The vibratory characteristics of obturators with different bulb height and form designs.

The aim of the present study was to investigate whether the vibratory characteristics of obturator prostheses are affected by bulb design, i.e.: the hollow or buccal flange type, and different lateral and medial bulb heights. Buccal flange and hollow bulb obturator prostheses were fabricated with two different lateral bulb wall heights and two different medial bulb wall heights. Ultimately, eight obturator prostheses were prepared for evaluation of their vibratory characteristics. The frequency-response functions were recorded on an FFT analyzer to identify their vibratory characteristics. A transient response simulation was carried out in which an impact was applied to the non-defect side. The decay rate, damping time and maximum amplitude of the retainers were statistically analysed by anova with Scheffé's test (P < 0.05). The decay rate of every buccal flange type was higher and damping time was shorter than those of every hollow type, except between a pair with low lateral and low medial bulb walls. The maximum amplitude values of four obturators with low medial bulb walls were significantly lower than those of four obturators with high medial walls. The buccal flange obturator prosthesis with high lateral and low medial walls showed the maximum decay rate and the minimum amplitude of the retainers on molars. Vibration analysis suggests that a buccal flange obturator prosthesis with high lateral and low medial walls is preferable.