Circumferential Vs. Sectional Matrix Bands - An Ultradent Blog

Editor’s Note: This blog was authored by Dr. Brett Richins, a full-time practicing dentist in the Salt Lake City, Utah, area. Dr. Richins also works part-time as a member of Ultradent’s in-house clinical team.

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As dentists, we are constantly faced with restorative challenges related to variations in anatomy, misaligned or missing teeth, and/or extensive missing tooth structure. There are countless solutions and tools available to help us achieve predictable and exceptional results for our patients.  There are times when selecting the best matrix system for a specific situation will make restoring a tooth much easier and will help us achieve our best possible outcomes. Two of the main categories we can choose from as restorative dentists are circumferential bands (like the Omni-Matrix™ retainer and matrix band) and sectional matrix systems (like the Triodent® system). Criteria for selecting the best system for a specific case can include size of the restoration, location and number of surfaces being restored, presence of adjacent teeth, accessibility, alignment of teeth, long-term plan for the tooth, and personal preference.

Triodent V3 Ring

Omni-Matrix Disposable Retainer and Matrix

Most of us have a go-to process and have become comfortable with a specific system. I have personally learned over the years that there are times when my tendency to always reach for the same tools can make my job more difficult than it needs to be. Sectional matrix bands have become a staple in many dental offices because of the ability for dentists to quickly and efficiently achieve excellent contours, ideal contacts, and well-adapted margins.

There is a learning curve when using a new system, and it is common to want to stick strictly to what we know. When I became comfortable with sectional matrix systems, I unintentionally left circumferential bands behind and never looked back, until I learned about Omni-Matrix bands. There are many situations where I personally have found circumferential bands to be superior and I have changed my approach when starting a restoration. Now, the first thing I do is look at the case holistically and decide what type of matrix system I feel will work best.

3D rendering of a Triodent band.

Sectional matrix systems are my personal go-to when doing a typical Class II restoration with well-aligned adjacent teeth and no missing cusps or extensive missing tooth structure. With a well-designed sectional matrix system, these types of typical cases can be a fast, predictable way to achieve ideal outcomes. However, if we don’t have circumferential bands as one of the tools in our toolbox, it is easy to find ourselves in a frustrating situation that could be avoided.

I personally have some common situations where a circumferential band will be my go-to solution. One of the most common reasons I will prefer a circumferential band is when there is no adjacent tooth or when I am restoring the buccal or lingual surface of a tooth. As a young dentist that was excited about sectional bands and had tunnel vision, I would often find myself rebuilding these teeth “freehand” without any matrix system. A circumferential band can help me quickly and easily place a restoration and keep it confined to the intended area. 

     Seating an Omni-Matrix Disposable Retainer.                                                                                                                                         Removing an Omni-Matrix Disposable Retainer.

Another situation in which a circumferential band can be helpful is when the patient has a missing cusp. This is a situation that often can be done with a sectional matrix, but it may result in an under-contoured restoration if there is not adequate tooth structure to support the ring. Pediatrics can also be a great indication for a circumferential band, as placing a sectional band on a primary tooth can often be difficult and the contours are not as critical. Whereas, a circumferential band will usually be more stable on a primary tooth and can be more efficient when restoring an MOD.

About Dr. Richins:

After earning his bachelor’s degree in biomedical engineering from the University of Utah in , Dr. Richins received his doctorate from the University of Pittsburgh School of Dental Medicine in . He is a member of the Academy of General Dentistry, the American Dental Association, and the Utah Dental Association. He continues to pursue his education and frequently attends advanced courses that cover topics such as Endodontics, Implantology, Cosmetic Dentistry, Oral Pathology, TMJ, Sleep Apnea, and much more. He has also done humanitarian dentistry in underserved areas of Jamaica, Vanuatu, and Appalachia. In addition to practicing dentistry, Dr. Richins spends one day a week working as a Clinical Advisor for Ultradent Products. Ultradent has been developing and manufacturing the highest quality dental products for over 40 years. Dr. Richins’s role at Ultradent allows him to be involved in testing and developing the latest dental products.

Proper contour, tightness and location of the contact can be elusive and difficult to control at the time of placing the restoration. An open or loose contact can be harmful to the periodontium and can shorten the lifespan of the restoration, in addition to being a daily source of frustration for the patient because of food impaction. The answer to this dilemma simply lies in the selection of your sectional matrix system.

Update your contacts: It’s about WHAT you know

The interproximal margins of your Class II restoration may finish at varying distances from the contact area, while the height of the clinical crown can differ from case to case. These factors have to be considered when choosing an appropriate matrix band.

Having a selection of matrix bands of varying heights will enable you to properly fit the matrix to the preparation. Dual-Force matrix bands from Clinician’s Choice (New Milford, Conn.) are available in three occluso-gingival heights (4.5 mm, 5.5 mm, 6.5 mm) to accommodate almost all sizes of interproximal preparations.

These thin, contoured stainless-steel matrices are placed using a Punch Plier that grips and perforates the occlusal tab of the wedge for secure placement. Once the restoration is cured, the same Punch Pliers can be placed anywhere on the matrix band for easy removal.

COTISEN supply professional and honest service.

