Dr. Lori Trost

	Dentists, more than ever before, are able to deliver some absolutely beautiful, lifelike and well-fitting final restorations. The pendulum has swung from the predominantly porcelain-fused-to-metal market to all-ceramic restorations, driven by lithium disilicate and zirconia substrate options that offer esthetics and durability.

	Because of these materials’ dominance, it is important to look at the cements chosen for final placement, their composition and mechanisms used by which to secure the final restoration placement. Securing a final indirect restoration has moved well beyond just conventional luting or cementing.

	Gone are the days of sole reliance on mechanical retention. Adhesive cements are readily available that provide both chemical and mechanical retention. These cements allow clinicians to rely on specific adhesive features that enhance the bond strength, create an efficient workflow and provide a more confident outcome.

Related article: 4 big benefits of resin cements

	The current landscape of cement choices is complex to navigate, and without a strong foundational knowledge of what cementation strategy to implement, cementation failures can occur. Clinical consideration must be given to the retention and resistance form of the preparation, margin placement, preparation of the intaglio surface of the restoration and adhesive cement characteristics, along with possible light curing to facilitate easier marginal and inter-proximal clean up.

	Here are some pointers to help dentists and their assistants steer through the decision-making process and determine which cement offers the best potential benefit given the clinical presentation.

	Begin by assessing the design, height and taper of the tooth preparation because this will determine whether the restoration needs to be cemented or bonded. The purpose of any cement is to fill the micro-gap that exists between the restoration substrate and the tooth. The cement translates the retention form of the preparation to the restoration.

	More ideal preparations permit traditional cementing options as well as allow for adhesive protocols. For those preparations that are clinically short or have a taper greater than 20 degrees, those indirect restorations will require bonding or an adhesive protocol.

	Understand that modern adhesive resin cements offer versatility in how they are placed and cured. They are usually a one or two paste system, delivered in a syringe and often coined “universal cements” because they allow for the clinician to choose which of the three bonding mechanisms is appropriate given the clinical case.

Related article: How to achieve esthetic results with direct composites

	Adhesion occurs via a total-etch method, which requires etching of the tooth accompanied by a bonding agent application; self-etch modality whereby a self-etching adhesive is applied to the tooth preparation prior to cementing; and a self-adhesive method, which is closest to traditional luting in that a bonding agent is not required.

	Another differential in all of these cements is their curing mechanism - some offer the ability to be light cured, while others require a dual or chemical cure. Keep in mind that light does not pass through zirconia, so when using this particular substrate, you must use a dual- or chemically-cured cement. Additionally, many of these cements feature a “wave or tack” cure of three to five seconds at the margins. Essentially, the tack cure facilitates an easier clean up around the margins while the cement is in a more gel-like phase.

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	Central to the cement’s performance is how well it will integrate with the substrate of the restoration. To achieve optimum bond strength, intaglio surfaces must be properly prepared. 

 surfaces require air abrasion of a 30-micron particle size for 10 seconds at 30 psi.

	Next, a primer application can follow that is specific for that particular substrate. On the other hand, do NOT air abrade glass ceramics! This may initiate internal cracks or fractures. Instead, apply a 5% hydrofluoric acid to the surface to create a retentive surface. Rinse, then follow with a ceramic primer application that is allowed to air dry.

	Evolving with the consumer demands, many cements are offered in several shades for improved esthetics. Another key feature is the specific monomers included in some formulations - MDP and 4-MET(A) - to ensure improved bonding values. Essentially, there is no need for a separate adhesive primer. This greatly reduces the risk of contamination, inventory and any errors that could affect the quality of the bond between the cement and substrate.

Fig. 1                                                                                              Fig. 2

	A 53-year-old male presented with a treatment plan to replace an existing f rst molar crown and prepare a crown on a second molar (Figs. 1-2).

	The patient was anesthetized and tolerated the crown preparations well. Both zirconia-style preparations were digitally scanned and those scanned impressions were sent to an off-site lab. Temporary crowns were fabricated and worn for two days. Upon return, the temporary crowns were immediately removed. Notice the healthy condition of the gingiva (Fig. 3).

	At this point, the selection of what cement would work best enters the decision-making process. Taken into consideration is the height of the preparation and taper. Both preps are retentive. This allows the choice of either bonding or traditional cementing.

	Given the three classifications of bonding mechanisms earlier mentioned, a self-etching adhesive resin cement, 

 (Coltene), is selected. SoloCem offers a one-step bonding approach to final cementation that reduces the risk of contamination during the process and also includes the MDP and 4-MET(A) monomers that ensure good bond strength to the zirconia substrate - no additional metal primer monomer is needed (Fig. 4).

