title: Comparison of pressure generated by cordless gingival displacement materials.
abstract: BACKGROUND
  Because pressure generated by a displacement cord may traumatize the gingiva, cordless gingival displacement materials are available to the clinician as atraumatic alternatives. However, whether the pressures produced by the different systems are equivalent is unclear.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the pressures generated by 4 different cordless gingival displacement materials.
  
  
  METHODS
  A chamber with a dimension of 5 × 5 × 2 mm was made from Type IV stone and silicone material to simulate a rigid and elastic environment. A pressure gauge was embedded into the wall of the chamber, and 4 materials (Expasyl, Expasyl New, 3M ESPE Astringent Retraction Paste, and Magic FoamCord) were injected into the chamber. The maximum and postinjection pressures were recorded with Chart 5 software and the Power Lab system. The pressures generated by the different materials were compared with a post hoc Mann-Whitney U test (α=.05).
  
  
  RESULTS
  The median postinjection pressures generated by Expasyl (142.2 kPa) and Expasyl New (127.6 kPa) were significantly greater than the pressures generated by 3M ESPE Astringent Retraction Paste (58.8 kPa) and Magic Foam Cord (32.8 kPa). Expasyl generated a maximum pressure of 317.4 kPa and Expasyl New of 296.6 kPa during injection, whereas 3M ESPE Astringent Retraction Paste generated 111.0 kPa, and Magic Foam Cord generated 17.8 kPa.
  
  
  CONCLUSIONS
  All cordless systems produced atraumatic pressures, with Expasyl New and Expasyl generating the highest pressures and, therefore, can be considered the most effective material.
authors: Senior Lecturer, Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand. Electronic address: vincent.bennani@stonebow.otago.ac.nz.
authors: Vincent
authors: V
authors: Bennani
authors: Graduate student, School of Dentistry, Faculty of Dentistry, University of Otago, New Zealand.
authors: Melissa
authors: M
authors: Inger
authors: Senior Teaching Fellow, Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand.
authors: John M
authors: JM
authors: Aarts
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D001252:Astringents / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004548:Elasticity; D005881:Gingiva / Q000033:anatomy & histology; D060745:Gingival Retraction Techniques / Q000295:instrumentation; D006801:Humans; D007616:Kaolin / Q000737:chemistry; D008422:Materials Testing; D008953:Models, Anatomic; D011145:Polyvinyls / Q000737:chemistry; D011312:Pressure; D012826:Silicone Elastomers / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D000538:Aluminum Silicates; D001252:Astringents; D002712:Chlorides; D003764:Dental Materials; D004129:Dimethylpolysiloxanes; D011145:Polyvinyls; D012826:Silicone Elastomers; D012833:Siloxanes; C034183:vinyl polysiloxane; D007616:Kaolin; D000077410:Aluminum Chloride; C013830:baysilon; C011934:mica