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 to capture finish line precisely. A clinical comparison between the paste and a combination of paste and cord technique of gingival displacement for digital impression is required. 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 (digital impression). Materials and methods: A series of four cases and eight teeth were conventionally prepared according to the guideline dimensions for porcelain fused to metal crowns, and allocated at random to two groups: gingival retraction paste system and retraction cord with paste (combination system). Segmental digital impressions were taken before and after gingival displacement. The stereolithography (STL) files were assessed in vertical dimension in the buccal and lingual aspects on a CAD superimposition software, 3D Tool. The differences in the amount of gingival displacement were measured and statistically analysed. Results: PB (paste only for buccal aspect) and CB (cord and paste for buccal aspect), demonstrated no significant difference in gingival displacement (P= 0.442), whereas PL (paste only for lingual aspect), and CL (cord and paste for the lingual aspect) 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. Keywords: Combination System, Digital Impression, Gingival Displacement, Intraoral Scanner, Retraction Paste, Vertical Displacement.