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Attuali orientamenti sulle restaurazioni in oro-ceramica:il piano di trattamento. Università degli Studi di Pavia.
Dimensional accuracy of resultant casts made by a monophase, one-step and two-step, and a novel two-step putty/light-body impression technique: an in vitro study.
Dimensional accuracy when making impressions is crucial to the quality of fixed prosthodontic treatment, and the impression technique is a critical factor affecting this accuracy.
PURPOSE:
The purpose of this in vitro study was to compare the dimensional accuracy of a monophase, 1- and 2-step putty/light-body, and a novel 2-step injection impression technique.
MATERIAL AND METHODS:
A stainless steel model with 2 abutment preparations was fabricated, and impressions were made 15 times with each technique. All impressions were made with an addition-reaction silicone impression material (Aquasil) and a stock perforated metal tray. The monophase impressions were made with regular body material. The 1-step putty/light-body impressions were made with simultaneous use of putty and light-body materials. The 2-step putty/light-body impressions were made with 2-mm-thick resin-prefabricated copings. The 2-step injection impressions were made with simultaneous use of putty and light-body materials. In this injection technique, after removing the preliminary impression, a hole was made through the polymerized material at each abutment edge, to coincide with holes present in the stock trays. Extra-light-body material was then added to the preliminary impression and further injected through the hole after reinsertion of the preliminary impression on the stainless steel model. The accuracy of the 4 different impression techniques was assessed by measuring 3 dimensions (intra- and interabutment) (5-mum accuracy) on stone casts poured from the impressions of the stainless steel model. The data were analyzed by 1-way ANOVA and Student-Newman-Keuls test (alpha=.05).
RESULTS:
The stone dies obtained with all the techniques had significantly larger dimensions as compared to those of the stainless steel model (P<.01). The order for highest to lowest deviation from the stainless steel model was: monophase, 1-step putty/light body, 2-step putty/light body, and 2-step injection. Significant differences among all of the groups for both absolute dimensions of the stone dies, and their percent deviations from the stainless steel model (P<.01), were noted.
CONCLUSIONS:
The 2-step putty/light-body and 2-step injection techniques were the most dimensionally accurate impression methods in terms of resultant casts
Sostituzione protesica di un incisivo centrale ad un giovane paziente con l'ausilio dell'implantologia.
Sostituzione protesica di un incisivo centrale ad un giovane paziente con l'ausilio dell'implantologia.
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