OBJECTIVETo design a tool for evaluating the sound transmission function of ossicular prosthesis and explore the impacts of ossicular prosthesis bead area and the effects of the mass of ossicular prosthesis on the sound transmission function in mechanical middle ear model.

METHODSTwo latex membranes were used to represent the tympanic membrane and oval window membrane. The ossicular prosthesis was fitted between the artificial tympanic membrane and oval window membrane during the test. Pure tune signals were used to stimulate the vibration of tympanic membrane. The vibration of oval window membrane was recorded by a laser Doppler vibrometer. The ossicular transmission function was evaluated by comparing the vibration velocities of oval window membrane. Two groups of titanium ossicular prosthesis with different head area and mass respectively were fitted into a mechanical middle ear model to evaluate their sound transmission functions.

RESULTSThe feeling threshold curve of mechanical middle ear model (MMEM) was similar to the hearing threshold curve of normal person. The transmission function of the prosthesis with small head area was better than that of prostheses with large head area at frequencies 1500-4000 Hz. The small-massed prostheses functioned better at higher frequencies and the large-massed prostheses functioned better at lower frequencies. But small-massed prostheses functioned better as a whole.

CONCLUSIONSThe MMEM was an idea tool to evaluate the transmission functions of different ossicular prostheses. Both the head area and prosthesis mass had an influence on the transmission function of ossicular prosthesis. So while designing the ossicular prosthesis or performing ossiculoplasty, both the head area and prosthesis mass should he taken into consideration.

Acoustic Impedance Tests ; Acoustics ; Ear, Middle ; anatomy & histology ; Models, Anatomic ; Ossicular Prosthesis ; Prosthesis Design

OBJECTIVETo build a digital visible model of the mandible in order to provide morphological data for image diagnosis and operation of mandible diseases.

METHODSA male adult cadaver specimen was taken for the purpose of study. A digital human databank was got after fixation, perfusion, refrigeration, embedding, section and photograph of the specimen. The thickness of each layer was 0.1 mm. To select mandible image data from chin to condyle and to draw an outline of mandible and teeth image of each layer in 2D Adobe photoshop 8.0. Finally, reconstruct 3D model of mandible was set up in Amira reconstruction software.

RESULTSA 3D model of mandible was formed accurately using of digital human data. The model was fine, visible and displayed cross-section image of mandible. The anatomical shape of nmandible and mandibular teeth were vividly reappeared in three-dimension. The location and trend of mandibular nerve canal were clearly appeared in the transparent model of mandible. The model could be revolved in 3D.

CONCLUSIONThe study got a complete and exact cross-section data. The visualization of mandible can be realized in Amira reconstruction software. The reconstituted organs can be recovered to the natural state.

Adult ; Cadaver ; Humans ; Imaging, Three-Dimensional ; Male ; Mandible ; Software ; Tooth