Clinical Perspectives on Materials and Techniques

INTRODUCTION
This year I am celebrating my 25th year of private practice and my 15th year as a clinical educator. Needless to say, dentistry has changed dramatically throughout the years. Recently, scientific trends and novel products have emerged that have revolutionized my adhesive-based practice. The intent of this article is to offer my clinical perspective on a few contemporary restorative materials and clinical techniques that currently enhance the level of care provided to patients in my practice, make me more efficient and profitable, and simplify my life on a daily basis.

Current Trends and Materials in Dental Adhesion
A broad but perhaps overt descriptive summary of contemporary dental adhesive research would be that achieving a durable adhesive-dentin interface is a “moving target.” Data continues to emerge that ostensibly questions previously held standards, introduces novel challenges and potential solutions, and quantifies the strengths and weaknesses of contemporary products and delivery protocols. The once succinct division of total-etch (etch-and-rinse) and self-etch (no rinse) products is now blurred, and contemporary adhesive trends and the recent introduction of new class of adhesives have dramatically simplified my adhesive-based cosmetic and restorative practice.
The Selective-Etch Technique—It has long been established that phosphoric acid conditioning of enamel produced distinct micromechanical etch patterns conducive to resin infiltration, yielding highly stable and durable bonds.¹ However, total-etch adhesive products are technique-sensitive and more prone to operator error. Self-etch products are simpler to use and less prone to exhibit postoperative sensitivity, but typically create inferior bonds to enamel as compared to total-etch products.² It is now accepted that selectively etching exposed enamel with phosphoric acid prior to applying self-etch products dramatically improves bond strengths.^1,3 Today, the “selective-etch” technique is currently accepted as the third mechanism of action along with total-etch and self-etch modalities. For several years now, I have used the selective-etch technique almost exclusively for posterior direct composite restorations to enhance bonds to cavosurface enamel, while taking advantage of the positive attributes of most contemporary self-etching adhesives.
However, we all must be aware that traditional self-etching adhesives typically employ mild acids, do not remove the smear layer, or open dentinal tubules. Inadvertent exposure of dentin to phosphoric acid during the selective-etch technique has been shown to reduce bond strength and long-term stability of the adhesive-dentin interface.⁴ Some available phosphoric acid etchant materials (such as Premier Etch [Premier Dental Products] and Caulk Tooth Conditioning Gel [DENTSPLY Caulk]) are more viscous and make selective etching simpler. However, some manufacturers have recently released more viscous etchant materials designed to stay put when utilizing the selective-etch technique. At the top of my list are Select HV (BISCO Dental Products) and Scotchbond Universal Etchant (3M ESPE).
Contemporary Universal Adhesives—The mere concept of a “universal” adhesive immediately has my attention. In my busy adhesive-based practice, a truly universal dental adhesive that is simple and effective to use in every direct and indirect clinical application has numerous benefits. Historically in our office, we have stocked several total-etch and self-etch adhesives, each of which was utilized for very distinct but often limited clinical situations. Reducing my inventory to a single product saves me money, time, and it also significantly reduces the vast potential for operator error when toggling back and forth between adhesives. Less expense, increased efficiency, and fewer errors translate into more productivity and profitability.
The first universal adhesive was introduced by 3M ESPE with the release of Scotchbond Universal Adhesive. This single-bottle, no rinse, self-etching formulation was specifically designed to be used in total-etch, self-etch, and selective-etch modes for direct applications, and all indirect applications, when used as the adhesive component for any of the RelyX (3M ESPE) family of resin cements. Even more recently, BISCO Dental Products released All-Bond Universal. It is also a single-bottle, no rinse, self-etch formulation that can be used with all 3 direct application techniques, and is compatible with any resin-based cement system without the need for a separate activator.
Scotchbond Universal Adhesive—I have been using Scotchbond Universal Adhesive for direct and indirect application in my practice for almost 2 years now.
While at first blush, the concept of a universal adhesive system may seem suspect, the primary chemistry of Scotchbond Universal Adhesive has been used by 3M ESPE successfully for years in every category of adhesive.
The acid monomer in Scotchbond Universal Adhesive is 10-methacryloyloxydecyl dihydrogen phosphate (MDP), originally introduced by Kuraray in 1981 and has a long track record of documented clinical success. MDP is a hydrophilic, mildly acidic phosphate monomer known for its moisture tolerance and ability to form strong ionic bonds with calcium in hydroxyapatite, as well as with zirconia and metal oxides. Additional stability and ionic bonding is produced by the Vitrebond copolymer, which along with the ethanol and water solvents, has long been credited for the moisture tolerance and reduction of technique sensitivity of Adper Scotchbond Multi-Purpose Total Etch (3M ESPE) adhesive. With MDP facilitating ionic bonds to zirconia without the need for additional zirconia primers, and the addition of silane to couple the acrylic monomers to etchable ceramics, Scotchbond Universal Adhesive simplifies modern all-ceramic resin adhesion.
Direct Applications—In both my office and lectures, I base the mode of adhesion (total-etch, self-etch, selective-etch) on the clinical presentation in direct restorative procedures. If the majority of the adhesive substrate is confined to enamel (for instance, a small Class III, or small Class II “box” prep), I utilize Scotchbond Universal Adhesive in total-etch mode to capitalize on stronger enamel bonds. In typical Class I, II, and V restorations where there is roughly and equal mix of enamel and dentin, I utilize the product in selective-etch mode. Given the advantage of increased enamel performance with these 2 modes, my primary indication for using Scotchbond Universal Adhesive in self-etch mode is limited to core buildups during indirect procedures. These are largely dentin-borne restorations, and phosphoric acid is simply not required.
With the exception of adding the additional phosphoric acid etching step in the total-etch mode, the clinical application procedures of Scotchbond Universal Adhesive are the same for total-etch, self-etch, and selective-etch modes. You simply need to remember “20:5:10.” The adhesive are applied and allowed to dwell for 20 seconds. It is thinned and the solvents are evaporated for 5 seconds with a steady stream of air and then light-cured for 10 seconds.

