Bite Point

Always Wear White to a Root Canal- Even if It's After Labor Day

 -by Rick Wilson DMD and writer extraordinaire Tom Bentley

http://www.tombentley.com/wordpress/

"Whatever you are trying to hide by wearing a feed sack only looks worse than it actually is." -Stacy London

With the change of seasons, it's time to take a look at fashion and the attire that we wear to dental visits, with an eye (and perhaps an eyetooth) to practicality too.

So, why wear white to a root canal, no matter the smart set's season?  Well, until we use a room-temperature plasma torch to cleanse the insides of infected teeth (see July 5th 2009's "A Plasma Torch For Dental Treatment. Really."), we are compelled to irrigate with the only thing that works: sodium hypochlorite, the same chemical found in bleach.  This substance is effective at both killing germs and dissolving organic debris.  We use long plastic drapes in addition to the traditional blue dental napkin—what they might lack in sartorial splendor they make up with a fabric fortification.  We also have our patients wear safety glasses for this and all procedures where aerosols are created or chemicals are used.  This eye protection is essential—you really need to insist on it or bring your own if your office doesn't provide it.  Reese demonstrates with a rather sultry look...

   

Even with all these precautions—and "caution" isn't merely the name of my iguana, but an office watchword—it's just possible that a little NaOCl (as it's called in the chemistry department) might splash on your clothing.  So, Labor Day or nay, throw fashion dictums to the wind at your dentist: if at all possible, white it is to all root canal procedures—it can only get whiter.

On the other hand, if the purpose of your visit is to remove some old amalgam fillings, Basic Black would be the thing.  If this ugly old metal gets flung around a bit and you're dressed like Morticia Addams, your wardrobe will never suffer a stain. Do be careful if you're rushing through the airline security checks though; you may be literally alarming.

 

 

For periodontal surgery or wisdom teeth removal, do I even have to state the obvious?  Red. (We will do our utmost to keep the highest percentage of your life-force within you, however.)

Did you know, by the way, that red clothing was always the most difficult to manufacture, and in fact there was only one way to do it for a very, very long time?  The best red dye was cochineal dye, and the Spanish Empire had a monopoly on this fantastically expensive commodity for most of the Renaissance and up until the 1800s.  Cochineal comes from crushing tiny female Dactylopius coccus: scale insects that live and feed on the nopal or prickly-pear cactus in South America.  The production of cochineal constituted a significant part of the Spanish Empire's economy.  In order to keep its monopoly on the substance, Spain encouraged misinformation about the source of the pigment—they called it granilla or wheat grains in order to hide its insect origin. Further, anyone caught smuggling cochinea from the Spanish colonies faced the death penalty.

Red clothing was thus very expensive.

In fact, for centuries only aristocrats and nobility were allowed to wear red clothing.  In most European countries, peasants caught wearing red clothing were severely punished. Those bright coccus bugs sacrificed their eye-catching essence, and even the canny middleman might lose his life playing with the noting of "better red than dead." In the chair, you probably won't miss the few drops of your vital fluids sacrificed for the greater dental good.

Nice summary of cochinea here:

http://www.mexicolore.co.uk/index.php?one=azt&two=lif&id=480&typ=reg

This leads us to think about how the significance of clothing has changed over time.  Even as recently as in our days as young lads, the social conventions regarding clothing were much more rigid than they are today, and also much more indicative of one's social status. Nowadays, our anything goes attitudes mean that wealthy businesspeople often dress like slumming college students and no one, regardless of socioeconomic status, will be punished by the force of law for owning a few nice sets of clothes.

It's wonderful social progress, yet it's also highly confusing, as so many visual social cues have been removed from our ken.

