Topics of the day:
1. Re: Damon
Portland OR USA
I think Dr. Thomas has an interesting point. How much round tripping affects our results? We all know what happens when we add a continuous wire to a vertical cuspid, trying to displace its roots distally. We all know what happens to crowded canines and lower incisors in extraction cases, when we align them without moving the cuspids distally first. We all know what happens sometimes when a deep overbite correction in the lower arch is attempted with a reverse curve of Spee, especially when we needed retraction of teeth in the upper arch. There are tons of examples, all totally predicted by force system analysis. I don't want to bore everybody illustrating the force systems involved in these cases- that's why I am appealing to clinical experience. I feel that evidence-based orthodontics is certainly a good tendency for our profession, but sometimes we don't need a statistical study when we already have the basic science to understand things to a certain extent. Round tripping is an effect of lack of planning of the force system and it at least increases our treatment time, despite of how we delude ourselves with bracket system A or B.
But for some things, like mainly biological effects, we do need evidence, and a lot. Recently, a meta-analysis of the literature on this was published and showed high correlation between root resorption and total amount of root movement in treatment. There is indeed a genetic component involved in root resorption (as showed by the research group here in Indiana ), but this and other studies show this is not a reason to just forget everything else.
A lot of orthodontic movement is made using undersized wires. Every experienced orthodontist knows how difficult it is to have full root control and use sliding mechanics at the same time, and most of them do use sliding mechanics, I believe the majority. Most techniques that use sliding mechanics do it with undersized wires, taking advantage of uncontrolled tipping of teeth using elastics at the level of the bracket, and correcting it later with wires of larger cross section and young's modulus.
The interesting thing is that, at the same time, a lot of orthodontists criticize Begg appliances and tip-edge because they have less root control (although they just take the easiness of tooth movement by uncontrolled tipping as an accepted reality). Aren't some edgewise orthodontists doing basically the same to a certain extent? In fact, I see little difference in the overall tooth movement process that happens with sliding mechanics with undersized wires and Begg mechanics, at least when we consider the importance of bracket-wire play and torsional modulus for the wire reaction to start accomplishing translation. I agree with the criticism on Begg mechanics and the possible problems with round tripping, but at the same time I see that most people ignore the effectiveness of space closure mechanics with loops with controlled force systems. Tipping is controlled with a high moment to force ratio and thus avoids round tripping or at least minimizes it. It is indeed a little bit more work, but isn't it worth it to qualify ourselves as people that know how to move a tooth correctly? Isn't that what ultimately an orthodontist should be able to do? I think loops, either with segmented or continuous wires, are still the best way to achieve effective tooth movement if you concentrate on moving the teeth the way you want, and not just letting they move they way they want and then fix it later.
With loops, we can at least have knowledge of the force system that is being used and do actual planning of tooth movement. I am happy a lot of orthodontists still haven't given up on their rational use. The more attempts people try to make orthodontics easier and at the same time more compromised and less sophisticated, the less distinction orthodontists will have from general dentists. I think this is a reality that people should start to realize. The number of orthodontic dentists is increasing dramatically- and worse for us- sometimes their treatment quality can be the same better than the one of a certified orthodontist. There is literature about this, check it out.
I must be clear regarding I have no problem with an orthodontist choosing bracket A, B or C if he understands what is going on with the biomechanics. I have no doubt that Dr. Dwight Damon has some excellent cases and is a probably an orthodontist better than average. However, emotional appeal on this is not a good strategy to argue in favor of Damon mechanics. I believe great results can be attained with any bracket system and the differences between them are far less important than biomechanics knowledge. I felt somehow uncomfortable as a scientist when I saw a lecture by one of the well known people involved with Damon mechanics, currently lecturing worldwide, where he showed a clinical case with a high cuspid, used Damon brackets and mentioned that the bracket system * avoids * the force system involved: the Damon system is a miracle to the extent it avoids the third law of Newton? This is offensive. Are we throwing in the trash all the research started by people like Dr. Baldwin and Dr. Burstone?
This is certainly going too far. The case indeed showed no movement of the premolar towards the cuspid space and no apparent open bite tendency in that area, but the lower arch was flattened due to a deep curve of spee and crimpable accessories where put between laterals and bicuspids of the upper arch (simulating friction and creating horizontal forces!), moving the lateral and bicuspid apart, thus preventing tipping towards the canine site. Even if the upper occlusal plane rotated a little bit due to the high cuspid, the lower occlusal plane rotation masked this 3 dimensionally. We would need a ceph to show this, which was not shown. In another case, he got a bad result totally predicted by bracket geometry analysis and blamed himself for not understanding the Damon system completely. This is really sad. Why are we relying more on brackets than on all the hard work done by our scientists? Imagine a world where the medical doctors start to put all the credit of their work on their instruments. This is what is happening in orthodontics right now. Reality doesn't change- the effect of treatment is understood and predicted with a basic force system analysis. I feel there is something really wrong with our profession if some people are comfortable to speak to people from Academia and have the courage to say such absurdities.
Finally, Dr. Kevin Walde asked about why I didn't mention the “wake up the tongue” thing, but I just refuse to talk about this- it's just not worth the writing. (:
I would like to offer some information for the group which I recently joined after a colleague here in Australia sent me Dr Viecelli's comments from the ESCO regarding self-ligating brackets. I have conducted two clinical trials in the lower arch of Damon 2 vs conventional brackets and ligation, and another with SmartClip. Both looked at the irregularity index during the initial 20 weeks of treatment. Basically I found no difference between conventional brackets with modules vs. Damon 2 or SmartClip by 20 weeks. The wire sequences were 0.014 Damon Copper NiTi for 10 weeks followed by 16x25 Damon Copper NiTi for 10 weeks (the recommended sequences at that time although this has since changed slightly to 14x25).
Should you wish to review these, both have been accepted for publication; the Damon 2 study should appear early next year in the Angle Orthodontist and the SmartClip article will likely be published next month in the November issue of the Australian Orthodontic Journal or early next year. Hoping the group finds this of interest.
We have witnessed a lot of dialog over the tears about the value of articulators. Here is a graphic description of the difference between a clinical assessment of occlusion and an articulator-mounted set of casts to truly view centric relation. (Please see the attached image file.)
We have all had transfers who appeared stating "he sais I'm ready to have braces off", but in this case, she is not ready by a long measure. Seeing the difference is always amazing in cases like this. After 2 years of braces, she is biting where her teeth tell her to bite, but this is not where the jaws and muscles fit.
Hullo Members of the group,
How about considering this new version of the defintion of Orthodontics-Version 5.1.
“Orthodontics and Dentofacial Orthopedics refers to the study and management of altered form and function of the components of the masticatory apparatus and related cranio-facial structures. Orthodontic service includes regulating, harmonising and balancing the form, position and relationships of the dentofacial structures to optimise esthetics and function.”
JCO October 2005 issue.
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