RESUMEN
Aim:Surface detail reproduction and dimensional stability of Poly vinyl siloxane impression material is most important property for final success of fixed partial denture. Purpose: This study was carried out to determine the effect of retraction cord medicaments (epinephrine, aluminum chloride and ferric sulfate) on the dimensional accuracy and surface detail reproduction of polyvinyl siloxane impressions. Method and materials: Polyvinyl siloxane impressions were made of standardized metal dies (American Dental Association [ADA] specification No. 19) and was treated with 1 of the 3 retraction cord medicaments. Dimensional accuracy was evaluated by comparing the average length of a line in the impressions to the standard die. Surface detail reproduction was evaluated by viewing the impressions under low-angle illumination at 10X magnification. Reproduction was considered satisfactory if 2 of 3 horizontal lines were reproduced continuously. The dies were also evaluated under the microscope before the impression was made. Results: The medicaments did not significantly affect the dimensional stability. Aluminum chloride and ferric sulfate had an adverse effect on surface detail reproduction. Epinephrine had no effect. Discussion: The changes in dimensional accuracy were within ADA guidelines, the surface detail reproduction was modified such that the impression would be considered clinically unacceptable. For optimal results, care must be taken to remove all traces of these retraction cord medicaments prior to recording of a polyvinyl siloxane impression.
RESUMEN
Wettability of addition silicone impression material is very important property for making an accurate restoration. This study examined the impression quality in clinical condition and the wet tability of impression and die material. Four commercially available addition silicone impression material (Express, Examix, Contrast, Perfect) and three die materials (Die-Keen, Vel-Mix, FujiRock) were studied. A total of 50 putty/wash and heavy body/wash impressions of wet intact permanent molar teeth were examined for definition of the gingival sulcus reproduction and then classified in quality ranking. The percentage of the sulcus reproduction ability of each material was calculated from the sulcus depths of cross-sectioned epoxy resin casts from the impressions and clinically measured sulcus depths. The same impression materials were used to produce 3 groups of die stone casts form void entrapment die had been exposed to milk. Voids in the impression. body and stone casts were counted under a stereoscopic microscope. From the experiment, the following results were obtained 1. Sulcus reproduction ability of additional silicone impression material were diminished in order of Express, Examix, Perfect, Contrast. The significant difference was found between Perfect and other material. Heavy body/wash combination was superior to putty/wash method in Perfect impression material. 2. In direct observation, bontrast showed least void in impression body but correlations were not found between sulcus reproduction and void production. 3. In void entrapment laboratory test, wettability were diminished in order of Examix, Contrast, Express, Perfect. Clinical impression recording seems not to correlate with laboratory test. 4. The wettability of die material to impression material was not different in Express, Examix, Contrast. But, in Perfect, Die-Keen had superior wettability to others.