Class II (interproximal) decay and/or a failing restoration that involves a posterior proximal surface is still a common finding in most dental patients. Many of these problems can be handled utilizing directly placed restorative materials. The challenge for the dentist has always been to recreate 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 periodontal 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 proximal surface is convex occlusally and concave gingivally. The proximal contact is elliptical in the buccolingual direction and located approximately 1 mm apical to the height of the marginal ridge. As the surface of the tooth progresses gingivally from the contact point toward the cemento-enamel junction, a concavity exists that houses 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 type of retaining device. While contact with the adjacent tooth can be made with a circumferential matrix band, it is practically impossible to re-create the natural convex/concave anatomy of the posterior proximal surface because of the inherent limitations of these systems. Attempts to “shape” or “burnish” matrix bands with elliptical instrumentation may help create nonanatomic contact, but only distorts or indents the band and does not recreate complete, natural interproximal contours.
Without the support of tooth contour, the interdental papilla may not completely fill the gingival embrasure, leading to potential food traps and areas for excess plaque accumulation. Direct class II composite restorations can present even more of a challenge to place for the dentist because of the inability of resin materials to be compressed against a matrix to the same degree as amalgam. This article will describe the use of an innovative sectional matrix system and instrumentation designed to facilitate placement of the matrix to ensure optimal results, both in physiological contact and in anatomic form. When utilizing this system with the latest in composite resin technology, direct class II tooth-colored restorations can be placed that exhibit natural anatomic proximal form and have predictable proximal contact.
TOOTH PREPARATION AND MATRIX ARMAMENTARIUM
Class II preparations that need a matrix band for restoration will require rebuilding of the marginal ridge, proximal contact, and often a large portion of the interproximal surface. The goal of composite placement is to do so in such a way that the amount of rotary instrumentation for contouring and finishing is limited. This is especially true for the interproximal surface. Because of the constraints of clinical access to the proximal area, it is extremely difficult to sculpt and contour correctly this surface of the restoration. Proper reconstitution of this surface is largely due to the shape of the matrix band and the accuracy of its placement. After removal of caries and old restorative material, the outline form of the cavity preparation is assessed. If any portion of the proximal contact remains, it does not necessarily need to be removed. Conserve as much healthy, unaffected tooth structure as possible. If the matrix band cannot be easily positioned through the remaining contact, the contact can be lightened using a Gateway 50-µm diamond strip (Brasseler USA).
A sectional matrix system, such as Composi-Tight Gold (Garrison Dental Solutions), is an excellent choice for class II composite restorations for many reasons. First, the matrix band is anatomically correct. Rather than being flat like conventional matrix bands, the sectional matrix band is kidney-bean shaped with a concave inner surface. This allows for the proper restoration of interproximal anatomy as described above. Secondly, the G-Ring, which holds the sectional matrix in place, also causes a slight separation of the affected tooth and the adjacent surface by compression of the periodontal ligament. When the G-Ring is in place and the matrix touches the adjacent tooth surface, proximal contact is assured.
Also, some instrumentation has been developed to aid in accurate placement of the sectional matrix to maximize the restorative result. Sectional matrix pliers known as Dryer-Pliers (DryerPliers, Inc) were developed specifically for use with sectional matrix systems to aid in the accurate placement and positioning of the matrix band. There is one plier for placement of the mesial sectional matrix and one for the distal. Since the sectional matrix band is extremely thin, it can be difficult to place with a hemostat or cotton pliers without deforming the band. The DryerPliers maintain the shape of the band while positively holding the matrix in the proper position for placement. After positioning of the matrix band, initial stabilization is secured through the use of a proximal wedge.
Wedge Wands (Garrison Dental Solutions) were developed as an adjunct to the Composi-Tight system to stabilize the matrix band and help create a gingival seal. The wedge is plastic, so it is bendable and able to conform better to the convex root (tooth) surface when pressure is exerted on it by the G-Ring. The delivery is unique, since the wedge is on a plastic handle and can be bent to the desired angle for placement prior to being placed in the oral cavity. Once positioned, a twist of the handle releases the wedge, and the handle is discarded. This delivery system avoids awkward placement using cotton pliers, where many times wedges are hard to angle into place and often dropped or mishandled.
CASE REPORT: A CLASS II DIRECT COMPOSITE RESTORATION
The patient shown in Figure 1 presented with an old class I amalgam that had decay on the mesial proximal surface. A fracture line can also be seen radiating from the restorative material across the mesial marginal ridge and down the proximal surface near the palatal portion of the proximal contact. After removal of the restorative material, associated decay, and preparation of the proximal cavity form, the operative area was isolated with a rubber dam (Figure 2) in preparation for the restorative process. Due to the depth of the preparation, a glass ionomer base (Fuji IX, GC America) was placed.
|Figure 1. This occlusal preoperative view shows class I amalgam in tooth No. 14 that is in need of replacement due to enamel fracture and recurrent decay.||Figure 2. An occlusal view after preparation is completed and the operative area is isolated in preparation for the restorative procedure.|
The potential for remineralization using glass ionomer cements in preparations close to the dental pulp is well documented by Ngo1-3 and others. A nonserrated plugger is used to shape the pulpal floor and proximal axial wall of the glass ionomer base (Figure 3).
