Patent Abstract:
A dental prosthesis fabrication and placement method is adapted for completion in one appointment. The dental prosthesis, such as a crown or short-span bridge, is a prefabricated composite shell that is modified by the addition of composite material and cured on-site to form a custom-modified device.

Full Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to systems and methods for performing a dental procedure, and, more particularly, to such systems and methods for fabricating and placing a dental crown or bridge.  
           [0003]    2. Description of Related Art  
           [0004]    The fabrication and placement of dental prostheses such as crowns and bridges typically requires at least two visits to the dentist&#39;s office to complete. At the first visit, the placement site in the patient&#39;s mouth is prepared, and a mold is made from which a permanent prosthesis is to be constructed. A temporary prosthesis is inserted into the site, awaiting the fabrication of the permanent device, which is usually performed at a remote location from the dentist&#39;s office. At a second visit, the permanent prosthesis is affixed into the site.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to a dental prosthesis fabrication and placement system and associated methods that can be completed in one visit. The dental prosthesis, which may comprise, for example, a crown or short-span bridge, is a prefabricated composite shell that is modified by the addition of composite material and cured on-site to form a custom-modified device.  
           [0006]    The method of the invention, which is for fabricating and placing a dental prosthesis, comprises the steps of placing a prefabricated prosthesis shell over a tooth that has a surface that has been prepared for prosthesis placement and trimming the shell to achieve desired seating on the tooth and optimal occlusion. The shell is then removed from the tooth, and the tooth&#39;s prepared surface is painted with a separating medium. An interior surface of the shell is painted with a bonding agent, and an uncured composite material is added to the shell&#39;s interior space.  
           [0007]    Next the shell is positioned over the tooth, and the composite material is partially light cured in situ. The shell is removed from the tooth and modified as desired to achieve optimal conformation. Any added composite is then fully light cured, and the shell is affixed to the tooth.  
           [0008]    The features that characterize the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description used in conjunction with the accompanying drawing. It is to be expressly understood that the drawing is for the purpose of illustration and description and is not intended as a definition of the limits of the invention. These and other objects attained, and advantages offered, by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a side view of a model of the patient&#39;s mouth.  
         [0010]    [0010]FIG. 2 is a side view of the model with the respective tooth prepared.  
         [0011]    [0011]FIG. 3 is a side view of the model with a shell crown placed therein.  
         [0012]    FIGS.  4 A- 4 C are views of the shell crown: FIG. 4A, a side view; FIG. 4B, an occlusal view; and FIG. 4C, an internal view.  
         [0013]    [0013]FIG. 5 is a side view of the mouth with the tooth to be crowned prepared.  
         [0014]    [0014]FIG. 6 is a side view of the shell crown placed over the prepared tooth.  
         [0015]    [0015]FIG. 7 is a side view of the shell crown having added material.  
         [0016]    [0016]FIG. 8 is a side view of the finished crown bonded to the tooth. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    A description of the preferred embodiments of the present invention will now be presented with reference to FIGS.  1 - 8 .  
         [0018]    The method of the present invention in a preferred embodiment comprises the steps of making a study model  10  of the patient&#39;s mouth (FIG. 1), comprising, for example, stone. This may be accomplished at an appointment prior to the prosthesis-placement appointment. Additional information that should be gathered include bite registrations and shade data. Using the study model  10  and additional information, the selected tooth  11  (or teeth) is prepared on the model in advance (FIG. 2) for fitting a custom shell restoration  12  thereto. The custom shell restoration  12  should be prepared to accurately reflect parameters such as color, as well as conformational parameters such as occlusion, proper contours, estimated gingival finish line, and interproximal contacts (FIGS. 3 and 4A- 4 C), and has in a preferred embodiment a minimum thickness of 0.3 mm and a preferred thickness of 1.0-1.5 mm.  
         [0019]    The shell  12  may comprise, for example, a polyacrylic glass composite such as manufactured by Ceramco, Inc. (division of Dentsply International), under the name Cristobol. This material is not intended as a limitation, and other composite compounds exhibiting appropriate handling and wear characteristics, such as Sculpture, BelleGlass, AtrGlass, and Targis, may be substituted by one of skill in the art without departing from the spirit of the present invention. Such materials are processed or polymerized by various combinations of light activation, heat, pressure, and vacuum.  
         [0020]    In an alternative embodiment for a single crown, a kit is provided comprising a variety of standardized size and shade premanufactured crown shells.  
