Modern Restorative Dentistry

The primary emphasis of modern restorative dentistry is to minimize the removal of healthy tooth structure. Loss of tooth structure is directly related to decreased tooth stiffness and an increased risk of complication and fracture. Strong, reliable adhesion is fundamental to our ability to conserve and mimic tooth structure. Today, we have gold standard two-step, self-etch adhesives (6th generation) and three-step, etch-and-rinse adhesives (4th generation) with documented long-term clinical success. These advancements eliminated the need for mechanical retention and led to an increase in the performance of conservative direct and indirect restorations.

In addition to advancements in adhesion, research investigations into the properties of natural tooth structure have improved our attempts to replicate the structural integrity of intact teeth. Studies have shown that teeth are biomechanically optimized regarding the combination of dentin and enamel and that each of these tissues imparts important structural properties. Furthermore, the important role of the dentinoenamel junction has been identified—providing optimal stress transmission to prevent cracks and fractures. The natural tooth is so remarkably well engineered that no restorative treatment, material, or procedure can fully replicate its performance, but nevertheless, that is the driving force of innovation in biomimetic restorative dentistry.

Biomimetic dentistry refers to dentistry that copies or mimics the natural teeth. This includes their biology, structure, esthetics, and biomechanics. In this regard, biomimetic dentistry is not a specific restoration or technique, but an approach that can be applied to any restorative procedure, including fillings, inlays, onlays, and crowns.

Using dental materials with optimal properties is an important part of achieving biomimetic results. The need to control polymerization shrinkage and stress has been a constant challenge associated with composite resin materials, and it becomes increasingly more important with larger tooth preparations because the strain from shrinkage is volume dependent. Popular strategies to mitigate this include the use of incremental filling techniques or indirect restorations. In addition, the use of low shrinkage materials with a lower elastic modulus (ie, less stiffness) has also become popular, but these materials do not replicate the physical properties and biomechanics of natural teeth.

I believe that the most promising and innovative materials to enter the market during the last 15 years are short fiber-reinforced composites (SFRCs). These materials (eg, everX Flow^™, GC; everX Posterior^™, GC), which incorporate silicate glass fibers into the resin matrix, have demonstrated many significant advantages in clinical studies, including decreased shrinkage strain, improved fatigue limit, and superior fracture resistance. SFRCs can be used for buildups for indirect restorations as well as for dentin replacement in direct restorations. For direct techniques, these materials are combined with an outer shell of conventional particulate filled composite. They can be used in bulk applications and simultaneously reduce residual stress and provide optimal physical properties and strength for the restored tooth that are comparable to those of indirect restorative techniques. This is a remarkable step toward the future of biomimetic restorative dentistry.

Matthew Nejad, DDS, maintains a private practice in Beverly Hills, California, and provides training through the Nejad Institute. He is an adjunct faculty member at the Herman Ostrow School of Dentistry at the University of Southern California in Los Angeles, California.