Do you always need a crown after a root canal?
I was taught, and many of you have heard, that any tooth that’s had a root canal needs a crown.  Recent research has disproved this, at least in some cases.
If a front tooth is basically structurally sound (i.e., not a mass of old fillings), a crown gives no benefit except when it’s needed for aesthetics.  I bond a filling into the access hole I drilled in the back of the tooth to do the root canal, and the tooth becomes structurally sound again.
When a root canal is done on a back tooth, the access hole is made in the chewing surface of the tooth.  Back teeth are subject to much greater chewing pressures than front teeth, so it’s not enough to just fill up the access hole in a back tooth that has had a root canal.  The chewing surface of the tooth has to be covered completely.  This can be done by an onlay, which covers the chewing surface of the tooth and part of the sides of the tooth, or by a crown, which covers the entire tooth, including all the way down the sides.
Onlays are more conservative because they preserve more of the original tooth structure, and they protect the tooth just as well as a crowns do. For this reason,  I try to do onlays on back teeth wherever possible, and only resort to crowns where there is no other choice.

By the way, the above column reminds me of one of my favorite dental course questions.  “What’s the biggest block to new knowledge?”  Answer:  “Old knowledge.”
There is always new research and new information;  that’s why I take so many courses.

More about ozone
In the April newsletter, I told you about our exciting introduction of ozone (or, as my patient, Guy, refers to it,
”special secreet sauce.”  You go, Guy!) to the practice.  Here’s more information:

What are some of the other dental uses of ozone?
—Wound-healing.  Since ozone kills germs and germ-poop, a surgical site can heal more quickly if ozone is applied to it after surgery.

—Cold sores (caused by herpes virus) can be sterilized in about a minute.  The pain often goes away instantly, and the ulcer is no longer contagious.  Best of all, in about 25% of the cases the herpes virus is inactivated so effectively that the ulcer does not return (in the other 75% of cases, the ulcer is still sterilized, but more virus is stored in areas called ganglia, to be released at a later date.  This usually happens when you and your body are under stress).

—Completely arresting tooth decay, sometimes with no drilling whatsoever.    Ozone kills the bugs that cause decay.  It sterilizes certain types of cavities (gumline cavities and chewing-surface cavities are prime examples).   To do this properly, I have to follow several steps.  Let’s take a chewing-surface cavity as an example:
Step one is to diagnose the decay as early as possible, using an electronic early-decay-detection system such as the laser Diagnodent I’ve had since 1999.  I was one of the first dentists in the area to have a Diagnodent, and now Michelle and Caroline have their own Diagnodents.   Use of this system will become part of a regular checkup for many of you (remember, the Diagnodent can’t “see” through crowns and fillings, so it was invented too late for the metal-mouthed among you.  Preventive dentistry wasn’t around to help you in childhood, but it is very much around in my office to help your kids).
Step two is to remove surface decay with an air abrasion unit (we have had one in each treatment room for many years).  A stream of tiny aluminum oxide particles, almost as hard as industrial diamond dust, selectively removes the soft decay, leaving healthy tooth structure relatively untouched.
Step three: decay-detecting dye checks to see if all the decay has been removed.  If not, ozone gas can be applied to the tooth (under a sealed “dome,” of course), to sterilize the remaining decay-infected tooth structure.
Step four:  a solution of minerals is applied to the tooth.  Since bacterial acids remove minerals from the tooth, leading to the decay hole we call a cavity, it’s helpful to put those lost minerals back into the tooth.
Step five:  a filling is bonded to the tooth, or,sometimes, the tooth is left alone to remineralize and “heal itself.”  The decay infection has been neutralized.

How many dentists use the Diagnodent?   The last time I saw this surveyed, the percentage was VERY low.  Same thing with air abrasion and decay detecting dye.  Why is this so?  I don’t know.  I’ve spent more than a year—a 365 day year, not a work year— of my life in continuing education classes and workshops.  Knowledge is my passion  (thanks so much, mom and dad, for passing that on to me).   I can just tell you why I do what I do.

—Treating sensitive teeth.   Ozone works extremely well at desensitizing teeth, especially teeth sensitive at or just above the gumline.  We’ve had other materials and methods for doing this, but ozone appears to be the easiest and most predictable.  It’s mechanism of action is unique;  it kills the bacteria in the tiny exposed “tubules” at the gumline.  Then we apply a remineralizing solution to seal the tubules so bacteria can’t get back in.
Cost of the treatment is nominal.  It’s $35 per tooth, and you don’t pay if the treatment doesn’t work.  Yes, we’re that confident that it WILL work.

—Sterilizing root canals.   There are   small “lateral” or “accessory” canals that branch off from the main canals that may contain diseased tissue.  Conventional instruments are well suited to remove the bulk of infected or inflamed tissue within the main canals, but cannot reach the bacteria and diseased tissue that lie in the accessory canals.  Here’s what we can do now that we could never do before:  we can sterilize the entire canal system, including lateral canals, by flooding the inside of the tooth with ozone gas after the main canals have been treated with conventional instruments and ozonated water.  The result: better success, and the tooth is no longer a possible source of sepsis.

Secret problems

It’s time to continue my series on serious dental problems you can have without any awareness. When a tooth has had a root canal, it loses the ability to feel pain from a deep cavity; there’s no longer a nerve inside thetooth to say, “OUCH!” You can develop a cavity around the restoration that covers the tooth (e.g., a crown) that is soextensive that the tooth cannot be fixed and will need to be extracted. All of this, because the tooth had no system to warnyou about the cavity. Moral of the story: nothing can make a tooth totally impervious to harm. When a tooth has had a root canal, it still needsfrequent checkups to rule out new decay.

Another silent problem is what dentists refer to as Cracked Tooth Syndrome; a tooth develops a hairline crack. Thesecracks start at a microscopic level, frequently under old silver-mercury fillings, and may have no symptoms for years.Over time, the fracture can start to spread, just as athletes can develop stress fractures when a bone takes repeated impact.When these “tooth stress fractures” spread, one of two things happens: either you start to get symptoms, or the toothbreaks apart. If the tooth breaks, you need a buildup and crown or an extraction. Not a good scenario. The moral of this story: if you notice any of the symptoms of stress fracture, call immediately for an appointment so wecan check it out.

The symptoms of cracked tooth syndrome can be varied and without any pattern. They include sensitivity to hot or coldliquids or to sweets, pain when you bite on that tooth, and spontaneous pain if the crack is close to, or has reached, thenerve. Also, the symptoms may rapidly come and go and even change; one week your tooth is sensitive to sweets, nextweek to chewing.

The last important silent problem I’ll discuss now is oral cancer. This disease is a great mimic. It can look like a smallinnocent sore or a huge ulceration with a hard white center and a red angry-looking edge. The scary thing is that oralcancer rates are on the rise. This rise is largely due to the increased prevalence in the mouth of HPV, the samevirus implicated in cervical cancer. That’s why we do an oral cancer screening at every checkup and we recommend a Vizilite early-cancer-detection examonce a year.