Few things in dentistry frustrate practitioners more than, after having created the perfect class II preparation and restored the tooth with composite resin, the dental floss twangs through a wimpy composite point contact, offering little or no resistance the rest of the way down. You may have won the battle with respect to eliminating caries, but you’ve lost the war of restoring the tooth to desirable physiologic contours. With time having run out, you skulk away to your next challenge, feeling beaten. Sound familiar? Given the plethora of “can-do” gizmos designed to remedy this common occurrence, it’s obvious that our profession is in search of a better mousetrap. The following roundup is intended to categorize the varying approaches to class II contact formation and name several of the devices that populate each category. While I’ve attempted to include all participants, I apologize in advance for any that may have eluded me.
WHAT ARE WE AFTER?
Before naming the different matrix-forming devices, it is prudent to review just what it is we seek when forming contacts within class II restorations. The normal adult interproximal contact is composed of 2 generally round or oval facets with surfaces that are flat or slightly concave, closely parallel to each other, and generally perpendicular to the local curve of the arch. When the teeth are at rest, adjacent facets are separated by an interproximal gap of about 10 to 15 µm, depending on postural conditions. The perfect contact is one in which surface-to-surface intimacy begins a millimeter or so gingival to the crest of the marginal ridges and continues gingivally for perhaps 2 to 3 mm before gracefully merging into the root form. From an occlusal perspective, it is equally desirable to have the contact as broad as the tooth’s natural form allows. In addition to providing a bracing function during mastication, this clever design of nature affords the underlying tissue protection from food impaction and the destruction that accompanies it. Given the predictability of eventual breakdown in the absence of this arrangement, it is little wonder that so many solutions have been offered to the profession.
CATEGORIES OF MATRIX-FORMING DEVICES
Class II matrix-forming devices fall into 3 categories. Enjoying wide popularity are the sectional matrix systems. Here we find little slices of dead-soft, anatomically shaped metal strips, held in place by retaining rings and accompanying wedges that also are intended to separate adjacent teeth. These might be considered a direct descendant of the still-popular Tofflemire retainer and stainless steel band. The second category includes several “self-contained” matrix systems in which the matrix band and securing device (and in one instance, the wedge also) are one unit. Last but not least, we have the “push-and-pull” devices that, when used in concert with conventional matrix systems, will by operator force create more desirable contact shapes within the matrices employed.
HARD STEEL AND SOFT BANDS
Sectional Matrix Systems
Let’s first examine the sectional matrix (SM) systems. Manufacturers such as Garrison Dental Solutions, makers of Composi-Tight and Composi-Tight Gold, and Danville Materials, makers of Contact Matrix, offer tidy little packages that include an assortment of precontoured, dead-soft, burnishable matrix formers along with their respective retaining/separating rings and placement forceps. DENTSPLY’s Palodent and Kerr’s Hawe Neos round out the quartet, with the latter departing from the fold by offering clear, hard plastic retaining rings and a choice of dead-soft steel or clear plastic contact forming matrices.
 |
 |
|
Figure 1. Shown are 3 matrix systems used in combination: Composi-Tight, Contact Matrix, and AutoMatrix. Note Coltene/Whaledent Flexi-Dam.
|
Figure 2. The same combination shown in Figure 1, plus the AdDent Trimax.
|
 |
 |
|
Figure 3. The finished restorations using combined systems.
|
Figure 4. Garrison Composi-Tight Gold shown with Wedge Wands for back-to-back DOs.
|
 |
 |
|
Figure 5. Complete DOs using Garrison Composi-Tight Gold and Wedge Wands.
|
Figure 6. Assorted sizes of Composi-Tight Matrices.
|
 |
 |
|
Figure 7. Contact Matrix from Danville Materials. |
Figure 8. Contact Matrix system in action. |
 |
 |
|
Figure 9. When using sectional matrices, contacts need be broken in 3 dimensions.
|
Figure 10. DENTSPLY Caulk AutoMatrix used with Premier wooden wedges.
|
SM Advantages. Sectional matrix systems offer considerable versatility. Most kits feature several sizes of dead-soft strips as well as an assortment of ring sizes. Matrix strips are usually precontoured to simulate the ideal proximal surface. When properly used, the separating effect of a well-placed retaining ring accompanied by the extreme thinness (0.0013 inches, in the case of Garrison’s system) will create contacts so tight that instrumentation is needed to remove the bands. Additionally, some of the SM systems are “stackable.” Both Garrison and Danville systems allow the operator to place multiple rings, thus allowing 2 or 3 teeth to be restored simultaneously and facilitating MOD restorations (Figures 4 through 8).
