a description of the preferred embodiments of the present invention will now be presented with reference to fig1 - 8 . 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 ( fig1 ), 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 ( fig2 ) 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 ( fig3 and 4 a - 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 . 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 . in an alternative embodiment for a single crown , a kit is provided comprising a variety of standardized size and shade premanufactured crown shells . 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 . a backup system for making a temporary crown should preferably be in place should the procedure of the present invention not be successful . 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 .
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 .