Figure 1. Pre-op pit and fissure caries.	Figure 2. Selective etching of enamel.
Figure 3. A universal adhesive (Scotchbond Universal Adhesive [3M ESPE]) was applied for 20 seconds.	Figure 4. The adhesive was thinned and solvents volatilized with air for 5 seconds.
Figure 5. The universal adhesive was then light-cured for 10 seconds.	Figure 6. One-week postoperative result.

As an example of use for Scotchbond Universal Adhesive in direct application, Figure 1 shows the preoperative condition of tooth to be restored with an occlusal composite using the selective-etch technique. Scotchbond Universal Etchant was applied to the enamel cavorsurface margins only for 15 seconds and thoroughly rinsed away (Figure 2). Next, the preparation was thoroughly dried and Scotchbond Universal Adhesive was simultaneously applied to enamel and dentin and allowed to dwell for 20 seconds (Figure 3). The adhesive layer was then air-thinned and solvents evaporated for 5 seconds (Figure 4), and light-cured with an Elipar S-10 LED (3M ESPE) curing light for 10 seconds (Figure 5). In this case, Filtek Supreme Ultra (3M ESPE) was applied in vertical increments, light-cured, and then finished and polished. Figure 6 shows the completed restoration.
Indirect Applications—Scotchbond Universal Adhesive can be used as the adhesive with light-cured only resin cements (such as RelyX Veneer Cement) in thin restorations such as ceramic or composite veneers, or in dual-cure and self-cure indirect procedures in conjunction with the recently released RelyX Ultimate Resin Cement. RelyX Ultimate Resin Cement is a catalyst-based system dispensed in a convenient dual-barrel, spiral mixing tip syringe. It contains a proprietary dual-cure catalyst to assure polymerization of Scotchbond Universal Adhesive where autocuring is desired or necessary. RelyX Ultimate Resin Cement comes in 4 popular shades, along with assorted dispensing tips for numerous applications. Matching try-in pastes are available. Residual excess cement is easily removed during the gel state after 2 minutes in self-cure mode, or immediately after brief light polymerization with traditional instruments and floss.

Figure 7. The provisional restorations were removed and the preparations thoroughly cleaned.	Figure 8. Scotchbond Universal Adhesive was applied to the intaglio surface of the lithium disilicate (IPS e.max [Ivoclar Vivadent]) restorations and air-thinned only.
Figure 9. The universal adhesive was applied to the preparations, allowed to dwell for 20 seconds, and then thinned with air.	Figure 10. RelyX Ultimate Resin Cement (3M ESPE).
Figure 11. RelyX Ultimate Resin Cement was dispensed into the lithium disilicate restorations and seated.	Figure 12. Initial polymerization was initiated with brief light-curing and the residual cement was easily removed with an explorer (or scaler).

