OBJECTIVE: Conduct a randomized, controlled, prospective clinical trial to compare success rates of polyvinylsiloxane and polyether impression systems.
METHODS: Dual-viscosity systems were a polyvinylsiloxane (Dentsply-Caulk, Aquasil Ultra Monophase/Aquasil Ultra XLV) and a polyether (3M-ESPE, Impregum Penta Soft HB/Impregum Garant Soft LB). Only the first impression of a case was evaluated by a prosthodontist with the dental laboratory quality control team. Primary outcome was impression success or failure using developed criteria. Fifty senior dental students participated where their sequence of impression systems alternated for each new case. A full-arch perforated plastic (COE-Disposable Tray) or a plastic dual-arch impression tray (Tri-Bite, Direct Dental) was used based on selection guidelines. To compare first impression success rates, a Wald test was used based on a logistic regression fitted using the method of generalized estimating equations.
RESULTS: Inter-rater agreement for detecting critical defects was 92% (finish line) and 94% (axial surface). 191 impressions were evaluated and the success rate and confidence interval for each system is given below.
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First Impression |
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Impression System |
Number |
Success Rate |
95% CI |
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Polyvinylsiloxane |
n=103 |
61% |
50% – 71% |
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Polyether |
n=88 |
54% |
43% – 65% |
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CONCLUSION: Statistically, a difference could not be shown for rates of success between these two impression systems, thus one system is not superior to the other. However a trend was evident with 7% greater impression success in the dental school environment when the polyvinylsiloxane system was used. Success rates may differ and are likely higher with experienced practitioners. Supported by Dentsply Caulk.