British researchers surveyed 15 dental-association guidelines in the United States, Britain, Japan and seven other countries; searched the dental literature for studies; recorded information by toothbrush manufacturers; and read 10 dental textbooks searching for advice on how, how long and how often to brush.
The review, published in the August issue of the British Dental Journal, found no randomized trials of brushing technique and little agreement on how to go about cleaning teeth.
Some sources recommend holding the brush at a 45-degree angle to the gum and making very short back-and-forth movements. Others prefer large, sweeping circles over the teeth with the toothbrush at right angles to the tooth surface.
No one could agree on how often and how long, either.
Octopus’ brooding cycle longest among animals
A Pacific deep-sea octopus called Graneledone boreopacifica has been found to have an egg-brooding cycle of 53 months — the longest period that any animal is known to protect its eggs.
Researchers observed the solitary female Graneledone in the Monterey Canyon, off the central coast of California, and when they revisited the site a little more than a month later, they found the octopus guarding a newly formed clutch of eggs.
The scientists returned to the site 18 times using a remotely operated vehicle to monitor the octopus and her clutch of about 160 eggs. She did not feed while nesting. Like other octopods, the Graneledone dies after its eggs hatch.
The researchers, who published their results in PLOS One, believe that the long brooding cycle might be a reproductive strategy. Laying fewer eggs and guarding them for so long allow the babies to grow and fully develop while still in their eggs, giving them the best chance for survival.
— The New York Times