But unbeknown to the consumer, the powers at the major toothbrush makers were not content. The ’60s, ’70s and ’80s had been devoted to improving bristle design, according to Dr. Paul Warren, a dentist and the vice president for global professional and scientific relations at Procter & Gamble Oral Care, which makes Oral-B toothbrushes. But as intelligent as the bristles had become, pursuing plaque into the nooks and crannies of the oral cavity, they still weren’t quite bright enough to outsmart human nature and its marked tendency toward indolence.

“They were great,” Dr. Warren said of the engineered bristles, “but people still weren’t brushing brilliantly.”

Image Samuel Heath's Novis bracket is an ingeniously simple British-made open-sided chrome device with slots for four brushes.

So newfangled handles began to be developed, not only to make toothbrushes easier to clutch but also to encourage people to brush properly  that is, to practice something called the “modified Bass technique.” Rather than scrubbing back and forth as if they were sawing firewood  the default mode  they were supposed to hold the brush at a 45-degree angle to the teeth, wiggling it up and down starting at the gum lime, as uncomfortable and counterintuitive as that may have felt.

While Dr. Warren, not unexpectedly, makes Procter & Gamble’s efforts sound like unalloyed public service, the profit motive may also have been involved. “These new products cost as much as $6” when they were introduced, Mr. Dair said. “There’s only so much you can do to a Popsicle stick to have it be the perception of a $6 product.”

Smart Design created the 1993 Wondergrip toothbrush, a child’s model for Johnson & Johnson. It drew inspiration from the Oxo line of oversize rubber-handle kitchen utensils, which Smart Design had come up with in the ’80s. “It was a blockbuster,” Mr. Dair said proudly. “That toothbrush was one of the first that didn’t fit. We broke the mold with that one.”

Dr. Warren acknowledged that when Procter & Gamble introduced its own line of fat-handle toothbrushes, also in 1993, there were complaints. “Yes, you began to get consumers saying, ‘This is handy, but it doesn’t fit into my bathroom holder,’ ” he said. “There was thought about that, and Oral-B developed a toothbrush holder, almost like a cigar case, you could leave on your counter or pack in your suitcase if you were traveling. If people wrote, they’d be sent back a toothbrush holder. I don’t know whether we still have them.”