A comparison of pressure generated by cordless gingival displacement techniques.
BACKGROUND
Handling properties of cordless gingival displacement materials is not well understood, resulting in incorrect use. Insufficient displacement of the gingival margin may result in a poor impression.


OBJECTIVE
This study investigated the pressure generated by a cordless displacement paste with respect to different techniques.


METHODS
Two chambers with dimensions of 5 × 5 × 2 mm were made from Type IV stone and silicone material to simulate a rigid and elastic environment. A pressure gage was embedded into the wall of the chamber, and a paste material (Expasyl) was injected into the different chambers. The final pressures generated by the Expasyl were recorded by Chart 5 software and Power Lab system. This was repeated by using a displacement cord (KnitTrax) as a control for the study. The different loading methods for the Expasyl material were compared with 1-way ANOVA (α=.05).


RESULTS
The mean pressure generated during placement of the Expasyl paste material in the silicone chamber was 143 kPa, which is significantly lower (P=.001) than the pressure generated by the KnitTrax cord (5396 kPa). Manipulating Expasyl after placement resulted in a pressure reduction of 73% in the stone chamber and 29% in the silicone chamber.


CONCLUSIONS
Pressure generated by Expasyl is minimal compared to the cord system. Pressure is generated during the injection of the Expasyl, and subsequent manipulation reduced the final pressure. Handheld and motorized delivery guns produce similar pressure, but the motorized gun was found to have a more constant pressure delivery.
Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, Dunedin, New Zealand. vincent.bennani@stonebow.otago.ac.nz
Vincent
V
Bennani
John M
JM
Aarts
Li Hong
LH
He
D002133:Calcium Sulfate / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D004548:Elasticity; D005881:Gingiva / Q000033:anatomy & histology*; D060745:Gingival Retraction Techniques / Q000295:instrumentation; D006801:Humans; D007267:Injections; D008422:Materials Testing; D003765:Models, Dental; D011312:Pressure; D012828:Silicones / Q000737:chemistry; D014160:Transducers, Pressure
D003764:Dental Materials; D012828:Silicones; D002133:Calcium Sulfate