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The newest leading bulk fills are simple, esthetic and long-lasting, but they still require the clinician’s focus.
In the past, concerns with bulk fills were common: Would shrinkage be a result of curing the entire restoration all at once? Can the curing light reach the depth of the box form? Can the composite successfully adapt to the cavity if most of the restoration is being placed at once?
These concerns were valid, especially since the majority of posterior restorations would need to fill up to 7 millimeters and early bulk fills could only be cured up to 3 or 4 millimeters. Plus, many dentists were using weak or dirty lights, preventing them from getting the most out of their cure time. With curing lights that didn’t cure at perpendicular angles or fast curing lights that didn’t cure as well in the three to five seconds advertised as slow curing lights did, there were a few obstacles to getting a lasting, esthetic restoration from a bulk fill composite.
Fortunately, times have changed. Faster bulk fills no longer equal less esthetic results. Many leading bulk fills on the market offer fast, esthetic results that dentists can be confident in. Here are five ways new bulk fills are providing better results.
1. Depth of cure
“The traditional composite cure depth is 2 millimeters,” says David R. Rice, DDS and founder of IgniteDDS. “Today's top bulk fills easily cure to 4 millimeters as long as one owns the appropriate curing light.”
This is an important factor to consider in depth of cure. No matter how good the composite is that you’re using or how well you’ve stuck to the script on applying and curing the material, if your curing light is ineffective, the whole restoration will be in shambles. “Tip design on one’s curing light dramatically affects the depth of cure,” Dr. Rice says.
Dr. Rice advises working with a curing light that has a tip diameter of 10 millimeters and making sure it is clear of any debris, which can compromise its efficacy. Debride the tip with a scalpel and polish it to make sure the light is concentrated on the area you’re working on.
“With bulk fill, you need to have a good, strong light,” says John Flucke, DDS. “You have to have a powerful light of at least 1,000 milliwatts per square centimeter, in my opinion. You’ve got to have a bright light to get those photons down into the composite, so you can get that photo-initiator to cure the composite.”
“Make sure you are using a cure light that is up to date and effective for the materials you are using,” says Leah Capozzi, DDS. “The number one cause for failure with composites is inadequate cure, so don't skimp on your curing times.”
The good news is that most high-quality lights on the market are in that range or higher. “Unfortunately, a lot of people have the idea that if they shine a blue light on the tooth, everything will be fine,” Dr. Flucke says. “The reality is that it requires a certain wavelength of blue light at a certain intensity. If you don’t have a good light, it doesn’t matter what kind of photo-initiating tricks a company’s using.”
With the right curing light, depth of cure on some bulk fill composites can reach up to 4 or 5 millimeters - without sacrificing esthetics. For deeper preps, rely on layering.
“Bulk fill composites cure in 4-millimeter increments,” Dr. Capozzi says. “Make a system for yourself that takes this into account. Use layers to keep your increments within 4 millimeters - don't just fill your prep up with one layer if it's more than 4 millimeters deep.”
Less layering means a lower risk of moisture contamination as well. “Placing with less increments results in less time placing and curing,” Dr. Capozzi says. “This decreases the risk of moisture contamination and allows that patient to spend less time open.”
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2. Decreased polymerization shrinkage
While dentists used to worry about shrinkage with a bulk fill composite, new developments prevent the issue from occurring.
“Decreased polymerization shrinkage is also a bonus and contributes to our ability to place in over 4 millimeter increments,” Dr. Rice says. “That translates to less post-op sensitivity when all bonding procedures are equal.”
“One of the ways they do this is by making the materials so highly filled that they can’t shrink much,” Dr. Flucke says. “The composite is composed of a resin, which is the plastic part of it, and filler particles. The more filler particles you put into it, the less it will shrink. As the plastic tries to shrink, the filler particles touch together.”
Some leading composites are using methacrylate monomers to lower polymerization stress. Addition fragmentation monomer (AFM) and aromatic urethane dimethacrylate (AUDMA) work together to provide stress relief without compromising wear resistance. AUDMA is a large monomer that limits the number of shrinkage zones, reducing the amount of shrinkage that occurs during polymerization. Use of these two monomers together allows a one-step placement up to 5 millimeters.
