Monday, December 4, 2017

Accelerated tooth movement with Orthodontics

 
Accelerated Tooth Movement with Orthodontics
 
 
 
Every now and then I have a patient or dentist ask me about some type of product that may accelerate orthodontic tooth movement.  I wanted to discuss a few facts and some of the research concerning some different methods advertised and/or investigated to essentially speed up tooth movement.
First of all, the public must realize (for that matter dentists must realize) that products are advertised to sell.  IF there is a product out there, they will pay to advertise that it is the best product (makes teeth move faster, produces less pain, makes you run faster/jump higher, etc., etc.) so consumers really need to consider the source.  Probably the most obvious example is the explosion of advertising from InvisAlign and other aligner trays making wild claims and generalizations, even producing research (funded by the company of course) supporting why their product is the best.  Keeping this in mind, the following information is from juried research, article and papers produced and published in the AJO-DO, the recognized clinical Journal for Orthodontic Specialists.
 
But before I go through the current research on accelerated tooth movement, I must absolutely stress that the FASTEST way to get through orthodontic treatment is:
 

1.   Use the correct appliances for the specific case (don’t try to use clear aligners to treat moderate or severe crowding, overjets, openbites, underbites, or otherwise difficult cases requiring significant movement or removal of teeth).  Just because you can improve crowding with aligners IN NO WAY equals a full correction.  Braces remain king.  They are faster, compliance independent, more accurate, more adjustable and provide more force to teeth than any aligner, even the specialty based Orchestrate Aligners that I employ.
    2.   Go to an accredited Orthodontist with specialty training (preferably a board certified specialist); someone who can accurately diagnose and safely treat your family THE FIRST TIME.

     

    3.    GOOD ORAL HYGIENE AND GOOD COMPLAINCE!!!  Most Orthodontists will tell you the number one cause of long/extended treatments is compliance and not the complexity of a given case; this means compliance with oral hygiene, compliance with avoiding hard foods and compliance with any rubber bands.  Broken brackets, loose wires, poor oral hygiene and not wearing rubber bands can add months if not a year or more to a normal treatment and lead to an incomplete correction.
     
     

    Now I need to provide a little science and biology so you as the public have some baseline level of understanding how teeth move to discuss accelerated treatment options/research.  Keep in mind the difference in B.S. in science v. BS in advertising!

     

    Most doctors and patients know that pressure from wires/braces/aligners moves teeth.

     

    The mechanism of Bone modeling is the independent process of activation-resorption of bone (catabolic action) or activation-formation of bone (the anabolic action) on the surface of any bone.

     

    Bone remodeling is a coupling or turnover of bone which starts with resorption then changes into bone formation and replacement of the old bone.

     

    Orthodontic tooth movement is affected by both modeling and remodeling of the bone.  Modeling of the bone is limited by the time it takes our inflammatory cells (osteoclasts) to resorb the surface of the bone around the tooth.  Once bone is resorbed (think of it being “eaten away” by the osteoclasts), cells that produce new bone called osteoblasts lay down the new bone.  These two cells are generally organized into multi-cellular units so that the process of resorption and formation are constantly working in sync.  The process of this resorption/formation is in turn regulated by biochemical factors such as blood proteins, hypoxia (low oxygen in the local tissues), chemical factors (see below) and by mechanical factors.


     

    So how do braces affect bone remodeling and modeling as they move teeth?

    Braces and other orthodontic appliances provide mechanical forces which lead to compression of teeth against the bone.  This compression leads to hypoxia (recued oxygen to the surrounding tissue and bone) which then triggers the osteoclasts (through triggering chemical factors to increase osteoclasts and osteoblasts) to chew away the bone in the compressed area.  There are also chemical factors that are triggered by the hypoxia (cytokines and prostaglandins) that cause increased production of the inflammatory cells as other chemicals and proteins trigger precursor cells (more generic younger cells) to differentiate (morph or develop) into adult inflammatory cells such as osteoclasts and osteoblasts.  The cumulative process of bone resorption turns out to be the limiting factor of tooth movement so theoretically, anything that can increase the speed of the resorption at the surface of the bone will increase the tooth movement as long as the forces remain on the teeth.  The remodeling or bone formation is faster so we will leave that process for another day. 

