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Repair Teeth Without the Drill: Non-Volatile Memory in the Dentist Chair

A new technique for repairing teeth without the drill, so dreaded by some, has been developed at King's College London.

It is called electrically accelerated and enhanced re-mineralization (EAER), and the inventors claim that it accelerates the natural movement of calcium and phosphate minerals into the damaged tooth. The technique employs a two-step process. First, the damaged area of enamel in the tooth is prepared, and then tiny electric current pulses are used to move the minerals needed for repair into the repair site. It is currently in development, and its developers suggest it could be available for general use in about three years.

To those of us with an interest in non-volatile (NV) memory, the process strikes a chord. The movement of material by electro-migration is a bane to developers of some types of emerging non-volatile memory, and the very driving force for others. (See PCM data retention and the impact of crystal electrodes (Part 1) and PCM data retention and the impact of crystal electrodes (Part 2).)

The building of links, usually conducting, by electro-migration-driven movement, by electro-chemical means (e.g., plating), by electro-crystallization, or by electric field, in a manner that can be reversed, are now all part of the emerging NV memory mix. Those same effects can also appear as reliability problems by shortening the life of some types of memory device as well as other solid-state devices.

The similarity between this new emerging dentistry and NV memory technology is illustrated in the two cross-sections shown in the figure below. On the right side is a cross-section of a generic NV memory with the active material between two electrodes (green). The conducting link required to write the memory to one of its logic states grows from one electrode towards the other.

On the left side of the figure is the cross-section of a tooth undergoing repair with the electric pulses. The repaired tooth material is growing into the active material. The active material (shown in pink in the tooth cross-section) is what must be applied as part of the preparation process described as the first step. This will also need to have a sort of electrode in contact with it in order to apply the electric pulses. Unlike most non-volatile memory, the material deposited as the repair does not have to be conducting. But the pink preparation material will need to be (unless the process of moving the material is electric field driven, in which case it could be dielectric and more insulating). In the figure, we have assumed that a ground link to complete the circuit is through the body and gum.

Clearly, the dentists and their patients do not require the growth to be reversed, so perhaps in an electronics industry analogy, this process should be more accurately classified as one-time programmable memory (PROM). In any case, it is certainly an interesting development.

A new company named Reminova, based in Perth, Scotland, has been set up to commercialize the research and is in the process of seeking private investment to develop the EAER technology. It is the first company to emerge from the King's College London Dental Innovation and Translation Centre, which was set up to take novel technologies and turn them into new products and practices.

This article was originally published on EBN's sister publication EE Times .

23 comments on “Repair Teeth Without the Drill: Non-Volatile Memory in the Dentist Chair

  1. Himanshugupta
    June 30, 2014

    Though its good technology and an alternate to drilling but what would be the typical time required to complete the procedure. If the rate of mineral accumulation is very slow then there is a problem. Also how discomfortable will the new technique be as compared to drilling?

  2. prabhakar_deosthali
    June 30, 2014

    I think this technology is still at the laboratory stage and a few years will be required to sort out all the technical and safety related issues to get the regualtory authority nod for use of this technology on patients.

     

  3. Ron Neale
    June 30, 2014

    As this process appears to involve passing current into the fabric of the tooth and the possiblity of return paths through the body, safety will be of great concern and even when all the development has been completed there will be a certification period although it may be possible to some degree to run both in parallel.

    As I stated, within the emerging NV memory community there is a great deal of experience of the current driven movement of material (ions and atoms) some wanted, some unwanted. It is difficult to comment further until we can move our level of information from the qualitative to quantitative. To that end I have submitted to the developers at King's College a list of questions requesting quantitative information related to their process. The list is as follows:

    1)What is the Voltage?
    2)What is the current or current density at the point(s) of contact? “Imperceptible current” is hardly a quantitative answer.
    3)What is the pulse width, pulse shape and and repetition rate?
    In other publications there is a quotation “low frequency electric currents” Does this mean AC or low repetition rate?
    4)How is electrical contact made to the solvent or electrolyte and what route does the return  current take? One of the readers has raised the possibility of nerve damage could you address that problem?
    5)How thick is the active material or electrolyte?
    6)How long does the process take?
    7)In other publications there is a quotation that cites a “healing hand piece” what is that. Is it something like the figure that has now been added as a speculative design to my EETimes piece.

    Given the answers to all or some of those questions we should be able to make some further assessment.

  4. Ariella
    June 30, 2014

    @prabhakar_deosthali yes, not every innovation makes it to our own dental offices. I asked mine about lasers in place of drills years ago, and we don't have that yet What he did adopt recently, though, is on-site production of crowns. He used to have to send out to a lab for that.  

  5. Susan Fourtané
    June 30, 2014

    Ariella, 

    3D printed crowns? They are becoming more and more common. There is a lab in Germany that has produced 3D printed crowns for years now. Very nice. 🙂 

    -Susan

  6. Susan Fourtané
    June 30, 2014

    Humanshu,

    Can you imagine anything more uncomfortable than drilling? :/ I welcome any technology that can replace drilling. 

    -Susan

  7. Ariella
    July 1, 2014

    @Susan the software and machines my dentist used were from a German company. the caps were actually milled, drilled down from a cube of ceramic type material. After the shape was attained, the dentist added on color and baked it in a small version of a kiln.

  8. Daniel
    July 2, 2014

    “I think this technology is still at the laboratory stage and a few years will be required to sort out all the technical and safety related issues to get the regualtory authority nod for use of this technology on patients”

    You are right Prabhakar. It may take time to get commercialized and for end user usage.