“A good analogy would be to take a handful of gravel and squeeze it in your hand,” Dr. Flucke says. “Let’s say that air is the composite resin and the gravel is the filler particles. You can only squeeze your hands together before those rocks won’t go any further together. If you can highly fill a composite, which is what a lot of these companies are doing, then you overcome the shrinkage factor because the filler particles don’t shrink.”
Self-adaptation and less shrinkage leads to stronger, healthier restorations.
“I place bulk flow into the box of my Class II preps,” Dr. Capozzi says. “Due to the self-adaptation and self-leveling properties, I feel confident with the marginal adaptation of the material. Pair this with the low polymerization shrinkage and the result is a well-adapted, solid restoration with less post-op sensitivity.”
3. Minimized internal micro-gap
“In the past, because you couldn’t get the light to go through more than 2 or 3 millimeters of composite at a time, companies would recommend layering the composite to cure it bit by bit,” Dr. Flucke says. “With all of those pieces being squished together and set, squished together and set, you have the potential for those pieces to not become one solid block of composite. If you don’t have to do that with bulk fill, that means you have to put fewer layers in so you have fewer chances for micro-gaps.”
The point of bulk fill is to simplify posterior restorations by allowing the clinician to apply the material in one step, saving time in the process. As a consequence, there is no need for an additional capping layer, which means less chance for micro-gaps.
“Even the best technique in condensing composite in layers cannot eliminate every micro-gap,” Dr. Capozzi says.
“Decreased layering equals decreased potential for micro-gaps between layers and a more sound restoration through and through,” Dr. Rice says.
Bulk fill materials offer true efficiency and quality in restorations. They are viscous and flowable without needing a flowable tip. With tip designs that provide easier access to deep cavities, there is no need for dispensing devices, additional layers or multiple steps, and dentists can be confident in bulk fill’s wear resistance and stress relief.
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4. Esthetics and handling
Another benefit of leading brands’ bulk fills are the esthetics. Before, clinicians had to choose between speed and esthetics. Now, bulk fills offer both.
“This requires a paired flowable composite that has the ability to opacify to mirror dentin. With it, bulk fills (despite their decreased shade variance) will be invisible,” Dr. Rice says.
Some leading brands use smart contrast ratio management to increase material opacity without reducing the depth of cure, leading to more esthetic restorations without sacrificing quality or time. By using a more translucent material, light can reach to the bottom of the restoration easier. Some materials become opaque as they cure, offering a more esthetic restoration while still allowing for the most effective curing possible.
Certain materials such as nanofillers also ensure wear resistance and polish retention.
“I’m excited about long-term results,” Dr. Flucke says. “I have some friends at the Arthur A. Dugoni School of Dentistry in San Francisco who did a study in which students did two restorations on each patient: one with a normal, incremental fill composite and another with a bulk fill, then compared them over time. Every time a patient came in for a cleaning, they would contrast and compare the old way with the new way. This is probably three years in, and they don’t notice any difference between the two materials. I’m excited about it.”
5. Increased efficiency and effectiveness
Clinicians have been choosing bulk fill restoratives for their strengths in adaptation and handling and their simple process. Now, bulk fills offer those benefits, plus superior esthetics, quicker bonding time and long-lasting quality.
“Add all that together and we deliver efficiency and effectiveness,” Dr. Rice says. “With today's busy pace, patients win as much as the practice when we minimize their chair time.”
“As a dentist, we often think the fast way is somehow compromising care, but when following the right protocols, new bulk fill materials really do allow us to do dentistry faster and more easily while still providing an incredible result,” says Amisha Singh, DDS.
“Bonding is not rocket science,” Dr. Flucke says. “It’s just making sure that the chemistry was there.”
Newer restoratives from top companies offer quality adaptation similar to flowable bulk fill materials, but at a faster pace. They even handle well and are easy to sculpt. Patients enjoy a shorter chair time, but they also appreciate that quality wasn’t sacrificed for time. New bulk fill materials offer superior wear resistance and polish retention, so your patients’ restorations will last longer and stay looking great.