“Nature does not hurry, yet everything is accomplished.” ~ Lao Tzu
In this blog post, I’d like to share some thoughts regarding an important – and still debatable – aspect of self-ligation treatment, relating to claims of “faster” treatment and shorter overall treatment times, and clarify why I personally do NOT use Self-ligation primarily for “faster” treatment, but for other clinically-relevant reasons.
The support for the use of self-ligation in orthodontics – particularly passive self-ligation – stands on the fact that such systems generally produce much less friction during tooth movement, reducing the need for higher forces. This, in turn, should result in overall faster treatment times – at least, in theory.
This perceived efficiency of self-ligating systems has been investigated in early studies on earlier SL bracket designs by many investigators such as Eberting et al, and N. Harradine and had found clinically relevant reduction in overall treatment times compared to conventional brackets. However, This was done using retrospective study designs that could have introduced Outcome Bias, and are usually less effective in accounting for variables such as the use of various treatment auxiliaries including intermaxillary elastics, different archwires and mechanics, and other treatment variability such as extractions or extraoral appliances. All of these issues – according to Pandis, Miles and Eliades discussing SL treatment efficiency in Chapter (6) in the textbook: Self-Ligation in Orthodontics (2009) – can significantly distort the results in such study designs. In addition, more recent studies have shown the treatment duration difference to be minimal and not clinically significant.
One of the main issues when using SL systems, and especially with Passive SL – is that the initial alignment and derotation tends to take longer than with conventional brackets systems. This may be due to the fact that in self ligation the initial archwire is not fully compressed into the bracket slot during initial alignment due to the bracket design and lack of pressure from elastic modules as happens with conventional systems. The time periods required for full derotation and alignment of the initial crowding may actually be longer and are not generally completed until the introduction of rectangular nickel titanium archwires such as (14 x 25) or even (18 x 25) NiTi archwires. I mentioned this in a previous blog post discussing passive self-ligation. So we can generally find that the initial alignment phase cannot be assumed to be any “shorter” with self-ligation; it may actually take longer to achieve complete alignment than with conventionally-ligated brackets.
Studies published by Dr. Hisham Badawi comparing Active, passive self ligation and conventional systems in terms of initial alignment deficiency have shown this to be the case.
Personally, my main reason for adopting self-ligation is primarily based on how the “Bracket-Mechanics” combination works; which basically means how tooth movements occur – individually and en masse – when using light forces in a reduced-friction environment, with early light guiding elastics and disarticulation. It is not about a particular bracket design per se, but about the entire system as a whole.
To explain further, in my initial dabbling with self-ligating bracket systems, I used them in combination with conventional mechanics that I had normally been trained to use and been using for a long time; i.e the bulk of my mechanics was related to conventional treatment mechanics and designed to either overcome friction or preserve anchorage due to the unwanted reactive effects of friction. This way of working did not seem to confer any added efficiency with SL brackets and I was simply becoming frustrated for not seeing any major difference with my treatment efficiency and results. However, once I decided to actually shift my paradigms and follow the recommended protocols – admittedly with some minor modifications of my own – I started observing more favorable effects and getting different results to my other comparable conventional cases. Once that initial learning curve was bypassed, I felt more comfortable using self ligation in different borderline clinical cases and getting better results than what I could achieve with conventional brackets and mechanics in the vast majority of these cases.
This was particularly noticeable in Class II Div 2 cases with moderate skeletal Class II discrepancies in adults and adolescents, where the combination of the three pillars of passive self-ligation usually leads to a smooth transition from a Class II Div 2 to a Class I without passing through the Class II Div I transitory stage that is common with conventional mechanics, and usually results in heavy anchorage support requirements and added complex and/or relatively invasive auxiliaries throughout treatment.
In my own experience, overall treatment times were not shortened in any meaningful way in many cases. In fact, I noticed they were – on many occasions – slightly longer than my usual average treatment times for comparable cases with conventional mechanics (between 3 to 4 months longer in some cases). However, this was outweighed – in my humble opinion – by the elegant simplicity of SL mechanics and smoother progression of some treatment stages ( e.g. Leveling & Overbite control) while minimizing the need for extractions in some cases as well as the need for other auxiliaries in many others. This was and still is my main reason for using SL systems and, perhaps, the biggest motivator for the patients themselves.
Overall Speed has been largely out of the equation as far as my own practice with self-ligation is concerned and I’m careful not to present it as a major advantage to most prospective cases at this stage.
Do you have experience with self-ligation mechanics?.. What are your thoughts and personal experiences regarding the issue discussed in this post?.. You’re welcome to share your comments in the comments section below.