SM Disadvantages. SM systems are often not suitable for large direct restorations that include oversized portions of the labial or lingual walls. In such cases, the pressure of the retaining ring is apt to collapse the sectional matrix. Interestingly, this drawback has been somewhat countered within the Garrison system with the introduction of its Wedge Wands. Properly engaging the flexible wedges will often prevent the band from collapsing by redirecting the forces of the bi-tine prongs. The flexibility of the wedges also allows for easier placement of the retaining ring.
PACKAGE DEALS
The AutoMatrix
The “self-contained” approaches referenced above might include 3 entries that need to be considered individually, owing to their diverse nature. The DENTSPLY Caulk AutoMatrix is representative of a self-tightening, self-retaining matrix device that doesn’t require a separate retaining ring to hold it in place. Instead, it relies upon the act of cinching it tight around the circumference of the tooth. Kerr offers a similar line of self-retaining matrix bands. Such systems are available with stainless steel or clear plastic matrix bands, with the former remaining more popular. A not-too-distant relative might be DENOVO Dental’s Preformed Matrix Bands, which rely upon 15 sizes of retainerless steel matrix bands.
AutoMatrix Advantages. The stainless steel AutoMatrix retainerless matrix is easy to place and can be used in most any size restoration as long as a gingival purchase can be secured. While possible to distort upon placement, it is more robust than SM matrix bands and is available in 3 widths and 2 thicknesses, with the “medium-thin” version measuring a thickness of 0.0015 inches. Originally designed to facilitate amalgam placement, this matrix system is frequently used for composite restorations as well (Figures 10 and 11). A proprietary tightening device and snipping device are part of the system and accompany introductory kits.
AutoMatrix Disadvantages. The primary drawback to the use of the AutoMatrix with composite resins parallels the same drawback that has typically been ascribed to the use of the Tofflemire retainer system. The AutoMatrix steel band isn’t precontoured, and in its present form is more apt to produce a high, narrow contact point along with a flat proximal surface unless combined with another modality (as will soon be described.)
The TrioDent Tri-Clip
 |
 |
|
Figure 11. Restored bicuspid using DENTSPLY Caulk AutoMatrix and Coltene/Whaledent Miris Composite.
|
Figure 12. Tri-Clip in place. |
 |
 |
|
Figure 13. 3M ESPE Filtek Supreme being introduced into preparation.
|
Figure 14. Completed Filtek Supreme restorations.
|
 |
 |
|
Figure 15. Dental Innovations Microbands. |
Figure 16. Diagram of Microband in place. |
 |
 |
|
Figure 17. The AdDent Trimax provides a light show.
|
Figure 18. The Contact Pro 2 device from CEJ Dental.
|
 |
 |
|
Figure 19. The ContactEase creating contacts in a MOD restoration.
|
Figure 20. Finished Filtek Supreme restoration. |
The TrioDent Tri-Clip is an ingenious device that in-cludes the matrix band, the separator/retainer, and the wedge in a single disposable device. It was developed by New Zealand’s Dr. Simon McDonald and represents the most recent entry to the “self-contained” roster. As its name implies, the device separates adjacent teeth, provides a matrix band against which to form one’s contact, and includes a polymer-formed wedge that is intended to be pulled through the contact once the assembly is in place. Placement can be accomplished with a special forceps provided by the manufacturer or by using the forceps that accompanies the Garrison or Danville kits. The Tri-Clip system includes “innies” and “outies”; that is, bands oriented for MO and DO restorations.