  9. Susan Fourtané
    July 2, 2014

    Ariella, 

    How interesting. Yes, Germany seems to be a hub for everything innovative in dentistry. The price of the 3D printed crowns also being cheaper that regular old works. And faster.  

    -Susan

  10. Ariella
    July 2, 2014

    @Susan I'm not sure what the actual difference in cost would be. As far as I know my insurance allows a set rate for the procedure, no matter which way the dentist obtains the crown. It probably costs him a bit less than sending out to the lab, but it also takes up more of his time. That's is why he said that for patients who want a whole set of teeth done, he would still have the lab do. Also the machine seems to have to form one crown at a time, so even at just 11 1/2 minutes a piece, it would still take quite a while to fill an entire mouth. And that time is on top of the time it takes for imaging, adjusting, and baking. 

  11. Susan Fourtané
    July 3, 2014

    Ariella, 

    I think we are talking about two different procedures here. What you describe your dentist is doing sounds like what my destist also does. 3D printed crowns are different. 

    -Susan

  12. Ariella
    July 3, 2014

    @Susan that could be. From what I've seen, the 3D scanning technique used is the same as the one used 3D printing, but the crown itself is milled. I did see here that 3D printing itself is used for models of teeth, particularly for othodontics:

    In digital dentistry, dentists forgo physical impressions and use intra-oral scanners, which provide a full view of the anatomy of the mouth, jaws and teeth, and allow labs to build precise models that fit right on the first try. Most of the scanners are compatible with 3D printers, said Stratasys' Director of Global Dental, Avi Cohen. Even for simple record keeping, he said, scanners make sense. Orthodontists, for example, “keep the original (or 'before') impressions for each patient for several years — five to nine, depending on location. For orthodontic practices of any size, this can create a huge storage problem since all those physical models need a home,” said Cohen.

    “But with digital files, they are stored electronically and models can be 3D printed on demand if necessary.” The next logical step, he added, would be popping the digital file into a 3D printer, and producing the right-sized object that the dentist can insert into the patient's mouth.

    The advantage of Veroglaze, Stratasys said, is that it is not only a sturdy polymer material suitable for all tooth needs, but is colored with the key A2 teeth color shade — the ivory “white” shade made famous by generations of toothpaste and mouthwash ads. Veroglaze, said Cohen, is Stratasys' “first step towards 3D printing teeth color models with remarkable color matching of the A2 color shade.”

    Read more: New niche for 3D printers in dentistry | The Times of Israel http://www.timesofisrael.com/new-niche-for-3d-printers-in-dentistry/#ixzz36PTex6Lw 
    Follow us: @timesofisrael on Twitter | timesofisrael on Facebook

  13. Daniel
    July 4, 2014

    Ariella, are you pointing about printing the crown externally by using 3D printer.

  14. Ariella
    July 4, 2014

    @Jacob it sounds to me like the concept of actually 3D printing what goes into the mouth is something not yet in practice. I think that in the current state, the choice of materials for caps and crowns works better with milling. 

  15. Susan Fourtané
    July 5, 2014

    Ariella, 

    Thanks for the link. When I mentioned 3D printed crowns I was neither supposing nor assuming about their implementation in dentistry. I was stating it as a fact. 3D printing that goes into the mouth is laready in practice. 🙂

    I met the director of the German lab that I mentioned earlier. This was a few years ago. They were already using 3D printing for implants and crowns that actually go into the mouth, not just models, but the final product. 

    The 3D scanning with milled crowns is not the same as the 3D printed crowns these guys have already been doing and that are already in the mouth of real patients. 

    I met him at my dentist's office and were discussing briefly about this and what they do. He also leads an implantology school. My next crown replacing a temporary one I have may be 3D printed, which I find super exciting. 😀

    -Susan  

  16. Susan Fourtané
    July 5, 2014

    Jacob, 

    3D printed crowns already exist at least in Germany, and are already being used in patients mouths. Read my comment below. 

    -Susan

  17. t.alex
    July 5, 2014

    Wow, amazing! This is the first time I heard about 3D-printed crown.

  18. Ariella
    July 5, 2014

    @Susan there could well be differences in different countries — even within the same country, as each dentist selects what s/he prefers. I'm surprised that you would have a temporary, though, as one of the primary advantages of using the 3D imaging technology in conjunciton with the machines that mill or print on the spot is that you don't have to wear a temporary while waiting for a lab to complete the work. I read an article in a dental journal that also emphasized that benfit. 

  19. Susan Fourtané
    July 6, 2014

    Ariella, 

    In this case it was not waiting for the lab but waiting for the bone to heal, which takes months, before the dental implant can take place. A temporary crown, created by my dentist on the spot, was needed for esthetical reasons before the whole process could be completed. 

    -Susan

  20. Ariella
    July 6, 2014

    @Susan I see. An implant invovles a lengthier process than a crown. I was warned it could take as long as a year from start to finish. 

  21. Daniel
    July 7, 2014

    “it sounds to me like the concept of actually 3D printing what goes into the mouth is something not yet in practice. I think that in the current state, the choice of materials for caps and crowns works better with milling.”

    Ariella, thanks for the clarification and hopes its get popularized very soon.

  22. Daniel
    July 7, 2014

    “3D printed crowns already exist at least in Germany, and are already being used in patients mouths. Read my comment below. “

    Susan, thanks for this updation.

  23. Susan Fourtané
    July 8, 2014

    Ariella, 

    Yes, that's what it takes. The healing process can't be rushed. The whole process has several steps and waiting times. 

    -Susan

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