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Dual-Force Active-Wedges wrap snugly around the proximal line angles, resulting in the reduction of composite flash on the buccal and lingual surfaces. Less flash means less finishing time on these areas. A curved occlusal lip on the properly fitted Dual-Force Matrix Band ensures a rolling marginal ridge, further reducing your finishing time.

The Dual-Force Matrix has an interproximal contour that establishes the ideal shape for your proximal contact. A sectional matrix that wraps the tooth well, is contoured both proximally and occlusally and is available in the most frequently required heights provides the first step on your way to an esthetic and functional Class II composite restoration. The Dual-Force Sectional Matrix fits all these criteria.

One more degree of separation

Once the appropriately sized sectional matrix band is accurately in place, it is essential that it be securely held and the matrix band sealed against the gingival margin by a wedge. Failure to ensure this may result in excess composite flash that is difficult and time-consuming to remove. This excess may also be under-polymerized, leading to a potential void in the margin.

The lowly dental wedge has undergone many transformations during its long history. From sycamore wood wedges to plastic wedges that can be cured through, their primary role has remained the same: fill the interproximal space and do their best to seal off the gingival margin with the matrix.

We need more from this wedge. We need it to be able to physically adapt to the contour of the gingival margin with even pressure and, speaking of pressure, cause the interproximal space to expand temporarily and rebound upon removal of the wedge.

Triangular wedges of any material have a tendency to want to back out of the space and inadequately seal the matrix to the tooth when they do stay in place. Plastic wedges were designed with a more anatomical shape in order to address the challenge of sealing the matrix throughout its contact with the proximal margin. However these lacked the ability to supply any separation pressure. On the other hand, larger wooden wedges could separate the teeth but lacked the complete sealing effect.

Dual-Force Active Wedges have several design features that provide up to 2 lbs of separation force while sealing the matrix band gap-free against the gingival margin. Placing these active wedges is smooth, as the leading tip collapses and re-opens once fully positioned. Small, lateral fins act independently of each other in order to apply the appropriate sealing pressure along the matrix band. A strong internal spine is responsible for exerting the separation pressure and provides stability when stacking Active-Wedges, should it be necessary to do so in cases of excessive interproximal space.

The #5 Active-Wedge, or Deep Seal Wedge, is designed for deep, subgingival margins. A convex extension of the Deep Seal Active-Wedge fits into the anatomical depression often encountered with deep subgingival margins, completing the seal at the band/tooth interface even in this difficult clinical scenario.

The ring: Essential for intimate proximal contacts

While the technological advancement of the Active-Wedge is impressive, the evolution of the separating ring in today’s sectional matrix systems is the game changer when it comes to proximal contact formation.

The ideal separating ring is easy to place; engages the sectional matrix in such a way that all cavosurface margins are sealed; provides separation forces that are adequate and consistent; constructed of both metal and plastic that are resistant to fatigue/breakage and resist the sticking of composite and adhesive; provides adequate vision for the clinician to place and polymerize the restoration; is available in smaller versions capable of fitting pre-molars or to provide more separating force; and can be stacked and oriented in a manner to avoid interference with rubber dam clamps and over-erupted cusps.

A separating ring that could satisfy this exhaustive list would result in a Class II composite restoration that would mimic the natural tooth’s proximal contour and function and would require very little marginal finishing. Most separating rings available today cannot fulfill the expectations of such a list.

Some rings require excessive hand pressure to open the ring in order to place it on the tooth. Vertical tines, intended to press the matrix firmly against the tooth, may only make a point contact with the matrix, possibly springing unexpectedly off the tooth or allowing flash to be formed from composite overflow.

Separating forces of various levels are generated in each of these systems but can diminish over time as the metal ring fatigues. Some rings have plastic tines or ring covers that can fracture, and both metal and plastic components of most systems become sticky with excess adhesive and composite, making clean up tedious. Separating rings that seat parallel to the occlusal plane may not be able to be stacked for MO/DO/MOD applications or be able to clear a neighboring rubber dam clamp or tooth.

Clinician’s Choice has re-engineered the separating ring using dual fatigue-resistant NiTi wires. Dual-Force Forceps easily open the ring, and an ideal engagement angle allows for easy placement. Strong, balanced separation forces generated by the dual NiTi rings remain consistent and resist dislodgement. Four lateral tines separated by a V enable the ring to sit atop the Active-Wedge and engage the Dual-Force Matrix at its gingival and occlusal edges. This stabilizes the wedge and seals the vertical proximal margins to minimize any flash formation.

The Dual-Force Ring sits at a 20-degree angle to the occlusal plane, enabling the stacking of two Dual-Force Rings or clearing of an adjacent rubber dam clamp or prominent cusp. Errant composite and adhesive is easily wiped off. The autoclavable ring, along with its superior fatigue-resistance, will provide reliable and predictable service restoration after restoration.

Any attempt to restore a tooth to its original form and function includes a plethora of variables, any of which, if not properly controlled, can lead to a clinical disappointment or even failure. Utilizing a sectional matrix system, such as Dual-Force by Clinician’s Choice, that addresses the challenges of the proximal contact, is vital to achieving your clinical success.