Australasian Dentist Magazine Nov Dec 2021

Category 116 AustrAlAsiAn Dentist ColUMniStS Orthodontic Clinicians’ Corner... with Dr Geoff Hall Welcome to this month’s edition of Orthodontic Clinician’s Corner, where Dr Geoff Hall will answer orthodontic questions asked by general dentists. If you have an orthodontic question you would like answered, forward your question to geoff@orthoed.com.au Dr Geoff Hall q1 Dear geoff, i have been doing orthodontics for some time, and i hear that you can use either a .018 slot bracket or a .022 slot bracket. i really don’t understand the difference and which one should i be using now? Dr BW, Wagga Response 1 Dear BW, this is an exceptionally interesting question and please bear with me whilst i explain some of the history of orthodontics, and hopefully this will help answer your question. When edward Angle developed the edgewise bracket in the early 1900s, all brackets utilised a .022 slot size with gold arch wires which were exceptionally malleable and very soft. Over time, these gold wires proved to be far too expensive, and hence back in the 1950s stainless steel wires were preferred over gold. the problem with stainless steel wires is that they are much stiffer than the gold counterparts – and in orthodontics it is very important to fill the bracket slot totally to achieve the desired prescription that is built into the bracket. using full sized stainless steel wires of .021 x .025 dimension are too stiff to be placed easily and efficiently into an .022 bracket slot. Hence in the 1950s and 1960s through Dr ricketts, it was proposed using a .018 slot bracket the largest sized wire that would need to be used to obtain the full advantage of the bracket prescription was a .017 x .025 stainless steel wire. in the 1990s, nitinol wire was being developed – and this now allows us to use far more flexible wires in the early orthodontic alignment stages, and especially when more significant levelling is required. Hence, if we utilise these flexible shape activated wires in the correct manner, it’s now far easier to place larger stainless steel wires when required. For example, to align teeth with a .021 x .025 niti prior to placing a .021 x .025 stainless steel archwire would then give the best of both worlds. there is no doubt that being able to utilise heavier and stiffer wires for certain situations is more beneficial and gives far more flexibility to final orthodontic outcomes. By that i mean, to be able to bring in impacted teeth with utilising large wires as a stabilising arch is of advantage, or even correcting deep curves of spee is far more efficient with thicker and stronger arch wires to overcome occlusal forces. the bottom line to this discussion would be that today with our super-elastic niti wires – all the advantages of the .022 slot system remain with very few of the disadvantages that were present back in the 1950s. there are very few schools or institutions that would teach a .018 bracket system – and logically speaking, the .022 bracket slot provides far more flexibility to provide efficient orthodontic care to each and every patient. q2 Dear geoff, i have just started doing orthodontics and have been doing another course for approximately 18 months – and they keep suggesting that i need to utilise their ‘special bracket system’ which has a variety of brackets based on the different malocclusions. is this really the appropriate way to practice orthodontics or are there other approaches that i can take? Dr Br, townsville, Queensland Response 2 Dear Br, From my understanding this technique recommends using specific brackets with built in over-corrections for every type of malocclusion and every type of treatment approach, eG whether extracting upper first premolars in a Class ii situation, or possibly compensating in a Class iii dental situation with upper incisor proclination, just to name a few situations. Once again more history of orthodontics: larry Andrews first developed the straight Wire Bracket system in 1972 and had 14 different bracket prescriptions based on the different types of malocclusions. Over time this has now been reduced for most orthodontists to basically use one bracket prescription – more for a simple inventory and guru following, rather than the best possible treatment outcome. in my opinion the correct approach will lie somewhere in between. By that i mean, having different torque brackets available can be very advantageous, but having different tips and rotations for a bracket system – is absolutely irrelevant, as this could be performed with any particular bracket system. By that i mean, if you need to get extra rotation of a tooth, then all one needs to do is position the tooth slightly mesial or distal from the mid-position of the tooth and this will provide the extra rotation, rather than cutting extra rotation into the bracket system. the same applies to the tip of the bracket – by changing the tip of the bracket from the conventional position of the long axis of the clinical crown will then also alter the tip of the tooth, once a straight wire is fully activated. in other words, once you learn how to make the various changes in bracket position, you can use any type of bracket system and not be reliant on one particular bracket system, to alter the tooth’s final tip and/ or rotation. Continued page 119