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Temporary anchorage devices: a paradigm shift
Sara Hosni, Associate Specialist Orthodontist at Northenden House Orthodontics and Consultant at Salford Royal NHS Foundation Trust and Glan Clwyd Hospital, presents a case using Infinitas Mini Implants. Sara discusses the advantages and risks associated with using temporary anchorage devices, as well as the indications and contradictions. Sara would like to thank Ben Lewis (Consultant orthodontist at Glan Clwyd) for his help in planning and overseeing this case.
Although temporary anchorage devices (TADs) have been available for clinical use for at least a couple of decades now, it’s fair to say that they are not yet being utilised to their full potential. We are well versed in the theoretical workings of TADs or, more specifically, miniscrews, but how often are we using them as realistic alternatives in otherwise complex cases?
Every now and then, a case comes along that challenges our well-rehearsed rhythm of the usual treatment mechanics and acts as a paradigm shift in how we practise clinical orthodontics. So, what exactly are TADs, and why are more and more people raving about them?
Temporary anchorage devices TADs are used for skeletal anchorage and are inserted into the bone to enhance orthodontic anchorage (Chen et al, 2006), either by supporting the anchor teeth (indirect anchorage) or by acting as anchor units in their own right (direct anchorage), eliminating the need for supporting teeth (Mizrahi and Mizrahi, 2007).
They are removed once their function has been completed. They have many advantages, which have been summarised in Table 1. The risks associated with TADs are well documented (Table 2); however, with appropriate training and diligence in case planning, most of these can be avoided. There are several indications and contraindications for the use of TADs, which are summarised in Table 3, as good case selection is key to achieving the intended outcome in a predictable manner. Impressive success rates for TADs, ranging from 76% to 96%, have been reported in the literature (Bearn and Alharbi, 2015; Son et al, 2014). It has been shown that success rates are directly correlated with various factors, including age, site of placement and miniscrew diameter (Lee et al, 2010).
Photo courtesy of Sara Hosni.
Figures 1 to 11 demonstrate a case where Infinitas TADs were used to provide both direct and indirect anchorage for the treatment of an anterior open bite and class 2 malocclusion. The alternative treatment option was a combination of orthodontics and orthognathic surgery, which the patient was not keen on. The plan was for the TADs to be placed palatally and ‘locked’ to the transpalatal arch in order to provide indirect anchorage for correction of the buccal segment relationship after extraction of the upper first premolars. They would then be used for direct anchorage for the intrusion of the upper buccal segments, thereby correcting the anterior open bite. The patient was compliant, the TADs survived the treatment duration, and in the end, we had one delighted patient who didn’t need orthognathic surgery.
TABLE 1: Advantages of temporary anchorage devices
TABLE 3: Indications and contradictions for the use of temporary anchorage devices
So, should we be offering this to all anterior open bite patients? Case selection is fundamental to achieving a successful outcome, so undoubtedly, there will always be cases that will still require a surgical approach. However, for a number of patients, the use of TADs can mean avoiding orthognathic surgery and the risks that come with it. Being critical of the finish, despite undertaking lower arch extractions, the patient still had some gingival recession of the lower left central incisor. A gingival graft was discussed to address the recession of the lower left central incisor.
Figs 2-6: Pre-treatment:
Case presented an anterior open bite and class 2 malocclusion. Photos courtesy of Sara Hosni
Pre-treatment anterior view.Pre-treatment maxillary occlusal view.Pre-treatment mandibular occlusal view.Pre-treatment left buccal view.Pre-treatment right buccal view.
Figs 7-11: Post-treatment:
A successful outcome. Patient had some gingival recession of the lower left central incisor. Photos courtesy of Sara Hosni.
Post-treatment anterior view.Post-treatment maxillary occlusal view.Post-treatment mandibular occlusal viewPost-treatment left buccal view.Post-treatment left buccal view.
In summary, TADs provide an alternative to conventional mechanics for anchorage control, and there is increasing interest in their use. Outcomes that would otherwise require orthognathic surgery or would not be possible may be achieved using TADs in combination with orthodontics.
Sara is an associate specialist orthodontist at Northenden House Orthodontics and a consultant at Salford Royal NHS Foundation Trust and Glan Clwyd Hospital. She qualified at the University of Newcastle and following a variety of hospital posts, Sara undertook her orthodontic specialist training at the University of Liverpool. In 2015, Sara gained her doctorate of dental sciences degree at Liverpool University.
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Sara Hosni, Associate Specialist Orthodontist at Northenden House Orthodontics and Consultant at Salford Royal NHS Foundation Trust and Glan Clwyd Hospital, presents a case using Infinitas Mini Implants. Sara discusses the advantages and risks associated with using temporary anchorage devices, as well as the indications and contradictions.