Journal of Aligner Orthodontics, 02/2022

Artificial intelligence is now involved in many aspects of our daily life. In digital orthodontic practice in particular, practitioners are constantly and mostly unknowingly confronted with different levels of implementations of artificial intelligence. The present article, the second in a three-part series, will seek to shed light on some of these algorithms using common examples from a standard orthodontic digital workflow. Keywords: aligner orthodontics, artificial intelligence, digital orthodontics, machine learning

Objective: The present study aimed to assess the cephalometric changes in patients with a clinically proven anterior open bite after clear aligner treatment (Invisalign, Align Technology, San Jose, CA, USA). The amount of planned movement was also compared with the amount of movement that actually occurred, as measured on the radiographs. Materials and methods: This retrospective study included 30 patients (11 women, 19 men; mean age 20 years) with anterior open bite (bite depth < 0 mm) treated using Invisalign clear aligners in both arches. The patients received non-extraction treatment with a mean duration of 20 months. Twenty-one parameters (eight linear, twelve angular and one ratio) were evaluated on cephalometric radiographs taken prior to (T1) and after treatment (T2). The amount of planned movement and the actual movement that resulted from the treatment were also compared. Results: Statistically significant molar intrusion occurred in the maxilla (0.66 to 0.83 mm) during treatment. Bite deepening was also statistically significant (mean 2.7 mm), but this was not the case for mandibular autorotation. Significant extrusions were recorded in the incisors (0.95 to 1.06 mm in the maxilla and 0.38 mm in the mandible). Significant changes in the interincisal angle (mean increase 10.84 degrees) were also recorded due to the significant oral inclination of both the maxillary (mean 4.73 degrees) and mandibular (mean 
5.53 degrees) incisors. No significant changes to the occlusal plane were noted during treatment. For most movements, the difference between the planned and measured amount was not significant. Conclusion: Clear aligners can be used to treat less severe cases of open bite. The clinical effect of bite deepening is achieved through a combination of intrusion of the lateral segments and extrusion and oral inclination of the frontal segments. In particular, the resulting oral inclination was greater than planned; in general, however, significant changes to sagittal relationships due to mandibular autorotation probably cannot be expected, and significant improvement of facial aesthetics is therefore also unlikely. Keywords: autorotation, clear aligners, extrusion, intrusion, open bite

Within the framework of treatment planning for missing teeth, the fundamental question is how to offer long-term solutions. One option is to close the space with a prosthetic restoration such as a dental implant or fixed or removable partial denture. Another option is orthodontic space closure, which makes it possible to avoid further tooth preparation, thus reducing the tooth substance required, or even generate new bone through the tooth movement into the gap due to the interdental fibres. Compared to space opening, however, space closure has far greater requirements in terms of anchorage. Preservation of the sagittal vertical overlap and adjustment of the dental midlines often necessitates use of skeletal anchorage, especially in cases of dental asymmetry. The present case report demonstrates a complex treatment using aligner orthodontics in combination with the Mesialslider (TADMAN, Gunningen, Germany) after loss of a maxillary molar, including a mandibular incisor extraction approach, closure of anterior open bite and solving of unilateral reverse articulation. Keywords: aligner orthodontics, anterior open bite, incisor extraction, Invisalign, Mesialslider, mini-implants, molar extraction, reverse articulation, skeletal anchorage, space closure

Thermoplastic sheets have become extremely popular for fabricating clear vacuum-formed orthodontic aligners and retainers. These appliances are preferred by patients due to their excellent aesthetics, ease of use and minimal discomfort. Although a single thermoplastic sheet is normally used to fabricate a single clear aligner or retainer, this clinical tip illustrates a judicious way to fabricate two retainers using a single, 1-mm-thick Duran thermoplastic sheet (Scheu Dental, Iserlohn, Germany). The two dental casts, either maxillary or mandibular, are orientated in a BIOSTAR model cup (Scheu Dental) in such a manner as to provide adequate distance between them, which results in stability of the casts along with uniform distribution of pressure during the pressure moulding process, both of which are required for optimal adaptation and accuracy. This modification to the manufacture of aligners and retainers is useful for fabricating any kind of clear thermoplastic appliance. This two-in-one approach to the fabrication of clear appliances optimises time, energy and effort, facilitates prudent use of resources and minimises waste, and thus can help to protect the environment by reducing use of plastic and laboratory costs. Keywords: aligner orthodontics, aligners, clear retainers, thermoplastic sheet