Abstract: This invention pertains to the area of orthodontic apparatuses, particularly those that have been precisely adapted to the specific morphology of each patient. The invention proposes a preform dissimilar to a plate; the form of which allows it to expand within a mold that reproduces a patient's morphology; it may be mass produced and easily adapted by the practitioner or prosthesis maker to each patient's morphology as well as orthodontic or dento-facial orthopedic apparatuses obtained from this preform and their manufacture process. Such apparatuses are, for example, Bonnet's N.L.E. (Nighttime Lingual Envelopes—Enveloppe Linguale Nocturne) or any apparatus presenting a general hollow body form, possibly with one or more openings, varying thickness, and which, because of this specific geometry, cannot be produced from a model in the form of a flat plate.