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ePaper created 2018-03-13, 09:28:55 | version 1.38.0
| industry report Hybrid Aligner Therapy Dr Wajeeh Khan, Germany Introduction Studies on treatment efficacy with aligners The orthocaps Hybrid Aligner Therapy (HAT) is a treat- ment option that broadens the indications of aligner treat- ments. This technique makes aesthetic treatment pos- sible for almost all malocclusions, without the need for complex labial or lingual systems. It also helps to reduce the number of treatment steps and treatment duration as a whole. Complicated tooth movements can therefore be carried out more effectively and quickly. In 1950, Elsasser published an article on the use of the Kesling positioner: “H. D. Kesling developed the concept of an appliance capable of moving teeth without brack- ets, bands or wires... This was the beginning of a new treatment concept using tooth positioners.”1 More and more patients today, want invisible orthodon- tic treatments instead of conventional fixed braces, yet still expect equivalent results. This increased demand for modern aligners or lingual appliances that we see today, was predicted by Kesling over 70 years ago and was also one of the motivations in developing his appliance. Limitations of lingual appliances The advent of modern lingual appliances, first intro- duced in 1967 by Kinja Fujita and developed fur- ther in the 1970s in the US, is the result of an ever- increasing demand for aesthetic alternatives in clinical orthodontics. The disadvantages of lingual appliances compared with conventional labial multi-band/multi- bracket appliances are high labour costs, reduced inter-bracket distance, difficult access during wire changes, speech problems, tongue irritation, compli- cated handling of the appliance and irregularities of lingual tooth surfaces. Limitations of aligner-based systems The main limitation of aligner-based systems, is the fact that they involve a removable appliance which cannot work unless worn by the patient as prescribed. A pre- requisite therefore, is maximum patient cooperation. Another limitation is the difficulty of achieving targeted and constant orthodontic forces throughout the treat- ment. Attachments are therefore essential to transmit the right forces to correct malpositions. Clinical studies to date, have mainly focused on one aligner system, which has dominated the market since 1999 namely, Invisalign. There are, however, no indepen- dent studies on the efficacy of other comparable aligner systems, such as orthocaps, ClearCorrect and eCligner. Differences in the treatment results between the systems mentioned should be expected, since there are differ- ences in the respective concepts, workflows and materials used. Apart from that, the known general limitations of all removable thermoplastic appliances apply. A few studies that point to these limitations are discussed in this article. Djeu et al. demonstrated that Invisalign did not per- form as well as fixed appliances in a comparison group with malocclusions.2 The Invisalign group lost 13 objec- tive grading system points compared with the fixed appli- ance group.2 The success rate with Invisalign was 27% lower than the success rate with fixed appliances.2 The aligner system was shown to have advantages in the clo- sure of small gaps and anterior tooth rotations.2 According to Phan and Ling, the Invisalign appliance can be used with limitations in patients with simple mal- occlusions.3 Furthermore, it was demonstrated that results are more difficult to achieve in comparison with fixed appliances.3 It was also mentioned that a combi- nation of this aligner with fixed appliances could shorten treatment duration and improve results.3 Kravitz et al. showed that the mean accuracy of tooth movements was 47.1% with Invisalign.4 The least accu- rate movement was extrusion of the maxillary central incisors (18.3%) and the mandibular central incisors (24.5%).4 Accuracy decreased significantly with rotations of more than 15°.4 According to Simon et al., the mean success of tooth movement with Invisalign was 59%.5 The mean accuracy of incisor torque was 42%.5 Premolar de-rotation showed the lowest accuracy, of approximately 40%.5 Distalisation of the maxillary molars was achieved in 87% of cases.5 The extent of the planned movements and the staging had a significant influence on the treatment result.5 In a review of 271 publications between April 2005 and December 2012, ten studies were selected for inclusion 42 ortho 1 2018