Let's look at a window into our more formal past.  In the 1941 film Broadway Limited, Victor McLaglen plays an engineer on the mighty Pennsylvania Railroad.  Here he is just before a Chicago to New York City run, bantering with the barista in the company coffee shop:

In the film, McLaglen's character is a pampered passenger for this particular run, as he has a few days off.  Like all travelers in those days, he was wearing a coat, tie- and a hat when outdoors.  He enters the dining car and finds it far more swank than he had imagined- ironic, considering that he normally has the one job on the train with the most responsibility to the safety and comfort of the passengers.  However, unused to being out of his work clothes, he forgets to remove his hat "indoors"; the look of deep chagrin on his face when he realizes his faux pas is funny and touching at the same time, and impossible to conceive in our laissez-faire couture culture of today:

  

 

 

 

 

We wonder, then- have we gained, or perhaps lost something, as a result of our boundless informality?

In sum, whether you wear your top hat or Topsiders on your visit to your favorite dentist, be aware that certain procedures might call for attention to your attire. (And always remember what your mother said about clean underwear.)

PS Oh, the GG-1 is here because it's just about the most beautiful piece of Art Deco engineering there ever was.  Another post...

Enamel Bonding, Dentin Bonding

"My name is Bond. Dentin Bond."

 

Ahhh, might-have-beens.  But I suppose "James" was a pretty good choice for 007's given name too...

The best dental restorations today are adhesive restorations; they're bonded onto or into the teeth that they help repair and maintain.  Like all technologies, dental adhesion is in a constant state of change and improvements are being made all the time.  Let's look at this vital aspect of modern dentistry and share a little insight into how the best restorations are currently achieved.

There are two fundamental parts of a tooth that we have to consider when we set out to bond to them: the enamel, and the dentin.

 

When we bond to enamel, we apply and then rinse away a 37% phosphoric acid solution.  No worries, your stomach is more acidic than this.  The solution etches the surface of the enamel, which is a substance made up of crystals.  Highly magnified, it looks like this afterwards:

 

The surface becomes rough on a very small scale.  We then apply a resin (the first part of these composite resin fillings of ours) that becomes micromechanically interlocked into the roughened surface.  The strength of this bond is incredible.  We can bond composite resin onto teeth in very functional areas and it often stays on for years without breaking or staining.  We measure bond strengths in MegaPascals or MPa, and 30 is a very good number to achieve.  (Don't worry about exactly what a MegaPascal is; all we need to do for the purposes of this discussion is to look at relative numbers.)  We need to hit at least 17 MPa to keep restorations sealed and on the tooth.

The first person to achieve this breakthrough was Michael Buonocore D.D.S., in 1955.

 

Bonding to dentin, though- that was a lot more difficult.  After removing decay with a drill there is a smear layer (yes, that's really its scientific name) of microscopic debris left all over the inside of the cavity prep.  This is removed with the etchant.  There are also tubules which are normal channels that run through the dentin:

 

According to the brilliant David Pashley:

"The success of bonding resins to acid-etched enamel is because of the fact that enamel contains little protein, and it can be dried without causing any collapse of the roughened surface. When Buonocore et al tried those same procedures on dentin, they were disappointed to find that the resin-dentin bond strengths to acid-etched dentin were very low (5 to 10 MPa) and were about the same as resin-dentin bonds made to smear layer-covered dentin. They did not know that acid-etching dentin transformed the surface from a hard, mineralized surface to a very soft, mineral-free, collagen-rich surface that collapses when air-dried. Although it is now known that acid-etching removes the smear layer and smear plugs, thereby making the tubules available for resin tag formation, drying the surface collapses the spaghetti-like collagen fibrils, making resin infiltration difficult.^"

Spaghetti.  Spaghetti is the key to understanding all of this.  Because once we've etched and rinsed the dentin, it looks like this:

 

 

The problem is, we can't leave the dentin soaked, or worse yet, underwater.  We have to dry it.  (And dentists, being as a class a somewhat compulsive lot, really tend to dry the teeth we work on, with a blast of air that the wind tunnel at NASA's Langley Research Center would be jealous of.)  Un-etched dentin has a compressive strength of 20,000 MegaPascals.  Etched dentin has a compressive strength of one MegaPascal.  Just one.  So here we create this wonderful substance to bond to- the dentin has this spaghetti-like mass of collagen which is highly chemically reactive and has a vast surface area- and what do we do to it?  We blast it down into a flat lifeless mass, like pizza dough that's been flattened and pulverized and all dried out.  The bond fails every time.  The stress in the filling material as it cures (usually with a light activation procedure) is higher than the bond to the dentin, and so gaps form.  Bond strength is terribly low.  Teeth are sensitive.  Painful to chew on because they're not bonded, the fillings actually move about when we bite.  Cavities recur more easily.  The left in this picture is collapsed, the right is properly expanded; in reality it can be far worse than the image indicates:

 

It's a disaster, and all because the pasta wasn't respected.

