Selecting the Right Restorative Materials
Practical tips for choosing and using today’s advanced restorative products
With so many advanced new materials on the market for both direct and indirect restorations, the evaluation and selection process has become a practical challenge. For restorative dentists, the days of relatively easy drilling and filling posterior restorations with amalgam are largely over, mainly due to patient demand for tooth-colored composite resin fillings for esthetic reasons, as well as the trend toward conservative dentistry. Yet many dentists have found these composite materials time and technique sensitive, with varying handling properties, and numerous steps—including layering and light curing.
When it comes to indirect restorations fabricated chairside or at the laboratories, material selection isn’t exactly easy. While many dentists would gladly stick with gold for posterior crowns, that time-tested material is not only expensive, but patients balk at its esthetics, preferring crowns made of new ceramic materials. Dentists are also being lured away from the porcelain-fused-to-metal (PFM) standard for multi-unit restorations by instead using milled monolithic ceramics—which can be cut back and layered in the anterior—for single crowns, bridges, and dentures, both traditional and implant-supported.
To help clear up the confusion and simplify selection, Inside Dentistry asked practitioners and other insiders to share their personal knowledge and preferences regarding the newer direct and indirect restorative materials, their clinical indications, and the most successful techniques.
Weighing the Options
As Sridhar Janyavula, BDS, MS, sees it, the choice of material boils down to both patient-related and tooth-related factors. A clinical research dentist at DENTSPLY Caulk, Janyavula considers patient history (eg, allergic reactions, dietary habits), treatment history, caries risk, prognosis of the restoration, gingival and surrounding tooth health, and ability to isolate. He also takes into account issues related to the tooth itself, its location, and the cause of the problem.
“You also have to consider occlusion, whether the patient has any parafunctional biting habit,” Janyavula explains. “Then too, shade is a factor. Most people want to have white teeth, but over time, teeth do get darker, so we must come to clear idea of the shade that will fit well.”
Similarly, John C. Kois, DMD, MSD, founder and director of the Kois Center in Seattle, Washington, identifies four main issues that determine the material to be used for a restoration. Patient diagnosis/risk assessment is most important and is described in more detail below. The other three factors include evaluation of the patient’s remaining tooth structure; patient-related issues such as finances, time, and insurance coverage; and the properties of the materials themselves.
The patient diagnosis/risk assessment enables the clinician to directly address the underlying issues and/or patient objective. It involves determining to what extent the following factors must be accommodated:
· Biofilm-mediated—ie, caries or periodontal disease
· Environmental/chemical-mediated—ie, acid erosion due to either extrinsic or intrinsic causes—or abrasion due to a foreign substance
· Occlusion, which creates loss of tooth structure due to friction
· Developmental disturbance of the tooth
An evaluation of these issues, Kois explains, determines whether the approach will be direct or indirect and what materials will be used. “In my practice, I tend to use direct composites when more conservative options are warranted. However, I move toward indirect restorations when there’s more extensive loss of tooth structure or when cuspal protection is much more critical.”
However, factors can sometimes be at odds with one another, such as function versus esthetics, notes R. Scott Clark, president of Dental Arts Laboratories. The primary issues in choosing a material are usually determined by evaluating function versus esthetic risk with each individual case. In addition, clinicians need to factor in the limitation of the product span—ie, single versus 3-unit versus long-span bridgework—and preparation requirements.
The complexity of material choice doesn’t end there. Jon Fundingsland, professional relations manager of 3M ESPE Dental, notes, “Choice of direct versus indirect techniques depends on the extent of the repair needed—can the remaining dentition be supported by bonding or is an indirect restoration needed? Is the tooth cracked? In some restorations, either direct or indirect techniques could be employed. Then the choice is up to the clinician.”
The Direct Approach
When considering the alternatives for direct restorations, Fundingsland explains that handling preferences and shade and opacity options have driven clinicians towards using a universal restorative for anterior restorations, saving a dedicated bulk-fill material that can be placed in 4 mm to 5 mm increments for posterior locations. “Nano-filled composites maintain the strength and wear properties of the hybrid category—which has weak long-term polish retention—but are able, due to nanotechnology, to display considerably improved retention of initial polish. This category of restorative was quickly adopted by the marketplace, and today is the most popular restorative.”
“Universals are the hottest adhesives in dentistry now that nearly all manufacturers incorporated 10-methacryloyloxydecyl dihydrogen phosphate (MDP); that ingredient was the holy grail of adhesion,” observes Robert C. Margeas, DDS, who is adjunct professor, department of operative dentistry at the University of Iowa College of Dentistry and maintains a private practice in Des Moines, Iowa.
Janyavula also admits to being a fan of universal bonding agents, because they enable the dentist to use a single product for a variety of clinical situations. “I can choose what technique to use for the same product, which depends on the patient, restoration, and clinical situation.” He especially prefers using a bulk-fill flowable to layering smaller amounts of material, which he says have a greater tendency to create voids. “The advantage of flowable composites is they adapt well and self-level; the dentist just squirts it in and it flows into the nooks and crannies into the deepest part of the proximal box,” he says. “I like these not just because they save time, but I feel confident that it has adapted well to the cavity.”
Kois uses both both hybrids and bulk-fill composites, typically using the latter for posterior teeth. “The manufacturers have expedited the outcome without any significant clinical compromises, and I haven’t experienced any problems once I understood their handling characteristics,” he explains.
For his practice, Howard Glazer, DDS, FAGD, of Fort Lee, New Jersey, favors flowable restoratives, particularly with “little moving targets” such as children, when “you want to get in and out as quickly as possible.” However, a caveat with bulk fill, he says, is making sure the curing light is physically able to cure to the full depth of the cavity preparation, beyond the highest cusp, which otherwise will prevent the light from penetrating beyond that point. Glazer, who recalls the silver alloy days when light curing and creating a tight contact were not issues, says verifying the amount of material inserted can be a problem when it is just squirted into the cavity. “Without measuring whether it is in fact 4 mm, a doctor could squirt in 5 mm or 6 mm of material, which could lead to problems when photocuring.”
As for cement, Margeas says, “If you asked me if I could only use one for everything, it would be resin-modified glass ionomer. You place it in the crown, have the patient bite, and 2 minutes later you clean it off.”