INTRODUCTION
The term “universal” seems to be used frequently in the adhesion/composite-resin-materials world today. It has always been a struggle to find such a material that can adequately replace 2 different types of tissues, namely enamel and dentin. In comparing dentin and enamel, dentin is more opaque and resilient, while enamel is more translucent and brittle. The other caveat is that aesthetics is an important consideration in the success of a dental restoration in the anterior region, where there is a higher demand for optimal layering, whereas, in the posterior, functional stresses of occlusion require a focus on the physical properties of a composite resin material for durability and longevity.
Advances in composite-resin technology have been largely on the filler side—changes in particle size, particle shape, or filler type—with the goal of maximizing the aesthetic potential of the material while maintaining the physical properties necessary to enable the material to withstand the stresses of masticatory forces in the oral environment. A recently introduced composite system (Mosaic [Ultradent Products]) contains nanofiller particles composed of zirconia-glass ceramic and 20-nm silica. This optimized balance produces a smooth and glossy surface in the finished restoration that is desirable for anterior aesthetics. In addition, this composite resin possesses mechanical properties that perform well in stress-bearing areas, such as posterior occlusal surfaces. Most of the time, a universal shade alone can provide excellent shade blending with natural tooth structure for both anterior and posterior restorations.
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| Figure 1. A preoperative occlusal view of a defective amalgam restoration in tooth No. 5 prior to removal of the material and the associated recurrent decay. | Figure 2. An occlusal view of the completed DO cavity preparation on tooth No. 5. |
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| Figure 3. The sectional matrix band (Triodent V3 [Ultradent Products]) was placed on the distal aspect of tooth No. 5. | Figure 4. The sectional ring was then placed to secure the matrix band. |
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| Figure 5. A 15-second total-etch using a 37% phosphoric acid gel (UltraEtch [Ultradent Products]) was done and then thoroughly rinsed with water. Any excess remaining moisture was then removed using a high-volume suction device (not an air syringe) to avoid over-desiccation and collapse of the exposed collagen, since that could lower the bond strength of the adhesive to the dentin. | Figure 6. After the etching procedure, the cavity preparation was cleansed with 2% Chlorhexidine (Consepsis [Ultradent Products]). This was done to help prevent the release of matrix metalloproteinases from the etched collagen that could potentially weaken the bond strength of the adhesive to dentin. |
Interproximal Surface Morphology of Posterior Teeth
Class II (interproximal) decay and/or a failing restoration that involves the proximal surface of a posterior tooth is a common occurrence in many dental patients. A good portion of these problems can be handled utilizing directly placed restorative materials. One challenge for the clinician is to accurately recreate a physical contact to the adjacent tooth and, at the same time, to restore proper interproximal anatomic form given the limitations of conventional Tofflemire-type matrix systems. The thickness of the matrix band, the ability to compress the periodontal ligaments of the tooth being restored, and the tooth adjacent to the matrix band can sometimes make the restoration of proximal tooth contact difficult at best. Anatomically, the posterior interproximal surface is convex occlusally and concave gingivally (below the contact point). The interproximal contact area itself is elliptical in the bucco-lingual direction, and it is located approximately 1.0 mm apical to the height of the marginal ridge. As the emergence profile of the tooth progresses gingivally from the contact point toward the cementoenamel junction, a concavity exists that houses the interdental papilla and interproximal bone. Tofflemire-type matrix systems consist of thin and flat metallic strips that are placed circumferentially around the tooth to be restored and affixed with some sort of retaining device. While contact with the adjacent tooth can be made with a circumferential matrix band, it is impossible to recreate the natural convex/concave anatomy of the posterior proximal tooth surface because of the inherent anatomic limitations of these systems. Attempts to shape/burnish metal matrix bands with instrumentation may help create nonanatomic contact, but they only distort/indent the bands and do not recreate complete natural interproximal contours. Without the support of tooth contours, the interdental papilla may not completely fill the gingival embrasure, leading to potential food traps and areas for excess plaque accumulation. Direct Class II composite restorations also present a greater challenge for the dentist to place than a material (ie, amalgam) because of the inability of resin materials to be condensed against and deform a matrix band to the same degree. Offering a solution to this clinical problem, this article will also describe the use of a sectional matrix system (Triodent V3 [Ultradent Products]). This matrix system was designed to facilitate the placement of composite resin and to ensure optimal results, both in physiological contact and in anatomic form. When utilizing this type of matrix system with the latest in composite-resin technology, direct Class II tooth-colored restorations with natural anatomic proximal form and predictable proximal contacts can be predictably placed.1-3
