Assessment of the of fixed dental prosthesis impressions received at commercial dental laboratories in Aljabal-Alakhdar region, Libya0

Abstract

Background: Crown and bridge prosthodontics needs an accurate and precise impression (positive replica) of the abutment teeth and the edentulous region to be rehabilitated for the dental technician to be able to construct the high quality and well adapted fixed dental restoration without mistakes. The aim of the current survey was to assess any visible mistakes commonly observed in fixed dental prosthesis impressions received at five commercial dental laboratories, frequency errors determination, and to determine any possible association between the preparation finish line errors and other assessed factors. Materials and methods: 150 fixed prosthodontic impressions were collected from five commercial dental laboratories located at Aljabal-Alakhdar region, Libya. All the fixed prosthodontic impressions which had been received by the visited commercial dental laboratories were assessed for many factors in relation to the accuracy such as the dental arch involved, prepared abutment teeth, dental impression materials used, and final techniques and viscosity of the impression, the type of impression tray, full-arch or segmental impression tray, the impression tray size, type of fixed dental restoration requested, mistakes in impression material or tray used, gingival tissue dilation errors, closed-mouth impression technique errors, and finish line errors. No attempts were made to determine the reason of the detected errors in each fixed prosthodontic impression assessed. Association between dental practitioner years of experience and gender and impression errors was evaluated. The association between categorical variables and the outcomes were examined by the use of Chi square and Fisher exact tests. Results: Condensation silicone was the most impression material used. Of the impressions evaluated 121(80.6%), 97% have at least one detectable error, 103(68.6%) had finish line errors, 53.9% had tooth preparation area errors. Visible contamination of impression with blood was seen in about 79(52.2%) of the assessed impressions. There was significant association between the type of dental impression material and errors in the preparation cervical finish line and tooth preparation area. Conclusion: In the present study, it has been found that a high frequency of recognizable errors was detected in crown and bridge impressions received by the five commercial dental laboratories. This can result in poorly fitted fixed restorations cemented for the fixed prosthodontic patients.