APPARATUS FOR INTRAORAL DISTRACTION OSTEOTOMY TO WIDEN THE UPPER JAW

Abstract: The technique of surgically assisted rapid palatal expansion comprises force application indirectly to the jaw by means of an expansion device fixed to the teeth by means of acrylic pads, or orthodontic bands on the premolar or molar teeth. The problems, being movements of teeth and relapse at the bone level during and after the expansion, necessitating over-expansion; the low level of force application leading to tipping of the teeth and the jaw-segments; and the postponement of further orthodontic treatment till after removal of the expansion device; and the limited expandability of the device, necessitating the fabrication of a new device in case of very narrow jaws, have been solved with the invention. The forces apply via metal bone-plates (1, 2) directly at a higher level. Interchangeable modules (composition of 3, 4, 5) of different sizes allow to continue expansion once one module has reached the limit of its expansion.

Description: APPARATUS FOR INTRAORAL DISTRACTION OSTEOTOMY TO WIDEN THE UPPER JAW The present invention pertains to a distraction device used to widen an upper jaw (maxillae) after osteotomy and fixation of an adjustable bridging onto the bone of the palate with the goal to gradually increase the distance between the two mutually opposite halves of the jaw. The device is used in maxillofacial surgery, in particular in orthognathic surgery in patients with narrow maxillae. It concerns a developmental disturbance, sometimes congenital as in cleft lip and palate, that can lead to a cross-bite, tooth crowding, hindered nasal breathing, a disturbed occlusion with the lower dental arch, and a psychosocial aesthetic problem. The aim of the invention is to restore the dental occlusion, to improve nasal breathing and to bring the face into normal proportions. The assets of this invention compared to tooth- borne appliances (that are patented by Leone, Schellino and Modica (EP 0846446) , by Palmisano (WO 9629964) , by Bernhard Fόrster (WO 9628110 and WO 9810708) , by Klapper aand George (EP 0706349) , are that there is no or less rotation of the jaw segments in the frontal plane by its high level of force application, that it results in orthopaedic and not orthodontic expansion, that dento-alveolar relapse is not to be expected during and after the expansion, that the interchangeable expansion- modules allow to continue expansion without having to resort to the fabri- cation of a new appliance, and that the orthodontist has all teeth available to start with active orthodontic treatment before the stabilisation period has ended. This is realised according to the invention because the device has following parts: two abutment plates, that are fixed to the palatal bone (processus palatinus ossis maxillaris) , whether with screws into drill holes (as in current description) or with other means such as pins, left and right under the soft tissues; a box-like extension, provided by a slot (in current description) or another hinge mechanism to fix the distraction module into or onto. The extension pierces the soft tissues; expandable parts (distraction modules) of different lengths, in current description four, with at both sides connections possibilities (in current description wings) that fit into or onto the extension of the abutment plates. The distraction module comprises a telescopic screw. The telescopic screw allows the distraction section to be kept compact, leading to a greater stretching with a small initial length. Modules of different lengths allow to choose in the individual case for the proper initial size, and, in the current description, to change for a bigger size when deemed necessary. The screws or pins used to fix the abutment plate to the palate have appropriate lengths in order to avoid damage to the roots of the teeth. After a latency period of four to seven days, activation can start, by l/3mm daily. After a distraction period of one to two weeks, and a stabilisation period of one to three months, the orthodontist can start with fixed orthodontic appliances. One or two months later, the apparatus is removed. Complete bony consolidation occurs in the median vertical distraction area and in the lateral horizontal distraction areas. Advantageously, the expansion screw is a mechanical jackscrew, which comprises three parts which fit into one another, the central segment having the largest diameter, in order to act as a connecting sleeve, and being provided at its ends with internal turns of opposite direction and different sizes, into which two mutually opposite telescopic arms fit, which are able to move into one another and have virtually the same length as the connecting sleeve, so that they can move completely into and out of the central connecting sleeve. The flat conical shaped wing (in the current design) at one of the sides of the telescopic arm allows the distraction module to be fitted into the extension box of the abutment plate. A colour or form code on the connecting sleeve allows to control the speed of the gradual stretching. Three bores with thread at one side of the connecting sleeve allow to block the movements of the module with a blocking screw. The apparatus is made of titanium. This material is well known for its optimum biocompatibility, both for incorporation into the bone (osteointegration) and for incorporation into the soft tissue parts. No allergies to titanium have been described. Dimetalosis has been ruled out . The most characteristic item of the invention is the application of the expansion force directly onto the bone, and not indirectly over the teeth. These and other characteristics of the invention will emerge from the following description, in which reference is made to the appended drawings, which show an exemplary embodiment of an apparatus according to the invention, and in which: Figure 1 shows a front view, looking from outside the mouth inwards of a distraction apparatus in the extended position on the palate according to the invention on a scale of 2:1; Figure 2 shows a top view of an apparatus in a contracted and extended position; Figure 3 shows a frontal view of a distraction module in a contracted position on a scale of 4:1; Figure 4 shows a side view of an abutment plate with box extension on a scale of 4:1; Figure 5 shows a top view of an abutment plate with an extension on scale 4:1; Figure 6 shows the top view of a distraction module in extended position on a scale of 4:1; In these figures, identical numerals refer to ident- ical or similar elements. A distraction osteotomy is a surgical operation for correcting deformity or curvature of a bone which is curved or too short, the bone being split into at least two bone segments being joined together again by dynamic osteosynthesis, that is to say gradual repositioning and fixation of the bone segments with the aid of guided rods, small metal plates, screws, pins, bone pegs or hoops. The distraction apparatus depicted in Figure 1 serves to widen the upper jaw, after a cortical bilateral hori- zontal osteotomy and a vertical median osteotomy. It comprises the following parts: two abutment plates 1, fixed with screws or pins on the palatal bone (processus palatinus ossis maxillaris) left and right of the midline; a distraction module, depicted in ffigure 3 and 6, in different lengths. The distraction module is a mechanical jackscrew consisting of three parts which fit into one another. The central one has the largest diameter, in order to act as a connecting sleeve 5 and is provided at its ends with internal threads of opposite direction and different sizes, into which two mutually opposite telescopic arms 3, 4 fit, which are able to move into one another and have virtually the same length as the central con- necting sleeve 5, so that they can move completely into and out of the connecting sleeve. The connecting sleeve 5 has three bores with internal thread 6 to receive a blocking screw. The free ends of the telescopic arms bear a male conical wing 7, fitting into the female sleeve 8 of the abutment plates 1 (in the current desing)

