Retention strength of impression materials to a tray using different adhesive methods
Marafie, Yousef Sadik
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Objectives: To compare the in-vitro retentive strength of impression materials to a newly developed impression tray using different adhesive methods as follows: A plain tray, tray with its newly developed method of retention “fleece", tray with conventional adhesive (CA), and tray with "supplemental" mechanical retention. Material and methods: Two types of impression materials vinyl polysiloxane (VPS), and polyether (PE) were applied to an impression tray which was secured to the lower member of a universal testing machine using a specially customized apparatus. The appropriate adhesive method was used for each group of specimens. When a conventional adhesive method was applied to a tray, manufacturer recommendations were followed for each type of adhesive and its corresponding impression material. For each type of impression material, a total of 10 samples for each of the 4 test groups were tested. The order of specimen fabrication and testing was randomized with respect to adhesive type and impression materials in order to reduce operator learning as a possible contributor to experimental variability. The adhesive condition groups were as follows: Group 1: No mechanical / No adhesive / With fleece Group 2: No mechanical / No adhesive / No fleece (Plain Tray) Group 3: No mechanical / With adhesive / No fleece Group 4: With mechanical/ No adhesive / No fleece An in-vivo pilot test determined the appropriate rate of separation relative to each type of impression material to program the instron machine accordingly. An Aluminum rod (6mm diameter) with aluminum rectangle (12mm width x18mm length) was lowered until penetrated the impression material filled in a tray. The impression material was allowed to set following the manufacturer recommended setting time. Pulling force at first separation was measured (peak load). Ten replications per test condition were made, and the results were anaiyzed using a 1-way ANOVA at a pre-set overall alpha of .05 with Tukey's post hoc multiple comparison test for each impression material. Results: Within each impression material/adhesive test condition, retentive “tensile” strength values using conventional adhesive were higher than those of all other treatment groups. For VPS, the conventional adhesive method group showed statistically higher retentive “tensile" strength values than when using any other adhesive method (P[less than 0.05). On the other hand, when PE was used the conventional adhesive method group also showed statistically higher retentive "tensile" strength values compared to all other adhesive methods groups. For both types of impression materials, significant differences were found between the conventional adhesive and the fleece "new adhesive method" (P[less than] 0.05). Mechanical retention did not always provide significantly greater retentive strength. Conclusions: The conventional adhesives used in this study provided significantly higher retentive strength between the impression materials and the tray than the fleece of the newly developed tray without its retentive "lips". Clinical implication: Within the limitations of this in-vitro study, tray adhesive provided relatively high retention compared to other variables tested.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact firstname.lastname@example.org.Thesis (MSD) --Boston University, Goldman School of Dental Medicine, 2009 (Department of Restorative Sciences and Biomaterials).Includes bibliographic references: leaves 52-55.
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