Figure 13. The completed restorations.

To demonstrate the protocol for utilizing Scotchbond Universal Adhesive in conjunction with RelyX Ultimate Resin Cement, the delivery of 6 anterior maxillary lithium disilicate all-ceramic crowns (IPS e.max [Ivoclar Vivadent]) will be utilized. In Figure 7, the provisional restorations were removed and the preparations were thoroughly cleaned with nonfluoridated prophy paste (Premier Dental Products). The lithium disilicate crowns were previously etched with 5% hydrofluoric acid by the dental laboratory. Scotchbond Universal Adhesive was dispensed, and the clinical assistant applied an even coat to the intaglio surface of each restoration, air-thinned the adhesive, but did not light-cure at this time (Figure 8). I simultaneously applied Scotchbond Universal Adhesive to each preparation and allowed the product to dwell for 20 seconds, and then thinned the adhesive layer and volatilized the solvents with 5 seconds of compressed air (Figure 9). The RelyX Ultimate Resin Cement kit is conveniently packaged with 4 shades and an assortment of spiral mixing tips and attachments (Figure 10). Each restoration was filled with RelyX Ultimate Resin Cement and seated onto the preparations (Figure 11). Residual excess cement was removed with an explorer (or sickle scaler) and floss (Figure 12), and then the restorations were definitively cured with dual curing lights (Elipar S-10). Figure 13 illustrates the final restorations at 6 months.

CONTEMPORARY COMPOSITE MATERIALS AND PLACEMENT TECHNIQUES
I have a number of favorite composite materials that I have used for years in various restorative and cosmetic applications. At the top of my personal choices list would be Filtek Supreme Ultra, Esthet-X HD (DENTSPLY Caulk), and KALORE (GC America). While these products have numerous merits, I want to focus on one particular contemporary composite material that that fits the criteria of simplifying a common but often challenging aspect of my daily practice. Like many practitioners, I am committed to utilizing a minimally invasive approach when at all possible. However, placing traditional viscous composites into conservative channels, pits, and box preps can be like trying to put a square peg into a round hole.

Figure 14. Fender Wedge (Garrison Dental Solutions) in place.	Figure 15. Composi-Tight 3D HR Ring (Garrison Dental Solutions).
Figure 16. Composi-Tight 3D HR is seated over the wedge after placement of the Slick Band (Garrison Dental Solutions).	Figure 17. Selective etching of the enamel was completed.
Figure 18. A self-etch adhesive (G-ænial Bond [GC America]) was applied and light cured.	Figure 19. G-ænial Universal Flo (GC America) was injected into the preparations.

Figure 20. The completed composite resin restorations.

