Growing replacement teeth

By Joel Garreau

As long as there are hockey players, there will be niche markets for false teeth. But the real news about the future of dentures is that there isn’t much of one.

Toothlessness has declined 60 percent in the United States since 1960. Baby boomers will be the first generation in human history typically to go to their graves with most of their teeth.

And now comes tooth regeneration: growing teeth in adults, on demand, to replace missing ones. Soon.

It turns out wisdom teeth are prolific sources of adult stem cells needed to grow new teeth for you. From scratch. In your adult life, as you need them. In the near future. According to the National Institutes of Health.

For thousands of years, losing teeth has been a routine part of aging. That’s over.

“We’re there, right now,” said Pamela Robey, chief of the Craniofacial and Skeletal Diseases Branch at the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health. “A lot of people will go and never lose a tooth. With good health care and proper habits, there’s no reason to lose a tooth.”

The introduction of fluoride into drinking water and toothpaste is viewed as one of the 10 greatest public-health accomplishments of the 20th century, according to the Centers for Disease Control and Prevention (CDC).

It did not occur without controversy. In the renowned 1964 black comedy “Dr. Strangelove,” Brig. Gen. Jack D. Ripper (Sterling Hayden) attacks the Soviet Union with nuclear-armed B-52s, hoping to thwart a communist conspiracy to “sap and impurify” the American people with fluoridated water.

Leslie Seldin has some perspective on this. He graduated from dental school in 1966 and was the editor of “The Future of Dentistry,” a report published in 2001 by the American Dental Association.

“When I was growing up” — in the ’50s — “reaching the teen years you’d develop enormous amounts of decay,” he said. It wasn’t until the ’60s, when most baby boomers were growing up, that fluoridation really started having a major impact.

By the ’90s, “if new patients came in that were young people, under 30, you really were surprised if you saw significant” cavities, Seldin said.

Fundamentally intact teeth, plus the increased attention to gum disease that can loosen them, have brought about a transformation.

“When I started out in dentistry, in my practice it wasn’t uncommon for people losing their teeth — you took out all their teeth and made a denture. You were working on a denture at all times,” Seldin said.

“Now, five new dentures a year, that’s a lot. We go out of our way to avoid them.”

So what’s the future of dentures?

“Hopefully, they will become a relic,” said Mary MacDougall, director of the Institute of Oral Health Research at the University of Alabama. “Like Washington’s false teeth.”

Regenerating a whole tooth is no less complicated than rebuilding a whole heart, said Songtao Shi, of the University of Southern California, who heads a team working on creating such a tooth.

Not only do you have to create smart tissue (nerves), strong tissue (ligaments) and soft tissue (pulp), you’ve got to build enamel — by far the hardest structural element in the body.

And you have to have openings for blood vessels and nerves. And you have to make the whole thing stick together. And you have to anchor it in bone. And then you have to make the entire arrangement last a lifetime in the juicy stew of bacteria that is your mouth.

It’s a nuisance, but researchers are closing in on it. They think the tooth probably will be the first complex organ to be completely regenerated from stem cells. In part, this is because teeth are easily accessible.

So are adult stem cells, abundant in both wisdom and baby teeth, and your immune system won’t reject your cells.

Nobody is predicting when the first whole tooth will be grown in a human, although five to 10 years is a common guess.

“The whole tooth — we’ve got a long way to go,” Shi said.

Top Social Media Sites of 2008 (Facebook’s Winning)

From TechCrunch

What were the top social media sites of 2008? ComScore came out with its worldwide traffic stats for November a few days ago (so these don’t include December). They are a mix of social networks and blogging platforms. Blogger, the orange line in the chart above, still rules the roost with an estimated 222 million unique worldwide visitors in November (up 44 percent from November, 2007). Facebook, the blue line, is on pace to pass it soon with 200 million unique visitors (up 116 percent). (Note, though, that this is more than the 140 million active users Facebook itself reports—go figure). MySpace is pretty steady at 126 million uniques. WordPress is a close fourth and gaining with 114 million (up 68 percent). And Windows Live Spaces is down 22 percent to 87 million uniques.

ComScore keeps a list of what it calls “social networking” sites, but these include blogging platforms and other social media sites as well. While the audience for blogs is still showing healthy growth overall, Facebook stands out as the social gorilla taking share from not only other social networks but blogs and other social media as well.

Below are the top 20 sites on comScore’s social networking list. It is really more of a social media site list, which is what I’m renaming it for this post. It is not definitive, but it gives a good lay of the land. (Here is a similar ranking from 2007). Note on this list the stubborn persistence of Yahoo’s Geocities at No. 6, the rise of Yahoo’s Flickr at No. 7, Six Apart at No. 10, and the presences of Chinese sites like Baidu Space and 56.com. The real surprise, though, is document-sharing site Scribd at No. 16, with nearly 24 million worldwide uniques.