Tri-Clip Advantages. The chief advantage of the Tri-Clip, in addition to obtaining snug contacts, is the speed of placement. Once one becomes familiar with it, the Tri-Clip can be placed in as little as 10 seconds. Additionally, fumbling with separate matrices and wedges is eliminated because of the integrated nature of the device, and the wedge usually results in instant hemostasis. Recent design improvements have resulted in a centrally wider band, allowing for more universal coverage of the proximal wall to be restored (Figures 12 through 14).
Tri-Clip Disadvantages. The all-in-one nature of the Tri-Clip may prove awkward for some users. Visualizing around the hefty retaining ring to perfectly position the matrix band is at times a challenge. Moreover, when adjacent teeth are irregular in position, the Tri-Clip’s “tines” hesitate to fully engage the intended surfaces. As with any new device, a learning curve ensues, which is aided by the manufacturer’s inclusion of an acrylic practice model.
The Microband
| Table 1. Web site addresses for those manufacturers discussed. | ||||||||||||||||||||||||
|
Familiar to all is the fabled Tofflemire retainer and stainless steel matrix band, which, if looked upon as an integrated device when the 2 are combined, is also a self-contained approach. The twist that may be unfamiliar to many is the Microband currently marketed by Dental Innovations. This revved-up version of the stainless steel band has been modified to optimize the placement of class II composites. According to Dr. John Summer, the company’s founder, Microbands are Tofflemire-type bands that have been specially engineered for use with composite resin in order to create more anatomically shaped contact areas of consistently correct tightness (Figures 15 and 16).
Microband Advantages. No special placement instruments are needed. Just grab your old Tofflemire retainers. These strips are exquisitely thin compared with conventional steel matrix strips. Microbands have microthin contact areas that are only 0.0004 inches (10 µm) thick. The incredibly thin metal foil in the contact areas is surrounded by a framework of 0.0015-inch-thick stainless steel, exactly the same material that comprises the entire body of most matrix products. The 0.0015-inch-thick framework keeps the foil contact areas tight during the restorative process. According to the manufacturer, the extremely thin contact areas eliminate the need to forcefully separate teeth. Since the contact areas are no thicker than the normal interproximal gap that exists between adjacent teeth at rest, there is no need to forcefully separate teeth in order to compensate for the thickness of the matrix.
Microband Disadvantages. Three Microband configurations are needed to have all bases covered: DUML (distal upper mesial lower); MUDL (mesial upper distal lower); and 3S (for 3-surface restorations). Additionally, properly locating the “thin zones” and contact openings is critical to success. Moreover, a technique involving loosening of the band and buccal-lingual squeezing of the band, after initial composite placement, is recommended by the manufacturer. Despite the learning curve, I found them to be surprisingly effective.
THE PUSHERS AND THE PULLERS
This final class of “contact-assist” items is intended to be used in combination with 2 previously discussed matrices, the AutoMatrix device or the Tofflemire retained steel band. Their purpose is simply to muscle the matrix snug to the adjacent tooth by physically pressing them against the proximal surface while providing anatomic form. AdDent’s Trimax Composite Instrument, CEJ Dental’s Contact Pro 2, and Envision Dental Solution’s ContactEase populate this roster.
The Trimax
AdDent’s Trimax is both a pusher and a puller. It consists of a blue plastic handle into which are placed removable, clear contact formers that create a snug contact and direct light to the composite placed in the box of the preparation (Figure 17). The kit contains 2 sterilizable handles and 60 disposable micro light tips in 3 sizes. The tip’s design is intended to optimize contact form. The end of the handle on which the tips are placed, as well as the orientation of the tip, will determine its use for MO or DO restoration placement.
Trimax Advantages. The Trimax has universal application. Its principal advantage, in my opinion, is facilitation of the AutoMatrix or Tofflemire retained band, rendering them “active” systems in the sense that something “akin” to a separating force is being applied when the Trimax is used. Thus, snug contacts are possible using systems that normally might result in an open contact because of band thickness and lack of preformed contours.
