Abstract
Maxillary expansion is a common orthodontic treatment used for the correction of posterior crossbite resulting from reduced maxillary width. Transverse maxillomandibular discrepancies are a major cause of several malocclusions and may be corrected in different manners; in particular, the rapid maxillary expansion (RME) performed in the early mixed dentition has now become a routine procedure in orthodontic practice. The aim of this study is to propose a procedure that reduces the patient cooperation as well as the lab work required in preparing a customized Haas-inspired rapid maxillary expander (HIRME) that can be anchored to deciduous teeth and can be utilized in mixed dentition with tubes on the molars and hooks and brackets on the canines. This article thus presents an expander that is completely digitally developed, from the first moment of taking the impression with an optical scanner to the final solidification phase by the use of a 3D printer. This digital flow takes place in a CAD environment and it starts with the creation of the appliance on the optical impression; this design is then exported as an stl extension and is sent to the print service to obtain a solid model of the device through a laser sintering process. This “rough” device goes through a post-processing procedure; finally, a commercial expansion screw is laser-welded. This expander has all the advantages of a cast-metal Haas-type RME that rests on deciduous teeth; moreover, it has the characteristic of being developed with a completely digitized and individualized process, for the mouth of the young patient, as well as being made completely of cobalt-chrome, thus ensuring greater adaptability and stability in the patient’s mouth.
Highlights
Maxillary expansion is a common orthodontic treatment used for the correction of the posterior crossbite that results from reduced maxillary width; several treatment modalities are employed with similar objectives [1]
This type of malocclusion may be corrected in different manners, including slow expansion [3,4,5], rapid expansion [6,7,8], surgically assisted expansion [9,10] and miniscrew-assisted rapid palatal expansion (MARPE) [11,12,13]
This article shows that a Haas-inspired rapid maxillary expander (HIRME), as well as a Haas-type rapid maxillary expansion (RME) appliance anchored to the primary teeth, is an effective device for solving posterior crossbite and the maxillary transverse deficit and for providing space for the maxillary permanent lateral incisors in the mixed dentition; at this dental age, it is possible to band the second primary molars without involving the permanent dentition, and this avoids the risk of damage to these teeth
Summary
Maxillary expansion is a common orthodontic treatment used for the correction of the posterior crossbite that results from reduced maxillary width; several treatment modalities are employed with similar objectives [1].Transverse maxillomandibular discrepancies are a major cause of several malocclusions [2].This type of malocclusion may be corrected in different manners, including slow expansion [3,4,5], rapid expansion [6,7,8], surgically assisted expansion [9,10] and miniscrew-assisted rapid palatal expansion (MARPE) [11,12,13].Materials 2020, 13, 2898; doi:10.3390/ma13132898 www.mdpi.com/journal/materialsAs reported in the 2015 article by Mutinelli et al [14], the rapid expansion of the maxilla is widely used to treat transverse deficiency [15], which means the opening of the mid-palatal suture [16] that has not yet completely ossified in growing individuals [17] and is characterized by a widening of the midpalatal suture, produced by forcing a lateral shift of the two horizontal processes of the maxilla.Two different devices are used to achieve this type of expansion: the tooth-borne (Hyrax type) and the tooth-tissue-borne appliance (Haas type).The main difference between the two devices is that the latter has an acrylic pad as reinforcement to the anchorage, and it covers the palatal mucosa bilaterally, where the activation screw is inserted in the center. Transverse maxillomandibular discrepancies are a major cause of several malocclusions [2]. This type of malocclusion may be corrected in different manners, including slow expansion [3,4,5], rapid expansion [6,7,8], surgically assisted expansion [9,10] and miniscrew-assisted rapid palatal expansion (MARPE) [11,12,13]. Two different devices are used to achieve this type of expansion: the tooth-borne (Hyrax type) and the tooth-tissue-borne appliance (Haas type). The Hass expander is a tissue-borne fixed appliance anchored to the first bicuspids and molars by means of four abutment bands and to the palatal vault by acrylic masses. A variant of the traditional design is one in which the device is completely anchored to the deciduous teeth; in particular, to the deciduous second molars and to the deciduous canines
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