After the base is fully set, a flat, cylinder diamond bur is used to refine the internal form of the preparation, including the walls of the glass ionomer base (Figure 4).
|Figure 3. The glass ionomer material is condensed into the preparation as a base prior to the addition of composite restorative material.||Figure 4. This view shows the completed class II cavity preparation after glass ionomer base insertion and refinement.|
The Composi-Tight Gold Sectional Matrix System was chosen to aid in the anatomic restoration of the mesial proximal tooth morphology of this maxillary first molar (Figure 5). The appropriate matrix band was chosen to best correspond anatomically to the tooth being restored, and also to the width and height of the proximal surface. The height of the sectional matrix should be no higher than the adjacent marginal ridge when properly placed. Because of the concave anatomic shape, the proximal contact will be located approximately 1 mm apical to the height of the marginal ridge. The mesial DryerPliers is used to place the selected sectional matrix band in the correct orientation. It is important to maintain the proper concave shape to the band, and that the appropriate DryerPliers be used in band placement. This is the reason there is a separate plier for mesial and distal applications.
Figure 6 shows the matrix band oriented in the mesial DryerPliers ready for placement. The Au 100 sectional matrix band (Garrison Dental Solutions) was positioned and placed using the mesial Dryer-Pliers to the mesial proximal area of tooth No. 14 (Figure 7). The orientation of the band and the positive fit in the Dryer-Pliers make precise placement possible, even in posterior areas with tight access. Next, the gingival portion of the band was stabilized and sealed against the cavosurface margin of the preparation using the appropriate size Wedge Wand flexible wedge. The size of the wedge should be wide enough to hold the gingival portion of the matrix band sealed against the cavosurface of the preparation, while the opposite side of the wedge sits firmly against the adjacent tooth surface. To place the wedge, the Wedge Wand is bent to 90º where the wedge meets the handle (Figure 8). The flexible wedge can now be conveniently placed with pressure without the use of cotton forceps, which often can be very clumsy. Once the wedge was in the correct orientation, it was released with a twist of the wand.
|Figure 5. A close-up view of sectional matrix bands and G-Rings from the Composi-Tight Gold system.||Figure 6. A sectional matrix band is being held in the DryerPliers. This instrument was specifically designed to facilitate precision placement of sectional matrix bands without deformation.|
|Figure 7. The mesial DryerPliers is used to place the Composi-Tight sectional matrix band on the mesial surface of tooth No. 14.||Figure 8. The Wedge Wand during clinical application. The wedge portion is bent at a 90º angle to the handle. This one-piece application eliminates the clumsy positioning and handling of wedges using cotton pliers or other types of instrumentation.|
|Figure 9. G-Ring forceps are used to position the G-Ring correctly in place to stabilize the matrix band against the proximal surface of the prepared tooth.||Figure 10. Thirty-seven percent phosphoric acid etchant is placed on the enamel margins for 10 seconds.|
The G-Ring forceps was then used to place the G-Ring into position. The feet of the G-Ring are placed behind the flexible wedge, and the ring is released from the forceps. The force of the G-Ring causes a slight separation of the teeth due to periodontal ligament compression. It also bends the flexible wedge to adapt and conform better to the external tooth surface, creating an excellent seal at the gingival margin of the preparation (Figure 9). Once the sectional matrix was properly wedged and the G-Ring was in place, the restorative process was started.
A 15-second, total-etch technique, 10 seconds on enamel margins (Figure 10) and 5 seconds on dentin surfaces (Figure 11), was performed using a 37% phosphoric etch. The etchant was then rinsed off for a minimum of 15 to 20 seconds to ensure complete removal. The preparation was then air-dried and re-wet with AcQuaSeal desensitizer (AcQuaMed Technologies) to disinfect the cavity surface, create a moist surface for bonding, and begin initial penetration of HEMA into the dentinal tubules. A fifth generation bonding agent (Optibond Solo Plus; Kerr Corporation) was then placed on all cavity surfaces. The solvent was evaporated by spraying a gentle stream of air across the surface of the preparation. The adhesive was then light-cured for 20 seconds.
