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Dynamics Sep 08 20/8/08 09:02 Page 5SmartCem2 - Self-adhesive cementSmartCem2 - Self-adhesive cementThe user-friendly self-adhesive cementSmartCem2 Composition• UDMA and EBPADMA Urethane Resin• PENTA• Proprietary photo-initiating system• Proprietary self-cure initiating system• Glass fillersSmartCem2 is the new self-adhesive cement from DENTSPLY with the perfect combination ofhandling and strength. Because it requires no separate etching and bonding steps and has greataesthetics, it is the ideal cement to use for your everyday cementation needs.Shelf-life without refrigeration and colour stabilityDuring the development phase of SmartCem2, it was recognised that thetraditional components used for the initiation of curing would not be suitablefor a self-etching, self-adhesive product. Since it was desired to have a dualcuring mechanism in SmartCem2, the formulation would require dual initiatorsystems. Thus, due to the use of acidic components within the formulationsof SmartCem2, both the visible light and self-cure initiators would be affected.Both initiator systems utilise basic components (e.g. amines), and thesecomponents would be expected to react with the acidic adhesion promoter.This would result in compromised storage stability if the components wereallowed to come in contact with each other in the package.A further complication involved the interaction of the acid componentswith the traditional benzoyl peroxide (BPO) self-cure initiator. This interactionwould also lead to degradation of the peroxide initiator over time, if allowedto be in contact with the acidic components during storage. Thus, theformulation of SmartCem2 needed a fresh look.The polymerisable resins are used in other DENTSPLY products, suchas Esthet•X ® Micro-matrix Restorative. These resins provide structuralreinforcement of the resin cement, as well as strong cross-linking of thepolymer network upon polymerisation. As a result, the mechanical andphysical properties of SmartCem2 are enhanced and strengthened.The adhesion promoter, PENTA, is well known to DENTSPLY adhesiveproducts, including Prime&Bond ® NT Universal Dental Adhesive System.This phosphoric acid modified monomer has been demonstrated to interactdirectly with the calcium in tooth structure, resulting in strong covalentbonding to the tooth surface (*reference 1).Micro-leakageThe extent to which a cement is able to seal the marginal areas around anindirect restoration can be demonstrated through the use of the in-vitro test forresistance to microleakage. In this test, non-carious human molars were used.Two class V cavity preparations were made on opposite sides of each noncarioushuman molar with the occlusal margins in enamel and gingival marginsin cementum. SmartCem2 showed no leakage in Class V Cavities, enamel anddentine, whereas other market-leading self-adhesive cements showed at least50% leakage to the apex.Based on research findings from the development of Xeno ® IV Dual CureSelf-Etching Dental Adhesive, the new, proprietary acid resistant amine wasincorporated as part of the visible light initiator system in SmartCem2.This amine is not reactive with the acidic components of SmartCem2,which makes the composition stable to storage conditions, ensuring that thevisible light activation of SmartCem2 will occur predictably during the life-timeof the product.The new, proprietary ingredients include the photoinitiator system, as well asthe self-cure reactive components of the dual cure material. The glass filler(69% by weight, 46% by volume) used contains fluoride fillers, similar to thoseused in other restorative products noted above.Bond StrengthsBoth the dual-cure and the self-cure modes were examined. As has been notedwith previous dual cure materials, exposure to visible light as part of the curingprocess generally leads to higher bond strengths, due to the more energeticconditions of curing. SmartCem2 showed the highest bond strengths to toothstructure when compared to 3 other market-leading self-adhesive cements.In-vitro Microleakage Gingival Dentine MarginsA second research problem involving the self-curing system within theSmartCem2 provided a novel, proprietary initiating system that also resultedin a shelf-stable material. In this case, the traditional benzoyl peroxide/aminesystem was replaced with a hydroperoxide/non-amine system.This new self-cure initiating system has several advantages;• The new system is insensitive to the acidic components of SmartCem2• The degradation of the traditional BPO component that leadsto changes in working and setting properties is eliminated• The degradation of the traditional BPO component with exposureto heat and prolonged storage times is eliminated, and• The effect of colour change of the materials using a BPO/amineself-cure is also eliminated.The overall effect of this new self-cure initiator system results in a shelf-stableproduct with stable and predictable handling properties (e.g. consistent workingand setting times), without color changes of the cured SmartCem2 cement overtime. Because the heat sensitive BPO/amine components were replaced,SmartCem2 has a significantly improved shelf-life without the need forrefrigeration of the product.Easy ApplicationThe real benefit of SmartCem2 is the application and handling compared tothe other self-adhesive cements on the market. Because it uses an automixsyringe, it means you avoid the hassle associated with hand mixing and ensuresyou always have enough material to hand (unlike capsules where you can easilyrun out of material mid-way through the procedure, or have excess materialwhich is wasteful.Gel-PhaseThe “gel-phase” of SmartCem2 ensureseasy clean-up of material and can beinitiated quickly with a few seconds of acuring light, reducing the waiting timeand ensuring a quicker procedure.To arrange for a free demonstration ofSmartCem2 in your practice, call todayon +44 (0)800 072 3313 to be one of the first to see this great new product.Bond Strengths to Tooth StructureREFERENCES1 Latta MA, Shear Bond strength and physiochemical interactions of XP Bond. Adhes. Dent. 2007;9:245-24804 DENTSPLY Dynamics | September - December 2008 www.dentsply.co.uk05