Journal of Aligner Orthodontics, 03/2021

Early interception of anterior crossbite has functional, structural and aesthetic benefits that have been widely enumerated in the literature. The goal of early interception usually involves proclination of the maxillary incisors, thus eliminating mandibular anterior shift; maxillary disjunction and protraction to correct transverse and sagittal deficiencies, respectively; and maintenance or improvement of mandibular compensation, thus creating as much horizontal overlap as possible. The present study illustrates a case treated for 24 months with a modified Catalan appliance incorporated into in-office aligners. The treatment results highlighted the efficacy of hybrid mechanics for mandibular compensation and protraction of the maxillary dentition. The 5-year follow-up demonstrated relative stability of the final outcome. Keywords: anterior crossbite, Class III treatment, clear aligners, extraoral traction appliance, growing patient, in-office aligners, interceptive orthodontics, maxillary arch expansion, removable orthodontic appliances

Objective: To evaluate the effects of Class II maxillomandibular elastics on Invisalign aligners (Align Technology, San Jose, CA, USA) and assess whether the type of fitting or immersion in a medium simulating the oral environment influence possible dimensional changes. Materials and methods: Twenty new pairs of Invisalign aligners were tested. Ten pairs had inserts for maxillomandibular elastics made by the manufacturer (precision cuts) and ten had cutouts. Epoxy resin casts were created for aligners, and were later mounted on articulators. Class II maxillomandibular elastics were attached to the fittings with a force of approximately 130 gf. The width and anteroposterior distance were measured at predetermined points prior to the use of elastics and 24 hours, 7 days and 14 days after force application began. Ten sets of models, each with a pair of aligners, were immersed in artificial saliva at 37°C over the experimental period, and the other 10 were kept in a dry environment. Results: Statistically significant changes were observed mainly in the first 24 hours. In the dry environment, the aligners with precision cuts suffered the most considerable deformations. Dimensional changes increased in both groups when they were maintained in a simulated oral environment. The highest values of changes were observed closer to the site where the elastics were fitted. Conclusion: Class II maxillomandibular elastics cause dimensional deformations of Invisalign aligners. The changes recorded in maxillary intercanine distance and the distance between mandibular first molars in the immersed aligners with both types of fitting were considered statistically and clinically significant. Keywords: aesthetic aligners, Invisalign, orthodontics

Objectives: To investigate the effect of layer height on the accuracy of orthodontic models utilising fused filament fabrication, particularly with regard to optimising in-office aligner manufacture. The suitability of fused filament fabrication was assessed by comparing the results to a high precision digital light processing control group. Materials and methods: Based on a digital sectioned maxillary model, 18 physical models were printed using fused filament fabrication technology at different layer heights (50.0 μm, 80.9 μm, 100.0 μm, 150.0 μm, 160.8 μm, 200.0 μm, 250.0 μm, 300.0 μm and 332.6 μm) using two different materials (polylactide PLA NX2 and lignin-based polymer Green-TEC PRO [Extrudr, Lauterach, Austria]). Two DLP models with a layer height of 20.0 μm were produced, representing the control group. Subsequently, all physical models were digitally scanned and compared via 3D superimposition using GOM Inspect software (GOM, Braunschweig, Germany). Results: The Dahlberg analysis and intraobserver intraclass correlation proved the accuracy of the 3D superimposition measurement to be excellent and repeatable. Models printed using fused filament fabrication technology from lignin-based polymer within the range of 100.0 to 332.6 μm decreased in precision as layer height increased. Furthermore, the analysis recorded declining precision of fused filament fabrication models below 100.0 μm. Models printed using lignin-based polymer were superior in precision compared to those made from polylactide. Conclusions: The accuracy and precision of fused filament fabrication models can be regulated by altering layer height; however, other parameters such as optimised printing material and print settings are necessary for consistent high quality. As such, fused filament fabrication printing is an accurate, cost-effective and sustainable technology to create aligner models in orthodontic practice. Keywords: 3D printing, 3D superimposition, digital light processing, fused filament fabrication, orthodontic models

Although the benefits of orthodontic treatment are well documented, the adult population has long been resistant to wearing metal braces. Smile makeovers have commonly consisted of masking misalignment with disproportionate restorative material and heavier tooth preparations. The advent of clear aligners, however, has allowed dental professionals to offer a smile makeover that is biological and minimally invasive. Moreover, by utilising technology and a simple 3D scan, it is possible to simulate the end result that patients can expect with different modalities, thus increasing the chances of case acceptance, patient motivation and informed consent. Keywords: adult orthodontics, aesthetic orthodontics, aesthetics, anterior reverse articulation, case report, crowding, diagnostic procedure, digital dentistry, facial dimension, interdisciplinary treatment, Invisalign, malocclusion, restorative dentistry

Objective: To describe a technique for fully digital in-house aligner fabrication to treat orthodontic problems encountered during the coronavirus pandemic. Case description: A 21-year-old woman presented to the outpatient department of the Division of Orthodontics and Dentofacial Deformities at the Centre for Dental Education and Research, All India Institute of Medical Sciences in New Delhi, India with the chief complaints of impingement due to a broken mandibular fixed retainer and relapse of mandibular incisor alignment. After resolving the impingement problem, a fully digital in-house aligner was used to correct the misalignment of the mandibular anterior teeth over a treatment period of 2 weeks without any support from an external laboratory. Conclusion: The use of CAD/CAM technology together with 3D printing and thermoforming, as described in the present report, may represent a feasible approach for treating mild orthodontic problems without the need to outsource laboratory support; it is therefore a practical treatment option during the coronavirus pandemic. Keywords: 3D printing, 3D scanning, aligners, incisor crowding, orthodontics, relapse