Clinical Use of a Sectional Matrix and Ring

Abstract

After a series of dramatic improvements in wear resistance, strength and ability to bond to dentin, resin composites have been used increasingly by clinicians for restoring Class I and II cavity preparations. Unlike amalgam, resin composites cannot always be formed effectively against the traditional matrix band to create optimal contacts.Several techniques have been introduced to achieve an optimal proximal contact. The examples are sectional matrix and ring, the Contact Pro hand instrument and use of Beta quartz glass ceramic inserts.1 Pre-wedging, where a wedge is inserted and pressed very firmly into the proximal space prior to preparing the tooth, is another recommended technique.2 Packable high-viscosity resin composites have been tested in vitro. The use of packable resin did not result in tighter proximal contacts when compared to the medium-viscosity hybrid resin composites.3–5A number of studies used a special measuring device, called the Tooth Pressure Meter,6 to quantify proximal contact tightness. In both in vitro and in vivo studies, a sectional matrix, in conjunction with the separation ring, was shown to result in increased proximal contacts relative to that which existed preoperatively. On the other hand, these same studies found that the proximal contacts were lighter than those that existed preoperatively when the traditional matrix band with Tofflemire and wedge were used. These studies supported use of the sectional matrix with separating ring in order to achieve tight contacts.7–8The metal matrix and Mylar strip were compared in an in vitro study for Class II resin composite restorations. The Mylar strip resulted in significantly higher amounts of excess material at the restoration margins when compared with metal matrices.9 Another study found that a separation ring used with both traditional circumferential and sectional matrices improved proximal contacts.10It is widely accepted that proximal contacts are very important features in healthy teeth. A lack of proximal contacts contributes to food impaction, secondary caries, tooth movement and periodontal complications.11 Even though the optimal level of tightness is not yet identified, it is most desirable to restore the tooth back to the situation1 prior to treatment. From the available literature, the sectional matrix with separation ring seems to be the most reliable device for restoring proximal contacts in posterior teeth.7–10 Originally, sectional matrix systems consisted of rings with simple tines. The Palodent Sectional Matrix (Darway, Inc, San Mateo, CA, USA) and the G-Ring (Garrison Dental Solutions, Inc, Spring Lake, MI, USA) are representative examples. More recently, the tines have been redesigned to be V-shaped to fit into the buccal and lingual embrasures. Examples of this design would be Omni-Matrix Sectional Matrix (Ultradent Products, Inc, South Jordan UT, USA) and the original V-Ring (Triodent, Katikati, New Zealand). More recently, the Composi Tight 3D Ring (Garrison Dental Solutions, Inc) and the V3-Ring (Triodent) matrix rings have included a silicon coating on the V-shaped tines. This article describes one of the currently available systems for assuring appropriate proximal contacts using the V-3 ring when restoring the proximal contacts of posterior teeth.The V3 Sectional Matrix System (Table 1) is one type of sectional matrix system. It includes the V3 Ring, V3 Matrices and Wave-Wedges. There are two sizes of rings: the universal green and the narrow yellow rings. Special forceps are used to apply the separating rings, while the Pin Tweezers are used for placing the Wave-Wedge and adapting the matrices to the preparation.12Step 1: A rubber dam was placed. The “pre-wedging” method was used prior to the preparation. The circle end of the wedge was grasped and the wedges inserted interproximally (Figures 1 and 2).Step 2: The preparation was completed while the wedges were pressed firmly in the interproximal spaces (Figure 3).Step 3: The matrices were grasped using the occlusal tab and slid interproximally. The occlusal tabs were folded on the marginal ridges of the adjacent teeth. The forceps were then used to place the rings occlusal to the wedges (Figures 4, 5 and 6). The buccal view of another case is shown to illustrate how the rings sit occlusally to the wedges (Figure 7).Step 4: After resin placement, the rings were removed with forceps. Both the wedges and the matrices were removed. The holes on the buccal and lingual ends of the matrix (Figure 4) allowed the clinician to grasp the bands and remove them easily.Step 5: The restoration was checked for optimal proximal contacts and finished (Figure 8). The occlusion was checked and modified, as necessary, then the restoration was polished. The complete restoration, immediately after removal of the rubber dam, is shown (Figure 9).This technique allows the clinician to restore Class II preparations in proper form and function. The minimal excess of resin at the buccal and lingual margins reduces the time required for finishing the restorations. The optimal proximal contacts, proper contour and heights are important factors in the longevity of Class II resin composite restorations.