         [0021]    At the treatment appointment the patient is anesthetized, and the tooth  13  (teeth) to be treated is prepared by a method as known in the art, including preparing the tooth  13  with a shoulder or prominent chamfer gingival margin. In a preferred embodiment old amalgam and bases are removed. Also in a preferred embodiment, the present technique is not used for single crowns posterior to the first molar and for bridges posterior to the second bicuspid. A bridge should preferably span no more than three teeth. Preferably all undercuts present in the prepared tooth  13  (teeth) are eliminated using an appropriate buildup or filler material. Hemostasis of the surrounding gingival tissue  14  is preferred. Gingival retraction cord should be trimmed and placed completely into the sulcus to achieve both retraction and hemostasis.  
         [0022]    A backup system for making a temporary crown should preferably be in place should the procedure of the present invention not be successful.  
         [0023]    Next the prefabricated crown or bridge shell  12  is placed over the prepared tooth  13  (or teeth) and trimmed to seat completely on the prepared tooth  13  (teeth) and to achieve optimal occlusion. The shell  12  should fit passively, yet completely, and should be checked to ensure that there are correct interproximal contacts. If the shell  12  does not fit completely, the tooth  13 , the interproximal contacts, the gingival margins, and the internal aspect  15  of the shell  12  should be relieved as needed. If interproximal contacts are insufficient, they can be corrected later.  
         [0024]    The shell  12  is removed from the mouth, the prepared surfaces of the tooth  13  (teeth) are painted with a separating medium, such as a thin coating of water-soluble lubricant. The internal aspect  15  of the shell  12  should be cleaned, etched and silinated if necessary, and painted with the appropriate bonding agent or adhesive. The interior  17  of the shell  12  should be filled approximately halfway, with a lining of soft uncured composite  16  placed over the adhesive (e.g., modeling compound and primer). Although it is preferable to use the same material for the direct reline as was used to construct the shell  12 , the composite shell  12  is compatible with standard composites used in the art of posterior dental restorations.  
         [0025]    The partially filled shell  12  is placed over the prepared tooth  13  (teeth) to establish the proper occlusion, and the gross excess composite that may establish undercuts with the adjacent teeth is removed. The composite  16  is light cured from the buccal, lingual, and occlusal aspects for no more than several seconds, typically approximately 5-10 seconds. The shell  12  is removed and inspected for the presence of voids, which are filled with small additions of uncured composite, and is again pressed into place over the prepared tooth  13  (teeth) and light cured.  
         [0026]    This process is repeated as many times as necessary to develop a fully adaptive internal aspect with complete gingival integrity. If there are insufficient interproximal contacts, they may be modified in the same manner by bonding additional material to the external surface of the shell  12 . Once the addition of material to the shell  12  has been completed, the modified shell  12  should be sufficiently polymerized to optionally harden the entire prosthesis by light curing for  6 - 10  minutes, preferably in a light curing oven.  
         [0027]    Next the shell  12  is trimmed to establish proper contours and to eliminate any gingival margin overhangs. The occlusion should be checked and refined as needed, and the external surface should be polished using an instrument such as, but not intended to be limited to, diamond, carbide, and silicone polishing instruments.  
         [0028]    A radiograph may be exposed to verify the accuracy of the fit. Prior to cementation, the internal aspect  15  of the shell is then microetched, silinated, and coated with an appropriate bonding agent. The prepared tooth  13  should be cleaned to remove all the separating medium, acid etched, usually with buffered phosphoric acid, and coated with the appropriate bonding agent. The retraction cord should be removed, and the crown  12  should be cemented with a dual-cure composite luting cement to achieve a fully bonded, single-appointment final restoration.  
         [0029]    It should be noted that the laboratory-processed shell  12  is likely to be polymerized significantly more than the reline portion of the crown  16 . It is this well-polymerized, most durable portion of the shell  12  that covers most of the tooth, thereby protecting stress areas and providing for minimal occlusal wear. The weakest area is the gingival margin, which should, at the very least, be as durable and provide the same integrity as the best direct composite restoration.  
         [0030]    In the foregoing description, certain terms have been used for brevity, clarity, and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for description purposes herein and are intended to be broadly construed. Moreover, the embodiments of the system and methods illustrated and described herein are by way of example, and the scope of the invention is not limited to the exact details thereof.

Technology Classification (CPC): 0