High-Tech Bioactive Cement Seals, Resists Decay Even in Moisture
Robert A. Lowe, DDS, who maintains private practices in Charlotte, NC, and Chicago, IL, acknowledges that a “magic” material for crown and bridge cementation that works well in all clinical situations just doesn’t exist. “First of all, you can’t depend on the cement to be the sole source of retention for a crown,” he suggests. “One must take into consideration the axial taper and height of the preparation, the clinical environment—the ability to maintain absolute moisture control—and the type of restorative material to be cemented.”
The cement’s purpose, Lowe emphasizes, is not only to retain the restoration, but to fill the space (microgap) between the restoration and tooth. “Even the best-fitted indirect dental restoration has a gap of 30 to 50 microns. It is important for the cement to fill that space, because bacteria are as small as 1 micron in diameter.” For that reason, he stresses that while bond strength is important, it is a major consideration only when the preparation is inadequate (ie, too short or too tapered).
“Older cements, such as zinc phosphate, were soluble and subject to breakdown in oral fluids,” Lowe says, “and although hydrophobic cement resins work well to fill the space between the restoration and the tooth, they require a dry field for optimal results, which can be difficult to achieve, particularly in the posterior region of the oral cavity.”
This, he says, is where Doxa’s bioactive cement, Ceramir® Crown & Bridge (C&B), comes in. “It is unique in that, in the presence of moisture, its calcium aluminate and glass-ionomer chemistry form nanocrystals that integrate with and become part of the tooth structure.” When cementing a crown in the subgingival environment, where it is difficult to control the moisture, it is not a problem with Ceramir C&B, Lowe says. In fact, he adds, in the presence of saliva, hydroxyapatite forms on the surface of Ceramir cement over time, sealing the margin with a “tooth-like” substance.
“The retention is as good as many of the resin and resin-ionomer cements on the market, without the need for silane coupling on porcelain or metallic primers on zirconium,” he insists.
Lowe says a clinical validation study1 to determine the performance of Ceramir C&B for permanent cementation reported no loss of retention, no secondary caries, no marginal discolorations, and no subjective sensitivity at 3-year recall, and all restorations rated excellent for marginal integrity. Further, in-vitro crown-coping retention studies and mean laboratory retentive forces measured for Ceramir C&B found it to be comparable to other currently available luting agents for both metal and all-ceramic indirect restorative materials.1 In a recent follow-up article by Jefferies et al, calcium aluminate cement (Ceramir C&B) was shown in-vitro to seal or reseal artificial restorative gaps between tooth and restorative material. Self-etching resin cements, resin-modified glass-ionomer cements, and glass-ionomer cement demonstrated no such ability to seal restorative gaps under similar simulated in-vitro conditions.2
Lowe also notes that, unlike resins, which set at a low pH and, therefore, cannot inhibit the acid attack from bacterial metabolism, Ceramir C&B, after complete set, maintains a basic pH and will help repel or neutralize acids while remaining chemically stable in the oral environment over time.
Bioactive materials such as Ceramir C&B will dominate future introductions in the cementation and adhesion category, Lowe predicts. He urges dentists to use all materials appropriately and points out that Doxa supports clinicians’ use of its products through a broad range of educational opportunities, including more than 150 live continuing education courses, instruction videos, research papers and abstracts, online CE courses, and the company’s local sales representatives for doctor and dealer support.
With Ceramir C&B, the bottom line, Lowe concludes, is a resilient, biocompatible dental luting cement that integrates with natural tooth structure, is stable in the mouth, and exhibits superb mechanical properties.
1. Jefferies SR, Pameijer CH, Appleby DC, et al. A bioactive dental luting cement—its retentive properties and 3-year clinical findings. Compend Contin Educ Dent. 2013;34(spec no 1):2-9.
2. Jefferies SR, Fuller AE, Boston DW. Preliminary evidence that bioactive cements occlude artificial marginal gaps. J Esthet Restor Dent. 2015. doi:10.1111/jerd.12133. [Epub ahead of print]
Doxa Dental Inc.
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Chicago, IL 60601