Enamel Surface Roughness following polishing teeth and removal of Braces

Surface roughness following Orthodontic de-bonding, re-shaping and polishing

 

Although I have addressed the benefits and sometimes need to re-shape teeth as part of orthodontic treatment and following removal of braces, I wanted to present the public with more specific studies which looked at surface roughness following interproximal reduction of teeth, re-shaping of teeth and (in the 2^nd study) following removal of bond cement when braces are removed.  I wanted this information out there for those few parents and patients that are nervous or concerned about the enamel following braces, specifically following any re-shaping or polishing of the enamel.

In the recent April 2017 American Journal of Orthodontics & Dentofacial Orthopedics, there was a study published (Meredith, Farella, Lowrey, Cannon and Mei; AJODO.2017.04.151) which used Atomic Force Microscopy to analyze the enamel nanotopography (surface of the enamel at a scape of 1/1,000,000,000 of a meter or a nanometer) following reshaping of enamel during Orthodontic procedures.  Without going into minutia detail, this prospective study used 64 teeth and performed various levels and types of re-shaping with diamond strips, diamond burrs (handpiece) and several polishing discs.

 

Control teeth (with no re-shaping or polishing at all) showed normal enamel roughness or ridges of 149 +/- 39 nanometers (1nm = one billionth of a meter). To give you a sense of the scale this study was measuring (and the extreme minimal effect of braces to teeth), consider that Viruses are 30 to 50nm in width, DNA is 2.5 nm in width and a single atom is .1 to .3nm in width!  So before you see the results, remember the scale we are employing  just to detect a difference in the enamel surface from pre to post-orthodontic debond and polishing.



DNA strand, 2.5nm

 

So the Results showed the initial re-shaping with diamond burs (handpiece) all produced rougher surfaces with values from ridges of 702 +/- 134nm, various strips ranged from 501 +/- 115nm down to 318 +/- 50nm with fine curved discs showing ridges of 224 +/- 65 nm.  The smoothest enamel was seen following a series of Sof-Lex discs leaving surfaces with ridges averaging 37 +/- 14 nm. 

  

A few things to take from this important study:

1. Enamel has natural ridges at the nanometer level; teeth are not glassy on the surface.
2. Your Orthodontist should be using round discs to polish teeth (Sof-Lex discs produced the smoothest surfaces, 3x smoother than normal average enamel).
3. Enamel can be re-shaped and re-polished to its original and even better surface quality
4. Sof-Lex discs can polish the surface of enamel to leave ridges and valleys the less than the height of a single virus or only 300 atoms high!

How does de-bonding and cleaning enamel after braces affect surface roughness?

 

I want to also include a summary from another similar atomic force microscopy study looking particularly at the surface of enamel following de-bonding (after braces are removed) also published in the AJODO (Mohebi, Shafie and Ameli; AJODO,2017.03.151).  In this prospective study, 30 teeth were bonded and de-bonded using composite cement and then the remnant cement was removed using different methods; a white stone bur and a tungsten carbide bur.

 

Results revealed no significant difference in surface roughness following removal of the remnant cement between the groups however the Tungsten bur was significantly faster/more efficient.  The surface roughness was increased when compared to the control teeth (average 87.7 nm) v. post-composite removal (average 179nm) which the study pointed out was known to be the case as investigators have repeated previously.

 

 

Ultimately, these two studies together reveal what is likely the most effective and efficient means to remove composite cement from teeth following deband:

 

1. Remove brackets
2. Remove residual composite cement with Tungsten Carbide bur
3. Polish surface with Sof-Lex disc method

Sof-Lex polishing discs with slow speed handpiece.

The public should keep in mind that it takes a fairly strong bond between bracket (braces) and the teeth to be able to move the teeth and the roots.  I always compare root movement to sticking a flat knife into a tub of cold butter and trying to move the knife sideways while keeping it upright.  This is exactly why clear aligner trays such as Invisalign, Clear correct and even Orchestrate3D (the specialist version of aligner trays) are so limited in their overall movements and why studies from the AJODO have repeatedly demonstrated the poor accuracy of tooth movements with trays (anywhere from 18% to 44%).  Of course the trade off is that fixed braces must be cemented well enough to withstand not only forces of movement but also forces of mastication; it should be no surprise that we expect some (extremely) minor surface roughness immediately following debond. 

 

How do I Personally clean cement from braces?

 

Ever since I have been in practice, I have always removed excess cement 1^st with a plier to scrape any large remnants, then with a Tungsten Carbide bur with a hand-piece to remove the more stubborn remnant composite (I use 3M Transbond cement for brackets/braces and Fuji II Glass Ionomer cement for bands) then I follow every case with a series of Sof-Lex discs (I use the soft color-coded system from black to dark blue to medium blue and finally with the super-fine light blue).  I think my experiences as a general dentist years ago, prior to specializing in Orthodontics, instilled in me a standard to follow.  In fact, so many times I had seen patients treated that came back to me with terrible scarring to the surfaces of the teeth and it always frustrated me to think of all of the work and time involved with Orthodontic treatment only to see the surfaces with gouges and scratches that could have easily been either prevented or polished (most of which I ended up polishing afterward for the patient).

 

Because of my experience and history as a general/cosmetic dentist prior to Orthodontics, it was no surprise to me to see the results from these recent studies and I am pleased the literature makes recommendations for the good of the patients that I know have worked for me and my patients for over twenty years.

 

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 35^th 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 20 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.