This invention relates to orthodontic techniques in general, and the reduction in time required for specific tooth movements in particular.
For well over a century, orthodontists have been engaged in the process of repositioning teeth from a bad relationship, or “malocclusion,” into a healthier and more esthetic arrangement. In order to move teeth, three elements are generally required: 1) force, 2) time and 3) space. The mouth responds to a sustained force placed on a tooth by rearranging, or “remodeling,” the jawbone around the root of the tooth. This remodeling creates space around the tooth allowing the tooth to move in the direction of the force. Not only does the tooth need space within the jawbone, but it is also imperative to have or create spacing between the teeth in order for movement to occur.
Over the years, orthodontists have invented devices, generally referred to as an “appliance,” that permit clinicians to deliver sustained forces to the teeth. Braces, or “orthodontic brackets and arch wires,” are the classic appliances that most, if not all, orthodontists use. Braces consist of small brackets that are glued, or “bonded,” to the crowns of teeth, and a wire is then inserted into slots in the brackets and held into place with a ligature or clip. The brackets do not generate forces themselves, but rather transfer forces to the teeth from the deflected wire, when it is inserted into the slot on the bracket and held in place by the ligature. The wire has a “memory,” i.e., a characteristic by which the wire tends to return to its original shape, and in doing so, exerts a force on the bracket that is in turn transmitted to the tooth. Through the application of various types, shapes and sizes of wires, the teeth eventually align themselves into a more ideal occlusion. The technical term used among orthodontists to describe braces is “comprehensive fixed appliance.”
Because the orthodontic treatment takes a long time, and of the obvious drawbacks of having foreign objects glued to a patient's teeth, appliances have been heretofore developed that can be inserted and removed by the patient, and worn part-time. A myriad of removable appliances have been developed over the years, but the vast majority of them are not “comprehensive” in nature. In other words, the removable appliances address specific movements or malocclusions, and are only used for a certain limited period of time. Treatment with removable appliances is often used in conjunction with braces or other appliances.
As mentioned above, Orthodontic tooth movement presently is accomplished by the application of mechanical forces to teeth. An apparatus is connected inside the mouth of a patient which applies, through the use of springs, rubber bands, composite material casting apparatus or other means, a mechanical force in the direction of desired tooth movement. These forces cause the bone to resorb (be removed) in the direction of force and cause the bone to grow on the other side of the tooth, to fill-up the space created by the movement of the dental root in the direction of the force.
This process of orthodontic force application enables teeth to move in the mouth within the boundaries of the neighboring teeth and tissues. The tooth movement is clarified by Wolffs Law which states, in effect, that bone under mechanical stress is remodeled to accommodate and reduce the stress. The common practical aspect to known techniques of orthodontic movement is that the mechanical apparatus, commonly referred to as “braces,” must be worn by the patient for extended periods of time, often several years or more in order to achieve the desired results. The classic orthodontic tooth movement treatment that requires the continuous application of forces to create the necessary tooth movement is expensive as it requires frequent modifications of the magnitude and direction of forces applied to different teeth to achieve the necessary results, requiring frequent adjustments by the treating Orthodontist. Moreover, wearing the mechanical fixtures known as “braces” creates a considerable discomfort for the patient, and at the same time this condition will cause an aesthetic concern to the patient as the mechanical fixtures (Braces) are visible to other people. In addition, the braces enable the accumulation of bacteria and viruses, harmful to the teeth and their surrounding tissues. For these reasons, it is very desirable to shorten the duration of orthodontic treatment in each and every case.
U.S. Pat. No. 3,842,841 teaches the application of a direct current to aid healing of bone fractures in the human body, but requires surgical implantation. A negative electrode (cathode) is surgically inserted into the site of a fracture, and a positive electrode (anode) is taped to the skin elsewhere. The precise biological process is complex; and the current flowing through the fractured bone increases the healing rate of the damaged bone tissue thus reducing the healing time of the injury, enabling the patient to return to normal life in many instances much faster relative to the classical treatment that is not using direct current as used in the prior art above.
