Journal of Aligner Orthodontics, 01/2023

A relatively new complication of aligner therapy is emerging in the literature. Many clinicians have witnessed unplanned tooth movements during aligner treatment and, for the most part, have not found an explanation for this. A common site of this occurrence appears to be the maxillary lateral incisors in cases where these teeth are relatively intruded. This has been described in the literature as the “watermelon seed” effect. Since then, other data have emerged regarding the biomechanics within aligners that may be responsible for it. Accordingly, this review aims to evaluate the available evidence regarding this complication of aligner therapy and consider strategies to minimise or eliminate it. Schlagwörter: biomechanics, complication, materials, plastics, tooth movements, unplanned

Objectives: To assess aligners’ potential to induce labiopalatal bodily movement or achieve torque control of incisors and evaluate the scientific evidence related to the impact of aligner modifications and their recommended geometries. Materials and methods: The electronic databases PubMed, Science Direct, Cochrane Central Register of Controlled Clinical Trials, IEEE Xplore, National Library of Medicine Catalog and Google Scholar were screened from January 1991 to February 2020. Quality assessment was performed using an individual scoring system and a 4-point grading system based on the Grading of Recommendations Assessment, Development and Evaluation tool. The studies were classified according to the aligner system, material and aligner modifications used. Results: Six studies were included for qualitative analysis: two experimental in vitro studies, one prospective study and three retrospective clinical trials. In total, the quality score for all the included studies was 26.2 points, corresponding to a grade C (low quality of evidence). The labiopalatal bodily movement and torque control of incisors using aligners were transmitted inconsistently. When comparing aligner modifications, the accuracy for torque movement was higher using Power Ridges (Align Technology, San Jose, CA, USA) (51.5%) than attachments (49.1%), with torque values of 7.9 and 6.7 Nmm, respectively. As yet, there is no specific recommendation for the modification geometry. Conclusion: The potential of aligners to induce labiopalatal bodily movement or achieve torque control of incisors without modifications is limited. The implementation of aligner modifications and adequate aligner system–dependent staging might increase the efficacy of these forms of movement. More studies, especially randomised controlled trials, are required to clarify the predictability of these tooth movements. Schlagwörter: aligner modifications, bodily tooth movement, forces, incisors, moments, root torque

Aligners are gaining in popularity as adults in particular dislike the appearance of fixed appliances; however, it is difficult to achieve bodily tooth movement, especially of molars, when relying on aligners alone. Additionally, reinforced anchorage is required in some cases, and the potential side effects of maxillomandibular elastics must be considered, such as unwanted shift of the anchor teeth. This could pose a serious problem, especially when unilateral elastics are applied, as these have the potential to cause midline shift, arch rotation, arch discrepancy and transverse occlusal canting. To avoid the risks of tipping and anchorage loss, as well as the strict requirements for elastic wear, mini-implant–borne sliders and expanders can be used. The anterior palate provides excellent conditions for inserting and ensuring stability of skeletal anchorage devices, as the amount and quality of available bone are far superior to those in other regions of the oral cavity. In this paper, the most frequently used combinations of mini-implant–borne appliances and aligners (Benefit for Aligner Technique) are presented to show how more predictable and faster results can be achieved in aligner therapy. Schlagwörter: aligners, asymmetry, Class II treatment, complex adult cases, distalisation, Invisalign, miniscrew, rapid maxillary expansion, skeletal anchorage

Orthodontic practitioners are eager to incorporate 3D technologies to better manage treatment planning. CBCT has created a turning point in the discipline because it allows practitioners to achieve a better understanding of patients’ anatomy and thus establish a more customised and precise approach, especially in cases of transverse expansion, anteroposterior torque and translation movements. Clear aligner treatment and the use of CBCT offer countless advantages, such as preservation of patients’ periodontal health, and this seems to herald a more promising future. The present article develops arguments in favour of the implementation of a biodigital protocol with the purpose of fully preserving the supporting tissues of each tooth and integrating 3D digital technologies for diagnosis and planning in all clear aligner treatments. Thus, the authors present a clinical case treated using the abovementioned protocol. Schlagwörter: biodigital protocol, CBCT, clear aligners, orthodontic treatment, periodontal health, periodontics