DTUS0610

Clinical solutions to common problems when placing Class II direct composites By Robert Lowe, DDS, FAGD, FICD, FADI, FACD Class II challenge Direct composite restorations that involve posterior proximal surfaces are still a common finding in many dental patients. Unlike dental amalgam, which can be a very forgiving material tech- nically and can be condensed against a matrix band to create a proximal contact, proper placement of com- posite restorative materials presents a unique set of challenges for the operative dentist. The adhesion process itself is well understood by most clinicians as far as isolation and execution, however, there are some steps in the place- ment process that cause difficulty and ultimately lead to a less than desirable end result. In this article we will look at three specific areas: management of the soft tissue in the interproximal region; creation of proximal contour and contact; finishing and polishing of the restoration. Management of the interproximal gingival tissue The most common area for the adhe- sion process to fail is the proximal gingival margin. Compounding this problem is the inability to gain access to the area to effect a repair without removal of the entire restoration. As stated by Dr. Ron Jackson, bonded restorations are unique in that minor defects (decay or microle- akage) at the marginal interface can often be “renewed,” or repaired by removal of the affected tooth struc- ture and repaired with additional composite restorative material. Because of the bond of the restor- ative material to enamel and dentin, the recurrence is usually self-lim- iting. This is not true with metal- lic restorations that are not bonded to tooth structure. However, if the defective area is at the proximal gin- gival margin or line angle, access is not possible. Therefore, precise marginal adap- tation of the direct composite restor- ative material and the seal of this margin in the absence of moisture or sulcular fluid contamination is of paramount importance. However, whether due to the sub- gingival level of decay and/or gingi- val inflammation, it can be difficult to seal the gingival margin with a matrix in the presence of blood. Proximal contact and contour Another challenge for the dentist has always been to re-create contact to the adjacent tooth and, at the same time, restore proper interproximal anatomic form given the limitations of conventional matrix systems. The thickness of the matrix band and the ability to compress the peri- odontal ligaments of the tooth being restored and the one adjacent to it can sometimes make the restoration of proximal tooth contact arduous at best. Anatomically, the posterior proxi- mal surface is convex occlusally and concave gingivally. The proximal contact is elliptical in the buccolin- gual direction and located approxi- mately one millimeter apical to the height of the marginal ridge. As the surface of the tooth pro- gresses gingivally from the contact point toward the cemento-enamel junction, a concavity exists that hous- es the interdental papilla. Conventional matrix systems are made of thin, 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 circumfer- ential matrix band, it is practically impossible to re-create the natural convex/concave anatomy of the pos- terior proximal surface because of the inherent limitations of these sys- tems. Attempts to “shape” or “burnish” matrix bands with elliptical instru- mentation may help create nonana- tomic contact, but only “distorts” or “indents” the band and does not re- create complete natural interproxi- mal contours. Without the support of tooth con- tour, the interdental papilla may not completely fill the gingival embra- sure, leading to potential food traps and areas for excess plaque accu- mulation. Direct Class II composite restorations can present even more of a challenge to place for the den- tist because of the inability of resin materials to be compressed against a matrix to the same degree as amal- gam, making it difficult to create a proximal contact. Finishing and polishing composite restorations Direct composite material does not carve like amalgam, although many clinicians wish that it did! Unfortu- nately, this means that most posterior composites are carved with a bur. This is not part of the finishing and polishing of the restoration. It must be remembered that cuspal forms are convex and cannot be carved with a convex rotary instrument that imparts a concave surface to the restorative material. Composite should be incremen- tally placed and sculpted to proper occlusal form prior to light curing. The finishing and polishing process is done to accomplish precise mar- ginal adaptation and make minor occlusal adjustments. Rubber abrasives further refine the surface of the composite, and surface sealants are used to gain additional marginal seal beyond the limitations of our instrumentation. Case report The patient shown in Figure 1 pre- sented with radiographic decay on the mesial proximal surface of tooth No. 3. The operative area is isolated using an OptiDam (Kerr Hawe). The decay is minimal, so the operative plan is to keep the preparation very conservative. After removal of the decay and completion of the proximal and occlusal cavity form, the operative area is isolated with a rubber dam in preparation for the restorative pro- cess. Figure 2 clearly shows that the proximal gingival tissue was abraded during cavity preparation and there is evidence of hemorrhage. It is not advisable to try and “wash” the hemorrhage away with water and quickly apply the matrix band. Even if this is successful, it is Clinical DENTAL TRIBUNE | March 201014A Available at pattersondental.com • High final hardness - Shore-D 40 • Setting time about 60 s • Scanable for powderless 3D-data registration of antagonists (CAD/CAM) • Perfect physical parameters • 2 Cartridges + 12 Mixing cannulas + CAD/CAM CIM T E C H N O L O GY IMP RESSIO N R dental Biß zur Perfektion RR-dental Dentalerzeugnisse GmbH E-mail: info@r-dental.com r-dental.com R-SI-LINE METAL-BITE TM® Universal and scanable registration material, that’s it! Anzeige METAL-BITE USA 2009/10:METAL-BITE 2009/10 01.11.2009 22:31 Uhr Seite 1 AD Fig. 1: This occlusal preoperative view shows a maxillary molar that has radiographic decay on the mesio-proximal surface. Fig. 2: After the cavity preparation is completed, bleeding is seen in the proximal area. Fig. 3: Expa-syl (Kerr) is placed into the proximal area with the delivery syringe then tapped to place using a dry cotton pellet. Fig. 4: After rinsing away the major- ity of the Expa-syl (note that a small amount of Expa-syl remains sub-marginal for additional hemor- rhage control), the proximal tissue is deflected away and bleeding is absent, allowing for easy placement of the sectional matrix band.