Fig. 3                                                                                                                      Fig. 4

	Both preparations were scrubbed with 2% chlorhexidine to remove any residual cement or debris. Both zirconia crowns were scrubbed with 

 (Ivoclar Vivadent) - a decontaminator - for 20 seconds, then thoroughly rinsed and air dried. A frosty internal surface appeared on both crowns.

	Care was taken to directly load the crowns evenly with translucent SoloCem. SoloCem is a two paste system that is delivered in an automix syringe. It offers low shrinkage, high sheer bond strength, low water sorption, increased radiopacity and excellent bond strengths to dentin.

	Because the monomers are already added to the cement formulation, the workflow was more efficient and certain of introducing no contamination. This is an important benefit, especially when performing quadrant dentistry (Fig. 5).

Fig. 5                                                                                                                      Fig. 6

	Both zirconia crowns were fully seated and occlusion was confirmed. A three-second tack cure followed at the buccal and lingual margins. (Fig. 6) Excess cement was removed and the margins were once again light cured for 20 seconds each.

	Again, both restorations were secured during this process. Keep in mind that 90 percent of bond strength in most of these cements occurs within the first 10 minutes, so it is critical to make sure when the restoration is seated, it is secured. Disturbing those early bonds could be detrimental. The final view of the restored maxillary molars is shown in Figures 7 and 8.

Fig. 7                                                                                                                      Fig. 8

	Many clinicians would define a successful crown or indirect restoration as to whether it “stays on,” but it really is much more than that. To simplify this process, clinicians must consider the value of a retentive preparation, plan for an optimal restoration type and thickness, and depend on a cement’s formulation to adequately bond to the tooth and the restoration in an efficient manner. Given all these variables, that is a lot of trust that needs to stand the test of time.

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"Control of the operating field from intraoral contaminants (blood and saliva) is absolutely essential to successful use of today’s modern dental materials. Rubber dam has long been the only way to adequately achieve isolation of the teeth during operative procedures, but can be difficult to use in some situations. This month Dr. Trost discusses alternative methods to maintain a ‘moisture free’ environment during adhesive dental procedures to ensure optimal restorative outcomes. ”-

	Remember the first time you punched holes for rubber dam placement in dental school? How about the clamp selection and then placement? The dread really escalated on second molars, didn’t it? Just as you are ready to begin your adhesion procedure for a Class II composite, the band looks like a swimming pool. And why does it seem the most difficult patients have an instant waterfall that conveniently “turns on” during the most critical timing of cementing a crown?

	We know moisture contamination not only contributes to adhesion dentistry failures, but also routinely interrupts daily procedures from bonding to cementation, causing time delays and clinical frustration. Let’s face it, achieving a dry field is difficult, and sometimes near impossible.

	But there are a growing number of innovative products designed to improve access, obtain isolation, manage tissues and even enhance crevicular dryness. Whether performing a restorative procedure such as direct bonding, isolating a Class V subgingival margin, or cementing an indirect restoration, there are products and techniques that can help you complete the procedure successfully. This article presents many of these products and techniques. After all, this is about making “everyday” dentistry easier, less frustrating and more predictable.

	No matter how “inconvenient” or “time consuming,” using a rubber dam remains the gold standard for procedural isolation, tooth protection and evacuation of unwanted tooth matter/restorative particulates (

). Rubber dams set the stage to execute adhesion dentistry properly by initiating a dry field, improving visibility and creating superior access. Rubber dams are fabricated out of stretchable latex or non-latex material and usually come in a 6” X 6” precut square. They also come in a variety of colors, scents and flavors.

	A template can be used to locate where corresponding holes should be located, then punched. Correct tooth hole size selection as well as hole spacing are essential for easier placement and seal. When placing the dam, care must be taken to correctly invert the dam around each tooth collar to establish a seal. Secure the dam with “Wedjet cords” from Coltène/Whaledent  or ligature floss around a tooth’s gingival collar.

	Framework and clamps come in both metal and plastic. A large assortment of clamps are available in a winged or wingless design. Our practice uses Ivory clamp #32 from Heraeus Kulzer (heraeus-kulzer-us.com) for the bulk of our procedures. We also like to take advantage of Cushee rubber dam clamps from Practicon. These cushion-like gadgets affix onto the rubber dam clamp, creating more gingival comfort and stability, while providing less metal/enamel contact-something many patients dislike. They are available in two sizes and are sterilizable.