U.S. Pat. No. 4,153,060 teaches a method and apparatus for electrically stimulating bone growth and tooth movement in the mouths of humans. A positive electrode is placed on the gum surface adjacent the bone structure which is to be resorbed. A negative electrode is placed on the gum surface adjacent the bone tissue which is to be accreted or built up. A current source is connected, such that a small current flows between the electrodes, which have the effect of stimulating bone growth in a specific direction. In a particular arrangement, the electrodes are placed on the gum surface adjacent a tooth, the positive electrode on the side towards which the tooth should move, and the negative on the side from which the tooth will move. Application of a small current to the electrodes will enhance the repositioning of the tooth in conjunction with normal orthodontic practices.
U.S. Pat. No. 4,854,865 teaches an improved method of orthodontic electro-osteogenesis using a biocompatible anode in contact with an electrolytic gel between the anode and epithelial gingiva at an area of osteoclastic or osteoblastic activity, and a biocompatible cathode in contact with a different type of electrolytic gel between the cathode and epithelial gingiva at an area of osteoclastic or osteoblastic activity. Electric current is then applied across the anode and cathode to stimulate osteogenesis. This method stimulates osteogenesis, which is a crucial element in tooth movement but is unable to demonstrate how to achieve desirable results, or to enable to complete orthodontic treatment in a shorter amount of time.
To date, there have been no recognizable inventions that demonstrate improvements in enhancing tooth movement, non-invasively, with the ability to effect one tooth or many teeth, to reduce the total amount of time over which an orthodontic appliance must be used in order to accomplish a given amount of tooth movement or repositioning.
It is therefore an object of this invention to provide a method to accelerate tooth movement which will shorten the overall time a patient has to wear an orthodontic appliance system which will overcome the drawbacks of the prior art.
Therefore, in view of the foregoing, it is an object of the present invention to reposition teeth in a patient's mouth by applying an electrical potential to the patient's gums in the immediate vicinity.
It is a further object of the present invention to increase the rate of movement of teeth undergoing mechanical stress in accordance with known orthodontic practices.
Actors in this operation are cells capable of responding to a circuit mounted in an housing that will be placed in conjunction with any type of existing orthodontic appliance for providing the necessary electric current output to electrodes located adjacent to a tooth to be positioned, in such a manner that electric current polarity, electric current direction and electric field strength will all increase the rate of teeth movement undergoing mechanical stress in accordance with known orthodontic practices.
It is an additional object of the present invention to provide a method and apparatus for stimulating and controlling bone growth in a patient's mouth in order to correct alveolar bone defects, close cleft palates, or maintain the alveolar ridge in edentulous patients (those who have lost their teeth).
In accordance with the above, the other objects, a method and apparatus for the initiation and enhancement of tooth movement comprises the disposition of an anodic electrode of a particular size and shape in the direction of applied force and a cathodic electronic of a particular size and shape on the opposite side of the tooth to be moved. A current source is connected to the two electrodes which causes the tooth to be repositioned in combination with an existing orthodontic appliance.
In accordance with the above, yet another objective of the present invention will be to benefit from the ability to administer simultaneously two or more methods to cells capable of responding to an exposure to each method alone from the biological, cellular and molecular stand point of tooth structure. The present invention will further show that the combined application of tooth pushing force and electric current together, which evokes additive or synergistic responses by the affected cells, allows the treating Orthodontist to reduce the dose of each of the stimulating factors in order to achieve an optimal response. This principle means that the addition of exogenous electric currents, which is the principle of the present invention, to the orthodontic mechanical force will enable the treating Orthodontist to reduce the amount of mechanical pressure necessary to achieve the desired results, and by following the teachings of the present invention will reduce the risk of root resorption associated with the application of orthodontic force alone.
