Larry Hosken. Technical writer. Puzzlehunt enthusiast.
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Surprisingly Little Evidence for the Accepted Wisdom About Teeth

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The following originally appeared on The Upshot (copyright 2016, The New York Times Company).

I brush my teeth twice a day, but not for as long as my dentist would like. I’d like to say I floss regularly, but that would be stretching the truth. I don’t scrape my tongue, I don’t rinse with mouthwash and I don’t use an interdental brush or Waterpik. However, I have one filling in my mouth, and I got that only when I had braces as an adult 15 years ago.

My wife, on the other hand, cares for her teeth fastidiously. She does all the things you’re supposed to do, and then some. But she has more fillings than I can count. I remember once, years ago, when one of her teeth broke while she was eating scrambled eggs.

Clearly, the stuff we’re doing might not make as much of a difference as we think. A couple of weeks ago, many of you were shocked to learn that the evidence supporting flossing daily was as thin as, well, dental floss. That’s just the beginning.

As my colleague Austin Frakt pointed out recently, for adults without apparent dental problems, there’s little evidence to support the use of yearly dental X-rays. This still doesn’t prevent many dentists from recommending them for everyone.

With respect to flossing, this shouldn’t have been news either. A systematic review in 2011 concluded that, in adults, toothbrushing with flossing versus toothbrushing alone most likely reduced gingivitis, or inflammation of the gums. But there was really weak evidence that it reduced plaque in the short term. There was no evidence that it reduced cavities. That’s pretty much what we learned recently.

What about everything else? It turns out there’s a whole journal dedicated to the idea that we could use more rigor in dental recommendations.Evidence-Based Dentistry either publishes systematic reviews or summarizes reviews from other organizations, like the Cochrane Collaboration.

The good news is that brushing appears to work. But it’s important to know that it’s brushing with fluoride toothpaste that matters, not the brushing alone. Doing that doesn’t just prevent gingivitis and plaque formation; it also prevents cavities, which is the outcome that we care most about.

My dentist has always recommended a powered toothbrush. The evidence seems to agree that, as many randomized controlled trials confirm, powered toothbrushes reduce both plaque and gingivitis more than regular toothbrushes. An older Cochrane review concluded that the rotating powered toothbrushes were superior to side to side powered brushes. I use the latter, and this disappointed me. But the difference between the two types, while statistically significant, was really small.

There appear to be no good randomized controlled trials on brushing frequency. The other studies that do exist, while flawed, seem to support twice-a-day brushing.

Surely the twice-a-year teeth cleanings matter? In 2005, Evidence-BasedDentistry highlighted a systematic review on the effects of routine scaling and polishing (you call it teeth cleaning). Researchers found eight randomized controlled trials that were on point, but they were all judged as having a high risk of bias. The results were all over the map. Their conclusions were that the evidence isn’t of sufficient quality to reach any conclusions as to the benefits or harms of scaling and polishing.

Regardless, I’ve been told by all the dentists I know to have it done every six months.

When filling cavities, some dentists advocate bonded amalgams over non-bonded amalgams. There’s pretty much no evidence to support that practice, though. The one randomized controlled trial didn’t seem to support their use, especially since they cost much more. Previous,nonrandomized controlled trials in children didn’t really show a difference either.

Has anyone ever told you to use an interdental brush to get at the plaque between your teeth? In 2015, Evidence-Based Dentistry summarized a Cochrane Review of seven randomized controlled trials looking at how interdental brushing in addition to tooth brushing compared with toothbrushing alone or toothbrushing with flossing. Almost no long-term benefits have been proven.

What about preventive dental visits themselves? In 2013, Bisakha Sen, Nir Menachemi and colleagues used data from the Alabama Children’s Health Insurance Program to follow more than 36,000 children to see how preventive dental visits affected dental care and spending over time. They found that preventive visits were associated with fewer visits for restorative dental care in the future, implying that there was an improvement in oral health. But they found that, for the most part, more than one annual preventive visit in children was not cost-effective.

No review of dental health would be complete without at least acknowledging water fluoridation. Much of the evidence is old because it’s getting hard to do studies. It would be somewhat unethical to withhold fluoridation at this point from some people, because the evidence in favor of the practice is so compelling.

In fact, fluoride is so important that the U.S. Preventive Services Task Force recommends that in areas where the water supply is deficient, providers prescribe oral fluoride supplementation to children. They recommend the use of fluoride varnish as well.

