Elastic Recovery of 3D-Printed and Polyvinyl Siloxane Gingival Mask Materials: An In Vitro Study

Background: Gingival masks are essential components of implant working models because they reproduce peri-implant soft tissue contours and support the evaluation of emergence profile morphology during prosthetic fabrication. During routine laboratory procedures, these materials may be temporarily displaced by customized healing abutments, provisional restorations, or definitive prostheses. Therefore, their ability to recover after deformation is clinically relevant. This in vitro study aimed to compare the elastic recovery of additively manufactured and polyvinyl siloxane-based gingival mask materials using three-dimensional deviation analysis and mechanical evaluation.
Materials and Methods: Sixteen implant working models were fabricated and divided into two groups according to the gingival mask material: additively manufactured resin and polyvinyl siloxane-based material, with eight specimens in each group. A customized healing abutment was inserted for 10 minutes to simulate routine laboratory procedures, followed by a 10-minute recovery period. Baseline and post-recovery scans were obtained using a laboratory scanner. Dimensional changes were analyzed by calculating root mean square deviation values within a predefined region of interest. Mechanical assessment of elastic recovery was performed using standardized disc specimens tested with a universal hybrid rheometer under displacement-controlled conditions. Data were analyzed using the Mann-Whitney U test at a significance level of 0.05.
Results: Following the recovery period, the investigated additively manufactured gingival mask material demonstrated significantly lower RMS deviation values than the investigated polyvinyl siloxane-based material (median [Q1-Q3]: 0.051 [0.046-0.057] mm versus 0.081 [0.077-0.087] mm; Mann-Whitney U = 0.00, exact p<.001). In the mechanical assessment, the investigated additively manufactured resin demonstrated significantly greater elastic recovery than the PVS-based material (median [Q1-Q3]: 98.63% [98.06-98.69%] versus 97.39% [96.93-97.56%]; Mann-Whitney U = 4.00, exact p=.002). The two experimental approaches yielded concordant findings under the conditions of the present study.
Conclusions: Within the limitations of this in vitro study, the investigated additively manufactured gingival mask material exhibited greater short-term elastic recovery than the investigated PVS-based material under the tested conditions. Because only one material from each category was evaluated, the findings are material- and protocol-specific and should not be generalized to other gingival mask materials. Further studies incorporating repeated loading and artificial aging are required to determine the clinical relevance of the observed differences.