ABSTRACT
This study used modal analysis to evaluate the vibratory properties of cast obturator prostheses fitted with soft lining material. Three types of buccal flange bulbs were prepared: a resin (R) type; a 2 mm-thickness relined (RM) type; and a type fully relined with MOLTENO, (M) type. A vibration generator excited the obturator, while a Laser-Doppler Vibrometer detected the vibrations at specified measurement points. Both the excitation and response signals were sent to an FFT analyzer, which calculated the frequency response functions. Then, using DAMPCAL simulation software, the decay rates and the maximum amplitudes of rest and clasp parts were calculated. Statistical analysis was performed by means of one-way ANOVA with Fisher's PLSD test. The results indicated that for impacts simulated on both the defective and non-defective sides, the R type showed a significantly higher decay rate than did the other samples (p<0.0001). When impacts were directed at the non-defective side, the R and M types showed significantly smaller maximum amplitude values than did the RM type (p<0.0001). Only the M type, however, showed significantly smaller values when impacts were directed at the defective side (p<0.0001).