     

    “The cumulative process of bone resorption turns out to be the limiting factor of tooth movement”


     

    So what are some ways to speed up bone resorption during orthodontic treatment?

    One of the ways researchers and clinicians have attempted to affect this process is to increase the number of osteoclasts in the area where tooth movement is desired; by increasing the number of bone-eating cells, you will increase the amount of bone that can be removed at one time (which as noted is the limiting factor in orthodontic tooth movement).  Think of goats in a grassy yard; one can clear a small yard in a week, two can clear the same field in 3 days, and so on. 
     
     

    With this goal in mind, research has shown that one way to increase the number of local osteoclasts is to purposely injure the surrounding bone.  Researchers cut grooves in the bone between teeth (a process termed “de-cortication”) and studied the effect on orthodontic tooth movement.  This process did in fact trigger a significant increase in osteoclast formation/aggregation and differentiation which led to accelerated tooth movement.  However it also required full mouth periodontal surgery and a perceived risk of other issues such as possible bone loss and/or recession.  Although in a healthy mouth the healing should be successful, there is always a risk of other problems/damage to roots/exposure of roots or just prolonged pain from the surgery.  This process is far from routine and most Orthodontists do not feel the risk of problems and the overall discomfort/risks of surgery justify the saved time in treatment on most patients.   

     


    An even more scientific way to increase tooth movement is to directly inject chemical factors and proteins that act directly on the cells to increase inflammatory cells and/or block the natural mechanisms that keep the inflammatory process in check.  The idea is to regionally increase osteoclasts chemically which then will lead to only local increases in bone resorption and therefore can increase tooth movement in those areas.  To understand this (you may want to skip the next paragraph and just know it is possible!), I have to explain the process and name some of these chemical factors.
     
    By the way, these same Factors in the blood/gingival fluids are those affected by pressure from orthodontic appliances (the effect of which begins within hours of the pressure exerted and lasts up to 5 days after the forces are applied).  So what are these chemical factors? One of these is known as Receptor activator  of nuclear factor Kappa B ligand (or RANKL for short); this factor directly accelerates production of osteoclasts.  Another factor is Macrophage colony-stimulating factor (M-CSF) which, as its name suggests, increases the units containing both osteoclasts and osteoblasts therefore increasing bone resorption.  In fact, the M-CSF recruits precursor cells that then can differentiate into fully functional osteoclasts/blasts.  A third class of natural fatty acids known as Prostaglandins will increase the production of RANKL (which then increases the production of osteoclasts).  Prostaglandins are produced in response to hypoxia and tissue damage; in fact this is the reason we take NSAIDS such as Aspirin, Motrin/Advil/Ibuprofen, and sometimes Indomethacin (for gout and arthritis) to reduce pain from inflammation as these drugs prevent or reduce production of Prostaglandins.
     
    So in turn, injection of RANKL, M-CSF or Prostaglandins will all cause in increase in production of osteoclasts and therefore an accelerated movement of teeth during orthodontics.  Again, for most clinical settings, this is more experimental and introduces risks solely for the purpose of accelerating the inevitable movement of teeth and is therefore not a common practice.  And the acceleration achieved may not be more than a few months.  It can also lead to increased sensitivity/pain and a risk of other unseen events.  It is more likely to be used in a specific area to move one tooth (a stubborn molar) or group of teeth faster versus other teeth across the arch.
     

     
    Image from :

    Accelerated orthodontic tooth movement: Molecular mechanisms
    Huang, Hechang et al.
    American Journal of Orthodontics and Dentofacial Orthopedics , Volume 146 , Issue 5 , 620 - 632

      

    Are there other devices that can increase the amount or activity of osteoclasts and speed up orthodontics?
     