G-ænial Universal Flo (GC America)—A few years ago, GC America released a novel material called G-ænial Universal Flo. It can be appropriately called an “injectable composite.” While the material may appear to be a flowable composite resin, it has excellent physical properties. It employs a novel 200-nm strontium glass filler homogeneously dispersed and coupled to the resin matrix using a proprietary silane process. With high fracture strength and wear resistance, this composite resin is indicated for small to moderate Class I, II, and IV restorations, and is ideal for Class V restorations of any size. It polishes to a high luster with traditional polishing techniques and comes in 15 shades, including a bleach shade, 2 cervical shades for darker than dark teeth, and has 2 translucent enamel shades that can be used to provide depth and vitality.
The “Box” Preparation—With contemporary adhesive dentistry, interproximal boxes for access and removal of caries represent the conservative norm today. However, smaller interproximal cavity forms pose unique challenges. Low vision and high-speed handpieces can be a lethal combination. Even the steadiest hand can easily mar an adjacent tooth. Traditional viscous composites can be difficult to adapt in tight spaces and G-ænial Universal Flo provides the adaptability and strength required to make box preps a breeze. However, due to its flowable consistency, the interproximal matrix must be incredibly stable, provide a definitive seal apically, and inherently provide the proper convex contour in the contact region. The new Composi-Tight 3D XR system (Garrison Dental Solutions) has numerous features for any Class II composite, but is especially handy with box preps and G-ænial Universal Flo. To demonstrate the benefits of both, let’s use the following clinical example:
Prior to establishing access to interproximal decay, I routinely select an appropriate-sized Fender Wedge (Garrison Dental Solutions) and place it between the interproximal contact (Figure 14). In addition to protecting the adjacent tooth during preparation, the wedge itself protects the gingival tissues from trauma and initiates separation of the teeth. The Composi-Tight 3D XR utilizes the same “Soft-Face” design as the original Composi-Tight 3D, but has the addition of retentive “teeth” to prevent pop-off and adds retention on more rounded teeth like the distal of canines (Figure 15). In my opinion, the Slick Bands (Garrison Dental Solutions) that come in assorted sizes and shapes are routinely practical for the majority of clinical presentations. I typically use Garrison’s wooden Soft Wedges, which are more anatomically shaped and longer than traditional wooden wedges. However, in this case, I used their Wedge Wand. It consists of a plastic version of the Soft Wedge that is attached to a “stick” (used to insert the wedge) that is subsequently twisted away and discarded. The placement procedure was to remove the Fender Wedge and the selected Slick Band between the prewedged teeth, and stabilize and seal the box with either a Soft Wedge or Wand Wedge. The Composi-Tight 3D HR band was expanded with Garrison forceps, and seated at a slight angle distal to the wedge for visibility and rocked mesially to the final position. The forceps were slowly released, and Figure 16 shows the assembly in place. Note the definitive apical seal and anatomical contour of the Slick Band. The cavosurface enamel was etched with phosphoric acid (Figure 17) for 15 seconds and then rinsed. Next, the preparation was dried, and a self-etching adhesive (such as G-ænial Bond [GC America] or Scotchbond Universal Adhesive) was applied according to the manufacturer’s instructions (Figure 18). The adhesive was then air-thinned and light-cured. Then, G-ænial Universal Flo was subsequently injected into the preparation (Figure 19) using the uniquely designed tip that is ideal for accessing tight spaces. It is sometimes advisable to place a small initial increment and spread to assure adaptation to gingival and lateral walls of the preparation, light-cure, and complete the restoration with second increment of G-ænial Universal Flo. In this case, the most mesial preparation was completed, and the distal preparation was treated in the same fashion. Figure 20 illustrates the immediate postoperative result. Note the obvious chameleonlike optical properties and also the lifelike luster of this single-shade restoration, as well as the natural anatomical contours.

CLOSING COMMENTS
The contemporary materials and techniques discussed and demonstrated in this article are integral to my practice on a daily basis. Materials like these have positively impacted the efficiency and efficacy of the restorative procedures that I provide for my patients. While the list is far from exhaustive, they represent a few prime examples of how contemporary materials and techniques can effectively reduce stress, save time and money, and simplify procedures that have been historically considered to be quite complex and challenging.

References

1. Osorio R, Monticelli F, Moreira MA, et al. Enamel-resin bond durability of self-etch and etch & rinse adhesives. Am J Dent. 2009;22:371-375.
2. Lührs AK, Guhr S, Günay H, et al. Shear bond strength of self-adhesive resins compared to resin cements with etch and rinse adhesives to enamel and dentin in vitro. Clin Oral Investig. 2010;14:193-199.
3. Erickson RL, Barkmeier WW, Kimmes NS. Bond strength of self-etch adhesives to pre-etched enamel. Dent Mater. 2009;25:1187-1194.
4. Sabatini C. Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives. J Appl Oral Sci. 2013;21:56-62.

Dr. Blank graduated from the Medical University of South Carolina, College of Dental Medicine in 1989 and maintains a full-time private practice at the Carolina Smile Center in Fort Mill, SC where he emphasizes complex restorative reconstruction and cosmetic enhancement procedures. He is the owner and chief clinical instructor for New Millennium Education, LLC, which offers affordable postgraduate clinical mentoring programs tailored the specific needs of clinicians seeking advanced training in contemporary aesthetic and full-mouth restorative dentistry. Dr. Blank has presented more than 150 lecture programs throughout the North America, Europe, Asia, Malaysia, India, Latin America, Africa, and the Middle East on a variety of advanced dental disciplines. He has authored more than 75 clinical manuscripts, contributed chapters to textbooks and has presented 6 scientific abstracts at the International Academy of Dental Research. He holds US Patent for a composite finishing instrument, and is the creator of the histological layering technique, a simplified method for creating polychromatic direct composite veneer restorations. He can be reached at via the Web site newmillenniumedu.com.

Disclosure: Dr. Blank reports no disclosures.