Abstract:
An impacted tooth appliance including a micropin bone anchor with a quadrilateral aperture formed therein, a rigid apertured ribbon secured to the impacted tooth by means of a rotatable bracket secured to the tooth, the ribbon pivoted on the bracket, and the ribbon and the micropin interconnected by means of spring-biased quadrilateral wire.

Description:
The benefits under 35 U.S.C. 119 are claimed of provisional patent application 60/922,891 filed Apr. 12, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     The conventional technique for recovering a deeply impacted tooth is to bond a bracket with a gold chain attachment in order to anchor the impacted booth. Following this, it is required to level and align the remaining dentition in the arch to serve as an anchor unit against which the impacted tooth is leveraged. As a result, movement of the impacted tooth has to wait until the remainder of the arch is aligned sufficiently so it can accept a stiff archwire. Then, the tooth is tied to the main archwire and tugged on to force eruption of the impacted tooth. The most difficult aspect of bringing down an impacted tooth is maneuvering it into the oral cavity. Once this is achieved, many types of auxiliary archwires are utilized to guide the tooth into the proper position. All of these designs use the main archwire or a transpalatal arch as the anchor unit for the movement of the impacted tooth. The cuspid tooth is the most commonly impacted tooth; however, these arrangements are applicable to other impacted teeth such as the anterior teeth or premolars. 
     BRIEF SUMMARY OF THE INVENTION 
     According to this invention, the correction of the cuspid or other tooth is no longer tied to the leveling and alignment of the remainder of the arch. The unique feature of this system is in treating malocclusions that are complicated with the correction of malocclusions addressed independently of the impacted tooth. The fact that correction of the remainder of the arch does not have to wait for recovery of the impacted tooth and vice versa saves months to years in treatment time since anchorage is provided from a micropin and not the dental arch. 
     More specifically, the impacted tooth appliance includes a threaded micropin secured to the patient&#39;s bone, an apertured rigid ribbon secured to the impacted tooth by means of a rotatable bracket, a quadrilateral aperture formed in the micropin and a spring-biased quadrilateral wire inserted at one end through the quadrilateral aperture and secured at the other end to the apertured rigid ribbon. After the tooth is exposed, the bracket and wire are removed and a tube or similar device is bonded to the tooth. Following this, an angled quadrilateral wire and spring appliance is secured at one end to the tube and at the other end to the micropin. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view of the tooth attachment means showing one feature of this invention; 
         FIG. 2  is an enlarged perspective view of the micropin according to this invention; 
         FIG. 3  is an enlarged elevational view of the complete appliance; and 
         FIG. 4  is a perspective view of the micropin wire and tooth attachment assembly according to one feature of this invention and with the micropin shown as being enlarged. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to this invention, initially impacted tooth  1  is exposed by means of a surgical procedure. Then a bracket including bracket base  2  is initially is placed in position using a bracket holder or hemostat and bracket base  2  is bonded to tooth  1 . Calibrated inflexible or rigid ribbon  3  is pivotally attached to bracket base  2  by means of pin  4  which is interlocked with respect to cone  5 . Ribbon  3  is made of an alloy such as NiTi, elgiloy, TMA or stainless steel. Cone  5  is snap fastened into bracket base  2 , in known manner, such that cone  5  rotates within bracket base  2 . Both bracket base  2  and cone  5  are round in configuration. Since ribbon  3  is pivoted to cone  5  which in turn is rotatable 360 degrees, ribbon  3  is universally moveable to any desired position. The rigid nature of ribbon  3  helps achieve the desired directional force and delivers torque control and an efficient transfer of force to the impacted tooth. Additionally, ribbon  3  prevents undesirable floating of the impacted tooth. This is important because the surgical access and bonding of the impacted tooth can be challenging, especially when the tooth is deeply positioned in the palate. 
     Apertures  6 , formed in ribbon  3 , emerge into the oral cavity as the tooth descends and are calibrated to aid the clinician in determining the proximity of the crown of the tooth from the oral cavity as the tooth is force erupted. Multiple apertures  6  are of a diameter large enough to accept a ligature wire and the length of ribbon  3  is sufficient to span the distance from the position of the impacted tooth to the oral cavity which is 10 mm or longer. 
     A distinctive feature of this invention is the use of a Class III lever system instead of sliding mechanics i.e., gold chain, etc. Anchorage is provided by a micropin, generally designated by the numeral  7 , using the cortical bone plate of the palate to stabilize the pin with the vector of force provided by rectangular spring wire  8 . Wire  8  is prefabricated from NiTi, TMA or blue or yellow elgiloy types of orthodontic alloys. 
