable pH environment over time.
TheraCal LC turns alkaline immediately upon exposure to moisture, reaching a pH of approximately 10–11. That alkaline environment supports healing, promotes pulp vitality, and facilitates apatite formation.1,2 What the data shows beyond that initial reading is equally important: TheraCal LC maintains a consistent alkaline pH of 10–11 over a 90-day observation period.11
This is where the chemistry differentiates. Some competing liner materials drop below neutral pH over the same period, which is clinically counterproductive in cases where pulpal healing is the goal. For clinicians who are skeptical that a resin-based material can behave this way, the BISCO product team puts it simply: an alkaline pH promotes pulp vitality, and the studies support that.1,2 TheraCal LC's calcium silicate chemistry, rather than HEMA-based RMGI chemistry, is what makes sustained alkalinity possible.
Q: Does calcium release actually help the pulp, or is it a marketing claim?
The calcium release from TheraCal LC is both measurable and mechanistically grounded.
Here's how the mechanism works: TheraCal LC incorporates calcium silicate particles suspended in a hydrophilic monomer. Water penetrates the resin matrix after placement, triggering the release of calcium hydroxide ions through ion exchange — this is BISCO's proprietary Thera Technology.
At 7 days, TheraCal LC releases 234.29 µg/cm² of calcium, compared to 127.46 µg/cm² for Ultra-Blend Plus (Ultradent), 99.56 µg/cm² for Dycal (Dentsply Sirona), 81.58 µg/cm² for Calcimol LC (Voco), and 5.32 µg/cm² for Lime-Lite Enhanced (Pulpdent).* Calcium release at this level stimulates hydroxyapatite formation and secondary dentin bridge formation.1,12
In vivo, TheraCal LC produced significantly higher hard tissue bridge formation and greater bridge thickness at 28 days compared to competing materials.13
One more distinction worth understanding: solubility. High solubility is one of the longstanding limitations of traditional calcium hydroxide liners — the material can dissolve over time, losing its protective function. TheraCal LC is not water soluble, meaning it doesn't dissolve when exposed to moisture.* It gains mass. The BISCO product team notes this directly: we have the data to show this doesn't wash out over time. That stability is what makes sustained calcium release clinically meaningful rather than a short-term effect.
Q: Can I really use TheraCal LC for direct pulp capping, or is it better suited as a liner?
TheraCal LC is indicated for both direct and indirect pulp capping, and that dual indication is not common among competing liner materials.
This is an area where clinician assumptions often diverge from what the IFU actually says. As the BISCO product team puts it, a lot of clinicians believe their current material can be used for direct pulp capping, but it may not be indicated. Reading the IFU matters, especially for a procedure where material contact with exposed pulpal tissue is direct.
TheraCal LC can be applied directly to a pulpal exposure after hemostasis is achieved, covering all exposed areas and extending at least 1mm onto surrounding sound dentin. It can then be used as a liner in the same preparation — no separate products, no additional steps. For best results, apply in layers not exceeding 1mm in depth and light cure for 20 seconds before proceeding with adhesive and restoration.
The Takeaway
The concern about TheraCal LC and cytotoxicity comes from a real place. Resin-modified materials as a class have a complicated biocompatibility history, and clinicians who have encountered critical in vitro data are asking a legitimate question.
What the evidence shows is that TheraCal LC was engineered around those concerns, not alongside them. It excludes HEMA, ethanol, and MDP. It achieves and sustains an alkaline pH, it has been evaluated against international biocompatibility standards. And its calcium release mechanism is backed by both in vitro and in vivo data.
The material works when it's used correctly. Follow the IFU, and the science will hold up.
Learn more about TheraCal LC and download the full product profile: bisco.com/theracal-lc/
References
*BISCO has data on file.
1. ADA definitions for direct and indirect pulp capping. ada.org/en/publications/cdt/glossary-of-dental-clinical-and-administrative-ter [Verify URL is live before publication.]
2. Okabe T, et al. Effects of pH on mineralization ability of human dental pulp cells. J Endod. 2006;32:198–201.
3. Kim M, Kim R. Physical and biological properties of bioactive glass-containing Bis-GMA-free pulp capping materials: An in vitro study. UCLA School of Dentistry, Biomaterials and Device Testing Laboratory, Section of Restorative Dentistry. 2025.
4. Lee BN, et al. Effects of a novel light-curable material on odontoblastic differentiation of human dental pulp cells. Int Endod J. 2017;50(5):464–471.
5. Sidhu SK, Nicholson JW. A Review of Glass-Ionomer Cements for Clinical Dentistry. J Funct Biomater. 2016;7(3).
6. Modena KC, et al. Cytotoxicity and biocompatibility of direct and indirect pulp capping materials. J Appl Oral Sci. 2009;17(6):544–554.
7. Stanislawski L, et al. Factors responsible for pulp cell cytotoxicity induced by resin-modified glass ionomer cements. J Biomed Mater Res. 1999;48:277–288.
8. Selimović-Dragaš M, et al. A comparison of the in vitro cytotoxicity of conventional and resin modified glass ionomer cements. Bosn J Basic Med Sci. 2012;12:273–278.
9. Huang FM, Chang YC. Cytotoxicity of resin-based restorative materials on human pulp cell cultures. Oral Surg Oral Med Oral Radiol Endod. [volume and year pending verification]; (3):361–365.
10. Hirose Y, et al. Effects of Extracellular pH on Dental Pulp Cells In Vitro. J Endod. 2016;42(5):735–741.
11. Lin YY. Chemical, Physical, and Antibacterial Properties of Contemporary Pulp Capping Materials. All ETDs from UAB. 2021. [Dissertation — confirm citation acceptability before publishing.]
12. Gandolfi MG, Siboni F, Taddei P, et al. Apatite-forming Ability of TheraCal Pulp-Capping Material. J Dent Res 90 (Spec Iss A): abstract 2520, 2011. [Conference abstract — search for full peer-reviewed publication.]
13. Cannon M, et al. Primate pulpal healing after exposure and TheraCal application. J Clin Pediatr Dent. 2014;38(4):333–337.