CFAST Help Sheet Replacing Missing or Debonded Brackets Brackets becoming deboned are not uncommon you will almost certainly experience this. The important thing to remember is - DON T PANIC! And tell your patient not to panic either. Missing or loose brackets are an inconvenience and do not constitute an emergency. They occur most commonly in the lower canine or premolar region however if lower molar brackets come off it is acceptable to decide not to replace these, especially if you are treating the upper arch only and the premolars are in good position. If there are repeated instances then check occlusion to ensure there are no premature contacts, go over post-op instructions with the patient and check bite guards. If brackets are cemented properly it is unlikely that debonds are a result of iatrogenic factors and more likely that patients are not adhering to post-op advice in what they are eating. From personal experience, when patients are charged for repeated instances, quite often the bond strength improves significantly! Identifying Bracket Position Bracket positioning is potentially a complex subject and open to much debate. For our purposes the lab will position them to achieve the best cosmetic result. If we do this manually then small mistakes become magnified when we are cementing multiple brackets leading to a less than ideal result, However, when replacing individual brackets, the process can be greatly simplified by following the below guidelines. Firstly we need to identify where the centre of the tooth is. The diagram below shows a simple way to do this:
Identify the point at which two lines that bisect the crown in half both horizontally and vertically meet. The bracket should be placed here with the bracket slot parallel to the incisal edge. As the below diagram illustrates, it is important to focus on just the tooth that requires the bracket and to ignore any references from surrounding teeth, as they often bear no relation to where the bracket to be cemented needs to be placed. A further point to note with the above diagram is that the gingival zenith (the highest point of the gingiva) and the midpoint of the tooth at the gingival margin may not be coincident. This is not uncommon with rotated teeth. Additionally, it is important to also take into consideration and incisal edge wear and recession.
In the above case, as is very common with adult teeth, there has been incisal edge wear which will most likely be corrected after the alignment stage with composite bonding. The goal with Cfast treatment is to achieve gingival symmetry so the bracket needs to be positioned midway between the where the incisal edge was originally and the amelodentinal junction, again with the arch wire slot parallel to the incisal edge before any wear had taken place. With premolar teeth the thought process behind bracket positioning is to prevent any movement of the posterior dentition. Hence brackets need to be placed as passively as possible to minimise any unwanted movements. In order to achieve this the brackets need to be positioned so that the wire passing through the bracket slots is as straight as possible.
When placing brackets on premolars the positioning of teeth are not relevant and one must ignore any crowding or rotations. The brackets are simply placed on the enamel surface where minimal deflection of the wire can be achieved. To clarify this further, in the clinical situation below we can see that in the first photograph with conventional orthodontics the brackets would be positioned as shown to derotate the premolars. The second photograph shows how bracket position for a cosmetically focused approach would differ. It can be seen in the second picture that the bracket has been positioned on the rotated second premolar so that there is as minimal a deflection as possible of the arch wire. A deflection of the arch wire nonetheless does exist however in the above case it is unlikely, given the limited strength of wires that are used and the very broad and tight contact points around the second premolar that it will move. If the contact points were weak or non-existent, then the decision would be made either to leave the bracket off this tooth, or to not treat this case given the potential for unwanted posterior occlusal changes. Bonding Sequence Firstly remove excess composite from tooth surface with a fine polishing diamond, stone or appropriate polishing disc being careful not to damage the underlying enamel. Choose the appropriate bracket from your spares kit. You can sometimes use the existing bracket but there may be too much cement on the fitting surface which may be difficult to remove thus compromising bond strength.
Etch and bond centre of tooth, air thin, cure. Then place some flowable composite on the fitting surface of the selected bracket and, using the above guidelines, seat the bracket in center of tooth. Use orientation guide on bracket to ensure it is correctly placed the dot goes gingivally and distally. Dr Biju Krishnan 2013. All rights reserved No part of this publication may be reproduced, stored in a retrieval system, copied, photocopied, translated or converted to any electronic or machine-readable form without the prior written consent of Dr Biju Krishnan and Cfast UK Ltd. You must not circulate this work in any form and you must impose this same condition on any acquirer. Whilst great care has been taken to ensure the accuracy, Cfast Ltd makes no claims that this document is entirely error-free and reserves the right to alter or delete anything stated or implied in them.