The novelty and usefulness of this invention is that the application of a specific electric current, through appropriate surface electrodes in the mouth, also can be utilized to stimulate bone accretion in the vicinity of a cathodic electrode and bone resorption in the vicinity of an anodic electrode, and that this biological stimulation accelerates the velocity of orthodontic tooth movement.
In accordance with the above, yet another objective of the present invention will be the augmentation of orthodontic anchorage non-invasively applying an electrical potential to the patient's gums in the immediate vicinity. Modern orthodontics is a field of medicine based on an understanding of growth and development, and is implemented by biomechanics. The biological response to the mechanical force(s) applied to the teeth will determine changes in their position. Inherent in this mode of therapy is Newton's third law of physics which states that for every action there is an equal and opposite reaction. A common example in orthodontics illustrating this point is when protruding upper front teeth are retracted against the posterior teeth (referred to as the anchorage segment/unit) of either arch, which causes the latter to be protracted in reaction. This is not always a desirable side effect and attempts to negate it are numerous, and are based on altering the balance on the mechanics side of the equation. However, our ever increasing understanding of the biology of tooth movement has offered the clinician a non-invasive simplistic method of altering this imbalance on the biological side of the equation. To achieve this, the specific made and fit appliance to a patient's mouth comprising the application of a specific electric current, through appropriate surface electrodes in the mouth, can be directed (with specifically placed electrodes), to cause bone apposition in areas to where tooth movement needs to be minimized, while causing bone resorption where movement is desired simply by changing the direction (polarity) of the flow of current in each of these areas. This effect can be modified according to the stage of treatment for the individual patient by programming the above mentioned specific appliance to perform the above mentioned function.
The invention will now be described with reference to the accompanying drawing which is a plain illustrative view of the apparatus which operates in accordance with the method for the invention.
Referring to FIG. 1., there is shown a schematic illustration of a longitudinal section of a human mandibular canine. The tooth is comprised of a crown 100 and a root 101. Centrally located within the body of the tooth is its root canal 102. The crown is visible in the mouth, while the root is not, because it is encased in soft connective tissue fibrous mesh known as the periodontal ligament (PDL) 103, and the PDL is surrounded by alveolar bone 104. The alveolar bone faces the PDL on one side, and is covered by the gingival and mucosal tissue (gum) 105 on the other. All these tissues, dental and paradental, contain living cells, which are responsible for the remodeling of all these tissues in response to orthodontic forces. This remodeling process is the mechanism that facilitates orthodontic tooth movement.
Referring to
In this preferred embodiment the electric current characteristics will be of a Direct Current with the capabilities to regulate and deliver constant current of 20 micro-Amperes (20 millionth of a one Ampere current) for duration of 4 hours, while the treated patient will wear the appliance 140 of
In this preferred embodiment the anodes 144 and 146 and cathode 143 and 145 are of the same diameter and size to guide the electric current activity at the root of the canine tooth. In yet another preferred embodiment the cathodes 144 and 146 will be of a larger diameter size whereas the anodes 143 and 145 will be at a smaller diameter size to distribute the electric field over larger area in the canine tooth root. And yet in another preferred embodiment, the anodes 143 and 145 will be of a larger diameter size, whereas the cathodes 144 and 146 will be of a smaller diameter size to distribute the electric field over larger area in the canine tooth root. In this preferred embodiment the polarity of the electric filed which is set by the placement of the anodes 143 and 145 and the cathodes 144 and 146 will be perfectly aligned and parallel with the axis of rotation defined by symbol 142 that are parallel and aligned with the canine tooth desired rotational movement direction 142 shown herein. In yet another preferred embodiment where the canine desired tooth rotational movement will be in an opposite direction to rotational direction 142 shown herein, the placement of anodes 143 and 145 and cathodes 144 and 146 will be different, such that the anodes will be placed at 144 and 146 shown in
In this preferred embodiment the electric current characteristics will be of a Direct Current with the capabilities to regulate and deliver constant current of 20 micro-Amperes (20 millionth of a one Ampere current) for duration of 4 hours, while the treated patient will wear the appliance 140 of