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Special Issues
July/August 2017
Volume 38, Issue 2
Peer-Reviewed

“Smart” Materials: Bioactivity in Crown-and-Bridge Cements

Lou Graham, DDS

“Biomineralization” refers to the exchange of calcium and phosphate ions with the tooth substance, forming new apatite or, in many cases, repairing existing demineralized apatite. Regarding dental cements, this type of bioactivity can lead to precipitation of apatite crystals on the surface of the cement in the presence of moisture (saliva). Preliminary evidence shows that this action can seal gaps in margins between restorative materials and tooth structure, which can be a tremendous benefit for a luting cement. A clinically “closed” crown margin is considered to be from 30 µm to 50 µm, where a sharp dental explorer cannot “feel” a perceptible “click.” Ceramir® Crown & Bridge (Doxa Dental Inc., ceramirus.com) is a bioactive luting agent that is not only insoluble in oral fluids, but has been shown to occlude artificial marginal gaps between restorative materials and the tooth. Also, by virtue of the availability of calcium and phosphate ions, in the presence of saliva the luting agent precipitates apatite crystals on its surface to further protect and seal the marginal area.

Key Takeaways

• Bioactivity is expanding in the dental profession by virtue of the many new “smart” materials emerging in the marketplace.

• With a set end pH of 8.4, Ceramir Crown & Bridge can buffer the effects from acid by-products in the crevicular environment, leading to a higher level of tissue biocompatibility.

• Ceramir Crown & Bridge dental luting cement is radio-opaque, biocompatible, and virtually sensitive-free when being placed.

About the Author

Lou Graham, DDS
Private Practice
University Dental Professionals
Chicago, Illinois

Fig 1. A patient presented with an in-office milled crown on tooth No. 3 that had been cold-sensitive since placement 2 years prior. Upon radiographic examination, the distal margin was open. Due to these circumstances, it was decided to remove the crown. The restoration was thus removed and the preparation refined (as shown).

Figure 1

Fig 2. An impression was made using a vinylpolysiloxane impression material (Aquasil®, Dentsply Sirona, dentsply.com).

Figure 2

Fig 3. During the provisional phase of treatment, the patient reported no sensitivity. At the delivery visit 3 weeks later, the provisional restoration was removed from the prepared tooth and the surface of the preparation was disinfected and cleaned with 2% chlorhexidine (eg, Cavity Cleanser™, Bisco, Inc., bisco.com; or Concepsis®, Ultradent Products, Inc., ultradent.com) to ensure a clean surface to cement to. The milled zirconium restoration is shown here.

Figure 3

Fig 4. Intaglio view of the milled zirconium restoration, which was then tried on the preparation.

Figure 4

Fig 5. The author’s sequence typically is to confirm the contacts first and then record a bitewing x-ray. Occlusal adjustments are performed as needed. In this case, once the seating was verified, the internal surface of the crown was cleaned with Ivoclean® (Ivoclar Vivadent, ivoclarvivadent.us) and air-dried. Zirconium crowns only need to be clean and dry, as metallic primers are contraindicated when using Ceramir Crown & Bridge. The cement was triturated for 8 seconds and dispensed into the crown (as shown).

Figure 5

Fig 6. Further dispensing of luting cement into crown.

Figure 6

Fig 7. The restoration was then seated to place and held with finger pressure for 15 to 30 seconds. The patient then bit down naturally to confirm full seating. At this point techniques can vary. Either finger pressure can be maintained or the patient can be instructed to bite down on a cotton roll, cotton wood stick, or any other option the clinician prefers. At the 3-minute mark, the cement is easily peeled away. The author then ties either a single knot or double knot in floss and pulls it apically through the contact and then out (he does not floss up and down initially).

Figure 7

Fig 8. Final set time was about 5 minutes, as this is a self-curing cement with no resin included in the calcium alumina formulation. The cemented definitive restoration of tooth No. 3 is shown here.

Figure 8

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