Vitreous carbon: a new material for middle ear ventilation tubes

Area of Science:

• Biomaterials Science
• Otolaryngology
• Medical Device Engineering

Background:

• Synthetic allotropic carbons, particularly vitreous carbons, have a long history of use as biomedical implants.
• Vitreous carbons exhibit favorable biocompatibility characteristics, making them candidates for various medical applications.

Purpose of the Study:

• To evaluate the middle ear compatibility of Sigradur, a type of vitreous carbon, in a preclinical animal model.
• To assess the suitability of Sigradur for different middle ear implant applications, specifically ventilation tubes and ossicular replacement prostheses.

Main Methods:

• Implantation of Sigradur material in the mastoid bulla of gerbils for periods ranging from 1 to 13 months.
• Histological and electron-microscopic examination of the middle ear tissues to assess biocompatibility and material integration.
• Clinical application of carbon ventilation tubes in 38 human patients.

Main Results:

• Light and electron microscopy revealed good middle ear tolerance to Sigradur, especially with unmodelled surfaces.
• Animal experiments indicated suitability for ventilation tubes but less ideal properties for ossicular replacement prostheses due to surface characteristics.
• Clinical use of carbon ventilation tubes in 38 patients yielded excellent results, attributed to biocompatibility, surface properties, and low weight.

Conclusions:

• Sigradur demonstrates excellent biocompatibility and tolerance within the middle ear environment.
• The material is highly suitable for middle ear ventilation tubes, offering significant clinical advantages.
• While promising, specific surface properties may limit its application as ossicular replacement prostheses.