The first layer of composite was placed using a flowable composite (Revolution 2, Kerr Corporation) to a thickness of about 0.5 mm (Figure 12). The flowable composite will “flow” into all the irregular areas of the preparation and create an oxygen-inhibited layer to bond subsequent layers of microhybrid material. After light-curing for 20 seconds, the next step was to layer in the microhybrid material. First, using a unidose delivery, the first increment of microhybrid composite (Premise, Kerr Corporation) was placed into the proximal box of the preparation. A smooth-ended condensing instrument was used to adapt the restorative material to the inside of the sectional matrix and preparation. This first increment should be no more than 2 mm thick. After light-curing the first increment, the next increment should extend to the apical portion of the interproximal contact and extend across the pulpal floor (Figure 13).
Once cured, the replacement of the dentin was complete. Using an endodontic file, stain was placed (Kolar Plus-Ochre, Kerr Corporation) in the areas where the major anatomic grooves would be placed in the subsequent layers and light-cured (Figure 14).
|Figure 11. After a 10-second etch of enamel surfaces, the dentin is etched for 5 seconds, giving a total etching time of 15 seconds for the prepared tooth structure.||Figure 12. Flowable resin (Revolution 2, Kerr Corporation) is applied as the first restorative increment.|
|Figure 13. The MO cavity preparation is shown after the proximal increment and pulpal floor have been condensed using microhybrid composite (Premise, Kerr) and a nonserrated plugger.||Figure 14. Ochre composite stain (Kolor Plus, Kerr) is applied to the pulpal floor prior to placement of the enamel increments of composite.|
The enamel increment was placed into the facial portion of the preparation, including the facial portion of the marginal ridge. The cuspal projections were sculpted, and the depressions between were created so that some of the stain in the previous layer would show through (Figure 15). A No. 2 Keystone brush (Patterson Dental) was lightly dipped in resin and used to feather the material toward the margins and smooth the surface of the composite. The palatal increment of microhybrid composite (Premise, Kerr Corporation) was placed in the same manner as previously described.
Figure 16 shows the restoration after completion of the enamel layer prior to matrix band removal. The DryerPliers was used to remove the sectional matrix after removal of the flexible wedge and G-Ring. Occlusion was checked with articulation paper and adjusted as needed using a carbide finishing bur. When placing composite materials using the described technique, very little finishing should be required except at the marginal areas. Rubber polishing abrasives are used to polish and adjust areas further. In this case, some Kolar Plus White (Kerr Corporation) was placed after polishing to re-create a snow-capped appearance to the cuspal areas, as seen on the adjacent natural tooth.
Figure 17 shows the completed restoration prior to the placement of surface sealant. The surface sealant (Optiguard, Kerr Corporation) was placed with the No. 2 Keystone brush, air-thinned, and light-cured for 20 seconds. Figure 18 shows an occlusal view of the completed class II composite restoration.
|Figure 15. The buccal increment is placed using a composite placement instrument and refined with a No. 2 Keystone brush. Notice the anatomic placement of cuspal inclines and marginal ridge.||Figure 16. An occlusal view of the completed MO direct composite after condensation and light-curing.|
|Figure 17. An occlusal view of the completed restoration after rubber dam removal prior to placement of the surface sealant.||Figure 18. An occlusal view of the direct MO composite restoration.|
A technique has been described utilizing a sectional matrix system and associated armamentarium, as well as a nanofilled microhybrid composite, to create an anatomically precise class II posterior composite restoration. The interproximal surface was also recreated with natural anatomic contour and has a predictable, elliptical contact with the adjacent tooth. With proper occlusal and proximal form, this “invisible” direct composite restoration will service the patient for many years to come.
1. Ngo HC, Fraser M, Mount G, et al. Remineralisation of artificial carious dentine exposed to two glass-ionomers. Paper presented at: IADR 80th General Session; March 6-9, 2002; San Diego. Abstract 3109.
2. Ngo HC, Fraser M, Mount G, et al. Remineralisation of carious dentine by glass ionomer: an in-vivo study. Paper presented at: IADR 79th General Session; June 2001; Chiba, Japan. Abstract 0919.
3. Xu X, Burgess JO, Turpin-Mair JS. Fluoride release and recharge of fluoride-releasing restorative materials. Paper presented at: 77th IADR General Session; March 10-13, 1999; Vancouver, British Columbia, Canada; Abstract 431.
Dr. Lowe graduated magna cum laude from Loyola University School of Dentistry in 1982. The following year he completed a general practice residency at Edward Hines VA Hospital, then maintained a private practice in Chicago, Ill, while also serving as assistant clinical professor in restorative dentistry at Loyola. In January 2000, Dr. Lowe joined the aesthetic practice of Dr. Ross W. Nash in Charlotte, NC. He is involved as a clinical evaluator of materials and products with many dental manufacturers, and has received fellowships in the Academy of General Dentistry, International College of Dentists, Academy of Dentistry International, and American College of Dentists. He is also an instructor at the Esthetic Epitome Continuum in Charlotte. Dr. Lowe can be reached at email@example.com or (704) 364-5272, c/o Mark Cody.