Orthodontic screw for a fast expansion on the anterior sector of the maxillary arch

Abstract: The apparatus for obtaining an at least prevailing or even exclusive expansion in the anterior sector of the maxillary arch comprises two substantially symmetrical components (1, 3) with arms (11, 12; 31, 32) fan-like stretching apart and to be combined with orthodontic bands (40); said two components (1, 3) are articulated to one another by means of a hinge (5); an expansion screw (7) acting between said two components (1, 3) is able to stretch them angularly apart by progressive actions to be exerted on the same screw.

Description: The present invention refers to an apparatus, that is, an orthodontic screw, for obtaining an expansion of the upper maxillary arch, said screw being able to cause a prevailing or exclusive expansion, especially of fast type, of the anterior arch alone. Palates have often been found to exhibit very small transverse diameters in the anterior sector arch and almost normal diameters in the molar arch. In these cases, it is not possible to apply a traditional fast expansion screw which stretches apart with a parallel movement, as it would imply an increase of both the anterior and posterior, that is molar, diameters. The invention refers to an apparatus allowing only the expansion in the anterior sector, which has proven to be very useful in such cases as LPS (PALATE-LABIAL SCHISTASIS), alteration of transverse diameters during children's growth and, in adults, after corticotomy. The publication ZAHNARZTLICHE RUNDSCHAU No. 119 of 8 March 1964, HEIDELBERG DE. page 78 XP002031839 "Wipla Schwenk-Dehnschraube" discloses a fan-like opening screw, with two arms from which appendixes emerge for connection with the resin of two corresponding plates intended to exert a pressure on the inner side of teeth belonging to the arch under treatment. This known apparatus is intended to displace the teeth within their relevant sockets for correction purposes, however, the structure of the same apparatus does not allows a spreading action for the detachment of the palate suture. Such an effect is actually obtainable only with apparatus fixedly applied to the teeth and able to exert a fast spreading action through mobile protheses of the type described above. Accordingly, said known screw proves to be unsuited for the correction of palate malformations characterized by reduced transverse diameters in the front sector and normal or approximately normal ones in the molar sector. Also known from patent FR 981973 is a mouth corrector comprising two orthodontic plates connected betwwen them by elastic means to exert a push onto the internal side of the teeth of the arch under corrective treatment. But also this known apparatus is intended to displace teeth in their respective sockets without interesting the relevant bony structures. Document WO 94/26196 discloses a palate expander with linear action to achieve a uniform palatal expansion only in a direction orthogonal to the sagittal plane. The present orthodontic apparatus comprises two substantially symmetrical components, with arms, mostly fan-like stretching apart, to be combined with orthodontic bands or equivalent means, and hinged to one another. An expansion screw (7) acting between said two components (1, 3) is able to stretch said components angularly apart by progressive actions exerted on the screw so as to act at least in a prevailing way on the anterior maxillary arch. The screw is advantageously engaged with bushes articulated to said two components in such a way as to ensure the alignment thereof with the same screw. Once the apparatus is in use, each of the two components articulated to one another has its arms oriented forwards with respect to the hinge, said arms being able to be modelled for their anchoring by orthodontic bands or other equivalent means. Either or both components may have at least two arms. Additional advantages, features and details of the invention result from the following description as well as the attached drawings of a preferred embodiment of the orthodontic expansion screw. In the drawings: Fig. 1 shows a front view of the orthodontic screw combined with the bands prior to the use; and Figs. 2 and 3 show the orthodontic screw in use in the maxillary arch before and respectively after the stretching apart of the above-mentioned components. According to the present invention, reference being made to the figures of the accompanying drawings, the apparatus consists of two components 1 and 3, each of which is provided with two arms 11 and 12, respectively 31 and 32, having a substantial radial development with respect to the whole of the two components 1 and 3. Said two components are articulated to a hinge 5 which is posteriorly located in the maxillary arch. The arms 11, 31, and 12, 32 are substantially symmetrical with respect to the sagittal plane X-X; the arms 11 and 31 are inclined indicatively of about 75° to the axis X-X, while the arms 12 and 32 are inclined of a smaller angle with respect to said axis. Provided at a limited distance from the articulation 5 and anteriorly located, is an expansion screw 7 provided with radial seats, which is symmetrically operable by a tool for a direct intervention on the apparatus in use. The two threaded lengths of the screw 7 engage within bushes 9 which are articulated to the components 1 and 3 at points 10, so as to ensure the alignment of the bushes 9 and thus of their threaded holes with the axis of the screw 7, in any mutual angular position of the two components 1 and 3 about the hinge 5, as obtained by acting on the screws 7, when changing the angle thereof with respect to the sagittal plane X-X. The foreward orientation of the posterior anchorages of arms 11 and 31 obtained by acting on the screw 7, brings about a slightly increased spacing thereof, accompanied by no, or at least a very limited, reduction of the posterior diameters, or even a slight expansion of the inter-first molar diameter and, to a lesser extent, of the inter-second molar. The arms 12 and 32 are mostly intended for application on premolars or canines, while the arms 11 and 31 are for application on far posterior teeth. The arms 11, 31 and 12, 32 can be modelled extemporarily and are apt to be welded to orthodontic bands such as those roughly indicated at 40, or to other equivalent means for the anchorage of the anterior maxillary arch, to achieve an at least prevailing or even exclusive expansion of the anterior sector, for the above-mentioned purposes. The modelling of the apparatus will be performed according to the dimensional and morphological characteristics of the maxillary arch of the patient. Once the apparatus, that is the orthodontic screw, is in use, the components 1 and 3 being substantially brought close to one another when the apparatus is positioned the first time in the oral cavity of the patient, by moving the components 1 and 3 angularly towards the sagittal plane X-X, a frequent intervention is carried out on the screw 7 and, in particular, on its core 71, to stretch apart the two components 1 and 3 about the articulation 5, thereby causing the stresses necessary to induce the corrections required by the apparatus in question. As for the traditional fast expansion screw, it is possible to test the bands on the first or second molars, depending on the case and possibility, and on the first premolars. After taking a position impression, the arms are welded to the bands and rounded or anyway adapted according to the production process. With children, after cementation, the expansion is operated through a half or a quarter of revolution per day and, within eight-fifteen days. The desired expansion is obtained together with a prevailing palatine suture detachment in the anterior sector. In adult patients, the expansion is to be associated to the corticotomy, so as to achieve the desired expansion also in these cases. The apparatus may be applied even to a patient having palate-labial schistasis, in which case a widening of the anterior diameters and a subsequent alignment is obtained. It is understood that the drawing shows only a practical exemplification of the invention, as this may vary in the forms and dispositions without nevertheless departing from its scope. The reference numbers in the attached claims are intended to facilitate the reading thereof in connection with the description and the drawing, and does not limit the scope of the claims.