Claims: CONCLUSIONS 1. Distraction apparatus for the expansion of the upper jaw after osteotomy and with application of the forces directly to the palatal bone with the aim to reconstruct the jaw by increasing the distances between the two opposing bone segments by means gradual stretching characterised in that it consists of following parts: two abutment plates (1) , that are fixed directly to the palatal bone (2) and of which an extension pierces through the palatal soft tissues into the oral cavity, having a design (8) that allows fix- ation of a the end (7) of the distraction module (3, 4, 5) ; expansion screws, called distraction modules (3, 4, 5), of different lengths, with bores for blocking screws (6) . Distraction apparatus according to conclusion 1, characterised in that the distraction forced apply directly via the abutment plates (1) on the bone and not via the teeth. 3. Distraction apparatus according to one of the proceeding claims, characterised in that the expansion screw (3, 4, 5) is a mechanical jackscrew, which comprises three parts which fit into one another, the central element having the largest diameter, in order to act as a connecting sleeve (5) , and being provided at its ends with internal threads of opposite direction and different sizes, into which two mutually opposite telescopic arms (3, 4) fit, which are able to move completely into and out of the central connecting sleeve (5) .

Inventors: MOMMAERTS MAURICE YVES, MOMMAERTS, MAURICE, YVES
Applicants: MOMMAERTS MAURICE YVES, MOMMAERTS, MAURICE, YVES
Application year: 2001
Main classification: A61C7
IPC codes: A61B17, A61C7, A61C8