TheraCal LC by Bisco: Comprehensive Clinical Review and Application Guide

TheraCal LC is a light-cured, resin-modified calcium silicate liner developed by Bisco Inc. and designed for direct and indirect pulp capping, as well as base and liner applications beneath composite, amalgam, and ceramic restorations. Since its introduction, it has attracted significant clinical attention because it combines the bioactivity of calcium silicate chemistry with the handling convenience of a resin-based, single-component system.

This review covers the material science, clinical indications, step-by-step placement protocol, and procurement considerations for practices evaluating TheraCal LC against other cavity liner options. If you are building a liner protocol from scratch or rationalizing your current armamentarium, see our complete guide to the best dental cavity liners for a full brand comparison.

Material Science: What Makes TheraCal LC Different

TheraCal LC is classified as a resin-modified calcium silicate material. Its matrix consists of a hydrophilic resin phase loaded with Portland cement-derived calcium silicate particles. When exposed to moisture from dentinal tubules or the pulp, the calcium silicate component undergoes hydration and releases calcium and hydroxyl ions into the surrounding tissue environment.

Three properties distinguish this chemistry from conventional calcium hydroxide liners such as Dycal:

1. Sustained ion release. Unlike calcium hydroxide cements that release ions rapidly and then deplete, TheraCal LC provides a more prolonged release profile, which is consistent with studies measuring calcium ion availability over time in simulated pulp fluid.
2. Dimensional stability. The resin matrix prevents the solubility and material disintegration that affect traditional calcium hydroxide liners when exposed to acid or moisture over time. A 2019 study published in the Journal of Dentistry found significantly lower solubility values for TheraCal LC compared to Dycal under simulated aging conditions.
3. Alkaline pH maintenance. TheraCal LC achieves an initial pH of approximately 10 to 11 upon setting, supporting an antimicrobial environment and promoting secondary dentin bridge formation, consistent with the mechanism described for calcium silicate materials in the dental literature.

Clinical Indications

Bisco positions TheraCal LC for four primary clinical scenarios, and the distinction between them is important for protocol selection:

1. Indirect pulp capping (IPC). Applied over a thin residual dentin layer when the pulp has not been exposed. The bioactive liner seals remaining carious dentin and promotes remineralization without requiring complete caries removal in deep lesions.
2. Direct pulp capping (DPC). Applied directly onto an exposed pulp of mechanical or traumatic origin. Clinical evidence for TheraCal LC in this indication is accumulating, with several case series reporting comparable outcomes to MTA in terms of bridge formation and pulp vitality at 12-month follow-up.
3. Liner under composite or amalgam restorations. Used as a protective base in Class I, II, and V preparations with deep preparations, replacing the traditional calcium hydroxide or RMGI liner in practices seeking bioactivity in a single-bottle format.
4. Liner prior to ceramic restorations. TheraCal LC is compatible with self-etch and total-etch adhesive systems, making it usable under full-ceramic crowns and inlays when deep preparations require pulp protection.

TheraCal LC is not indicated as a final restorative material, nor as a bulk fill. It is a liner in the strict sense and should be applied in thin increments (0.5 to 1.0 mm maximum) to maximize light penetration and ensure adequate cure throughout the material.

Step-by-Step Placement Protocol

The following protocol reflects Bisco's manufacturer guidelines and the procedures described in published clinical reports. Deviations in technique, particularly regarding layer thickness and light-curing parameters, are a common source of clinical underperformance.

1. Preparation and isolation. Complete cavity preparation and achieve adequate isolation. Rubber dam is the standard of care. Rinse and gently dry the cavity with a light air stream, taking care not to desiccate the dentin or traumatize any exposed pulp tissue.
2. Hemostasis in DPC cases. For direct exposures, achieve hemostasis with a sterile cotton pellet and sodium hypochlorite at 2.5%. Proceed once bleeding is controlled. Do not proceed if hemorrhage persists after adequate hemostasis attempts, as this indicates an irreversible pulpitis.
3. Syringe dispensing. Dispense TheraCal LC directly from the syringe using a disposable tip. Do not mix with other materials. Apply in a thin, controlled layer (0.5 to 1.0 mm) over the deepest portion of the preparation or directly over the pulp exposure. Avoid covering the entire preparation floor, as placement should be targeted to the critical zone only.
4. Adaptation. Use a small condenser or ball burnisher to gently adapt the material to the preparation walls. Avoid pressing aggressively against an exposed pulp. The material has sufficient initial viscosity to remain in place without spreading under light pressure.
5. Light curing. Cure for 20 seconds with a LED light-curing unit at minimum 600 mW/cm2, with the tip positioned as close as possible to the material. Because TheraCal LC is opaque and contains fillers, light attenuation is significant beyond 1.0 mm. Any material placed deeper than this threshold will not achieve adequate polymerization.
6. Bonding and restoration. After curing, apply your adhesive system and place the final restoration using standard protocol. TheraCal LC is compatible with all major adhesive systems in both total-etch and self-etch configurations.

