Journal of Dental Medicine

Background and Aims: Since impression materials usually contact with saliva, blood, and oral soft tissues, their microbial contamination are harmful in immunocompromised patients. The aim of the present study was to determine the bacterial and fungal contamination in common impression materials.

Materials and Methods: In current lab trial study, 5 different samples from each 4 impression materials were homogenized in 1 ml Tween 80 and then 100µl of each sample were cultured onto blood agar, EMB, or sabouraud dextrose agar. Bacterial and fungal cultures were incubated at 37º C and 30º C, respectively. The isolated bacterial and fungal colonies were enumerated and identified using specific diagnostic media and tests. Data were analyzed using Kruskal-Wallis test.

Results: Totally 75% of samples had one or several bacterial contaminations. Iranian alginate and Speedex (putty) were the most contaminated samples. On the other hand, Speedex (light body) and foreign alginate showed lower contamination. Species of Micrococcus, Staphylococcus, Bacilluses, Corynebacteria, gram negative Citrobacter, Actinomycetes and Neisseria were isolated from the analyzed impression materials. Aspergillus, Penicillium, Alternaria, Cladosporium and Sepdonium were the fungi isolated from impression materials. Statistical significant difference was shown between bacterial contamination of Iranian and foreign alginates (P=0.001). There was no statistical significant differences between the bacterial and fungal isolated colonies (CFU/gr) of 4 tested impression materials (P=0.21).

Conclusion: Several opportunistic bacteria and fungi were isolated from impression materials especially from Iranian alginate and Speedex putty which indicated their contamination.

  Background and Aims: Making accurate impressions of prepared teeth when they are adjacent to dental implants is of great importance. In these situations, disregarding the selection of appropriate impression material and technique, not only can affect accuracy of transferring of the 3-dimentional spatial status of implant, but also can jeopardize the accurate recording of tooth. In the present study, the accuracy of two impression materials with taper impression copings for recording implant position and surface details was evaluated.

  Materials and Methods: One metal reference model with 2 implants (Implantium) and a preparation of three grooves on a tooth according to ADA no. 19 standard was fabricated. 10 medium- consistency polyEther (PE) impressions using custom trays and 10 polyVinyl Siloxane (PVS) putty wash impressions using prefabricated trays with conical impression coping were made. Impressions were poured with ADA type IV stone. A Coordinate Measuring Machine (CMM) evaluated x, y and angular displacement of the implant analog heads and also accuracy of groove reproduction were measured using a Video Measuring Machine (VMM). These measurements were compared to the ones from reference model. Data were analyzed using one-way ANOVA and T-test.

  Results: Putty wash PVS had less linear discrepancy compared with reference model (P > 0.001). There was no significant difference in the surface detail reproduction (P = 0.15).

  Conclusion: Putty wash PVS had better results for linear displacement compared with medium consistency PE. There was no significant difference in surface detail reproduction between the two impression materials.