TheraCem - The Next Generation Cement by Joseph S. Kim, DDS
Indirect restorative materials have evolved rapidly over the past few years, providing clinicians with a variety of options to better serve their patients. However, more choices in the substrate material often result in more steps in the cementation protocol, usually with specific and additional procedures that address the peculiarities of the chosen material. In addition, a cement chosen to increase the retention of the indirect restoration comes with the cost of increased technique sensitivity and chair time to deliver the restoration.
Dental cement technology represents one of the major advancements in restorative dentistry. For over a century, older cements such as zinc phosphate and zinc oxide eugenol allowed for predictable retention of indirect restorations and various formulations are still used today. However, these materials may require protective measures in deeper preparations to avoid pulpal irritation, and are susceptible to dissolution in water. Glass ionomer cements were invented in 1968, and similar to earlier silicate based products, they have the major benefit of releasing fluoride.1 However, while this cement is easy to use, it is also water soluble, and even modern resin modified varieties ideally require at least 15 minutes of protection from moisture contamination after placement.2
With advances and simplification of bonding protocols, resin cements have become more popular due to the high retention bond strengths which are achieved through micromechanical and chemical adhesion. Bonding is required for certain substrates often due to fragility or minimal surface area available for adhesion to the tooth; this includes composite and ceramic inlays and onlays, and for full coverage restorations that may exhibit compromised angulation of the preparation or minimal height. Unlike most other cements, resin cements are insoluble to water and oral fluids.
Traditionally, resin cements required preparing tooth by etching, priming, curing, soft tissue management to stop any bleeding, and isolating the tooth from moisture. These steps were time consuming and often the tooth was not optimally prepared due to technique sensitivity, such as excessive etching and desiccation of the dentin. Also, subgingival margins were often difficult to manage after exposure to the etchant and again after application of the adhesive.
Self-adhesive resin cements offer a simple solution to the traditional compromise between retentive bond strength and technique sensitivity. By combining the benefits of bonding with a cementation protocol that is easier than for traditional cements, self-adhesive resin cements provide outstanding retention with maximum simplicity. The self-adhesive feature means there is no need to apply etchant, primers, or adhesives to the prepared dental surfaces. This translates to greater predictability in preparations with subgingival margins, where etchants or bonding agents may cause bleeding.
BISCO’s latest resin cement advances this concept with universal adhesion to all popular substrate materials. TheraCem is a dual-cured, calcium and fluoride-releasing, self-adhesive resin cement indicated for luting crowns, bridges, inlays, onlays, and all types of posts. Delivering a strong bond to Zirconia and most substrates, along with easy clean-up and high radiopacity, TheraCem offers clinicians reliable and durable cementation of most indirect restorations. Due to innovative chemistry, TheraCem achieves a high degree of conversion, which improves physical properties for added bond strength, without the need for refrigeration when it is not being used. For clinicians, this means that peace of mind can be nearby and ready to use in every operatory.
In the first case, a tooth with a subgingival margin preparation has been cleaned with an ultrasonic scaler and was gently dried in preparation for cementation. Note how the margin goes deeper subgingivally on the distolingual. (Figure 1) With TheraCem, a clean, prepped dentin or enamel surface is all that is needed to achieve excellent bond strengths, with the added benefit of sustained calcium and fluoride release. While TheraCem forms a strong bond to most substrates, including zirconia.
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