Improving Proximal Contours for Direct Resin Restorations

One of the most challenging aspects of direct posterior resin restorations is achieving good proximal contacts with proper contours. This can become especially challenging when the resulting proximal preparation is wide and the adjacent tooth leaves a large space interproximally.

PROXIMAL CONTACT GOALS
The goals of posterior direct restorations include (1) tight contact with the adjacent tooth’s proximal surface, (2) contour gingival to the contact that fills the space without food traps, and (3) buccal/lingual contours that prevent food impaction interproximally.^1-3
These goals often are not met routinely as circumferential matrices tend to constrict the buccal and lingual contours, resulting in inadequate contacts and poor anatomical form.^4-5 Sectional matrix and ring retainers were introduced in an attempt to combat this and to allow the practitioner to achieve better contacts and contours. But, those also had some challenges when the proximal preparation resulted in a box that extended to include a portion of the buccal and lingual walls, or space was present between the tooth being treated and the adjacent tooth. The proximal tines of most rings would jump into the preparation and have no tooth structure against which to brace. This would result in a constricted contact and narrowed anatomy of the restoration.

TECHNICAL ASPECTS IMPROVE RINGS

Figure 1. Ring straddling the wedge placed interproximally.	Figure 2. Triodent V3 Rings: molar (green) and premolar (yellow).
Figure 3. Stacked rings allow placement at adjacent proximals.	Figure 4. Preparation for a MOD direct restoration on a mandibular first molar with an open contact on the distal.

The newest generation rings, such as the V3 Ring (Triodent), were developed to overcome the negatives of the prior rings available. These rings have wider tines that are able to contact more tooth structure, even when preparation has eliminated portions of the buccal and lingual cusps interproximally, or when there is a greater distance with the adjacent tooth. As with its predecessor (V Ring [Triodent]), the tines are designed to straddle the wedge instead of sitting adjacent to it, making placement easier (Figure 1).^6-8 The added benefit is that proximal separation is greater, making for a tighter final contact. As all teeth are not created equal, no single ring is ideal for every situation, and what fits a molar proximal may not be ideally suited for a premolar contact. With that in mind, 2 different sized V3 Rings were designed; a green for molar contacts and a yellow for premolar contacts (Figure 2). An added improvement from the original ring design is that the tines have an increased angle to the ring’s loop to make stacking the rings for placement on adjacent proximals easier when both the mesial and distal will be restored on the same tooth (Figure 3).
A typical clinical situation involves the need to restore both proximal surfaces on the same tooth. This can be challenging, especially when caries removal requires more of the interproximal to be removed. The goal in today’s restorative dentistry is to conserve as much tooth structure as possible and only remove carious dentin and enamel. However, this can still result in challenges when restoring the interproximal surfaces.

CASE REPORT

Figure 5. Sectional matrix placed on the mesial/distal along with wedges and stacked V3 retainer rings.	Figure 6. Application of Bond1-SF adhesive (Pentron Clinical Technologies).
Figure 7. Adhesive was vigorously scrubbed with the frocked tip of the syringe for 20 seconds on the prepared surfaces.	Figure 8. The glistening appearance of the prepared dentin surface following application of Bond1-SF was visually verified before curing.
Figure 9. The adhesive was light-cured for 10 seconds.	Figure 10. A cone burnisher was used to adapt the nano composite (Artiste Nano Composite, Shade B3 Dentin [Pentron Clinical Technologies]) into the preparation.
Figure 11. First layer of the cured nanocomposite, showing the development of lobes within the dentin layer.	Figure 12. Artiste Maverick posterior pit tint (Pentron Clinical Technologies) was applied with an endodontic file to accent the pits and fissures, then light-cured.
Figure 13. Acorn burnisher being used to adapt the enamel layer of nanocomposite (Artiste Nano Composite, Shade B [Pentron Clinical Technologies]).	Figure 14. The restoration was then light-cured.
Figure 15. Direct resin restoration prior to finishing and polishing.	Figure 16. Retainers, wedges, and sectional matrix removed.
Figure 17. Direct resin restoration following contouring with finishing carbides and diamonds.	Figure 18. The completed direct composite resin restoration following finishing and polishing. Note the natural contours and proximal contacts.

