Orthodontic appliance

Details Orthodontic appliance Orthodontic appliance

2002-04-29

2004-05-11

O'Connor, Cary E. (Department: 3732)

Dentistry

Orthodontics

Means to transmit or apply force to tooth

C433S024000

Reexamination Certificate

active

06733288

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the use of a prepreg for the production of a composite and to an active orthodontic method of treatment. The invention further relates to an active orthodontic appliance comprising an arch wire consisting essentially of a fiber-reinforced composite comprising at least one fiber and a matrix, as well as to a process for manufacturing an active orthodontic appliance.
BACKGROUND OF THE INVENTION
In active orthodontic treatment teeth are rearranged by removable or fixed orthodontic appliances in order to achieve better occlusal stability, function as well as appearance. Orthodontic treatment is based on the principle that if prolonged pressure is applied to a tooth, tooth movement will occur as the bone around the tooth remodels. Tooth movement can be bodily movement, tipping, root uprighting, rotation, extrusion or intrusion.
The state-of-the-art methods to move teeth are based on using fixed orthodontic appliances. These appliances comprise metallic or ceramic brackets adhered to the teeth and a metal arch wire (e.g. nickel-titanium alloy), which is bent in such a way that it transfers a desired force to the teeth. Shortcomings of the state-of-the-art method are e.g. structural complicity of the appliances which can cause oral hygiene problems resulting in decay, and poor appearance of the appliance. To overcome the appearance problem, tooth colored ceramic brackets and fiber-reinforced composite brackets (Adam et al, U.S. Pat. No. 5,318,440) have been introduced. However, despite the development of the bracket materials, one problem still occurs, i.e. the quite frequent loosening of the brackets from the tooth surface. The problem is due to the fact that high strength metals and ceramics (such as titanium alloys and zirconium oxides) are difficult to adhere to the tooth surface in clinical conditions.
Recently, fiber-reinforced composites (FRC) have been introduced for dental use. One application of FRCs is to replace metal wires used as an orthodontic arch wires. This has been described by Kusy & Kennedy (U.S. Pat. No. 5,987,376), Goldberg & Burstone (U.S. Pat. No. 4,717,341) and Kobayashi et al (U.S. Pat. No. 5,759,029). The system uses continuous unidirectional glass fiber wire as a translucent, i.e. aesthetic, arch wire in combination with traditional brackets. In all of these inventions, a cured FRC arch wire, i.e. FRC arch wire with a finally polymerized matrix, and brackets is used.
OBJECT OF THE INVENTION
The object of the invention is to provide an active orthodontic appliance that does not have the above-mentioned drawbacks. It is thus an object of the invention to provide an appliance having a simple, reliable and aesthetic structure, which allows the maintenance of good oral hygiene.
Another object of the invention is to provide an active orthodontic appliance that may be attached to teeth without using brackets. An object of the invention is also to provide a process for manufacturing said appliance. Yet another object of the invention is to provide a novel use for a prepreg as well as to provide a new method of active orthodontic treatment.
SUMMARY OF THE INVENTION
The invention relates to the aspects defined in the annexed claims.
The invention relates to the use of a prepreg comprising at least one fiber and a matrix to be cured during application, for the production of a fiber-reinforced composite, for active orthodontic therapy.
The invention further relates to an active orthodontic appliance consisting essentially of an arch wire in at least one part, directly contactable with teeth and consisting essentially of a fiber-reinforced composite comprising at least one fiber and a matrix, said arch wire comprising a loop directly contactable with a tooth or teeth to be moved by the appliance.
The invention also relates to a process for manufacturing an active orthodontic appliance comprising the steps of:
a) shaping a first portion of a prepreg consisting of a composition comprising at least one fiber and a matrix in its non-cured form, to the shape of the tooth or teeth to be used as support for the appliance,
b) shaping a second portion of the prepreg to the shape of the tooth or teeth to be obtained by the appliance,
c) curing said prepreg to obtain a composite, and
d) forcing the second portion of the composite obtained to the original shape of the tooth or teeth to be moved by the appliance.
The invention still relates to an active orthodontic method of treatment comprising the steps of
a) shaping a first portion of a prepreg consisting of a composition comprising at least one fiber and a matrix in its non-cured form, to the shape of the tooth or teeth to be used as support,
b) shaping a second portion of the prepreg to the shape at the end of the orthodontic treatment,
c) curing said prepreg to obtain a composite,
d) forcing said second portion of the composite to the shape at the beginning of the orthodontic treatment to obtain an orthodontic appliance, and
e) contacting said appliance to said teeth for the duration of said treatment.
DETAILED DESCRIPTION OF THE INVENTION
In this application, by curing it is meant polymerization and/or crosslinking. By matrix, it is understood the continuous phase of the composition and by matrix in its non-cured form it is meant a matrix that is in its deformable state but that can be cured, i.e. hardened, to a non-deformable state. The matrix in its non-cured form may already comprise some long chains but it is essentially not yet polymerized. By prepreg, it is meant a semi-manufactured product, that is, a product that is non or partly polymerized yet still deformable. The polymerization of a prepreg leads to a composite. The words “composite” and “cured prepreg” may be used interchangeably.
The invention relates to the use of a prepreg comprising at least one fiber and a matrix to be cured during application, for the production of a fiber-reinforced composite, for active orthodontic therapy.
By application, it is meant the manufacturing of an active orthodontic appliance, that is, the operation performed by a dentist or a dental technician to provide an appliance suitable for specific needs of the patient, starting from a prepreg. The manufacturing comprises also the assembly of the device from semi-finished products and the curing to obtain said device.
The main difference of the present invention with the prior art is that in the present invention, the prepreg is cured to composite during the manufacturing of the appliance itself, whereas in the prior art, the prepreg is first cured to form a composite and thereafter the appliance is manufactured from said composite.
According to an embodiment of the invention, said composite is for direct contact to the teeth involved in said active orthodontic therapy. The composite of the invention may therefore be used in an orthodontic appliance without brackets, thus achieving one of the objects of the invention. The appliance may be attached to the teeth by means of dental adhesive, for example.
The invention further relates to an active orthodontic appliance consisting essentially of an arch wire in at least one part, directly contactable with teeth and consisting essentially of a fiber-reinforced composite comprising at least one fiber and a matrix, said arch wire comprising a loop directly contactable with a tooth or teeth to be moved by the appliance.
The appliance according to the invention thus has a simple and reliable structure allowing the maintenance of good oral hygiene. In addition, the appliance according to the invention is aesthetic since it does not require brackets and it is possible to make the appliance of the same color as the patient's teeth, so that the appliance is almost invisible. A further advantage of the appliance according to the invention is the increased convenience and comfort to the patient, due to the lack of brackets.
In summary, it can be said that the activation of the present inventive arch wire to move the teeth is obtained by polymerizing the fully impregnated prepreg's mat

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