Top Social Media Sites (ranked by unique worldwide visitors November, 2008; comScore)

1. Blogger (222 million)
2. Facebook (200 million)
3. MySpace (126 million)
4. WordPress (114 million)
5. Windows Live Spaces (87 million)
6. Yahoo Geocities (69 million)
7. Flickr (64 million)
8. hi5 (58 million)
9. Orkut (46 million)
10. Six Apart (46 million)
11. Baidu Space (40 million)
12. Friendster (31 million)
13. 56.com (29 million)
14. Webs.com (24 million)
15. Bebo (24 million)
16. Scribd (23 million)
17. Lycos Tripod (23 million)
18. Tagged (22 million)
19. imeem (22 million)
20. Netlog (21 million)

Here’s a screenshot of the actual data:

Seattle refuses to use salt; roads “snow packed” by design

By Susan Kelleher, Seattle Times consumer affairs reporter

To hear the city’s spin, Seattle’s road crews are making “great progress” in clearing the ice-caked streets.

But it turns out “plowed streets” in Seattle actually means “snow-packed,” as in there’s snow and ice left on major arterials by design.

“We’re trying to create a hard-packed surface,” said Alex Wiggins, chief of staff for the Seattle Department of Transportation. “It doesn’t look like anything you’d find in Chicago or New York.”

The city’s approach means crews clear the roads enough for all-wheel and four-wheel-drive vehicles, or those with front-wheel drive cars as long as they are using chains, Wiggins said.

The icy streets are the result of Seattle’s refusal to use salt, an effective ice-buster used by the state Department of Transportation and cities accustomed to dealing with heavy winter snows.

“If we were using salt, you’d see patches of bare road because salt is very effective,” Wiggins said. “We decided not to utilize salt because it’s not a healthy addition to Puget Sound.”

By ruling out salt and some of the chemicals routinely used by snowbound cities, Seattle has embraced a less-effective strategy for clearing roads, namely sand sprinkled on top of snowpack along major arterials, and a chemical de-icer that is effective when temperatures are below 32 degrees.

Seattle also equips its plows with rubber-edged blades. That minimizes the damage to roads and manhole covers, but it doesn’t scrape off the ice, Wiggins said.

That leaves many drivers, including Seattle police, pretty much on their own until nature does to the snow what the sand can’t: melt it.

The city’s patrol cars are rear-wheel drive. And even with tire chains, officers are avoiding hills and responding on foot, according to a West Precinct officer.

Between Thursday and Monday, the city spread about 6,000 tons of sand on 1,531 miles of streets it considers major arterials.

The tonnage, sprinkled atop the packed snow, amounts to 1.4 pounds of sand per linear foot of roadway, an amount one expert said might be too little to provide effective traction.

“Hmmm. Six thousand tons of sand for that length of road doesn’t seem like it’s enough,” said Diane Spector, a water-resources planner for Wenck Associates, which evaluated snow and ice clearance for nine cities in the Midwest.

Spector and snow-control experts in four cities said sand is typically mixed with salt and used for trouble spots.

“The occasional application of salt is probably not going to have a lasting effect” on the environment, Spector said. But she cautioned it’s highly dependent on where it’s used, how often and how much is applied.

Seattle’s stand against using salt is not shared by the state Department of Transportation, which has battled the latest storms in Western Washington with de-icer, 5,800 tons of salt and 11,500 cubic yards of salt and sand mix, said spokesman Travis Phelps.

Many cities are moving away from sand because it clogs the sewers, runs into waterways, creates air pollution and costs more to clean up.

Its main attraction is that it typically costs less than one-fifth the price of salt, according to Spector.

“We never use sand,” said Ann Williams, spokeswoman for Denver’s Department of Public Works. “Sand causes dust, and there’s also water-quality issues where it goes into streets and into our rivers.”

Instead, it sprays an “anti-icing” agent on dry roads before the snow falls and then a combination of chemicals to melt the ice.

Cheryl Kuck, spokeswoman for the Portland Bureau of Transportation, said her city prepared the streets last week with the “anti-icing” spray. Once the snow started, Portland used chemical de-icers, followed by plowing with 55 plows and treating trouble spots with sand and gravel.

Although the city had plowed 29 of its 36 major routes, “nothing is clear,” Kuck said late Monday afternoon. “This is a difficult and challenging situation that’s going to take us a long time to recover from.”

Wiggins, of Seattle’s transportation department, said the city’s 27 trucks had plowed and sanded 100 percent of Seattle’s main roads, and were going back for second and third passes.

“It’s tough going. I won’t argue with you on that,” he said. But here in Seattle, “we’re sensitive about everything we do that impacts the environment.”

Reporters Sara Jean Green and Christine Clarridge contributed to this report.