To recap, there’s good evidence that brushing twice a day with fluoride toothpaste is a good idea, especially with a powered toothbrush. For children, there’s good evidence that the use of fluoride varnish or sealants can be a powerful tool to prevent cavities. The rest? It’s debatable.

I should note that the lack of evidence doesn’t mean that many of these things don’t work. It just means that we don’t have good studies to back their use. In that case, we must weigh the potential harms against the unproven benefits. With flossing, which is cheap and easy, it still might be worth doing. With scaling and polishing, as well as preventive visits, which are expensive and can hurt, it’s more questionable.

We should also recognize that there are a lot of things outside of our control. Some are genetic. The strength of our enamel most likely determines how easily bacteria can break through defenses. Salivary flow and composition help determine how easily we can clear dangerous bugs. Tooth morphology can leave some teeth more susceptible to infection.

Other things have little to do with dentistry. What you eat can affect your dental health. More important may be mother-to-child transmission of bacteria. Children aren’t born with mouthfuls of germs. Studies show that cavity-causing bacteria get passed directly by parents (mostly mothers) to children, probably by sharing silverware or by other mouth-to-mouth transmission. There’s a reason that mothers with lots of cavities sometimes have children who suffer the same.

There are things we can do to prevent cavities and preserve our oral health. We should focus on those things. We should study the things we debate. But we should also be willing to admit that some of the things we do make no difference at all, and perhaps, should be reconsidered.

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lahosken
29 days ago
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"To recap, there’s good evidence that brushing twice a day with fluoride toothpaste is a good idea, especially with a powered toothbrush. For children, there’s good evidence that the use of fluoride varnish or sealants can be a powerful tool to prevent cavities. The rest? It’s debatable."
San Francisco, USA
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Semaphore Flags Message Maker

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I put together a web app to send messages in semaphore, an archaic flag-based alphabet system.
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lahosken
40 days ago
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It's kind of adorable. http://www.cockeyed.com/lessons/semaphore/index.php?wave=sbkgebg%20yvzn%20nysn%20tbys%20fvreen
San Francisco, USA
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La Cucaracha: On the GO with that new smartphone game? (toon)

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cucatacomango

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lahosken
63 days ago
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San Francisco, USA
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A couple of small epiphany's in a day in the life.

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It was a bemusing and somewhat vexing problem that at first blush was all caused by a watch. It's 5ish in the afternoon on a Saturday and I'm clutching an adult beverage at a function when the phone rings. I stare at the magic box doing it's best to attract my attention. I sigh and take the call. It's a local Captain who is taking a boat way offshore on Monday and his autopilot is now kaput ostensibly caused by a Garmin Quatix watch. This is a new one to me and he now has my attention.

He launches into the saga. He has a original Quatix watch, and tried to connect it to the autopilot while underway. The autopilot immediately freaks out, and has to be put in standby to get control of the boat. The watch is disconnected from the system and he attempts to reengage to autopilot. The odd thing is now the autopilot seems fine until you engage it. Instead of doing its "Otto Pilot" thing it now pops up the "Shadow Drive" is on message and does nothing else. What this normally means is the helm has been manually turned, the autopilot thinks you want control of the boat, and gives it to you. This isn't supposed to happen when you first engage it, and I have never seen one do this. I agree to visit the boat on Sunday morning to see what can be done and will bring the latest software with me.


The boat is a new and large center console fishing boat from a good builder. It has three Garmin 7616 MFD's installed by the factory in the dash. I take a quick glance at the gear connected to it and don't see anything of concern other than older software.

The Captain shows me the problem, and what the hell. The damn thing goes straight to "Shadow Drive" when you engage it. So step one is to do a full software upgrade and see if that corrects the problem. This takes about 20 minutes to do. It's is a zen thing and I have some level of confidence all will be okay when done, but it isn't. The problem stubbornly remains. I take a closer look at the autopilot set up It seems to be okay, and the Shadow Drive is disengaged. What's up with this? I think maybe I should look at the autopilot's computer and see what the idiot LED light is saying.

I go off to the truck to get some boat disassembly tools and the first epiphany slowly seeps in. It's a funny thing about our brains. The Captain had mentioned the Shadow Drive message in his call to me. I had played with the autopilot and seen the Shadow Drive message a dozen times so I erroneously assumed it had one. I slowly realized on the walk back to the truck his boat doesn't have a shadow drive at all. It's a steer by wire system as the image of the boat's Teleflex Optimus 360 joystick appears floating in my head. Something else is going on here.

