Apr. 2, 2002 COLUMBUS, Ohio - A small adhesive patch promises relief from dental pain up to 45 times longer than a topical anesthetic gel, a new study suggests.
Researchers at Ohio State University compared the effectiveness of the DentiPatch, a small adhesive patch that contains the numbing agent lidocaine, to a topical anesthetic gel. Patients using the patch reported feeling half as much pain from a needle stick, and some patients reported less discomfort during procedures that required the dentist to scrape underneath the gums.
The study reported that the traditional gel's anesthetic effects lasted about a minute, compared to 45 minutes for the DentiPatch.
"The fear of needles and needle-stick pain is a major deterrent to dental care for many people, not to mention other potentially uncomfortable procedures," said Michele Carr, a study co-author and an assistant professor of dental hygiene at Ohio State University.
The DentiPatch, produced by Noven Pharmaceuticals, was first available to dentists in 1996. About an inch long, the patch releases lidocaine when it's placed on the gums. The painkiller diffuses through the gums, eventually numbing a tooth's nerve.
The patch works best for patients who need a deeper than usual cleaning, Carr said, since its effects last longer and the anesthetic penetrates deeper than that of a topical gel. Patients with mild or moderate periodontal disease - where the bone that surrounds the teeth begins to deteriorate - often need the area under the gums scraped to remove plaque and tartar buildup.
Also, patients needing an anesthetic injection on the upper jaw or the roof of the mouth may benefit from the DentiPatch, since its painkilling drug penetrates through layers of tissue. A gel, on the other hand, only numbs the top layer of tissue.
The study appears in a recent issue of the Journal of the American Dental Association. Carr's co-author was John Horton, a professor of periodontology at Ohio State.
Sixty patients participated in the study, which compared the numbing effects of the DentiPatch to those of a topical gel that contained the painkiller benzocaine. Subjects underwent one or more of the following dental procedures: a needle stick without injection, a needle stick with injection and scraping of the tooth and underneath the gum.
The patients rated the pain they felt using the verbal pain score (VPS) scale, which rates pain on a scale of zero (no pain) to four (very severe pain).
One group of 20 patients compared the DentiPatch to a placebo patch as well as a topical gel to a placebo gel. The researchers wanted to examine how each anesthetic worked compared to using no painkiller. The patients underwent both needle sticks without injection as well as scraping procedures. Not surprisingly, patients felt less pain during either procedure with both the DentiPatch and the benzocaine gel as compared to the placebo patch and gel.
A second group of 20 subjects compared the patch directly to the gel. For the needle stick trial, patients reported an average pain score of 1.2 (mild pain) with the patch vs. a score of 2.4 (moderate to severe pain) for the gel. Scraping procedures were also more bearable with the patch than the gel (a VPS of 1.4 vs. 2.1).
The third group evaluated the effectiveness of the DentiPatch to cut down on pain from a needle stick with an injection: pain scores dropped from an average of 3 (severe pain) while using a placebo to 1.1 (mild pain) while using the patch.
"The pressure of liquid being injected into the tissues causes pain," Carr said. "We wanted to know how the pain from an injection compared to a needle stick by itself."
Dentists often use a topical gel to numb the tissue before giving a patient an injection. But the effects of a numbing gel rarely last longer than a minute or two, and don't penetrate the layers of tissue, Carr said.
The anesthetic effects of the DentiPatch can last up to 45 minutes, she said, which gives dentists and hygienists enough time to scrape the teeth and the area under the gums. The disadvantage to using the patch, however, is that takes about 15 minutes to reap maximum anesthetic benefits. Gels start acting within 30 seconds, Carr said.
The DentiPatch is also expensive. At $2 a patch, a dentist may shy away from using it.
"But a patient who fears needle stick pain may find it well worth the extra money," Carr said.
A drawback to all topical anesthetics is that they don't work well on the lower jaw. While each tooth in the upper jaw has its own nerve pathway, the teeth in the lower jaw are served by only one major nerve on the right and left sides.
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