	Rubber dam hybrids represent a new category for isolation. These innovative approaches have been incorporated into the traditional rubber dam design and each offer their own unique features to further promote user-friendliness. The OptraDam from Ivoclar Vivadent is a dam appliance that creates access to both arches by retracting the lips and cheeks. Its design offers comfort, a pre-printed arch template and integral framework. Clamps are not necessary with this device.

	The Insti-Dam from Zirc also incorporates the frame with the dam. It comes with a single pre-punched hole and is flexible for a kind fit. The Handi-Dam from Aseptico also features the pre-framed design and is flexible, but best used with a clamp.

	One of my favorite isolation gadgets is the OptraGate from Ivoclar Vivadent (

). This appliance is terrific for isolating the upper and lower anterior regions. It works by applying only lip and cheek retraction, quadrant based. The device comes in three sizes and is easily placed to hold the patient open, providing optimal anterior access. The OptraGate is a must for any esthetics because it creates a great backdrop for access, isolation and comfort.

	Narrowing the isolation and access to one tooth presents more of a challenge, but there are several products worth mentioning and mastering that can help. The majority of restorative dentistry involves cementation of an indirect restoration. One of the easiest methods to isolate teeth on either side of that soon-to-be cemented/bonded restoration is “plumber’s tape” or Teflon tape (

). You can find it at the local hardware store. Although very delicate in nature, this material is easy to cut and apply to a dry tooth surface. It is especially helpful in those interproximal areas where bond or cement like to “hide” out. Teflon tape is extremely thin and also provides mesial or distal form for direct bonding or even veneer placement.

	Greater Curve matrix bands from Greater Curve are another method to focalize an indirect restoration when cementing. Their enhanced curvature enables them to achieve a tight cervical fit, thus sealing off crevicular fluids. This is especially helpful when cementing an inlay or onlay. Care must be given to first try in the restoration with the band in place to make sure the restoration seats properly.

	Using clear matrix bands is another trick designed to isolate direct restorations. Contour Strips from Ivoclar Vivadent create a framework for direct bonding because they can be trimmed and contoured, even stretched a bit or wrapped around the tooth, for a customized scaffold that can be tucked gently under the subgingival collar.

	There are some great products on the market designed to manage sulcular fluids and irritated tissue. These products, when used properly, enable clinicians to be more confident in achieving fluid control, isolation and tissue management. ViscoStat Plus From Ultradent is a tried and true hemostatic agent containing 22% ferric chloride that stops bleeding in seconds. It does not interfere with bonding and easily washes away. It is a must for successful bonding and impression-taking. ViscoStat Clear, also from Ultradent, is a chemical mix of 25% aluminum chloride, with the main focus on easy removal and no remaining residue (

	Hemostasyl is another new entry for site-specific hemostatic areas from Kerr Corp. This viscous substance incorporates 15% aluminum chloride into a bright blue paste that once placed, does not slump (

). It adheres well to tooth structure, soft tissue and matrix bands. That fact alone provides a great backdrop to combine a subgingival matrix band and this material to create an isolated working area-be it bonding, Class V restoration or cementation.

	Achieving subgingival access has become easier. Traditionally, cord was gently placed in this area to create easier access but problems surfaced with tissue trauma, cord residue or heightened bleeding. To address this problem, DMG America  developed the Zekrya Gingival Protector. This crescent-shaped tip attaches to a metal handle that is easy to position when it’s needed to finish a veneer margin or access a Class V caries.

	Along that same thought process, KerrHawe introduced Cervical Matrices (

). These thin, soft and clear contoured matrices allow direct placement of a restoration to the point of minimal finishing. They make that “ever so difficult” subgingival access easier and isolated.

	The Isolite Dryfield Illuminator from Isolite Systems was created to enable elevated access and visibility (

). This product stands alone for uninterrupted retraction, constant illumination and steady moisture control. Every team member can benefit from this device by virtue of reduced humidity and efficient procedural flow.

It comes down to providing better dentistry

	All of the above mentioned products or gadgets are great tools to add to your dental “game day” onslaught. The beauty of combining some of these products further enhances the isolation or access that can be achieved for improved bonding and better dentistry as a whole, leaving a smile on everyone’s face. 

Lori Trost, DMD, maintains a private practice in Columbia, Ill. Her practice merges contemporary esthetic dentistry with a minimally invasive approach to patient care. She lectures nationally, works with a variety of dental manufacturers on product evaluation and new materials direction, and also has been published in a variety of dental journals. She can be reached at 