Bulk-Fill Composites in Pediatric Restorations
The advantages of this material class make it ideal for young patients
Joshua Wren, DMD
Dentists specializing in pediatrics share many challenges with dentists in general practice, but with some added twists. For example, esthetics are important for children, just as they are for adults, but parents may opt to make esthetic compromises if a primary tooth is not expected to remain in the mouth much longer. Being comfortable in the dental office is also important for young patients, just like adults, but a child is often much more honest about the degree of his or her discomfort. Finally, the efficiency of the dental procedure is important to both children and adults, but pediatric dentists know just how quickly a treatment can turn from routine to bad when the minutes drag on.
For these reasons, pediatric dentists place a high priority on products and treatments that are efficient and predictable. The ideal treatment proceeds as quickly as possible while providing results that will last as long as necessary to prevent retreatment. This is important not only in the name of providing quality care, but also in establishing trust with young patients and helping them learn to be comfortable in the dental chair.
Tackling Caries with Composite Resins
Caries is one of the most prominent issues faced by the pediatric dentist. Data from the National Health and Nutrition Examination Survey showed that 42% of children aged 2 to 11 years have had dental caries in their primary teeth. The survey also estimated that 23% of children aged 2 to 11 years have untreated dental caries.1
These figures highlight the need for pediatric dentists, and dentists in general, to provide ready access to caries treatment, and to perform treatment that is effective and economical, as well as suitable for the unique behavioral and emotional factors associated with pediatric patients.
When treating caries, pediatric dentists typically choose from a small pool of options. Stainless steel crowns and amalgam remain viable options,2 but in many families, esthetics is a priority even for primary teeth. In many parts of the world, composite restorative materials have now nearly completely replaced amalgam treatments for teeth in the posterior.3
When choosing composite resin materials, it is important to understand their various classifications and how they have evolved to their current state. The early generations of composite resin products are categorized as “macrofills” according to their particle size. The relatively large particles in these products provided good strength but made restorations that were difficult to polish.4 Microfills, the next generation, delivered much better polishability but were not known for strength.5
Hybrids, microhybrids, and nanohybrids then followed—materials that were designed with high filler loading to provide strength.4 However, as these materials age, they can suffer esthetically as a result of the wearing away of resin particles from the surface.6 This problem is addressed by a nanocomposite material, which is made with lab-engineered particles, as opposed to the milled and ground particles of hybrids, microhybrids, and nanohybrids.4 The particles in this material form nanoclusters that combine the strength of larger particles and the long-lasting esthetics of smaller particles.6
Dispelling Bulk-Filling Myths
In addition to understanding of the various types of composite resin materials and their strengths and weaknesses, the dentist can also consider which placement technique to use in different clinical situations. The case described in this article involved a posterior preparation approximately 5 mm deep, making it a model candidate for the bulk-filling technique. While the standard of care for preparations greater than 2 mm deep has long been placement of composite in layers,4,7-9 this is time-consuming and not optimal for a pediatric case.
The bulk-filling technique was somewhat controversial for a period of time, due to several factors. One main concern initially stemmed from the packable composites that were first used with the technique in the 1990s. Packable materials, with a high viscosity and high filler load, did not always adapt well to the preparation surface.10,11 Furthermore, it was discovered that the 4 to 5 mm depth of cure that was supposedly possible with these materials was not consistently being achieved.12 Finally, there have been concerns related to polymerization shrinkage stress.13
Fortunately for pediatric dentists and anyone who regularly restores teeth with 4 to 5 mm preparations, bulk-fill composite materials have now advanced to a point where they are regularly used with confidence. Numerous studies have demonstrated adequate results for polymerization properties and marginal quality, and the latest materials are also formulated to create lower polymerization shrinkage stress than the layering technique while still maintaining an acceptable post-cure depth.14-16 With these advances, bulk-fill composites can now be a reliable and predictable tool for treating posterior caries lesions very efficiently and have also become much more esthetically pleasing.