Dentists Back Sealants, Despite Concerns
Cavities or chemicals? That’s the dilemma for parents worried about a controversial substance found in the popular sealants that are painted on children’s molars to prevent decay.
The chemical is bisphenol-A, or BPA, which is widely used in the making of the hard, clear plastic called polycarbonate, and is also found in the linings of food and soft-drink cans. Most human exposure to the chemical clearly comes from the food supply. But traces have also been found in dental sealants.
Although the Food and Drug Administration has reassured consumers that the chemical appears to be safe, it has received increasing scrutiny in recent months from health officials in the United States and Canada.
The National Toxicology Program, part of the Department of Health and Human Services, has raised concerns about BPA, particularly over childhood exposure to the traces that leach from polycarbonate baby bottles and the linings of infant formula cans. The 2003-4 National Health and Nutrition Examination Survey by the Centers for Disease Control and Prevention found detectable levels of BPA in 93 percent of urine samples collected from more than 2,500 adults and children over 6.
BPA has estrogenlike effects, and animal studies have suggested that exposure may accelerate puberty and raise a potential risk of cancer. This month, the journal Environmental Health Perspectives reported that the chemical might interfere with chemotherapy treatment. And last month The Journal of the American Medical Association reported that adults with higher levels of BPA in their urine were more likely to have heart disease or diabetes.
Despite these concerns, the American Dental Association remains strongly in favor of sealants. Dentists note that numerous studies show that any exposure they cause is negligible and temporary, lasting no more than three hours after the initial application. And other studies have found no detectable levels of BPA in most American-made sealants. Meanwhile, sealants have been shown to offer years of protection against cavities.
“This is such an enormously valuable tool to prevent tooth decay,” said Dr. Leslie Seldin, a New York City dentist and consumer adviser for the American Dental Association. “The BPA issue, I think, is so minuscule in impact that it doesn’t really warrant the attention it’s been getting.”
Dental sealants have the consistency of syrup so that they can seep into the crevices of molars. A light is used to harden the sealants, which are then buffed smooth. The coatings prevent the growth of bacteria that promote decay in the grooves of molars.
Just this month, a review of 16 studies by the Cochrane Collaboration, a nonprofit group that evaluates medical research, showed sealants offered significant protection from cavities. In the seven studies that compared sealants and regular brushing alone, the 5- to 10-year-olds who used sealants had less than half as much decay on biting surfaces four and a half years after the treatment. One study with a nine-year followup found that only 27 percent of sealed tooth surfaces had developed cavities, compared with 77 percent of unsealed surfaces.
The Cochrane review did not address BPA, but it did cite a March review article in The Journal of the Canadian Dental Association, looking at 11 major studies of BPA exposure from dental sealants. That review, financed by the nation’s health system and conducted by researchers with no industry ties, concluded that patients were not at risk for exposure to the chemical. And it noted that dentists and patients could further limit any exposure with simple steps like buffing tooth surfaces and gargling and rinsing after sealants are applied, all of which are standard practices in most dental offices.
The review also found that three products did not release detectable amounts of BPA: Helioseal from Ivoclar Vivadent; Seal-Rite from the Pulpdent Corporation; and Conseal f from SDI (North America). All carried the 2007 American Dental Association seal.
The amount of BPA exposure can vary depending on the sealant. In a 2006 article in The Journal of the American Dental Association, researchers from the United States Public Health Service and the Centers for Disease Control and Prevention studied the effects of two dental sealants on 14 men, based on saliva and urine samples. They found that patients treated with an Ivoclar Vivadent product called Helioseal F showed no change in urinary or salivary levels of BPA, while patients treated with Delton Light Cure sealant, from Dentsply Ash, were exposed to about 20 times higher doses of BPA.
Linda C. Niessen of Dentsply International said in a statement that the A.D.A. says sealants are safe, and she notes that any exposure from a sealant is “significantly lower and occurs infrequently” compared with other sources of BPA.
Parents concerned about BPA exposure should ask their dentists what type of sealants they use and whether it has been tested for BPA. But researchers from the Centers for Disease Control and Prevention offered this bottom line: “Sealants should remain a useful part of routine preventive dental practice.”
Step #1: Let your kids pick out the supplies. There are lots of fun character toothbrushes and toothpastes on the market. Escort your kids to the store, and have them pick out their favorite. They’ll be much more willing to brush their teeth if they’re excited about their toothbrush and toothpaste.
Adjusting occlusal contacts is frequently required at the time of try-in and/or post-insertion. If there is a minor occlusal adjustment needed, my suggestion is to use only a rubber abrasive polishing wheel and not a diamond. A diamond is needed only if there is a significant adjustment to be made.
If a diamond is used in this process, proper polishing of the surface is necessary to achieve a smooth surface. A polished ceramic surface is less abrasive than one that is glazed, so there should be no need for re-glazing of the restoration. The larger the diameter of the polishing wheel used, the more efficient and effective the process. A point may be necessary to get into the depth of the anatomy, however it is the least effective because of its size.
The three key points for this procedure are:
1. Diamond: Use a fine grit diamond in a friction grip slow speed handpiece. An electric handpiece is more effective than one that is air driven. Run the handpiece at 20,000 RPM with water spray. Avoid a high-speed handpiece because it will create excessive heat and trauma in the ceramic. A light touch is required to avoid excessive heat and vibration. You will then need to use a rubber Polishing Wheel. (Left: Fine Diamond.)
2. Rubber Polishers: I use Brasseler’s Dialite LD (lithium disilicate) and ZR (zirconia) series. Each have a medium and a high shine wheel. An electric handpiece should run at 10,000 RPM to a maximum of 15,000 RPM, with only light pressure used. Electric handpieces have constant torque even at a slow speed, so they are more effective than air driven handpieces. Begin the process with the medium shine wheel. This step should take approximately 30 seconds. Next use the high luster rubber wheel with the same technique as described above. (Right: Medium Dialite LD.)
3. If you use Polishing Paste: Polishing paste should be used with a bristle brush wheel in a slow speed latch handpiece. The product I use is the Dental Ventures of America Zircon-Brite ‘G.’ This is very effective for polishing the grooves in the posterior anatomy. (Left: High Shine Dialite LD.)
This Article was first posted on Spear Education. http://www.speareducation.com/spear-review/2012/08/clinical-tips-for-polishing-ceramics-e-max-and-zirconia/