Study On Pressures On Anterior Area Of Edentulous Analog Generated By Different Impression Materials And Customized Trays

ObjectivesThe aim of this study evaluated the pressures exerted under a simulated maxillary edentulous analog by different impression materials and differently designed custom trays.Materials and methods1:Calibration of a FSR pressure sensorAfter a FSR pressure sensor (Arduino, Interlink Electronic Inc, USA) had been put between two cylinders with diameter of 5 mm was under universal testing machine (Zwick/Roell, Bz2.5/UNls, Germany) for calibration of the pressure sensor, the pressures exerted by the testing machine and the corresponding output voltage value produced by the pressure sensor were recorded, respectively. The procedures were repeated twice.2:Different customized traysThe type II resin (Shanghai Zhangjiang biomaterial Ltd, Shanghai, China, Lot:100620) was used to fabricate four types of customized trays. The customized tray were prepared with no escape hole/no relief, escape hole/no relief, no escape hole/relief, or escape hole/relief. To customized trays with escape holes, a big hole with diameter of 6 mm was located lcm behind the incisive papilla; small holes with diameter of 2mm were evenly distributed in the anterior area of the analog and the distances between holes were about 4-7mm. To customized trays with relief, a relief spacer of about 1.7 mm was between maxillary edentulous analog and customized trays.3:Impression taken and Pressures monitoredA FSR pressure sensor was placed at anterior area of maxillary edentulous analog. Three impression materials were heavy body, light body vinyl polysiloxane (3M ESPE AG, Seefeld, Germany) and alginate impression material (Dentsply, Tianjin, China) were used in this study. After one of three impression materials had been loaded onto one of four customized trays, the tray was being seated about for 20 s under hand pressure and maintained in the position till the impression material was set. The procedures were performed by the same researcher using the same seating velocity and ways. Peak pressures and end pressures were recorded at interval time of 10 s. The procedures were repeated three times.ResultsResults were analyzed using factorial AVONA and Turkey HSD test. Significant differences were found among the peak pressures produced by different impression materials and different customized trays (p<0.01). Heavy body vinyl polysiloxane and alginate produced significant higher peak pressure than light body vinyl polysiloxane (p<0.01). The customized tray with no escape hole/no relief produced the highest peak pressure than the others (p<0.01). The presence of escape hole and relief significant decreased the peak pressure (p<0.01). The customized tray with no escape hole/relief resulted in much lower peak pressure than the tray with escape hole/on relief (p<0.01). No significant different peak pressures were found between the tray with no escape hole/relief and the tray with escape hole/relief (p>0.05). No significant different end pressures were found among the different impression materials and different customized trays (p>0.05).Conclusions1:Heavy body vinyl polysiloxane and alginate impression material produced significantly higher peak pressures than light body vinyl polysiloxane.2:Customized trays with escape hole/relief and with no escape hole/relief resulted in lower peak pressures than the others.3:The heavy body vinyl polysiloxane used with no escape hole/no relief tray produced the highest peak pressures, while light body vinyl polysiloxane used with escape hole/ relief tray resulted in the lowest peak pressures.4. The end pressures were not significantly different among the different impression materials and different customized trays.