Abstract
Background: This study was aimed at comparing the accuracy of impressions of a reference typodont (RT) reproducing a totally edentulous maxilla made with three impression materials: polysulfide, polyether, and polyvinyl-siloxane. Methods: The RT was scanned using a desktop scanner, obtaining a reference scan. Ten impressions for each of the three tested materials were made using a mechanical device with a standardized and consistent modality. A laboratory scanner performed the digitization of each impression. We produced digital models by processing “in reverse” the scans of the physical impressions using a dedicated software, obtaining three groups (n = 10), respectively. The groups were titled: “polysulfide,” “polyvinyl-siloxane,” and “polyether”. The scans in .stl format were imported into Geomagic Control X and then compared to RT to evaluate the accuracy of each scan by calculating trueness and precision in µm. Recorded data were subjected to descriptive statistics. Results: Trueness (arithmetic proximity) values (95%CI) were: polysulfide = 249.9 (121.3–378.5), polyvinyl-siloxane = 216.8 (123.1–310.6), polyether = 291.1 (219.9–362.3). Precision values (95% CI) were: polysulfide = 261.9 (108.8–415), polyvinyl-siloxane = 209.4 (111.9–306.8), polyether = 283 (227.9–338.1). Statistically significant differences were not detected between the means of the experimental groups, both for trueness and precision. Conclusions: The accuracy of the scans obtained from polyvinyl-siloxane, polysulfide, and polyether impressions can be considered comparable in a fully edentulous maxilla.
Highlights
Different impression materials have been suggested over time, such as polysulfide, polyvinyl siloxane, irreversible hydrocolloids, zinc-oxide eugenol pastes, and polyethers [7,12,13]
The protocol for a digitally produced complete denture starts with the digitization of an edentulous arch that can be performed using intraoral or laboratory scanners
Multiple comparisons were not performed because the overall test did not show significant differences across samples
Summary
Edentulism, defined as “the absence or complete loss of all-natural dentition (teeth)” [1], is a debilitating and irreversible condition [2], considered as the “final marker of disease burden for oral health” [3].To date, the oldest and most widespread treatment of total edentulism is the conventional complete denture [4,5,6], in which the first operative step is represented by a correct impression procedure [7].The procedure can be accomplished using different techniques: mucostatic [8], mucocompressive, selective pressure [9], functional [10], and neutral zone impression [11]. The oldest and most widespread treatment of total edentulism is the conventional complete denture [4,5,6], in which the first operative step is represented by a correct impression procedure [7]. Different impression materials have been suggested over time, such as polysulfide, polyvinyl siloxane, irreversible hydrocolloids, zinc-oxide eugenol pastes, and polyethers [7,12,13]. The protocol for a digitally produced complete denture starts with the digitization of an edentulous arch that can be performed using intraoral or laboratory scanners. This study was aimed at comparing the accuracy of impressions of a reference typodont (RT) reproducing a totally edentulous maxilla made with three impression materials: polysulfide, polyether, and polyvinyl-siloxane. A laboratory scanner performed the digitization of each impression.
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