Trimax Disadvantages. As with any good idea, proper technique is imperative. First, the forming tip must be properly oriented and considerable force applied in order for the Trimax to be effective. Secondly, determining just the right amount of composite in its initial placement so not to overflow the box when introducing the Trimax requires a short learning curve. Finally, the rigidity of the matrix band being used will influence the shape of the final contact. Thinner band materials are more apt to result in narrower contacts because of the band’s easier deformation, while thicker bands may result in less snug, broader contacts because of a more uniform deformation. Still, use of such a device renders the AutoMatrix (or similar) a viable approach during instances that would have previously rendered them inappropriate. I use this system frequently.
The Contact Pro 2
The Contact Pro 2 by CEJ Dental is similar in form and function to AdDent’s device. It differs in that the Contact Pro 2 is one piece and comes in 2 sizes. It is also designed to push and pull a matrix into tight proximal contact while directing light into the cavity box. Advantages and disadvantages of this item parallel those listed for the AdDent Trimax (Figure 18).
The ContactEase
Envision’s ContactEase is essentially a modified rubber dam clamp forceps. It’s intended to be a “go-to” MOD maker but can also be used for 2-surface restorations. The operator places the diamond-coated, semi–egg-shaped tips halfway into the boxes after having injected composite, then squeezes the handles of the forceps to actuate snug contacts. This is a simple concept but surprisingly effective (Figures 19 and 20).
ContactEase Advantages. Again, the ContactEase allows the more effective use of passive systems such as AutoMatrix and Tofflemire retained steel bands. It feels familiar and is easily sterilizable. The forceps design allows for considerable pressure to be applied when attempting to create a snug contact.
ContactEase Disadvantages. In addition to those cons listed for the Trimax (they are all applicable here), the ContactEase can be difficult to position deep in the posterior recesses of the mouth, particularly in patients with small mouths.
WRAP-UP
I’d like to offer a few comments on the root of all evil with respect to placing class II composite resins; namely, the composite itself. Few will disagree that the time needed to carve and finish composite resins has been problematic for even the most skilled operators. Hybrid composites, even the latest microhybrids, while great improvements over their predecessors, are difficult to carve and polish once cured. However, take note: nanoparticle-based hybrids such as 3M ESPE’s Filtek Supreme are introducing handling and finishing characteristics that are likely to shave 10-minute increments off your finishing time. While fodder for another article, combining this new nanotechnology with one or several of the matrix modalities referenced above can result in posterior restorations that can be completed easier, faster, and better.
Suggested Reading:
- Abel MG. Contemporary restoration of class II caries. Direct posterior composites. Dent Today. 2002;21:94-97.
- Szep S, Frank H, Kenzel B, et al. Comparative study of composite resin placement: centripetal buildup versus incremental technique. Pract Proced Aesthet Dent. 2001;13:243-250.
- Derrick RE. Establishing a tight contact in a class II resin-based composite restoration. J Am Dent Assoc. 2000;131:1326-1327.
- Lacy AM. An effective technique for extended proximal contacts in composite resin restorations. Pract Periodontics Aesthet Dent. 1996;8:287-293.
- Bertolotti RL. Overcoming obstacles to placing posterior direct resin restorations. Dent Today. 2000;19:66-71.
- Summer J. Interproximal contacts. Part 1: anatomy and physiology of interproximal contacts. [Dental Innovations website]. Available at: http://www.thinmatrix.com/contentmgr/showdetails.php/id/219. Accessed on May 10, 2003.
Dr. Goldstein is a graduate of the University of Connecticut School of Dental Medicine and practices general dentistry in a group setting in Wolcott, Conn. He enjoys promoting the cosmetic side of his practice and has found it helpful to incorporate high-tech methodology into his daily routine to accomplish this. Dr. Goldstein serves on the staff of contributing editors at Dentistry Today and contributes regularly to many dental periodicals. He lectures on both digital imaging in dentistry and on the use of such high-tech methodology to advance the cosmetic and restorative practice. Dr. Goldstein can be contacted at martyg924@cox.net. Information on the Comfort Zone Cosmetics seminars can be found at smilevision.net.