    Resonance vibration is a process of vibrating an object equal to the natural frequency of an object to amplify the amplitude of that object (similar to two voices harmonizing which increases the amplitude of their voices together).  Resonance vibration of 60Hz to molars in rats for 8minutes once a week has in fact shown to increase molar movement by 15% compared to controls by stimulating more expression of RANKL which increased osteoclast formation around the molars.  Using this theory and similar experiments, one company has produced an appliance called AcceleDent which has been marketed with claims it can increase the rate of orthodontic movement however objective researchers point out that AcceleDent only produces vibration at one fixed frequency far lower than the studies (4 Hz).  As of recently, there have been no peer-reviewed studies to confirm claims by AcceleDent by evaluating the biological effects or even the clinical effects. It is likely that such a low resonance of 4Hz is not harmful but it is also likely that it is clinically insignificant if effective at all in its current form.

    Lasers have been shown to accelerate tooth movement in human studies however there are also studies that revealed no accelerated movement with the same low-energy lasers on soft tissue.  In fact some studies showed the opposite with movement actually slowing.  Unfortunately it is difficult to equate one patient or clinician with another and forces in the mouth can very complex and vary as teeth move and energy in the appliances is reduced. 
     


    Magnetic fields have also been studied to see how they may affect bone remodeling.  Animal studies followed by histologic evaluation has shown increased bone remodeling from both static (constant) magnetic fields and pulsed magnetic fields by increase both resorption of bone and increased production of bone at the apposition side.  In addition to these mechanisms, the static magnetic field reduced the hyalinization in the ligaments around the teeth which was thought to contribute to the accelerated tooth movement.  Unfortunately other studies did not repeat these results and even worse, one study was able to demonstrate root resorption from the magnetic field which effectively kills this option for the practicing clinician at least for the time being.
     
     
     
     
     

    Electric current in small amounts (but constant) has been studied in animals and this significantly increased tooth movement (100% increase in some samples); the histologic study showed significantly increased resorption at the anode site and significant bone formation at the cathode side with a significantly increased osteoclast production throughout the ligament surrounding the teeth (the PDL).  Researchers are still struggling with a source for the electricity (they are considering enzyme batteries, something above my clinical knowledge for sure and certainly not yet a reality).

     
     

    Vitamin D3 (1,25 Dihydroxy vitamin D3) injections in animals have shown to increase bone remodeling by 25 to 150% by stimulating formation of osteoclasts (dose dependent) in conjunction with orthodontic forces on the teeth.  The nice effect of D3 is that researchers also found an increase of osteoblast formation and therefore an increased bone formation following the resorption. The researchers pointed out this makes the effect of D3 more balanced when it comes to overall bone volume.  To achieve this effect however, there were significant and frequent quantities of injections making human use questionable and certainly requiring more research to investigate the systemic effects of such treatment.

    As mentioned previously, Prostaglandins (PGE1, PGE2 or their chemical analogs thromboxane A2) also lead to increased resorption of bone and researchers have studied this phenomenon by injecting PGE to increase tooth movement.  In humans, submucosal injections around local areas in the mouth has been shown to increase tooth movement by about 50%.  Of course this same logic means anti-PG drugs such as pain relievers Aspirin and Ibuprofen will slow tooth movement by reducing the effects of mechanical forces in producing PGE’s which in turn prevents the increased ramping up osteoclast formation.
     
    So what does this all mean?  Can we speed up Orthodontics?
     