Tooth Preparation and Matrix Selection
Class II cavity preparations that need matrix bands for restoration will require the rebuilding of the marginal ridge, proximal contact, and, often, a large portion of the interproximal surface, as well as the occlusal surface. The goal of composite placement is to do it in such a way that the amount of rotary instrumentation for contouring and finishing is limited. This is especially true for the interproximal surface. Because of the constraints of clinical access to the proximal area, it is extremely difficult to sculpt and correctly contour this surface of the restoration. Proper restoration of this surface is largely due to the shape of the matrix band and the accuracy of its placement.4 After removal of the old restorative material and any recurrent dental caries, the outline form of the cavity preparation is completed using rotary instrumentation (#330 carbide bur [SS White Burs]). If any portion of the proximal contact remains, it does not necessarily need to be removed. Conserve as much healthy, unaffected tooth structure as possible. If the matrix band cannot be easily positioned through the remaining contact, the contact can be adjusted using an interproximal abrasive device (ContacEZ).
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| Figure 7. The bonding resin (Peak Universal [Ultradent Products]) was placed on all etched enamel and dentin surfaces. | Figure 8. The adhesive was then light cured for 20 seconds using an LED curing light (VALO Grand [Ultradent Products]). |
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| Figure 9. The first increment of composite, a flowable resin (PermaFlo [Ultradent Products]), was placed into the preparation up to a depth of 0.5 mm to ensure accurate adaptation of the first increment of composite to the geometry of the cavity preparation. | Figure 10. The next increment was the universal composite resin (Mosaic [Ultradent Products]), placed using a composite placement instrument (Mini 4 Goldstein Flex-Thin Composite Instrument [Hu-Friedy]). |
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| Figure 11. Prior to light curing, a sable brush (#2 Flat Keystone [Patterson Dental]) was used to smooth and adapt the uncured composite resin. | Figure 12. Once the composite was light cured, the occlusion was checked with articulating paper (AccuFilm 2 [Parkell]). |
A sectional matrix system, such as Triodent V3, is an excellent choice for Class II composite restorations for many reasons. The matrix band is anatomically correct, and the unique design of the matrix allows for the proper restoration of interproximal anatomy as described above. Once the cavity preparation is completed and proper isolation is achieved, a sectional matrix band with the appropriate size is selected. The correct size (cervico-incisally) should extend slightly beyond the gingival cavosurface margin so that the interproximal wedge can engage and seal the gingival margin of the cavity preparation without indenting or deforming the matrix material.
In adhesive dentistry, the 2 main enemies of resin bonding are saliva and blood. When performing Class II direct composite restorations, the gingival tissues often come into play, and, most of the time, this can have a negative impact (eg, bleeding) on the procedure if the operating field cannot be controlled. Since adhesive resins and composite materials are hydrophobic, moisture (eg, saliva and/or blood) control in the operating field is important for successful adhesive bonding to tooth structure. In addition, some gingival margins in proximal boxes in Class II cavity preparations can be located on root surfaces (dentin) and are already subject to a compromise in the ability to bond resin restorations successfully. By using a super-pulsed diode laser (Gemini dual-wavelength diode laser [Ultradent Products]) to reduce marginal gingival tissue, keeping the restorative margin supragingival (whenever possible and as biologic width perimeters allow), and stopping any bleeding prior to matrix and restorative material placement, the chances of successful adhesion and long-term success of the definitive restoration can be increased substantially.5
CASE REPORT
Class II Posterior Direct Composite Restorations
A patient presented with radiographic decay and marginal ridge fracture on the distal surface of tooth No. 5, which had previously been restored with an occlusal amalgam (Figure 1).
