Background and Objectives: Accurate impression taking is a prerequisite for achieving passive fit between the implant and superstructure. This study sought to assess the accuracy of impressions taken from 15° and 25° angulated implants by two plastic and metal stock trays using the splinted open tray technique. Materials and Methods: This in vitro experimental study was conducted on 20 gypsum casts. An acrylic model was fabricated with a first premolar to first premolar edentulous area and second premolar and first, second and third molar teeth present in both sides. Two implants were placed vertically at the site of lateral incisors. At the site of first premolars, one implant with 15° angulation and another one with 25° angulation relative to the midline were inserted. Ten plastic and 10 metal stock trays were used for open tray impression taking with addition silicon impression material at the site of copings. Casts were poured and coded. Measurements were made using coordinate measuring machine (CMM). The data were analyzed using t-test (for normally distributed data) and non-parametric tests (for non-normally distributed data).Results: The A1 distance was 7.253±0.053mm in plastic and 7.249±0.42mm in metal tray group. These values were 9.807±0.026mm and 9.802±0.009mm, respectively for A2, 34.483±0.132 and 34.462±0.112, respectively for A3, 28.210±0.1332 and 28.193±0.011, respectively for A4 and 52.709±0.032 and 52.717±0.041, respectively for A5. These differences were not statistically significant (P>0.05). Conclusion:Both plastic and metal stock trays are accurate for position transfer of parallel and angulated implants in splinted open tray technique.

Introduction:In present study, we evaluated the effect of plasma collected from packed red blood cells (PRBCs) at various weeks after donation on peripheral blood mononuclear cells (PBMCs). Methods: In this experimental study, plasma prepared from twenty PRBCs in the first, second, fourth, and fifth weeks after donation. PBMCs were also isolated from healthy donors and treated with different concentrations of prepared plasma in vitro. NO and MDA levels were measured in culture supernatant using Griess reaction and thiobarbituric acid method, respectively and cell activity was evaluated using MTT assay. GraphPad Prism (version 5) software was used for statistical analysis (repeated measure) of the data. P values less than 0.05 were considered statistically significant. Results: Our results indicated that plasma prepared from PRBCs during the early weeks increases the activity of PBMCs and enhance NO production. We also found that these plasmas have various effects on concentration of MDA released from PBMCs depending on time and concentration. Conclusions: We concluded that plasma of PRBCs can have immunostimulatory or immunosuppressive effects on PBMCs, depending on the concentration and duration of blood bag storage.