What, then, can we do?  Well, in 1985 or so, two independent researchers solved this technical problem of dentin bonding with an innovation called self-etching primers.  These researchers were Takeo Fusayama and John Gwinnett:

 

These researchers developed the class of dental bonding agents called self-etching primers.  These primers etch and bond all in the first application of liquid, and they take a novel approach- they enlist the smear layer into the bond itself.  They churn it up and make a hybrid layer out of it, a layer that is composed of the resin from the filling and also the debris from the smear layer, all activated and mixed into the spaghetti-like mass of etched dentin.  This technique can now get into the 32MPa range on dentin, and also treats the enamel properly to get an enamel bond as well.  It looks like this:

 

This technique is so excellent that, since adopting it some 12 or 14 years ago, I can say that I have never had a restoration fail from leakage and lack of bonding in its own right- they may fail from fracture, or decay around the restoration, but I do not see recurrent decay under the restoration primarily; it has to start externally, due to the patient overdoing the sugar and underdoing the flossing.

We still use etch-and-bond separately for front teeth and situations where the enamel bond is the most important factor, like chipped front teeth.  This method still gives higher enamel bonds.  We bias the relative bond strength between enamel and dentin to the clinical situation.  There are also one-bottle self-etch primers now which I suppose are being made to "simplify" the procedure; however for various technical reasons, in late 2010 these products do not get good results at all.  In fact there are only two existing self-etch products (both two-bottle) that I'd even consider using to restore a back tooth with a bonded composite resin restoration- Kuraray's SE Bond and Danville Engineering's Prelude SE.  They are so superior to any others that they are the only choice in 2010, and there's a lot of science to back it up.

The longevity of these restorations is quite good as well.  Silver amalgam restorations seal against the tooth by corroding, a process that reaches its peak at the two year point.  After that it's all downhill.  Composite resins bonded with self-etch primers seem to hold their bond strength to both enamel and dentin for at least 8-12 years, after a small initial decrease.  Their longevity may be quite longer.

For the technically minded in the audience- ok, for geeks like me- here are two of my source articles; they are excellent reviews of the literature and the progress in this vital aspect of dentistry:

 http://www.dentistrytoday.com/materials/1483.html

http://www.compendiumlive.com/article.php?id=2451

The reason for this rather technical review?  If you have a composite resin restoration placed and it's very sensitive, especially to cold and to chewing on it, there are three main possible causes:

-The bite is "high" and needs to be adjusted;

-The decay was deep and a root canal issue is brewing; or

-Total etch was employed and the bond is not good.  I'm sticking my neck out when I say this, but the science tells us that total etch is too technique sensitive to rely upon, and thus self-etch is the only rational way to restore a back tooth with composite resin at the present time.

Medical Privacy Checkup and HIPAA- Guest Post by Elisha Hoffman Abrams

I am pleased to host a post by guest Elisha Hoffman Abrams.  Ms. Abrams is a great friend and also one remarkable attorney.  She approaches Consumer Protection and Elder Care issues with passion, intensity and caring.  Her practice also emcompasses Estate and Life Planning, Contracts, and General Law.  Ms. Abrams is a consummate legal researcher, having that rare talent of knowing where and how to look for information so that her clients have an accurate and thorough, yet rapid, answer to their legal questions. 

"Let's call Elisha Abrams" is in fact a phase that has echoed down the hall of our office whenever we plan something that has legal ramifications.

