Dental Condition as A Factor Modifying the Transmission of the Sound Vibration in the Skull Bones

Abstract

Dental deficiencies coexist with hearing loss, and dental treatment can improve hearing acuity. To prove that different dentition affects the transmission of acoustic vibrations through bone conduction, we prepared six dry human skulls to reconstruct teeth and soft tissues. We measured the transmission of vibrations from the maxilla to the cochlea, in the toothless jaw (TJ), jaw with lateral defects with frame dentures (FD), toothless jaw with complete dentures (CD), and jaw with reconstructed dentition (RD). Each skull was flexibly suspended. The maxilla was stimulated with the bone vibrator Radioear B71. The vibrations of the pyramid were measured perpendicularly using the Polytec PSV-400-M2 scanning vibrometer. Characteristics of frequencies differed simultaneously on the left (l) and right (r) side of each skull. In all states (from 234 Hz to 5 kHz), we identified 10–21 resonant (R) and 9–21 antiresonant (AR) frequencies unilaterally (+/− 5%). In about 30% of cases, they were each time inconsistent with the “physiological” state-RD. In the 500 Hz–2 kHz frequency range (necessary for understanding speech), the effective vibrations velocities vRMS (mm/s) near cochlea were significantly lower in RD than in tree states, where (depending on the dentures) the least energy reached cochlea in FD and the most in TJ.