In vivo and in vitro changes in strength of orthopedic calcium aluminates

Abstract

SummaryCalcium aluminate bars were formulated to study the effect of real and simulated biological environments on strength. Static fatigue tests revealed that the strength of these potential internal bone prostheses decreased to ca. 60% of their initial strength after less than 100 min while being held at constant stress in solution. Calcium aluminate bars aged for 12 weeks in water or Ringer solution were also found to exhibit large losses in strength, while bars implanted in vivo for the same period of time weakened somewhat less. Semi-quantitative analysis of the solutions in which the calcium aluminate bars were aged revealed that Al'+and Ca2 +were being leached from the bars in both the saline and water baths, while the concentration of M$+was decreasing in the Ringer solution.Scanning electron microscope (SEM) studies revealed extensive microstructural changes in specimens aged in water or saline solution for 1 and 12 weeks. Similar but far less extensive changes were seen in bars aged in vivo in rabbits for 12 weeks.

Mechanical properties of calcia stabilized zirconia following in vivo and in vitro aging

“…The in vitro aging was performed as previously described by Schnittgrund et al [9], by placing rods in jars containing Ringer's solution. They were allowed to soak for 1.…”

“…Schnittgrund et al [9] showed losses of 40% within 100 min when calcium aluminate bars were aged under conditions of static loading and 10% when aged in vivo for 3 months. In contrast were the studies of glassy carbon which failed t o show any statistically significant losses of flexural strength in the in vivo aging studies and which were shown to be comparatively resistant to static fatigue [lo].…”

Porous Ceramics as a Bone Substitute in the Medial Condyle of the Tibia:An Experimental Study in Sheep

“…The implants were made from porous ceramics produced as described by Lyng et al (1973 Frakes et al (1974) and Schnittgrund et al (1973) indicate that the strength of alumina may deteriorate due to stress corrosion both in vivo and in uitro. However, according to Schnittgrund e t al.…”

The Effects of Calcium Aluminate Cement According to Particle Sizes on Calvarial Bone Defects in Rats

“…To achieve this goal, a lot of methods and devices have been proposed such as guided tissue regeneration, bone graft, and application of growth factors [1]. Past studies have shown that calcium aluminate has excellent biocompatibility [2], host adaptability and mineralization capacity [3], which facilitates hard and soft tissue reconstruction [4]. However, in order to use calcium aluminate cement clinically as a bony cement, the conventional setting time(about 7 hours) needs to be shortened to below 60 minutes.…”