Dental implants are well known in the dental arts as a means for providing a prosthetic tooth or teeth as an alternative to a fixed bridge or removable dentures. The dental implant procedure begins with first surgically exposing the jaw bone and then drilling the surface of the bone where the prosthetic tooth is to be attached and then inserting an implant. A flap of skin is then sewn over the site and during a healing period that follows, the bone becomes biologically attached to the surface of the implant. Later, after the implant has become thoroughly attached to the bone, the flap is removed. Next, an abutment is screwed onto the implant for ultimate attachment to the prosthetic tooth.
In order to provide the proper shape and orientation of the prosthetic tooth or teeth to be provided, an impression is made of the dental implants and the remaining teeth and gums. In this procedure, a coping or temporary extension is attached at the site of each individual implant by threading the coping into the implant. Next, impression material contained in an impression tray is imposed around the coping and other dental work. After the impression material hardens and copings are unscrewed, the tray is removed. There is a problem, however, because accurate impressions are rarely produced using copings to form the implant impressions. This is a result of distortion of the impression material as the material sets.
In order to solve this problem, a metal impression confirmation system has been devised such as disclosed in U.S. Pat. No. 5,055,047 issued to Names on Oct. 8, 1991. This document discloses the use of a metallic frame comprising individual foundation elements that are attachable to each implant. The frame provides a rigid base around which an impression material may be molded. The molded impression retains dimensional stability by virtue of the rigidity of the frame which is removed from the mouth while still embedded in the hardened impression material. The frame is attached to individual copings by the use of resin bonding, a plurality of metallic wings between adjacent copings to form the frame.
While this solution may provide some advantages, it creates new problems of its own. First, each wing must be individually resin bonded to another structure which requires increased chair time and discomfort to the patient. But more importantly, the metallic frame structure which is the result of the Names process is too rigid to be successfully withdrawn from bores of the implants when the axes of the implants are misaligned, i.e. non-parallel, as often occurs. This makes withdrawal of the impression and coping framework difficult and sometimes even impossible.
Additional patent background art of which the applicant is aware includes U.S. Pat. No. 6,213,773 issued to Gittleman; U.S. Pat. No. 5,125,841 issued to Carlsson et al.; U.S. Pat. No. 6,149,433 issued to Ziegler et al.; and U.S. Pat. No. 2,644,231 issued to Brennan. However, none of the devices disclosed in these patents provides a solution to the problems of dental implant impression confirmation described above.
There is therefore a need in the art for an impression material reinforcement system for use with taking impressions of dental implants which is convenient to use and which supplies the necessary rigidity to the impression material so that accurate impressions of the dental implant copings can be taken.