"ORTHODONTIC BRACKET WITH VARIABLE PRESCRIPTION"

FIELD OF THE INVENTION:

This invention relates generally to orthodontic appliances, and more particularly, to orthodontic brackets used in corrective orthodontic treatment. BACKGROUND OF THE INVENTION

Orthodontics is a Dental specialty that involves the application of forces to correct malpositioned teeth improving the esthetical and functional conditions.

The most common form of orthodontic treatment involves the use of orthodontic brackets and wires. Orthodontic brackets are small slotted bodies configured for direct attachment to the labial or lingual surfaces of the patient's teeth. Once the brackets are affixed to the patient's teeth, a curved arch wire is inserted into the arch wire slot of each bracket. The arch wire acts as a template or track to guide movement of the teeth into proper alignment.

The teeth's crowns angulations and inclinations are different from each other, for this reason, the brackets have specific characteristics for each tooth. The values of the torques and tips in the brackets are called prescription.

There are many prescriptions proposed by different authors, like Roth, Ricketts, Andrews, MBT, etc. Each prescription shows certain inclinations that allows ideal intercuspation between upper and lower teeth at the end of treatment. Variations in shapes and dimensions of facial bones demand different tooth inclinations, justifying the great number of suggested prescriptions.

In order to achieve the ideal dental positioning, the current state of the technique requires the selection of a certain type of prescription at the start of treatment. If by the end of treatment changes in dental position are

needed, two alternatives are available: bend the arch wires or rebond the brackets with a different prescription.

Dr. Duran Von Arx proposed the MECHANICAL DEVICE

FOR USE IN ORTHODONTICS, described in patent WO2006/ 030033 A1 with the purpose of enabling a change in the bracket prescription to avoid bending the arch wire or rebonding the brackets. It comprises a base bonded to the tooth and a removable cover that fits in the base. The difference from the current bracket is the presence of the arch wire slot in the removable cover and not in the base that is fixed to the tooth. Since the arch wire slot follows the removable cover, it makes a bracket with interchangeable prescription.

In spite of not being available commercially, some difficulties are expected in the fabrication because of the complex fixture design system which involves clamps in the base.

The expected difficulties in the clinical routine are related to the time spent in appointments. Each bracket needs to have its cover removed individually to allow the removal of the arch wire, and then reinserted bracket by bracket for the installation of the new arch wires. Yonder more difficult, such procedures modify the clinic routine, because they require special tools to handle the removable covers. Similar difficulties are expected in the VERTICAL STRAIGHT WIRE ORTHODONTIC APPLIANCE HAVING

INTERCHANGEABLE ANCHOR COMPONENTS proposed by Dr. Philip Nord in the patentWO/1998/ 053754.

In view of these problems, the present invention offers a bracket with interchangeable prescription in which the clinical procedures for the removal and installation of arch wires are the same as commonly applied in the current state of the technique, without the need of special instruments. The clinical routine is similar to a conventional bracket.

This is possible because the arch wire slot is located on the base of the bracket that remains fixed during treatment, allowing it to be replaced only when a prescription change is intended.

SUMMARY OF THE INVENTION

The present invention is directed to an orthodontic bracket for use with an arch wire for applying corrective forces to a tooth. The present invention, bracket with variable prescription, comprises two separate pieces: a platform which is bonded to the tooth and the bracket's body, self-ligating or not, that is fitted in the platform from its base.

In this configuration the bracket's body that has specifications such as thickness, height, torque and tip of the bracket can be replaced while the platform remains fixed to the dental surface. This mortise mechanism of the bracket's body to the platform allows the prescription choice that better applies to the individual finishing of each case, with no need to rebond the brackets or bend the arch wires.

These aspects of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention. BRIEF DESCRIPTION OR THE DRAWINGS

Fig.1 - conventional orthodontic bracket in upper perspective.

Fig.2 - bracket's body in upper perspective. Fig.3 - platform in upper perspective.

Fig.4 - platform in frontal perspective. Fig.5 - bracket's body in frontal perspective. Fig.6 - coupling point from bracket's body to the platform in upper perspective. Fig.7 - bracket's body connected to the platform in upper perspective.

Fig. 8 - bracket's body connected to the platform in frontal perspective.

Fig.9 - second embodiment of the orthodontic bracket with variable prescription in upper perspective.

Fig.10 - coupling point from bracket's body to the platform of the orthodontic bracket of Fig. 9.

Fig.11 - bracket's body connected to the platform of the orthodontic bracket of Fig. 9. Fig.12 - bracket's body of the third embodiment of the orthodontic bracket with variable prescription in upper perspective.