Clinical Protocol
After local anesthetic was administered, and after caries removal and the creation of the cavity outline form, the operative area was isolated using a rubber dam in preparation for the restorative process (Figure 2). The Triodent V3 Sectional Matrix System was used here to aid in the anatomic restoration of the distal proximal tooth morphology of this maxillary first premolar tooth. The appropriate matrix band size was chosen that would best correspond anatomically to the tooth being restored and, also, to the width and height of the proximal surface (Figure 3). When properly placed, the height of the sectional matrix should be no higher than the adjacent marginal ridge. The tab on the matrix band is bent over using an index finger to hold the band securely while the wedge is placed. This tab also ensures that the height of the matrix band corresponds to the height of the adjacent marginal ridge so that the marginal ridge of the restoration will be located at the proper height. Because of the concave anatomic shape when applied, the proximal contact will be located approximately 1.0 mm apical to the height of the marginal ridge. Next, the gingival portion of the band was stabilized and sealed against the cavosurface margin of the preparation using the appropriate size anatomic wedge. The size of the wedge should be wide enough to hold the gingival portion of the matrix band sealed against the cavosurface of the preparation while the opposite side of the wedge sits firmly against the adjacent tooth surface.
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| Figure 13. A 20-fluted carbide composite finishing bur (#9904 [SS White Burs]) was used to adjust the occlusion prior to polishing the restoration. |
Figure 14. A high-luster polishing, white abrasive point (Jiffy Polishers [Ultradent Products]) was used to polish the surface of the composite restoration. |
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| Figure 15. A composite polishing brush (Jiffy Brush [Ultradent Products]) was used to impart the final luster on the composite surface. | Figure 16. An occlusal view of the completed Class II DO posterior composite restorations on tooth No. 5. A beautifully anatomic restoration was placed using a universal composite material (Mosaic), shown here seamlessly with the natural tooth structure. |
Once the sectional matrix was properly wedged and the ring was placed (Figure 4), the restorative process for tooth No. 5 commenced. A 15-second total-etch protocol (10 seconds on enamel margins and 5 seconds on the dentin surface) was done using a 37% phosphoric etchant (Ultra-Etch [Ultradent Products]) (Figure 5). The etchant gel was then rinsed off for a minimum of 15 to 20 seconds to ensure complete removal. The preparation was then air-dried and re-wetted with an antimicrobial (Consepsis [Ultradent Products]) to disinfect the cavity surface and to create a moist surface for bonding (Figure 6).
A total-etch bonding agent (Peak Universal [Ultradent Products]) was then placed on all cavity surfaces (Figure 7). Chlorhexidine (0.2%) is included in the bonding agent and will help inhibit the release of matrix metalloproteinases from the etched collagen that have been shown to weaken the dentin bond over time.6 The solvent in the applied universal adhesive was then evaporated by spraying a gentle stream of air across the surface of the preparation. The adhesive was then light cured for 20 seconds (VALO Grand [Ultradent]) (Figure 8). The 12.0-mm lens diameter of this curing light and its uniform irradiance allows for a quality cure for even the largest multi-surface composite restorations. The first layer of composite resin was placed using a flowable composite (PermaFlo [Ultradent Products]) at a thickness of about 0.5 mm (Figure 9). The flowable composite intimately adapts into all the irregular areas of the preparation, particularly the line and point angles of the proximal box where most composites will fail due to poor adaptation. This lessens the chance of creating voids between the adhesive and the first layer of composite and, once cured, creates an oxygen-inhibited layer to bond subsequent layers of composite material. After light curing for 20 seconds, the next step was to layer-in the next composite material.
