Design and manufacturing of patient-specific orthodontic appliances by computer-aided engineering techniques

Authors and full affiliations: Sandro Barone, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale

Keywords: Orthodontics, eruption guidance appliance, temporomandibular joint

Abstract (original) Orthodontic treatments are usually performed using fixed brackets or removable oral appliances, which are traditionally made from alginate impressions and wax registrations. Among removable devices, eruption guidance appliances are used for early orthodontic treatments in order to intercept and prevent malocclusion problems. Commercially available eruption guidance appliances, however, are symmetric devices produced using a few standard sizes. For this reason, they are not able to meet all the specific patient’s needs since the actual dental anatomies present various geometries and asymmetric conditions. In this article, a computer-aided design-based methodology for the design and manufacturing of a patient-specific eruption guidance appliances is presented. The proposed approach is based on the digitalization of several steps of the overall process: from the digital reconstruction of patients’ anatomies to the manufacturing of customized appliances.

A finite element model has been developed to evaluate the temporomandibular joint disks stress level caused by using symmetric eruption guidance appliances with different teeth misalignment conditions. The developed model can then be used to guide the design of a patient-specific appliance with the aim at reducing the patient discomfort. At this purpose, two different customization levels are proposed in order to face both arches and single tooth misalignment issues. A low-cost manufacturing process, based on an additive manufacturing technique, is finally presented and discussed.

Purpose: digitalization of several steps of the overall process: from the digital reconstruction of patients’ anatomies to the manufacturing of customized appliances.

Design/methodology/approach: A finite element model has been developed to evaluate the temporomandibular joint disks stress level caused by using symmetric eruption guidance appliances with different teeth misalignment conditions

Findings: The obtained results demonstrate that standard symmetric implants, which are not customized for the patient-specific anatomy, present critical issues when applied to generic asymmetric anatomie, instead the creation of tailor-made systems would create fewer problems and greater adaptability.

Limitations: The relative placement between maxilla and mandible has a significant influence on the overall patient health

Benefits: low-cost manufacturing process

Practical implications: Improved patient life and lower production costs

Originality/value: Better ergonomics of dental implants thanks to the creation of specific models for each patient created with 3D-CAD and AM.

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Link: https://journals.sagepub.com/doi/pdf/10.1177/0954411917742945