Evaluation of the Proximal Anatomical Form Quality of Different Precontoured Sectional Matrix Systems in Complex Proximal Posterior Resin Composite Restorations: Randomized Clinical Trial.

The importance of the interdental anatomy of a class II direct composite restoration is one of the most underestimated topics in direct posterior composite restorations. The proximal emergence profile of the restoration and the contact area should be designed to maximize arch continuity and to minimize food impaction. A thorough knowledge of proper contacts and contours and how they ought to be duplicated as well as predisposing factors for proximal contact loss as proximal caries, embrasure size and position, and marginal ridge location and thickness, all of which contribute to achieving ideal occlusal harmony.

Conventional circumferential matrix systems produced poor proximal contact points with proximal overhangs or open contacts, and they failed to produce optimum contact points; thus, their usage should be prohibited.

It was found that, optimum contact points were highly associated with the sectional matrix system; there was a 70% lower risk for non- optimum contact points than the circumferential matrix system. Open and tight contacts were highly associated with the circumferential matrix system regardless of operator experience. Sectional matrix systems with separation rings should be implemented as the first choice in clinical decision making for proximal posterior restorations.

Although in vitro and in vivo studies showed that the use a contoured sectional metal matrix band with a separation rings results in optimum contact point and emergence profile, its use is technique sensitive due to rounded contours and thin thickness of matrices, which can cause a depression or bending in the matrix material during placement, rendering it unusable. Also, this matrix systems have shortcomings and does not give the expected result in all class II cavities. The variation in depth, width of the box, distance between the cervical cavity margin and the adjacent tooth requires customization of the interproximal space.

As the main objective is to recreate proximal contacts and contour that mimic the natural teeth making this area self-cleansable, preserving the periodontium, improving the restoration durability as well as maintaining the mesio-distal dimension of either dental arch. This mission is more complicated with badly broken-down teeth. By defining a badly destructed tooth we can say that it is a tooth that has lost a significant amount of tooth material which may be due to caries affection, fractures, or even extensive endo treatments. The result is that the remaining tooth structure becomes friable and weakened and presents a challenge during restoration due to increased distance between the cervical cavity margin and the adjacent tooth and the situation is more complicated if part of the buccal and lingual walls are missing making the ordinary sectional matrix liable to collapse after placing the separation rings.