Are electric toothbrushes better than manual ones?
One type is: The kind with a rotation-oscillation action, such as the Braun Oral B plaque remover. That's the take-home message from an analysis of 42 studies involving 3,855 patients, published in April by the Cochrane Collaboration, a nonprofit international organization that evaluates medical research.
These rotation-oscillation devices get rid of plaque -- the sticky stuff that collects on teeth near the gums and contains bacteria that cause cavities and gum disease -- 11 percent more effectively than manual toothbrushes, and reduce gum inflammation 6 percent more effectively over a three-month period, according to the study.
The other six types of electric toothbrushes studied "offered no consistent advantage," the lead author, Dr. Peter Robinson of Sheffield University in England, wrote in an e-mail interview.
Cliff Whall, a medical physiologist who heads the "Seal of Acceptance" program for the American Dental Association, puts it this way: "There is nothing magical about a power toothbrush."
If a person does things right -- brushing with bristles angled toward the gumline twice a day, flossing once a day and visiting a dentist regularly -- a manual toothbrush can be just as good. "There is no need for anyone to feel they are doing themselves harm by not using an electric toothbrush," Whall says.
But Dr. Richard Niederman, director of the Forsyth Center for Evidence-Based Dentistry in Boston, argued that few people use manual brushes optimally, and said the study suggests the Braun Oral B is superior to manual brushing.
Do cheap sunglasses protect the eyes as well as expensive ones?
Yes. All you need to protect against sun damage is a pair of glasses that offers 99 or 100 percent protection against both UVA (ultraviolet A) and UVB (ultraviolet B) rays. Those labeled "UV 400" are also effective.
"If your sunglasses block 100 percent of UVA and UVB,you don't have to spend $250 for designer glasses," said Dr. Kathryn Colby, director of the clinical research center at the Massachusetts Eye and Ear Infirmary.
Epidemiological evidence suggests that decades of exposure to the sun's rays can lower the age at which people get cataracts, or cloudiness of the lens inside the eye.
Normally, people begin to get cataracts in their 70s and 80s, but fishermen and others who work in the sun may get cataracts in their 50s and 60s, said Dr. Elliott Myrowitz, assistant professor in the department of ophthalmology at Johns Hopkins. Cataracts are highly treatable with a surgical procedure in which doctors remove the old, cloudy lens and insert an artificial one.
Cancer of the surface of the eye, though rare, may also be linked to sun exposure.
Aside from basic UVA and UVB protection, the only thing to consider when buying sunglasses is that they are physically comfortable enough that you don't keep taking them off, Myrowitz said, and that they are not so dark that your vision is impaired.
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