    In short, yes we can speed tooth movement up in a research setting with many mechanisms however the vascularity of the oral tissue is going to carry any pharmacologic agent/chemical throughout the body and there must be significantly more research before a widespread method will be available to speed treatments.  Also, some of the methods to accelerate tooth movement involve purposely damaging or injuring the tissue which, in my opinion, borders on unethical if not outright malpractice.  Currently treatments that appear to speed treatment (such as special brackets or trays) only partially move teeth, tipping the crowns into apparent alignment without uprighting the roots and allowing time for the bone to remodel and stabilize; it is inevitable these “faster” cases will only relapse in the future.  Others are just inflating expectations and geared toward increasing sales to the public more than basing treatments on evidence (they are after all just companies pushing products).  Use of extra-oral devises may be based on theoretical grounds and research evidence may support the root idea, but clinical significance has yet to be established and is likely not valid enough to justify peer-reviewed scientific research.  My opinion is that in a competitive market what we see are more gimmicky products being pushed in an effort to present some false fa├žade of expertise in new products to separate one doctor from another.  I also believe that many of these products go along with aligner trays that are not producing adequate results in an effort to make aligner corrections somehow better than traditional braces (which will likely never even be close to the case despite what the public is fed by Align advertising).
     
    The speed at which tooth movement can be accelerated by current methods is likely insignificant to minimal and just does not rise to the level of endorsement by knowledgeable specialists.  It is true that products are advertised by companies and even recommended by dentists that act on hear-say knowing it “probably won’t hurt and may help”, but a true specialist practices using evidence based procedures.
     
    The exception currently is the use of tissue damage through decortication (and now more limited scarring of the bone or even just flapping the gingival back away from the bone and placing it back) to accelerate movement of teeth.  I use this process in cases where I don’t have the anchorage to move a tooth forward (usually a lower molar to pull it forward and replace a missing molar) or there is an impacted molar.  I especially like to reserve removal of 3rd molars in these cases when I start braces so that if I do run into problems moving a tooth, I can have the third molars (wisdom teeth) removed at a specific time and the decortication performed at the same time.  PGE injection can be used in the same manner however I do not prescribe to wide spread use for the sole reason to increase tooth movement by 20 to 30%.
     
    I hope this addresses some questions about accelerated tooth movement and dispels some myths.  In today’s world of advertisers driving treatment standards and pushing products directly to the consumers (around the dentists and specialists) as has happened with InvisAlign, Clear Correct and Smile Club, it has become increasingly more important for patients to seek practitioners that tell them what they need to hear and not just what they want to hear.  If we stop acting on evidence-based research and turn instead completely to profit driven billion dollar companies to sell us their products with false and/or exaggerated claims, there will be no good doctors that can compete with advertising; the best will retire and the others will just sell you what you want to prevent going out of business. 
     
    I want to give special credit to Dr. Hechang Huang, Dr. Ray C. Williams and Dr. Stephanos Kyrkanides for their most excellent summary of literature reviewed (160 scientific articles cited in this one study alone; many of which were used to produce current clinical standards) and presented in the 2014 article on the AJO-DO:
     
    Accelerated orthodontic tooth movement: Molecular mechanisms
    Huang, Hechang et al.
    American Journal of Orthodontics and Dentofacial Orthopedics , Volume 146 , Issue 5 , 620 - 632
     
    If you have questions or comments concerning this or any orthodontic question, please feel free to make a complimentary new-patient appointment at either my Steiner Ranch location or my North-central Austin location on West 35th street and MoPac.
     
    Dr. James R. Waters is a 1996 graduate from UTHSC Dental School in San Antonio, 1997 graduate of Advanced Dentistry from the UNMC in Nebraska and the 2001 Valedictorian graduate from the prestigious Saint Louis University Orthodontic Program receiving the J.P. Marshall award for clinical excellence in 2001.  He holds a Bachelor’s Degree in Science, Doctorate in Dental Surgery, a post-doctorate certificate in Advanced Dentistry, post-doctorate Degree in Orthodontics & Dentofacial Orthopedics and a Master of Science Degree in Orthodontics and is a Diplomate of the American Board of Orthodontics.  Dr. Waters and his wife of 21 years live in Austin, TX with their 4 children where he has a thriving, multi-faceted Specialist practice with locations in Steiner Ranch and North-Central Austin.  You can learn more about Dr. Waters at BracesAustin.com.