Axel D. Haubold

Carbon-coated subperiosteal dental implants for fixed and movable prostheses

Subperiosteal dental implants are not intended to replace conventional dentistry but provide an alternative method of treatment for the patient who cannot otherwise tolerate a dental prosthesis. Success can be achieved in the maxillae and in the mandible without the risk of serious complications. There are good prospects for a long-term favorable prognosis when appropriate surgical and prosthodontic criteria are observed.

Vapor-deposited carbon-coated tooth root implants: preliminary evaluation of a stylized tooth implant system in dogs.

The results of this preliminary evaluation of a tooth implant model combining a stylized tooth root design and a thin, highly biocompatible microporous carbon coating, although tentative, add support to the feasibility of developing a statisfactory system for the immediate replacement of selected teeth in healthy bone.

Preliminary Histologic Evaluation of A Biocompatible Mesh for Tracheal Reconstruction

The purpose of this study was to evaluate a porous Dacron - urethane mesh tracheal prosthesis in large dogs with surgically created discontinuous defects of the cervical trachea. Some protheses were carbon coated in an attempt to improve biocompatibility. Histology was performed on 2 dogs. The mucosa regenerated entirely covering the prosthesis. Respiratory epithelium was formed over a large central portion of the tracheas.

Surface Chemistry of Pyrolytic Carbons for use in Mechanical Heart Valves

Pyrolytic caibon (PYC) of the type first developed at General Atomic (1) in the 1960s is a synthetic material that provokes a minimal thrombogenic response. This ability for blood to tolerate PYC contact, more so than any other synthetic material, along with superior mechanical durability, led to the successful application of PYC in long term blood contact devices such äs mechanical heart valves (1). However, following more than 20 years of clinical experience with a follow-up in excessof 10 million patientyears for implanted PYC heart valve components (2), the exact mechanism or particular properties that provides the minimal thrombogenic response of PYC is still not well understood (3). This lack of understanding for minimal thrombogenic response is particularly important today because other carbon materials have been either proposed or introduced into clinical use for long term implant (4). These materials include copies of fluidized-bed derived caibons such äs the material prepared by Sorin (Italy), Uglesitals (Russia) and Carbosystal (Israel). These materials are allotropic forms of carbon that vary in crystallographic stmcture within a continuum ranging from the hexagonal close-packed graphite stmcture to the tetrahydral diamond stnicture. Allotropic carbons structures are disordered or turbostatic, consisting of a mix of graphite-like and diamond-like characterislics and tend to be amorphous rather than crystalline. Such variability in stnicture produces very different mechanical properties in these carbon materials (1). It is important to recognizethat these materials are very different and that it is not valid to extrapolatebiocompatiblity properties based merely on the fact that the materials are carbonaceous. The objective of this study was to compare the surface chemistry of newer forms of carbon proposed for clinical use to the traditional carbon materials with demonstrated biocompatibility.

Gaseous Flow Through Thin Carbon Films

Thin carbon films, when used as coatings on prosthetic devices, must be a barrier to gases and physiological fluids. Using CO2 at room temperature, the gas permeability of carbon films ranging in thickness from about 200 to 500A was measured. The average permeability constant of 21 carbon films was determined to be 1.91 (+/- 1.02) x 10(-12) cm3-cm/cm2-sec-mmHg. This value is quite comparable to or smaller than that of nuclear graphites, which are considered to be impermeable to gases.

Design and Materials Evaluation for A Dental Implant System: Carbon Coated Tooth Replicas

32 carbon coated tooth replicas were implanted in the jaws of 8 mongrel dogs for periods ranging from 3 months to 2 years. Fourteen of 16 molor implants and 10 of 16 premolar implants had 0.5 min. of mobility or less. Histology of specimens from 4 dogs sacrificed at 3 months showed new bone directly in contact with the implant surface.