Enhancing Efficiency of Posterior Direct Composite Restorations
Circumferential matrix system improves visibility and accessibility
Sam Simos, DDS
As the demand for amalgam restorations decreases, dentists are now faced with multiple challenges associated with providing functional, durable, and esthetic posterior direct composite restorations. Not only do posterior direct composite restorations require an inherently technique-sensitive adhesive protocol (ie, incremental composite layering and curing),1 but their placement is also often hindered by difficult access and poor visibility. In addition, posterior direct composite restorations are notoriously prone to polymerization shrinkage, microleakage, and the consequential postoperative sensitivity and secondary caries that can develop when the correct placement techniques are not diligently followed.2
However, the efficiency, simplicity, and predictability of placing posterior direct composite restorations are also affected by the manner in which their morphology is created-most notably the interproximal contours and cervical anatomy. Proximal concavities, insufficient space between teeth, and misalignment can all wreak havoc when dentists attempt to restore the emergence profile and create natural interproximal contacts.3
Interestingly, an estimated 97% of clinicians say that achieving proper isolation of a Class II lesion is difficult in at least 1 out of 10 cases.4 This is significant, especially considering that the No. 1 reason for composite failure is recurrent decay, and the proximal box is the most vulnerable area.5
Since the Tofflemire matrix system was first introduced in the 1940s for placing amalgam restorations, a variety of matrix systems that enable dentists to better contour and adapt direct composites in proximal and cervical areas have been introduced (eg, sectional matrices, precontoured transparent matrix systems, circumferential matrices) and have subsequently evolved. For example, the sectional matrix systems available today facilitate the creation of superior contacts when compared with Tofflemire systems.6 On the other hand, circumferential precontoured matrix systems contribute to proximal contacts that are more occlusally located and a reduction in overhang when compared with sectional matrices.7,8
The functionality of sectional matrix systems is limited because they cannot be used in cases involving a missing adjacent tooth, misaligned or severely rotated teeth, or when significant tooth loss prevents placing a separating ring. Likewise, conventional circumferential matrices are functionally limited in that they are unable to produce consistently accurate tight contacts and natural anatomic contours, provide limited visibility and access due to the retainer or applicator, and present challenges to achieving isolation.
The following case demonstrates a technique for the placement of a minimally invasive and anatomically correct Class II posterior composite restoration using a circumferential matrix system that is designed to improve visibility, instrument accessibility, and restorative outcomes.
A 55-year-old man presented with a failing amalgam restoration in his maxillary right first molar (ie, tooth No. 3) (Figure 1). A thorough examination was performed, and recurrent but isolated decay was noted in both the mesial and distal interproximal areas of the tooth. The agreed upon treatment involved removing the failing amalgam and decay and placing a direct composite Class II restoration.
After the patient was anesthetized, isolation was established with a rubber dam. The failing amalgam restoration and decay were removed, and a mesial-occlusal-distal (MOD) Class II preparation was performed (Figure 2). The preparation was cleaned, rinsed with water spray, and then dried. Care was taken to not desiccate the tooth structure.
A circumferential matrix system (Palodent® 360 Circumferential Matrix System, Dentsply Sirona) was placed by first gripping the matrix body and then sliding the band over the tooth using a downward oscillating motion. The band was easily adjusted (ie, tightened, loosened) by twisting the thumb wheel, and then wedges were inserted to improve the seal, ensuring anatomically natural contours (Figure 3).
Next, the preparation was etched using 32% phosphoric acid (Uni-Etch®, BISCO, Inc.), rinsed, and dried-again, being careful not to desiccate the tooth structure. A universal dental adhesive (Prime&Bond elect® Universal Dental Adhesive, Dentsply Sirona) was then applied to the preparation for 20 seconds using a disposable microbrush applicator. After the excess solvent was gently evaporated with clean, dry air from a dental syringe for 5 seconds, the adhesive was light cured for 20 seconds.
Once the adhesive was applied and cured, a flowable composite (TPH®3 Flow, Dentsply Sirona) was placed to create the interproximal walls and serve as a foundation for filling the remainder of the restoration. After this increment was light cured for 20 seconds, the circumferential matrix was removed (Figure 4).
To build up the Class II restoration, a universal nanohybrid composite (TPH Spectra® ST, Dentsply Sirona) was placed in 2-mm increments that were light cured for 20 seconds each. A single universal CLOUD shade was sufficient to complete the remainder of the restoration.
To shape the restoration into the final desired tooth form as well as establish proper anatomical details, a series of finishers (Enhance® Finishing System, Dentsply Sirona) were used. The restoration was then polished to a high gloss using a polishing cup (Enhance® PoGo® Polishing System, Dentsply Sirona). The material's spherical fillers facilitated faster polishing, imparting a noticeably enhanced surface gloss (Figure 5).
The requisite armamentarium for placing posterior Class II direct composite restorations includes an appropriately strong and durable material as well as a consistently predictable and easy-to-use matrix system. When combined, they enable dentists to simply and efficiently establish interproximal contours and cervical anatomy while simultaneously enhancing the manner in which the morphology of the overall restoration is created.
In this case, the use of a versatile circumferential matrix and a universal nanohybrid composite allowed the patient to receive a dependable minimally invasive restoration that will last for years to come (Figure 6). The patient was very happy with the treatment outcome, and he was impressed with the short procedure time, especially considering the size of the restoration required.
About the Author
Sam Simos, DDS
1. Heintze SD, Rousson V. Clinical effectiveness of direct class II restorations - a meta-analysis. J Adhes Dent. 2012;14(5):407-431.
2. Juloski J, Carrabba M, Aragoneses JM, et al. Micro-leakage of Class II restorations and microtensile bond strength to dentin of low-shrinkage composites. Am J Dent. 2013;26(5):271-277.
3. Patras M, Doukoudakis S. Class II composite restorations and proximal concavities: clinical implications and management. Oper Dent. 2013;38(2):119-124.
4. Dentsply Sirona. Class II Total Practice Solution brochure. Class II Total Practice Solution web site. https://www.class2restorations.com/sites/default/files/Class_II_Brochure_Updated_ML425003B.pdf. Published September 27, 2017. Accessed September 13, 2019.
5. Spencer P, Jonggu Park QY, Misra A, et al. Durable bonds at the adhesive/dentin interface: an impossible mission or simply a moving target? Braz Dent Sci. 2012;15(1):4-18.
6. Durr-E-Sadaf, Ahmad MZ, Gaikwad RN, et al. Comparison of two different matrix band systems in restoring two surface cavities in posterior teeth done by senior undergraduate students at Qassim University, Saudi Arabia: a randomized controlled clinical trial. Indian J Dent Res. 2018;29(4):459-464.
7. Kampouropoulos D, Paximada C, Loukidis M, et al. The influence of matrix type on the proximal contact in Class II resin composite restorations. Oper Dent. 2010;35(4):454-462.
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