Comparative Evaluation of Gingival Displacement Achieved by Mechanical and Chemical Retraction Systems Using Digital and Conventional Impression Techniques: An In Vivo Pilot Study.

Abstract

Introduction: The success of fixed prosthodontic treatment ultimately depends on how accurately the final impression captures the prepared tooth, because even minor errors can compromise the fit, function, and longevity of the restoration. Achieving this precision requires careful management of the gingival tissues, particularly around the cervical margin, so that the finish line is clearly exposed and accurately recorded. Gingival displacement—whether achieved through mechanical means such as retraction cords or through chemical agents that provide haemostasis and tissue shrinkage—plays a critical role in creating the necessary access while preserving periodontal health. Although digital impression systems have reduced many limitations associated with conventional materials, the need for effective gingival retraction remains unchanged for precise marginal reproduction. In this context, evaluating and comparing mechanical and chemical retraction methods in both digital and conventional workflows is essential to identify a technique that provides adequate displacement with minimal tissue trauma, ultimately supporting predictable, biologically sound, and long-lasting prosthodontic outcomes.

Objectives: Evaluation of lateral gingival displacement in subjects after using Non impregnated gingival retraction cord (00); Cord (00) impregnated with 25% aluminum chloride; Cord (00) impregnated with 20% ferric sulfate

Methods: Ten healthy individuals in the 20–30 age range were chosen. To reduce tissue fatigue, gingival retraction was performed on the left maxillary first molar using a Latin block design by three gingival displacement materials (Mechanical, Ferric sulphate, Aluminium chloride). Both traditional and digital techniques were used to create impressions. For traditional impressions, casts were poured, dies were sectioned and gingival displacement was measured by die sectioning method. For digital impressions, intraoral scans were done and amount of gingival retraction was measured by Exo Cad Software. SPSS version 21.0 was used to measure and statistically analyse the horizontal gingival displacement.

Results: When compared to other retraction systems, ferric sulphate had the largest mean horizontal gingival displacement. The Shapiro-Wilk test revealed that the data had a normal distribution (p = 0.466). Group differences were found to be statistically significant using a one-way ANOVA.

Conclusions: Ferric sulphate showed better gingival displacement than other displacement systems used. Accurate and repeatable displacement value measurements were made possible by digital impression techniques.