The patient presented with an open contact between the first and second molars with resulting interproximal caries as a result of chronic food impaction. Following caries removal, it was noted that the distal box was relatively wide, but the mesial box preparation was narrow due to the minimal caries in this area (Figure 4). Sectional matrices were placed at both the mesial and distal of the tooth to be restored. A small wedge (pink) was placed at the mesial, and a large (purple) distally. Triodent V3 rings were placed at both the interproximals (Figure 5).
The preparation was rinsed and lightly dried to eliminate any pooled water. A solvent-free self-etch adhesive (Bond1-SF [Pentron Clinical Technologies]) was vigorously rubbed into the prepared dentin and enamel surfaces for 20 seconds (Figures 6 and 7). The resulting surface should have a glistening appearance (Figure 8): once this was visually verified, it was light-cured for 10 seconds (Figure 9).
A layer of dentin shade B3 nanocomposite (Artiste Nano Composite [Pentron Clinical Technologies]) was adapted to the pulpal floor, proximal boxes, and over all prepared dentin surfaces. Lobes were formed and pits/fissures developed with a cone burnisher (PKT-3R, Zoll Dental), then light-cured (Figures 10 and 11).
To replicate a more natural aesthetic appearance, a brown tint (Artiste Maverick posterior pit tint [Pentron Clinical Technologies]) was applied with a No. 8 endodontic hand file to the pits and fissures created in the dentin layer of composite. This was then light-cured (Figure 12).
A layer of shade B enamel nanocomposite (Artiste Nano Composite [Pentron Clinical Technologies]) was placed over the dentin composite, using an acorn burnisher (21B [Zoll Dental]) to adapt it and to create the desired anatomy (Figure 13). The restoration was light-cured from the buccal, then the lingual, and finally the occlusal surfaces (Figure 14). The restoration was now ready for finishing and polishing (Figure 15).
Next, the rings, wedges, and matrix were removed (Figure 16). As the proximal contacts are often very tight as a result of using this ring system, it may be necessary to use a locking hemostat to remove the matrix. Needle-shaped finishing carbides (ETS 8.5 [Brasseler USA]) and diamonds were used to remove any flash on the buccal and lingual. This was followed by football-shaped carbides (H379F [Brasseler USA]) and diamonds (D051 379F [Brasseler USA]) to contour the cavosurface margin (Figure 17). Final polishing was performed with polishing disks (Fini [Pentron Clinical Technologies]) followed by polishing paste (Fini Polishing paste [Pentron Clinical Technologies]) on a felt point (Felt buff polisher [Pentron Clinical Technologies]) (Figure 18).

CONCLUSION
Posterior direct resin restorations can be accomplished with excellent proximal contours and tight contacts by using well-designed rings, matrices, and wedges. This, in combination with a simple layering technique using modern nanocomposite resin materials, allows the dentist to mimic the aesthetics and anatomy found in nature.

References

1. Strydom C. Handling protocol of posterior composites—part 3: matrix systems. SADJ. 2006;61:18,20-21.
2. Loomans BA, Opdam NJ, Roeters JF, et al. Influence of composite resin consistency and placement technique on proximal contact tightness of Class II restorations. J Adhes Dent. 2006;8:305-310.
3. El-Badrawy WA, Leung BW, El-Mowafy O, et al. Evaluation of proximal contacts of posterior composite restorations with 4 placement techniques. J Can Dent Assoc. 2003;69:162-167.
4. Peumans M, Van Meerbeek B, Asscherickx K, et al. Do condensable composites help to achieve better proximal contacts? Dent Mater. 2001;17:533-541.
5. Loomans BA, Opdam NJ, Roeters FJ, et al. A randomized clinical trial on proximal contacts of posterior composites. J Dent. 2006;34:292-297.
6. Keogh TP, Bertolotti RL. Creating tight, anatomically correct interproximal contacts. Dent Clin North Am. 2001;45:83-102.
7. González-López S, Bolaños-Carmona MV, Navajas-Rodríguez de Mondelo JM. Individualized wedge. Oper Dent. 2006;31:390-393.
8. Cueto Suárez MA, Peña López JM, Fernández Terán A, et al. Passive wedge. Quintessence Int. 1996; 27:243-248.

Dr. Kurtzman is in private general practice in Silver Spring, Md, and is a former assistant clinical professor at the University of Maryland, Department of Endodontics, Prosthetics and Operative Dentistry. He has earned Fellowship in the AGD, ACD, ICOI, and the Pierre Fauchard Academy; Mastership in the AGD; and ICOI and Diplomate status in the ICOI. He has lectured internationally on the topics of restorative dentistry, endodontics, implant surgery/prosthetics, removable/fixed prosthetics, periodontics, and has more than 160 published articles. Dr. Kurtzman is on the editorial board of numerous dental publications, a consultant for multiple dental companies, and a former assistant program director for a university-based implant maxi-course. He can be reached via e-mail at dr_kurtzman@maryland-implants.com.

Disclosure: Dr. Kurtzman reports no conflicts of interest.