Here, then, Elisha Abrams sheds a little light on those HIPAA forms and medical privacy issues:

GET A MEDICAL PRIVACY CHECK-UP

    How private is your medical information, and is it insulated from nefarious prying eyes?  Whenever you go to the doctor, dentist, hospital, pharmacy, or contact your health insurer, you are divulging confidential health information that should be protected from getting in the wrong hands.  The Health Insurance Portability and Accountability Act (HIPAA) is a federal law that requires health care providers to take measures to protect your medical privacy.  If your medical history is an open book for all to see, now is the time to start a new chapter, and take steps to ensure your privacy rights under HIPAA.

ASSERT YOUR PRESCRIBED RIGHTS

    Next time you go to the hospital, see your doctor or pharmacist, or speak with your health plan provider, you will be given a privacy notice.  This notice will explain their privacy practices, and how your health care provider will use, share, and disclose your personal medical information.  You will also be asked to complete authorization forms that will give you the right to consent to, or opt out of having your health information disclosed or shared with family members, friends, employers, life insurers, marketing firms, or other third parties.  These privacy notices and authorization forms can be lengthy, convoluted, and confusing.  Read and understand the fine print, and if you have questions, do not hesitate to speak with your health care provider before you agree to sign them.  If you are admitted into the hospital, you can choose to not be listed in the hospital’s directory.  This directory usually has the patient’s name, condition, and room number.  Caveat, if you opt to not be listed, this will mean that friends, family members, or well-wishers will be unable to find out anything about you.  Also, do not count on having any cards, balloons, or flowers delivered to your hospital room.  If you do want your health care provider to be able to discuss your medical information with your spouse, friend, or family member, be sure to sign a consent form that authorizes your doctor, pharmacist, or health plan to share and discuss your information with them.  You can also request that your provider send your health information to a particular address, or that they contact you at a particular number. 

CHECK UP ON YOUR MEDICAL RECORDS

    Under HIPAA, in addition to your being notified about the privacy practices of your health care providers, and how they will use, share, and disclose your medical information, you also have the right to see and obtain copies of your medical records.  It is good medicine to exercise this right to insure that your records are accurate.  If you do discover inaccuracies in your records, you can ask to have them corrected.  You should be provided access to your records within thirty days, and you may be charged for the cost of copying and delivery.  You can also request that your provider send your health information to a particular address, or that they contact you at a particular number.  If you believe that your privacy rights have been violated under HIPAA, you should contact your health care provider, and the U.S. Department of Health and Human Services Office for Civil Rights at: 1-800-368-1019.  For more detailed information about HIPAA access: www.hhs.gov/ocr/hipaa, or call the HIPAA Hotline at: 1-866-627-7748.  To insulate yourself even more from “Peeping Toms,” be extra vigilant if you opt to divulge your personal information on surveys, health screenings, sweepstakes, or on health web sites.  Always, look at the privacy policy, and ask how your information will be used and accessed. 

Please send your consumer questions to elisha.abrams@gmail.com, or write to 2401 Pennsylvania Ave., Suite 1C-46, Philadelphia, PA 19130, Tel: 215-765-4828, Web Address: www.legallyinformed.com. Blog: legallyinformed.wordpress.com.

 

Dental Lasers- A Coherent Treatment Strategy

It's hard to believe, but this cute little device:

 
-is an AMD Picasso dental laser.  I'm among those who appreciate excellent design, and this one delights us and our patients with both its form and its function.

Many are aware that the term laser stands for Light Amplification by Stimulated Emission of Radiation.  The term "radiation" here is used in the general sense, which includes visible light.  Lasers put forth coherent light, which means that the light rays scatter very little; they travel in a tight beam for a very long distance.

The Picasso dental laser is designed for soft tissues, meaning that it cannot "drill" teeth for us.  This may or not be a good idea anyway, since hard tissue lasers designed for use on teeth do their work by heating teeth in very small areas at a time, essentially ablating or exploding tooth structure on a tiny scale.  What this specifically does to the remaining tooth structure on a microscopic level is not yet fully understood.  We therefore have not adopted that particular technology in our practice yet, opting instead for electric handpieces or drills, the very finest made.  Their noise and vibration is the least possible with current tech, and their safety is totally proven.