The console is opened, and yep it's a steer by wire Reactor and I had overlooked the SBW designation when I checked the N2K device list. Further it's telling me via the LED idiot light it thinks it feels okay. I scratch my head and try to figure out what to do next.

When solving a problem in a system with lots of stuff hanging on it information is important, and the Captain had some. He had done some excellent and smart problem solving before I had arrived as evidenced by all of the boat's documentation spread out on the berth.

Buried in the back of the console were two gateways. The first was for the engine interfaces, and the second was for the autopilot. Look he says "the autopilot interface LED is doing a two blink." This means in effect that it's talking to the steering system but not the the autopilot.

The second epiphany starts to coalesce. In my first conversation with the Captain he mentioned something about a Garmin GNT-10 being installed on the boat with issues. This black box transmits ANT+ from the network to devices like like a Quatix watch. The dealer had installed it on in the boat after the fact. 

According to the Captain it had been plugged directly into a N2K port on the back of one of the MFD's and didn't work. I wasn't surprised about that. The boat dealer had just recently returned and installed it on the Garmin network, or so they thought. The last of the puzzle fell into place and I now knew exactly what was wrong.

NMEA 2000 is a version of CAN bus, and uses in many cases the same deviceNet connectors. So in effect there are what appears to be two nearly identical NMEA 2000 networks in the boat. They look the same but one is CAN bus only, and the other is NMEA 2000. The two don't play nicely together at all.

So what happened was the dealer's installer added the GNT-10 to the CAN bus network, and not the NMEA network. This is what was causing the havoc with the autopilot.

So how do you tell the two networks apart? The first thing to look for is a network with only three "Tee's" in it like the drawing above shows. The second way to tell is the tag on the Reactor's cable that says "Do not connect to a NMEA 2000 bus." In this case the opposite happened and a NMEA 2000 device was plugged into a CAN bus network.

This problem should not have happened in the first place and I can only make some broad assumptions about why it happened. The reality is the installation of the GNT-10 after the fact was a waste of money because the three factory installed 7616's were already ANT+ capable.

If I was to guess both the Captain and the owner have Quatix watches and somewhere along the line an inquiry was made to the dealer if they would interface to the installed systems. Someone there made a determination that a GNT-10 was needed and arranged to have it installed, twice and incorrectly both times. I left the GNT-10 in place now unplugged but it should be removed. Sheesh, what a way to spend a Sunday morning, but the boat is fine now and well offshore today with a happy Captain as I'm writing this.
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lahosken
91 days ago
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If someone b0rkens a boat's GPS-autopilot-etc network, do you call them a LANlubber? Still waiting for the first wearable tech-caused shipwreck.
San Francisco, USA
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(Untitled)

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pocket litter posted a photo:

Oklahoma City



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lahosken
110 days ago
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I researched this staircase. It's not up to code.
San Francisco, USA
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Waterspout to Tornado to Waterspout to Tornando

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Back in January we had a cracker of a front pass through Sarasota. Not that I didn't know it was coming, I did. Cold fronts are a regular event here. Almost weekly at some times of the year. They typically roll in diagonally on a long southwest to northeast sagging line. This one was coming in late at night. The evening cooling tends to calm the associated T-boomers down on most occasions. Yadda yadda yadda, big deal. Severe thunder storm warnings are also a dime a dozen here and off to bed I go with a good book. I never saw the tornado watch that appeared at 12:45am. At 2:03am the cell phones start squawking I grab mine, fumble for reading glasses, and holy crap, what the hell going on? This thing didn't calm down, in fact it got meaner, a whole lot meaner. There were warnings galore lined up.


I plunked myself in the living room and turned on the TV. All of the local TV stations had dragged in their meteorologists who were clothed just one small step above pajamas. Warnings were scrolling at the bottom of the screen, but what I was paying attention to was the Doppler radar images which were showing rotation just off the coast due west of me.

Above is a cool NOAA screen shot from the event showing three potential areas of rotation embedded in the front. Note the areas of bright red right next to the bright green where shear is occurring. The one in the center created the tornado that will strike Siesta Key and move onto the mainland. It came to earth at 3:17 am in the Gulf of Mexico as a EF2 tornado and in just five minutes traveled 1.14 miles as it roiled across Siesta Key crossed the intercoastal and continued to ravage the mainland. Hence the title of the piece.

