فهرست مطالب majid sadeghpour shahab

Inappropriate transfer of pressure during final impression making in fabrication of complete denture can result in ridge resorption. This study aimed to assess the effect of vent size and spacer thickness on pressure produced during maxillary edentulous impression making by different impression materials in vitro.
This experimental study was carried out using a maxillary edentulous model, two types of impression materials (regular body addition silicone and zinc oxide eugenol) and two types of trays with spacer thicknesses of 0 and 1.5 mm and each thickness with four vent sizes of 0, 0.5, 1 and 2 mm. Totally eight types of trays for each impression material (80 samples) were used. Impressions were made and transferred pressure in the first molar area of edentulous ridge and mid-palatal raphe was measured (g/mm2) by two load cells. Data were analyzed using two-way ANOVA, post hoc Tukey’s test and t-test.
As the vent size or thickness of spacer increased, the mean pressure on maxillary edentulous ridge decreased from 59.0±2.22 to 36.8±2.50 and 98.5±5.85 to 42.8±2.11 g/mm² in ridge area and 35.0±1.66 to 19.4±1.74 and 52.1±3.80 to 22.3±1.25 g/mm² in mid-palatal raphe for regular body addition silicone and zinc oxide eugenol, respectively. Comparison between groups indicated that there were significant differences in the magnitude of pressure in use of the two materials and areas with different vent sizes and thicknesses of spacer (P Impression pressure changes significantly by change in tray design or impression material. For making impressions of an edentulous maxilla, using a tray with a 1.0 mm or larger venthole or 1.5 mm spacer thickness is recommended. Key Words: Dental Impression Materials, Dental Impression Technique, Dentures, Maxilla

Candidiasis is one of the most common fungal infections in oral cavity. About 85% of this infection is caused by Candida albicans a flora of mouth. Since one of the problems in denture users is it's contamination with C.albicans and discoloration, and lack of information about adhesion of C.albicans to different resins, we designed this study to compare the effect of two types of acrylic resin on adhesion of C.albicans.

This was an experimental study within that 36 samples from Bayer and Acropars acrylic resin were added in tubes containing suspension of 1×106 (CFU/ml) of C.albicans. Then tubes were incubated at 37οc for 40 and 120 minutes. After incubation, the samples were transferred in 1ml of sterile saline and after resuspension by shaking a known quantity of each was inoculated on sabouraud dextrose agar and incubated at 37οc for 48 hours and after that, formed colonies were counted and were analyzed by Mann-u- Whitney test.

These two acrylic resins did not reveal statistical significant differences in two 40οc and 120οc different lengths of the time from the point of adhesion. Also Bayer acrylic resin did not show any significant differences from the point of adhesion in to different lengths of times. But dissimilarly was significant for Acropars acrylic resin which indicated adhesion with the passage of the time.(p<0.1)

These two Acrylic resins do not have any priority to each other from the view point of non-adhesion to Candida albicans, but Bayer acryl is more appropriate particularly for those who are with weak hygiene and are more susceptible to fungal infections. Surface roughness of acrylic resins and their components, characteristic and surface factors have essential role in adhesion of C.albicans.