Claims: Orthodontic apparatus, especially of fast expansion type, for the upper maxillary arch, able to achieve at least a prevailing or even exclusive expansion in the anterior sector, comprising two substantially symmetrical components (1, 3) with arms (11, 12, 31, 32) fan-like stretching apart with orthodontic bands (40) or equivalent means fixed to said arms, these components being articulated to one another about a hinge (5), and an expansion screw (7) acting between said two components (1, 3) being able to stretch them angularly apart by progressive actions on the screw, said arms being anterior arms (12, 32) and posterior arms (11, 31) characterized in that the posterior arms (11, 31) are inclined about 75° to the axis (X-X) in a general anterior direction, while the anterior arms (12, 32) are inclined a smaller angle than the posterior arms with respect to the axis (X-X) in a general anterior direction where the axis (X-X) is the anterior-posterior axis in the sagittal plane. Orthodontic apparatus according to the preceding claim, characterized in that the screw (7) is engaged with bushes (9) articulated (at 10) to said components (1; 3) to ensure the alignment thereof with the same screw. Orthodontic apparatus according to the preceding claims, characterized in that each of the two components (1; 3) has its arms oriented forwards with respect to the hinge, when the apparatus is in its applied condition. Orthodontic apparatus according to claim 3, characterized in that either or both components is provided with two arms.

Inventors: MODICA REMO, SCHELLINO ELEONORA, MODICA, REMO, SCHELLINO, ELEONORA
Applicants: LEONE SPA, LEONE S.P.A.
Application year: 1996
Main classification: A61C7
IPC codes: A61C7