No abstract

Quality standards for impressions for crown and bridge work in general dental practice in the UK are a cause for concern if the sample of cases seen in this study is typical.

A report is presented of a study which was carried out to investigate the standard of impressions for anterior crowns received at a commercial dental laboratory in Great Britain. Aspects examined were the type of tray and its suitability to the impression technique used, fixation of the impression to the tray, the method of storage in transit, contamination, defects on the preparations and defects elsewhere affecting the occlusion. The quality of the actual preparation was not examined in this study. Similar details were noted for the opposing impression. Of the 50 cases examined only 12 were recorded as totally satisfactory, with 26 cases being recorded as not being of an acceptable standard for the construction of an adequate restoration. The results are presented with the conclusion that in this survey the general quality of impression was unacceptable.

No abstract

Metal and rigid plastic stock trays give greater accuracy in the putty/wash silicone twin mix impression technique compared with flexible plastic ones for crown and bridge work. Those using the latter should be aware of their shortcoming in this respect.