The International Journal of Oral & Maxillofacial Implants, 02/1989

The editorial staff of The International Journal of Oral & Maxillofacial Implants is pleased to have the opportunity to publish six papers from a June 1988 internal symposium associated with the Special Collaborative Implantology Program of Tübingen University, West Germany. Our deep gratitude is expressed to Prof Dr Willi Schulte and his colleagues for their cooperation and willingness to provide these manuscripts for the edification of our readers. The Journal continues to seek meaningful works from the international dental, medical, and basic science communities to assist our efforts to improve patient care.

The results of regular follow-up of various endosseous titanium implant systems are presented together with an overview of the results with Tübingen Frialit® aluminum oxide ceramic implants. Using ITI implants, pathological findings for sulcus depth and peri-implant bone degradation were found significantly more frequently than with the other titanium implants. Clinical mobility was present significantly more frequently with TPS implants than with the IMZ system, whereas an increase in the depth of the peri-implant sulcus alone occurred significantly more frequently with the IMZ and ITI than with the TPS implant system. The observation period for Brånemark implants is too short to permit final evaluation. However, pathological findings have not occurred to date. Keywords: Brånemark implant, endosseous implant, IMZ implant, ITI implant, recall, titanium, TPS implant, Tübingen Frialit implant

Electrognathographic measurements on 18 patients with implant attached mandibular complete dentures showed larger and more stable chewing patterns compared to their former dentures without implants. Strain gauge measurements revealed mechanical stress acting on the implants even during the fixation of the bar. In addition to simulating the periodontal ligament, the intramobile element (IME) of the IMZ system compensated minor, clinically undetectable mismatches inherent with technical procedures (casting, soldering). Although the implants are loaded with tensile and compressive stress, tensile stress dominated during the chewing process. The implants were also loaded during swallowing. This load reached half of the value of the chewing loads. Keywords: chewing patterns, functional use of implants, implant stress

To characterize the galvanic corrosion of supraconstructions consisting of Ni-Cr alloys that come in contact with titanium implants, the resultant substance loss was determined. The measurement of the released substance masses was conducted by analysis of the electrolyte solutions with the aid of atomic absorption spectrometry and by approximate calculation using current density time curves, according to Faraday's law. The results of this study show that both methods allow a clear differentiation of the corrosion behavior of various Ni-Cr alloys that come in contact with titanium. Keywords: atomic absorption, current density, galvanic corrosion, Ni-Cr supraconstruction, substance loss, Ti implant

The microstructure of Ti-Ta and Ti-Nb alloys diffusion bonded to a 99.7 wt% Al2O3 ceramic for dental implants is subdivided into a reaction double layer containing the phases TiAl and Ti3Al, a transition region of coarse α-Ti plates in ß-Ti, and the unaffected bulk metal, the α-Ti/ß-Ti structure of which can be refined by annealing at 800 °C for 1 hour after bonding. Optimized joints fabricated by diffusion bonding in a high vacuum at 1,200 °C from a 99.7 wt% Al2O3 ceramic and Ti-Ta alloys fitted in their thermal contraction behavior to that of the ceramic by the addition of 30 to 40 wt% Ta showed a fracture resistance of 2.3 MN/m3/2. Approximately 80% of the bend test specimens notched at the Ti-Ta/alumina interface failed by crack extension parallel to the interface within the ceramic, which is typical for a metal-ceramic bond of high to medium interfacial strength. Keywords: bond strength, dental implant, interfacial microstructure

All implantable devices must be sterile. However, autoclaves produce poor surface properties that jeopardize the integration process. The application of a modified ultraviolet light source has proven to enhance bioreactivity by controlling surface properties, but it lacks validation of its sterilization capabilities. Forty-eight titanium implants were contaminated with spores of the biological indicator Bacillus stearothermophilus and subjected to dynamic sterilization by ultraviolet light. Forty-seven of the implants were successfully sterilized, as indicated by not producing turbidity in a suitable growth medium. This sterilization technique only requires a 20 second exposure to achieve sterility. Keywords: sterilization, titanium implants, ultraviolet light

Improper implant angulation is one of the most difficult problems to overcome in the fabrication of implant-supported and implant-retained restorations. Several techniques using the UCLA abutment have been developed to solve these problems. The creation of large screw-access holes for moderate angulation and the fabrication of telescopic copings and overlay castings for severe angulation problems are discussed. Keywords: hexagon, overlay casting, screw-access opening, telescopic copings, UCLA abutment

The amount of viable bone in a composite graft that consisted of autogenous iliac bone marrow, allogenic rib, and porous hydroxyapatite was quantified using standard histologic techniques and an optical insert disk prior to placement of endosteal implants in an augmented mandible. It is suggested that this technique could be used in such cases before deciding whether to proceed with implant insertion. Keywords: atrophic mandible, bone quantification, composite graft, endosteal implants, porous hydroxyapatite