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Published on: April 29, 2014
The efficacy of different gingival displacement methods for definitive digital impressions: A randomized controlled
Mohamed F El Ashry1, Sanaa H Abdelkader2, Ihab A Hammad2
1Assistant Lecturer, Division of Fixed Prosthodontics, Department of Conservative Dentistry, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
Objectives:
The aim was to assess the amount of gingival displacement in digital impressions and gingival height loss up to one month after cementation of the final crowns.
Methods:
Thirty-two participants with maxillary premolars indicated for full crown restorations were randomly allocated into four groups according to the gingival displacement method: Retraction cord with astringent (RCA), Cordless paste with astringent (EXP) (Expasyl; Acteon LTD), Cordless paste without astringent (MF) (Magic FoamCord; Coltenewaldent AG) and Laser troughing (LT). Preoperative digital impressions were made, followed by full crown preparation and then application of the gingival displacement methods. The prepared teeth were scanned immediately after gingival displacement procedures. Horizontal and vertical gingival displacement and sulcus depth were measured in the intraoral scans. After the final cementation of the crowns, gingival height loss was assessed on the 7th,15th, and 30th day timepoints. Data were analyzed using One-way ANOVA and Two-way Repeated Measures ANOVA, followed by multiple pairwise comparisons using Bonferroni adjusted significance level.
Results:
Group RCA exhibited a statistically significant superior horizontal and vertical displacement and sulcus depth compared to the other groups followed by Magic FoamCord (P < .05). The horizontal and vertical displacement values for Group RCA were 0.66 ± 0.04 mm and 0.66 ± 0.008 mm, respectively. In contrast, for the remaining groups, horizontal displacement ranged from 0.25 mm to 0.38 mm, while vertical displacement ranged from 0.24 mm to 0.48 mm. After one month, RCA recorded the highest statistically significant loss in gingival height compared to all other groups (P < .001).
Conclusions:
Vertical and horizontal displacement were most pronounced with impregnated cords, followed by Magic FoamCord, and were less significant with Expasyl and Diode laser. The use of an impregnated cord resulted in a greater loss of gingival height after one month.
Clinical Significance:
For capturing the finish line in digital impressions for subgingival preparations, the use of impregnated retraction cords or cordless retraction paste without astringent in conjunction with compression caps proved effective in achieving displacement of gingival tissues. However, traumatic pressure should be avoided with impregnated cords to minimize gingival height loss.