Fig.13 - platform of the third embodiment of the orthodontic bracket with variable prescription in upper perspective.

Fig.14 - bracket's body connected to the platform of the third embodiment of the orthodontic bracket with variable prescription. DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Fig. 1 , this is a conventional twin bracket having a base 1 which abuts the tooth surface, two pairs of tie-wings 3 and an arch wire slot 2 for receiving the arch. Referring to Figs. 2-8, this is a first presently preferred embodiment of the "orthodontic bracket with variable prescription", object of the present patent, comprised by two components: the first, named bracket's body 25 , is composed by a base 1 that has in one of its extremes two medial hooks 8; an arch wire slot 2 adapted for receiving the arch wire and tie-wings 3 (Fig.2). The second component named platform 4 has in one of its sides a bonding surface 5 which adheres to the tooth and on the opposite side two guide slots 6 and the medial elevation 7 that has semicircle shaped edges (Figs. 3 and 4).

The bracket's body 25 has next to its base two reentrances 9 to provide width enlargement of the guide slots 6 from platform 4 (Fig. 5). After they are fabricated in an independent way, the base 1 of the bracket's body 25 is attached by sliding it along the guide slots 6 until it touches the medial elevation 7 which indicates the final sliding position of the base 1 in the interior of the guide slots 6 (Figs. 6, 7 and 8).

The stabilization between the bracket's body 25 and the platform 4 is obtained by mortise between medial hooks 8 of base 1 with the edges of the medial elevation 7. The medial hooks 8 have concavities with

proper dimensions to fit the convex shape present on the edges of medial elevation 7. During the sliding of the base 1 in the interior of the guide slots 6 the medial hooks 8 touch medial elevation 7 and under slightly pressure are deflected in a lateral way until they exceed the maximum width on medial elevation 7, and then return to their original shape. Thus, the mortise to the convex edges on medial elevation 7 will be perfect. The full attachment between the base 1 and the platform 4 is obtained through the guide slots 6 with proper dimensions that allow correct contact between these components when they are attached. During the orthodontic mechanics the two attached components form a single structure (Figs. 7 and 8).This way, the arch wire slot 2 remains fixed, allowing clinical procedures for the removal and installation of arch wires to be the same as the regularly applied in the current state of the technique, with no need of special instruments. When it's necessary to change the characteristics of the bracket, in its thickness, height, torque or tip, the base 1 is dislocated from the platform 4 and the bracket's body 25 is replaced by another with the desired specifications (Fig. 6). The medial hooks 8 have vertical posts 10 to facilitate the separation between the base 1 and the platform 4 (Figs. 7 and 8). The configuration of the "orthodontic bracket with variable prescription" allows this procedure as many times as necessary for ideal tooth positioning. Evidently, there will be available bracket's bodies 25 with many prescriptions that might be attached to the platform 4.

Referring to Figs. 9-11, in a second presently preferred embodiment, we see a strengthened fixture system between the base 1 and the platform 4. In this configuration, the base 1 has besides its medial hooks 8 two lateral hooks 11 with the concavities facing outwards and the platform 4 has besides the medial elevation 7 two lateral elevations 12 with the medial edges in a semicircle shape with the convexity facing inwards. The lateral hooks 11 Qf the base 1 and the lateral elevations 12 of the platform 4 have proper dimensions to make precise mortise with each other.

With reference to Figs. 12, 13 and 14, in a third presently preferred embodiment, the present invention includes an extension 13 from the bracket's body 25 in direction to medial elevation 7. The extension 13 has a vertical segment 14 to mortise the extreme of the medial elevation 7, allowing the stabilization between the base 1 and the platform 4.

The guide slots 6, medial elevation 7, lateral elevations 12, medial hooks 8, lateral hooks 11, extension 13 and vertical segment 14 can be disposed either in a gingival/occlusal direction or in a mesial/distal direction. The guide slots 6 can be located in the platform 4 or base 1 of the bracket. The configuration of the orthodontic bracket with variable prescription is applicable to the conventional brackets that hold the arch wire by elastic or wire ligature ties and also to the self-ligating ones, which have their own mechanism for closing the arch wire slot.

The configuration of the orthodontic bracket with variable prescription is applicable to the brackets bonded to the labial or lingual surface, and metallic, ceramic, or any other material.

Obviously the orthodontic bracket with variable prescription described will be made in many sizes and with different variations in thickness, height, torque and tip inclination so it can reach the ideal dental positioning required for diverse clinic situations.