Clinical Evidence Summary

The peer-reviewed literature on TheraCal LC has grown considerably since its introduction. A 2014 study in the Journal of Endodontics evaluated its cytotoxicity against human pulp fibroblasts and found acceptable biocompatibility, comparable to MTA and superior to some conventional calcium hydroxide formulations. A subsequent in vivo study published in Clinical Oral Investigations assessed its performance in direct pulp capping over 24 months, reporting bridge formation rates of 78 percent at 6 months and 91 percent at 24 months, with pulp vitality maintained in the majority of cases.

These outcomes are favorable, though the evidence base remains smaller than for MTA-based materials, which have over two decades of controlled trial data. Clinicians should treat TheraCal LC as a well-supported first-line liner option for IPC and DPC scenarios, while reserving more established alternatives such as Biodentine or ProRoot MTA for complex cases with larger exposures or signs of symptomatic irreversible pulpitis at the margins of reversibility.

Handling Advantages and Limitations

Advantages:

• Single-component, no mixing required. Supplied in a syringe for direct placement.
• Light-cured, providing on-demand working time with controlled set.
• Radioopaque, allowing verification in post-operative radiographs.
• Dimensionally stable over time, with low solubility under clinical conditions.
• Compatible with all adhesive generations and restorative materials.

Limitations:

• Layer thickness must stay at or below 1.0 mm for complete light cure. This requires discipline in preparation depth assessment.
• Not suitable as a bulk base material. Practices that rely on a dual-purpose base and liner may need to supplement with a glass ionomer base for very deep preparations.
• Higher unit cost compared to calcium hydroxide liners. This is offset by the single-bottle format, which eliminates waste from mixed materials.
• The clinical evidence base, while positive, is thinner than for MTA materials in direct pulp capping scenarios requiring long-term follow-up data.

Procurement and Inventory Considerations

TheraCal LC is distributed primarily through Patterson Dental, Henry Schein, and Benco Dental in the United States. Standard pricing for a 1.2 g syringe (the single-unit format) typically ranges from $38 to $52 depending on distributor and practice volume tier. A starter kit with two syringes and dispensing tips is also available through most distributors.

For practices managing procurement across multiple vendors, the price differential on TheraCal LC between distributors can reach 20 to 30 percent, particularly for practices without negotiated pricing agreements. A single syringe yields approximately 10 to 15 clinical applications depending on technique, making the cost per application competitive with RMGI liner alternatives when factoring in the time eliminated from mixing.

Practices that have integrated a price comparison platform into their procurement workflow consistently identify TheraCal LC as one of the products with the highest price variance across vendors, making it a reliable candidate for automated price monitoring.

TheraCal LC vs. Other Cavity Liners: Quick Positioning

Comparing TheraCal LC with the other major cavity liner options helps define its role in a rationalized armamentarium:

1. TheraCal LC vs. Dycal. TheraCal LC is superior in dimensional stability and long-term ion release. Dycal degrades over time in the oral environment and cannot be used reliably under resin systems without the risk of leakage at the interface. For practices still using Dycal as a default liner, TheraCal LC is a clinically justified upgrade.
2. TheraCal LC vs. Vitrebond Plus (RMGI). Vitrebond Plus offers excellent adhesion to dentin and a proven track record as a base material in deep preparations. TheraCal LC offers greater bioactivity and is the better choice for pulp proximity situations. For preparations that are deep but clearly away from the pulp, Vitrebond Plus remains a valid and cost-effective option.
3. TheraCal LC vs. Biodentine. Biodentine (Septodont) offers a pure calcium silicate chemistry without a resin matrix, and has a more extensive body of evidence for direct pulp capping, including in symptomatic pulps. Its limitation is the mixing step and the 12-minute initial set. For cases where handling convenience is prioritized and the clinical situation is a standard IPC scenario, TheraCal LC is the more practical choice. For complex DPC in a mature apex, Biodentine or MTA remains the more supported option.

Summary

TheraCal LC represents a well-formulated evolution in cavity liner chemistry. Its combination of calcium silicate bioactivity, resin stability, and single-component delivery makes it one of the most clinically useful liners currently available for both indirect and direct pulp capping in restorative practice. The material performs best when placed in strict accordance with the manufacturer's thickness guidelines and cured with a calibrated, high-intensity LED unit.

Its main trade-off is cost relative to conventional liners and a still-developing long-term evidence base for DPC in complex presentations. For the majority of clinical scenarios in a general practice, however, TheraCal LC is a justified addition to the cavity liner armamentarium and a strong candidate for the primary liner position in any practice moving away from calcium hydroxide.

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References

1. 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(6):571-579.

2. Cannon M, Gerodias N, Viera A, Percinoto C, Jurado R. Primate pulpal healing after exposure and TheraCal application. J Clin Pediatr Dent. 2014;38(4):333-337.

3. Camilleri J, Sorrentino F, Damidot D. Investigation of the hydration and bioactivity of radiopacified tricalcium silicate cement, Biodentine and TheraCal LC. J Mater Sci Mater Med. 2013;24(6):1527-1538.

4. Poggio C, Ceci M, Beltrami R, Dagna A, Colombo M, Chiesa M. Biocompatibility of a new pulp capping cement. Ann Stomatol (Roma). 2014;5(2):69-76