     Another feature of this invention is the ability to isolate and treat the impacted tooth independent of the rest of the arch. This is achieved using anchor micropin  7  instead of the dental arch as edgewise (rectangular or square) wire  8  is able to generate a vector of force that can be directed from a proximal point to deliver the desired movement at a distal location. For the purpose of receiving wire  8 , quadrilateral apertures  9  and  10  are formed in block  11  and are disposed at a 90-degree angle to each other. Wire receiving hooks  12  and  13  extend from the upper surface of block  11 . Quadrilateral apertures  9  and  10  are large enough to accept a 0.016×0.022 mm wire with minimal rotational play. 
     In order to receive a dental wrench, nut  14  is disposed between block  11  and disc  15 . Also, micropin  7  includes two separate pairs of threads including conventional threads  16  and microthreads  17 . Threads  16  and microthreads  17  extend downwardly from neck  18  of micropin  7  and microthreads  17  are provided for a more secure and immovable connection for micropin  7  to the cortical bone. Corkscrew-type tip  19  is formed on the end of micropin  7 . 
     The orthodontic wire makes possible various types of orthodontic movements by providing three-dimensional control of the direction of the force provided. This is accomplished by virtue of micropin  7  providing a stable anchor unit so that the tooth is guided to the desired position due to the torque control made possible by the rectangular wire locked into either quadrilateral aperture  9  or  10  at its distal end. 
     Micropin  7  is placed near the midpalatine suture in the area of the first molar. Cortical bone is thickest in this area and provides better anchorage for the pin. Following this, spring  20  is formed in wire  8  and activated by bending it manually, so as to achieve the desired force, and then inserted into block  11  of the micropin. Spring  20  is loaded with 600-800 grams of force in order to deliver 150 grams of force to the impacted tooth and is formed by means of one or more coils in wire  8 . The proximate end of wire  8  is tied to ribbon  3  positioned on the impacted tooth bracket using a 0.09 mm ligature wire. 
     The impacted tooth is brought down into the oral cavity normally within 4-12 weeks. As the tooth descends into the oral cavity, the extruding end of the ribbon can be adjusted for patient comfort during a routine office visit. The desired force is delivered to the impacted tooth to provide a light continuous and controlled force for optimal results and to minimize the risk of root resorption. The force is calibrated and controlled at all times during the treatment to deliver optimal force to the tooth for its movement. 
     The efficiency of the system is due to the Class III lever system. In Class III levers, the fulcrum is at one end of the lever (the micropin), but the load (the impacted tooth) is at the other end, and a force or effort is applied between the two (by a spring-loaded wire). The lever cannot give any mechanical advantage. The main advantage of Class III levers is the increased acceleration of movement of the tooth. Regardless of where the force is applied, the force must always be greater than the resistance of the load. However, the advantage is the speed and acceleration attained with this lever system. The longer the arm, the lower the amount of force needed to move the tooth. The components are assembled in a similar fashion to a door hinge to allow a 180-degree swivel in one dimension. 
     Once the extrusion is complete and the crown of the tooth breaks through the oral mucosa, ribbon  3 , bracket base  2  and related structure are removed and replaced with a bondable eyelet or tube  21 , as shown in  FIG. 4 . This will allow movement of the tooth into the arch using a light and continuous force. This is vector force mechanics as opposed to sliding mechanics and this phase of the treatment is independent of the rest of the dental arch. The only requirement is for this movement to be orchestrated with the rest of the arch such that adequate space is available for the tooth at the desired location in the arch. 
     Following this, a new rectangular wire  22  and spring  23  assembly is inserted, at one end, into either aperture  9  or  10  of micropin  7  or into a new micropin placed in a better position for the forward movement of the palatially-positioned tooth and inserted into tube  21  at the other end in order to move the tooth forward toward the arch. Wire  22  is angled with spring compression  23  disposed between tube  21  and the converging point of the angled wire in order to exert tension on the tooth. Both ends of wire  22  are bent downwardly to prevent wire  22  from sliding out of micropin  7  or tube  21 . Once the tooth arrives in the proximity of its final position, tube  21 , micropin  7 , wire  22  and spring  23  are removed and a conventional bracket is bonded to the tooth. The tooth is then treated along with the rest of the arch to correct the malocclusion. 
     Therefore, by this invention, an impacted tooth is lifted out of its deeply embedded position using a lever system. The impacted tooth is connected to the active arm of the lever with a rigid ribbon bracket and lifted out with the extrusion force generated from the lever arm. The lever arm is adjustable to control the amount of the force as well as the direction of the force delivered to the impacted tooth, as desired, including labial, lingual, or extrusive vectors as treatment demands. The correction of impacted tooth is independent from the remainder of the dental arch so that treatment of a separate malocclusion can be accomplished simultaneously.