Using a uni-dose delivery system, the first increment of composite resin (Mosaic) was placed into the proximal box of the preparation. Next, a smooth-ended composite placement instrument (Mini 4 Goldstein Flexi-Thin Composite Instrument [Hu-Friedy]) was used to adapt the restorative material to the inside of the sectional matrix and preparation (Figure 10). Each increment of composite material should be no more than 2.0 mm thick. The buccal increment was placed into the facial portion of the preparation, including the facial portion of the marginal ridge. Then the cuspal parabolisms were sculpted, and the sulcular depressions in between were created using the Mini 4 Flexi-Thin. A #2 Flat Keystone brush (Patterson Dental) was lightly dipped in resin, dried thoroughly with a 2 x 2 gauze sponge, and then used to feather the material toward the margins and to smooth the surface of the composite (Figure 11). After the restoration was fully light cured, the occlusion was checked with articulation paper (AccuFilm 2 [Parkell]) and adjusted (as needed) using a thin, 20-fluted carbide composite finishing bur (#9904 [SS White Burs]) (Figures 12 and 13).
When placing composite materials using the above described technique, very little finishing should be required, except at the marginal areas. Rubber polishing abrasives (Jiffy Polishers [Ultradent Products]) were used to further polish and adjust areas (Figures 14 and 15). After a 5-second etch of the restorative margins with 37% phosphoric acid, a surface sealant (PermaSeal [Ultradent Products]) was placed using a micro brush, then air thinned and light cured for 20 seconds. Surface sealants help to seal any microscopic marginal imperfections that may remain after the finishing and polishing process.
Figure 16 shows an occlusal view of the completed direct Class II composite resin restoration on tooth No. 5.7,8
CLOSING COMMENTS
A technique has been described utilizing a sectional matrix system and an associated armamentarium and a universal composite to create anatomically precise Class II posterior composite restorations. The interproximal surface was recreated with a natural anatomic contour, and an elliptical contact with the adjacent tooth was predictably made. With proper occlusal and proximal form, this Class II direct composite restoration should serve this patient for many years to come.9
References
- Christensen GJ. Remaining challenges with class II resin-based composite restorations. J Am Dent Assoc. 2007;138:1487-1489.
- Boer WM. Simple guidelines for aesthetic success with composite resin—part II: posterior restorations. Pract Proced Aesthet Dent. 2007;19:243-247.
- Shuman I. Excellence in class II direct composite restorations. Dent Today. 2007;26:102-105.
- Brackett MG, Contreras S, Contreras R, et al. Restoration of proximal contact in direct class II composites. Oper Dent. 2006;31:155-156.
- Lowe RA. Tissue management for restorative dentistry. Dent Today. 2018;37:86-89.
- Pashley DH, Tay FR, Imazato S. How to increase the durability of resin-dentin bonds. Compend Contin Educ Dent. 2011;32:60-66.
- Lopes GC, Vieira LC, Araujo E. Direct composite resin restorations: a review of some clinical procedures to achieve predictable results in posterior teeth. J Esthet Restor Dent. 2004;16:19-31.
- Nash RW, Lowe RA. Recreating nature using today’s composite materials. Restorative Quarterly–A Supplement to the Compendium. 2000;3:3-10.
- Lowe RA. Morphologic and esthetic precision in the placement of class II direct composites. Contemporary Esthetics and Restorative Practice. 2004;8:28-30.
Dr. Lowe received his DDS degree from the Loyola University School of Dentistry in 1982. He previously taught at the Loyola University School of Dentistry while building a private practice in Chicago. Dr. Lowe currently maintains a full-time practice in Charlotte, NC. He can be reached at boblowedds@aol.com.
Disclosure: Dr. Lowe has received honoraria from Ultradent Products.
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