An Evaluation of the Efficacy of Different Gingival Retraction Materials on the Gingival Tissue Displacement (A Comparative In Vivo Study)


Background: An accurate adaptation of the crown to the finish line is essential to minimize cement dissolution and topreserve periodontium in fixed partial denture cases. An accurate adaptation of crown is possible only whenpreparation details are captured adequately in the impression and transferred to cast. For these reasons, gingivaldisplacement is necessary to capture subgingival preparation details.The aim of the present study is to measure invivo the horizontal displacement of the gingival sulcus obtained by using three new cordless retraction materials(Magic Foam Cord®, Racegel and Astringent Retraction Paste) in comparison to medicated retraction cord.Materials and method: Thirty-two patients requiring porcelain fused to metal fixed partial denture for replacement ofa missing maxillary posterior tooth (either one of thepremolars or the first molar). The patients are randomly dividedinto four groups of eight patients each according to the type of gingival retraction material used as follows: Group I:Medicated retraction cord (racemic epinephrine hydrochloride 0.3 ± 0.2 mg per inch of cord, #00), Group II: MagicFoam Cord® (expanding polyvinyl siloxane), Group III: Racegel (25% aluminum chloride gel) and Group IV: AstringentRetraction Paste (15% aluminum chloride paste). Three depth orientation grooves were prepared in the buccal andpalatal surfaces of a maxillary premolar parallel with the long axis of the tooth, extending from the middle third to thegingival third with the level of the free gingiva using a flat-ended diamond fissure bur. Impression of the gingivalsulcus was then made using monophase polyether impression material (Impregum™ Penta™ Soft, 3M ESPE, Germany),before and after gingival retraction with either of the aforementioned gingival retraction materials. The sulcus width,before and after gingival retraction was measured on the master cast (in μm), after its sectioning longitudinallybucco-palatally at the middle of the prepared grooves using a rotary diamond disc. The measurement carried outby using digital microscope (Dino-Lite)at a magnification of 230X. The horizontal gingival displacement (the distancefrom the end of each prepared groove to the crest of the gingiva) measured by subtracting the gingival sulcus widthafter retraction from that before retraction.Results: The findings of the present study showed that the highest mean of horizontal gingival displacement isrecorded by Group IV (Astringent Retraction Paste) (250.7900 μm), whereas the lowest mean of horizontal gingivaldisplacement is recorded by Group III (Racegel) (78.0988 μm). One-way ANOVA test showed statistically highlysignificant differences among groups (p< 0.01). Least Significant Difference test (LSD test) was also used to makemultiple comparisons among groups and revealed a statistically highly significant difference between each twogroups (p< 0.01).Conclusion: The two new gingival retraction pastes (Astringent Retraction Paste and Magic Foam Cord®) could beused for gingival retraction as alternatives to medicated retraction cord. They offer advantages of simplifiedplacement technique and shorter application time with greater gingival retraction. Meanwhile, the use of Racegelalone is not recommended for gingival retraction since it provides the least gingival displacement.