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Purpose: To investigate, in vitro, the dimensional accuracy of two impression techniques (squared impression copings and squared impression copings sandblasted and coated with impression adhesive) made of vinyl polysiloxane and polyether impression materials. Materials and Methods: A master cast (control group) with four parallel implant abutment analogs, a passive framework, and a custom aluminum tray was fabricated. Four groups (n = 5 each group) were tested: squared Impregum (SI), squared Express (SE), sandblasted adhesive squared Impregum (ASI), and sandblasted adhesive squared Express (ASE). The measurement method employed was just one titanium screw tightened to the framework. A stereomicroscope was used to evaluate the fit of the framework by measuring the size of the gap between the abutment and the framework. The results were analyzed statistically. Results: The mean values for the abutment/framework interface gaps were: master cast, 31.63 Mum (SD 2.16); SI, 38.03 Mum (SD 9.29); ASI, 46.80 Mum (SD 8.47); SE, 151.21 Mum (SD 22.79); and ASE, 136.59 Mum (SD 29.80). No significant difference was detected between the SI or ASI techniques and the master cast. No significant difference was detected between the SE and ASE techniques. Conclusion: Within the limitations of this study, it can be concluded that Impregum Soft medium consistency was the best impression material and the impression technique did not influence the accuracy of the stone casts. Int J Oral Maxillofac Implants 2010;25:771-776. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study compared the dimensional accuracy of a stone index and of two impression techniques (squared impression copings and modified squared impression copings) for implant-supported prostheses. Materials and Methods: A master cast with four parallel implant-abutment analogs and a passive framework were fabricated. Vinyl polysiloxane impression material was used for all impressions with a metal stock tray. Three groups of impressions were tested (n = 5): index (I), squared (S), and modified squared (MS). The measurement method employed was just one titanium screw tightened to the framework. The measurements (60 gap values) were analyzed using software that received the images from a video camera coupled to a stereomicroscope at 3100 magnification. The results were evaluated statistically (analysis of variance, Holm-Sidak method, a = .05). Results: The mean abutment/framework interface gaps were: master cast = 31.63 Mum; group I = 45.25 Mum; group S = 96.14 Mum; group MS = 51.20 Mum. No significant difference was detected among the index and modified squared techniques (P = .05). Conclusion: Under the limitations of this study, the techniques modified squared and index generated more accurate casts than the squared technique. Int J Oral Maxillofac Implants 2010;25:715-721. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this in vitro study was to compare the dimensional accuracy of a stone index and of 3 impression techniques (tapered impression copings, squared impression copings, and squared impression copings splinted with acrylic resin) associated with 3 pouring techniques (conventional, pouring using latex tubes fitted onto analogs, and pouring after joining the analogs with acrylic resin) for implant-supported prostheses. MATERIALS AND METHODS: A mandibular brass cast with 4 stainless steel implant-abutment analogs, a framework, and 2 aluminum custom trays were fabricated. Polyether impression material was used for all impressions. Ten groups were formed (a control group and 9 test groups formed by combining each pouring technique and impression technique). Five casts were made per group for a total of 50 casts and 200 gap values (1 gap value for each implant-abutment analog). RESULTS: The mean gap value with the index technique was 27.07 microm. With the conventional pouring technique, the mean gap values were 116.97 microm for the tapered group, 57.84 microm for the squared group, and 73.17 microm for the squared splinted group. With pouring using latex tubes, the mean gap values were 65.69 microm for the tapered group, 38.03 microm for the squared group, and 82.47 microm for the squared splinted group. With pouring after joining the analogs with acrylic resin, the mean gap values were 141.12 microm for the tapered group, 74.19 microm for the squared group, and 104.67 microm for the squared splinted group. No significant difference was detected among Index, square/latex techniques, and master cast (P >.05). CONCLUSIONS: The most accurate impression technique utilized squared copings. The most accurate pouring technique for making the impression with tapered or squared copings utilized latex tubes. The pouring did not influence the accuracy of the stone casts when using splinted squared impression copings. Either the index technique or the use of squared coping combined with the latex-tube pouring technique are preferred methods for making implant-supported fixed restorations with dimensional accuracy. [ABSTRACT FROM AUTHOR]