Back to soft tissue lasers, then.  What, exactly, can our laser do?  Our primary reason for adopting this innovation is to prevent, one hundred percent, any bleeding from the gums into a dental restoration in progress.  Many times cavities or old restorations are below the gumline and as we go about the process of restoring these conditions we face working right next to gum tissue that is already irritated.  Hopping mad, at times.  Once gums start bleeding as we work next to them, it's very difficult to stop.  The thing is, our modern ability to bond or adhere to teeth is dependent on having a clean, dry operating field.  The Picasso laser ensures that we can maintain these ideal conditions.  A little lasering about and the gums are suddenly behaving like they'd just had a good talking to by Emily Post.  It's magical.

Our adoption of the dental laser has thus vastly improved our tooth restorations for patients in the most challenging conditions.  And there are even more benefits.  Laser soft tissue treatments imply little to no post-treatment pain.  Lasers can even be used in the mouth with topical anesthetics or even without anesthetic up to a point.  The Picasso has power settings that go up to 2.5 Watts, yet the lower power range is often the most useful.  The laser light can also be continuous or pulsed, 30 times on/off per second.

Some additional uses of dental soft tissue lasers are:

-Exposing partially erupted teeth for orthodontics

-Contouring gums in the smile zone to achieve symetry of the left and right sides of the smile

-Exposure of dental implants when they are ready for their restoration

-Treatment of painful cold sores, apthous ulcers, herpetic ulcers and denture sores (with adjustment of the denture as well)

This last use is superb.  The process involves two painless 30-second sweeps of the pulsed laser light over the lesion.  In most cases, they resolve within two days with minimal pain, rather than taking 10 to 14 days with severe pain.  I occasionally get apthous ulcers myself and they are dreadful, interfering with speech and eating... Freedom from two weeks of an apthous ulcer is better than any iPad app yet invented.

Oh, one last thing.  You didn't seriously think that you'd escape a picture of this, did you?-

 

3-D Optical Imaging of Teeth

At the present time, we take physical impressions of teeth and jaws in many situations.  We use these impressions to make crowns, implant crowns, guides for implant surgery, dentures... Many dental conditions are best handled by making a prosthesis of some sort outside of our patients' mouths, and accurate impressions are a key step in making this happen.  It bears thinking about that we must impress both soft and hard tissues, often at the same time and with the same impression, sometimes while juggling hygiene checks or spinning plates. 

Before impression materials were invented, artificial teeth, especially dentures, were ill-fitting contraptions that were much more about appearance and bling than they were about chewing food.  A quick pic of one of George Washington's two known sets will illuminate:

 

They really didn't fit his jaws with any precision, and the springs were to keep them in.  Not comfortable! 

We can now imagine the revolution in dental treatment that occurred when accurate impression techniques and materials were developed.  Dentures would actually fit.  More than that, broken and decayed teeth could actually be repaired with crowns.  Before the existence of accurate impression techniques, there was no hope for repairing the effects of tooth decay and trauma in an esthetic and functional manner.  These passages from Anthony Trollope's excellent The Eustace Diamonds, written in 1871, shows his character Lizzie Greystock's feelings about the risk of irreparable damage to her teeth- and beauty- from riding a horse too fast in a hunt:

"And then, what if at some desperate fence she were to be thrown off and break her nose and knock out her front teeth! Was the game worth the candle?"

"What other rich people did, she would do. But now, in her five minutes of misery, she counted it all up, and was at a loss to find what was to be her return for her expenditure. And then, if on this her first day she should have a fall, with no tender hand to help her, and then find that she had knocked out her front teeth!"

"Lizzie understood most of it,--more at least than would nine out of ten young women who had never ridden a hunt before. She was to go wherever Lord George led her, and she was not to ride upon his heels. So much at least she understood,--and so much she was resolved to do. That dread about her front teeth which had perplexed her on Monday was altogether gone now. She would ride as fast as Lucinda Roanoke. That was her prevailing idea."

