Written by Dentistry Today Monday, 07 April 2014 13:50
George Freedman, DDS
As the profession has moved from amalgam to composite for Class II restorations in posterior teeth, much of the traditional instrumentation has proven less than adequate for the new materials. Early matrix systems were designed for amalgam restorations that could be packed against the interproximal foil to achieve tight contacts. The restoration was also sculptable for several minutes after placement, allowing the practitioner to shape the interproximal margins and emergence profiles. Composite is not “packable” and tends to yield to the springback of metal matrices, compromising the contact. It is polymerized fully prior to matrix removal, and is too hard to sculpt with hand instruments. It must be polished with diamonds and carbides.
Poor anatomical contacts between posterior teeth with proximal restorations are potentially problematic. Even a small gap between the new restoration and the neighboring tooth (as narrow as 0.1 to 1 mm), tends to pack foods that subsequently act as an orthodontic separator. As the gap increases, it traps more food, often leading to periodontal disease and secondary caries on both teeth. This decay is often asymptomatic, making it difficult to diagnose until quite advanced, when the patient requires endodontic treatment or possibly an extraction.
There was a great need for a new set of instruments that would overcome the problems presented by tooth-colored posterior restoratives. Initially, circumferential bands were tried, but it was difficult to establish correct contact as this type of band tends to create tin-can restorations where the contact point is too close to the marginal ridge. Interproximal contact is often light or absent as the matrix band distends the interproximal area of both sides of the tooth. The band on the unprepared side of the tooth pushes the tooth toward the cavity preparation. When the circumferential band is finally removed, the tooth springs back into its original position, opening the newly established restorative contact.
More recently, sectional matrix systems have overcome many of these problems. The key issues for dentists with these new systems were difficulty in placing the separating rings, the tendency of the separating rings to spring off the teeth, and the struggle of manipulating the tiny matrices and wedges with gloved hands. A number of innovations solved these problems, including rings that gripped the interproximal undercuts securely, ring tine design that allowed the wedge to be positioned before or after the insertion of the ring, and perforated tabs on the matrices that were easily grasped by custom tweezers.
Separating rings can be inserted from the distal or the mesial, and some of the systems are designed to allow the simultaneous restoration of multiple adjacent teeth. The rings must be sterilizable (matrices and wedges are single-use) and should retain their spring through many uses. Most rings are manufactured of titanium or stainless steel. The matrices must be as thin as possible and preferably precontoured buccolingually and incisogingivally. They must have enough height in the middle to reach subgingivally. The wedges must be contoured to fit the interproximal space, and rigid enough to slightly separate the teeth. For greater clinical convenience and efficiency, dedicated matrix kits are excellent component organizers.
The newly introduced V4 ClearMetal Matrix System features microwindows. It is the only transparent matrix system with the advantages of metal malleability for optimal polymerization. The V4 System creates natural contours with ease, and the added benefits of a ring, matrix, and transparent wedge make it a great match for bulk-fill resins and deep cavities, giving the dentist peace of mind that the composite is sufficiently cured before the matrix is removed. For more information, call toll-free (800) 552-5512 or visit ultradent.com.
Garrison Dental Solutions
The Composi-Tight 3D XR Sectional Matrix System is clinically designed for use with short or malpositioned teeth and between canine and first bicuspid during Class II restorative procedures. Its Soft Face silicone ensures true matrix band adaptation, reducing flash and finishing time while improving contacts. While the 3D XR ring was designed for use with difficult dentition, clinicians will find that it works exceptionally well with standard height teeth, providing predictable results. For more information, call (888) 437-0032 or visit garrisondental.com.
The FenderMate flexible wing separates the teeth, pressing the matrix toward the cervical margin, avoiding overhang. Its optimal curvature and preshaped contact accommodate the most conservative Class II preparation; no ring is needed. With the facility to insert it lingually and/or buccally, the dentist can maintain a smaller, more conservative preparation, thus preserving healthy tooth structure and easily restoring a proper contact. For more information, call JS Dental Manufacturing at (800) 284-3368 or visit jsdental.com or directadental.com.
The Mega V system offers many advantages. The wide tines are split into a V, allowing easy wedge placement. Converging tines prevent popoffs and inclined hoops allow easy stacking. The bands are made of a special alloy, and the profile of the hoop spreads the stress throughout more of the hoop, reducing distortion and maintaining superior separating force. Contact Matrix matrices are ultrathin yet are made of a springy alloy to resist crumpling. For more information, call (800) 827-7940 or visit danvillematerials.com.
Greater Curve Dental
The versatility of the copyrighted Greater Curve technique will amaze you. So simple it’s a wonder G. V. Black did not think of it. It has a fast setup with complete isolation for Class II, III, and IV composites. No wedging and/or separating springs are needed. You can bridge wide-open embrasures ef-fortlessly and restore anterior and posterior teeth with smooth, tight anatomical contacts. There is nothing better for sequestering subgingival Class Vs. For more information, call (866) 493-3437 or visit greatercurve.com.
The Palodent Plus Sectional Matrix System offers wide applications for sectional matrix system use and delivers predictable, accurate contacts consistently. The system includes a molar and premolar ring and a variety of matrices, wedges, wedge guards, and placement instruments. The rings provide consistent separation force and excellent stability on the tooth while working with the matrix and wedge to seal and shape the restoration, minimizing the amount of finishing required. For more information, call (800) 532-2855 or visit the Web site palodentplus.com.
Because the ultrathin matrix bands are precontoured, they save time and are easier for dentists. These Tofflemire matrix bands are thin, which allows for the development of more consistent contact in posterior teeth. The matrix bands are available in regular and primary teeth sizes (PT matrix bands). For more information, call (800) 621-6729 or visit cosmedent.com.
Fly Cast Technologies
PinkBand, the innovative, rubberized, silicone-coated dental matrix band, was awarded as one of Dentistry Today’s 2013 Top 100 Products. It was evaluated at THE DENTAL ADVISOR by 27 independent dental consultants who placed 497 composite restorations in patients and concluded that there was significantly improved moisture control when compared to standard and sectional matrix bands. PinkBand Ultra Thin does not crumple during placement. PinkBand Regular comes in a 0.0015-in size, and Ultra Thin is 0.001 in. For more information, call toll-free at (847) 260-8330 or visit pinkband.org.
The Preformed Matrix Bands eliminate the need for retainers—just fit, wedge, and throw them away. The matrix bands save time because they are easy to fit, there’s no sterilization, and they’re disposable. They also reduce patient stress and increase your field of view inside the mouth. The stainless steel bands are thin enough to be contoured easily yet strong enough to re-tain the required form. Kits include 15 different loop sizes to ac-commodate most molar restorations. The bands come in 2 heights: pedo and adult. For more information, call toll-free at (800) 854-7949 or denovodental.com.