Comparison of Gingival Displacement using Paste Technique and Combination Technique (Cord And Paste) in Digital Impressions: A Pilot Study

Abstract

Statement of the problem: Digital impressions require a good amount of gingival displacement which can be acquired by the various displacement systems. However, a comparison between the paste and combination technique for digital impressions is lacking.

Purpose of the study: The purpose of this pilot study was to evaluate which gingival displacement system would show better gingival retraction in digital intraoral scanners.

Materials and methods: A series of four cases and eight teeth were conventionally prepared according to the guideline dimensions for PFM crowns, and allocated at random to two groups: gingival retraction paste system and retraction cord with paste or combination system. Segmental digital impressions were taken before and after gingival displacement. The STL files were then assessed in vertical dimension in the buccal and lingual aspects on a CAD superimposition software, 3D Tool. Four groups were formed: paste only on buccal aspect (PB), combination on buccal aspect (CB), paste only on lingual aspect (PL) and combination on lingual aspect (CL). The differences in the amount of gingival displacement were measured and statistically analysed. 

Results: PB and CB demonstrated no significant difference in gingival displacement (P= 0.442), whereas PL and Cl showed a significant gingival displacement (P= 0.042 or P<0.05), with paste showing better gingival displacement.

Conclusion: Within the limitations of the study, vertical gingival displacement achieved using the paste and the combination technique was equal. Additional use of a cord for gingival displacement did not provide better retraction when the intraoral scanner impression was made.