JOURNAL OF PROSTHETIC DENTISTRY THE

Vol. 100 No. 5      NOVEMBER - 2008

ISSN: 0022-3913      UBIC: 171

SUMMARY

Statement of problem. Oral mucosa can distort under impressions. To reduce or control mucosal distortion, modem impression techniques aim to reduce or control the impression pressure. If changing seating velocity significantly changes pressure, then this effect should be considered for clinical impressions of mucosa. Purpose. The purpose of this study was to investigate the relationship between seating velocity and pressure generation during simulated impressions. Material and methods. Vinyl polysiloxane impression material (Express) was placed between 2 approximating discs in a universal testing machine. The velocity at which the discs approximated was varied. The 7 selected seating velocities were 0.75 mm/s, 1 mm/s, 1.25 mm/s, 1.5 mm/s, 2 mm/s, 2.5 mm/s, and 3 mm/s. The pressure generated at the center of the disk was recorded. Five separate recordings were made for each velocity. One-way ANOVA and post hoc tests (Tukey 3 and DunnettT3) (α=.05) were used to evaluate peak pressure data at each velocity. Results. The mean (SD) of the recorded pressures for each velocity were 239 (6.67) KPa, 273 (14.89) KPa, 347 (11.97) KPa, 425 (19.73) KPa, 487 (17.84) KPa, 547 (21.25) KPa, and 624 (32.60) KPa, respectively. As the velocity increased, there was a significant (P<.001) concurrent increase in peak pressure. Conclusions. In this in vitro experiment, changing the velocity of seating had a significant effect on the peak pressure produced during simulated impressions. (J Prosthet Dent 2008; 100:384-389)

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