I can remember being struck, when I first read this superb book, by how the usually fearless and audacious Lizzie was so afraid of damaging or losing her front teeth- because in 1871, there was absolutely no way to repair this sort of injury, and she would have irretrievably lost her beauty.

How far we have come.  One of these front teeth was severely broken down and we restored it with a crown.  The other is completely missing- and we restored it with an implant.  More than that, we restored the very bone that supports the teeth and gums:

 

This type of treatment always involves accurate impressions.  Here's an example of an H & H impression, note the incredible detail:

 

This is the kind of thing we build upon these impressions:

 
 

Then of course they always look better once the porcelain is on!

 

Still, physical impressions have their drawbacks.  They can be flawed, necessitating retakes.  They can be lost in transit.  They can be negatively affected by moisture and blood- although we use a system for individual crowns that scoffs at such trivialities.  It's called "H & H" and it's brilliant.  Although impression materials taste far better than they used to, they can trigger a strong gag reflex in susceptible patients.  They are also analog by nature, and much of our current dental prosthetic work is capable of being designed and produced by digital means.  Crowns, even porcelain ones, can be designed by CAD-CAM technology: (http://www.gsd.harvard.edu/inside/cadcam/whatis.htm)

In fact, there are devices like the CEREC that will mill a porcelain onlay or crown right at the side of the dental chair, allowing placement after a reasonable waiting time, which can be spent by the patient catching up on emails with their ubiquitous handheld devices.  This avoids the need for a second visit to insert a crown; it all happens at one sitting.  The only reason that we have not adopted this tech in our practice is that all-porcelain crowns are not the only type of restoration we need to do, in fact they make up a small portion of the mix.  Crowns can be all metal, all porcelain, porcelain and metal, zirconia and porcelain, all zirconia... It's like going to the yogurt aisle in the supermarket, there's overwhelming choice!  We have to use what's best for a given situation.

Another area of dental tech that uses CAD-CAM technology to create medical devices is Invisalign orthodontic treatment.  When we take physical impressions, they are never poured into a physical stone model.  Rather they are micro-CAT scanned and the digital information is used to create a 3-D computer model of the arch of teeth, then the Aligner trays are manufactured via CAD-CAM processes.

It makes sense, then, to eliminate the analog portion of the process entirely and scan in a digital representation of the teeth, gums, and any other areas of the mouth that need to be imaged for a given treatment.  This can be done with visible light rather than  X-rays.  The information is thus already contained in 3-D computer space in voxels, which are like the pixels in your digital camera but with three coordinates in space rather than two, and with the requisite color or gray scale information as well.  This information can then be used as the basis on which to manufacture crowns, implant crowns, Aligners for orthodontic tooth movement- anything that a physical impression can do.  Accuracy goes up; essentially it becomes the voxel size.  They also can be reproduced as needed and can't be lost in the mail.

One of the drawbacks of optical impressions is that if our eyes can't see a part of a tooth that needs to be impressed, the scanner will not either.  The margins or edges of crowns sometimes go under the gumline, and physical impressions may always be needed to capture that area.  Also, when it comes to manufacturers and product lines, we don't know which to bet on yet.  It's reminiscent of the dilemmas that consumers faced back in the 80's with tape video recording technology- VHS or Betamax.  All of us who are of a certain age can recall who won, and now of course we've progressed through an alphabet soup of successor technologies: DVD, BlueRay, DVR...

Here's a link for one, though, for those who wish to explore a bit further:

http://www.sirona.com/ecomaXL/index.php?site=SIRONA_COM_digital_impression_cerec_connect

(Note that the materials choices for crowns are starting to widen, another positive development.)

Sometimes the gaps between the restoration and tooth are a bit too large for my comfort as well:

http://www.jopdentonline.org/doi/abs/10.2341/09-178-L

Still, this technology of optical dental impressions is coming, and we plan to adopt this innovation in our practice as soon as standards are developed and as soon as the results surpass what we can achieve with physical impressions.  I'm especially keen to apply this technique to Invisalign.