What's unusual is there are few if any cases of a tornado starting as a mesocyclone waterspout then becaming a tornado as it moved onto land or is it now a landspout? Within a minute or two it became a waterspout again as it crossed over the intercoastal waterway, or is it still a tornado? And then again a tornado on the main land.

This is the catch. There are all sorts of fuzzy verbal boundaries and lots of forms of, okay hold your breath now, Cyclogenesis

At the micro end of this scale you have gustnados that can look like a tornado, but aren't. Landspouts are generally considered to be a relative of a typical waterspout but it's over land. Don't forget the mountainado and snowspout either. At the nano level there are dust devils, sand augers, fire whirls and dozens of other similarly named whirlwind manifestations.

So here is a clear rule of thumb. If any of these forms of Cyclogenesis, and I'm using the term loosely are attached to a mesocyclone storm cell (bad ass thunderstorm) consider them very dangerous whether on land or in the water. Even if some of these weather events aren't attached to a mesocyclone they can still be extremely dangerous.

I waited a day for all of the emergency activities to finish and walked the entire tornado path starting on the beach. It was scoured clean and very flat. Damaged beach furniture had been put in piles but I think only half of them were found. I couldn't help thinking beach goers will be finding the balance of them while swimming in the gulf for years to come.

The six story Excelsior condo took the brunt of the tornado's wrath coming in from the gulf. Windows blown out, cars were damaged, but the most notable damage was caused by the roof being stripped off. This allowed the next few hours of very heavy rain to soak the building's interior largely ruining everything.

Here is were my observations differ from the official report that stated the wind field was 350 wards wide. You can clearly see the path where the tornado crossed the road and I would say the wind field was less than 100 yards wide, and the real damage was confined to a width of a few hundred feet.

The bay side portion of the condo was luckier. Not that they escaped unscathed by any means. The spacing between the rows of condos was pretty large and the tornado spent  a chunk of its time there. It did cross over and got close to removing the entire roof on one of the buildings which will required substantial repairs. It then shredded its way through some oak trees and entered the intercoastal waterway. A quarter of a mile later it hit the mainland with vengeance.

The two story home on the water was completely demolished, and resulted in the only injuries which were fortunately not life threatening. Fire and rescue personnel extracted two women from the second floor with lift bags.

The tornado then coursed its way through a residential neighborhood for a distance of about two long city blocks.

A walk along the now blue tarped damage path was accompanied by the buzzing of dozens of chainsaws grinding through fallen tree limbs. The majority of the damage was blown in garage doors and windows, roof shingles and other roof issues along with damage from large branches and fallen trees and then it dissipated into thin air.

On the whole the National Weather Service does a great job, but most of us aren't paying any attention. I spoke to a neighbor who was on the edge of the damage. He was clueless, but the noise woke him up and went out onto his porch. His comment was it was raining shingles, branches and leaves. He understood exactly what the noise was and bailed for his bathroom. So this engenders the question, how does the weather service know there is a tornado?

The answer in most cases is they don't. What they can see via radar are places in a storm cell that have shear that creates rotation and may cause a tornado. When you hear there is a tornado on the ground it's usually because someone saw it and called in a report. There are a few exceptions to this. The screen shot above is a radar image showing a tornado's debris ball. This is what was causing shingles to rain down on the neighbor.  It's those few white and pink pixels at the end of the hook signature. This doesn't happen often due to weather conditions, what type of debris it is, and how much of it is there.

So what's the take away from all of this other than these are random and devastating acts of the weather god's wrath. There are several. Boaters, although not enough of them, generally pay close attention to the weather and me more than most.  It's a Darwin thing.

I had known the front was coming for a couple of days, but if I had taken a closer look, and I did have the tools to do this with my link to the NOAA/NWS Storm Prediction Center. They had been concerned about severe weather development in SW Florida two days earlier and had been tracking the front. I had just glanced at the weather maps and radar summaries thinking it's another damn front again. It would be a rainy day and not good one to be on the water.

My problem was this occurred less than two miles away from me, a friends boat was badly damage when a palm tree was ripped up and thrown at his craft, and two good friends lived within a block of the tornado's path. The thing that saved a lot of people's bacon including mine was the fact that most of us have magic information boxes in our pocket and if you turn on the "Emergency Alerts" switch at will at least tell you there are things like tornado warnings going on. That's what woke me up. Is yours turned on?


The radar images are from NOAA websites and the photos were take by the author.


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lahosken
130 days ago
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"Gustnado" was only the second-coolest word I learned from this article
San Francisco, USA
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