No abstract

The dependence of cytotoxicity on particles size in titanium (Ti) and nickel (Ni) was investigated by biochemical functional analysis and by microscopic observation of cellular morphology, in vitro using human neutrophils as probes and in vivo in animal implantation test. The biochemical analyses of cell survival rate, LDH, superoxide anion, cytokines of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and observation by scanning electron microscopy (SEM) showed that Ti fine particles (2 µm) stimulate neutrophils and increases the quantity of released superoxide anions, whereas Ni particles deform or disrupt the cell membrane of neutrophils. The 2 µm Ti particles, smaller than neutrophils of about 5-10 µm, were phagocytized by cells in vivo and the results were similar in vitro, which lead to the remarkable release of TNF-α. These results showed that there is the size-dependent cytotoxic effect in Ti fine particles and the effect is the most pronounced when they are smaller than cells. On the other hand, Ni particles caused the disruption of neutrophils in vitro and necrosis of tissue in vivo mainly through ions produced by their dissolution.

No abstract

We started to use Hotz plates in 1995 and have noticed that some patients cannot continue to use the plate until 1 year old. The purpose of this study was to survey the usage of Hotz plates in patients with cleft lip, alveolus, and palate. The subjects consisted of 48 patients with unilateral cleft lip, alveolus, and palate. They were classified into a usage group (39 subjects) or a discontinued group (9 subjects) depending on whether they continued to use the plate until 1 year old. The results were as follows: There were no statistically significant differences between the groups in age at initial usage of the plate, the width of the alveolar cleft at the time of initial usage, the width of the palatal cleft at the time of initial usage and at 1 year old, and the number of erupted teeth at 1 year old. There was a statistically significant difference between the groups in the width of alveolar cleft at 1 year old. The proportion of subjects having a 0 mm width of the alveolar cleft at 1 year old was significantly greater in the discontinued group than in the usage group. We conclude that patients who cannot continue to use the plate have a narrow alveolar cleft.