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At least 577 records · Page 32Linked to original sources
PubMed1990

The rate of incisor dentine calcification and of mandibular growth in the molar region of the ovariectomized rat.

In 14 ovariectomized and 15 control rats, killed at intervals over a 117-day period, the height of the mandible in the molar region was determined radiographically. Mandibular height was significantly related to time after operation in both groups, but their rate of mandibular growth was not significantly different. In a separate study, the rate of dentine formation in the right mandibular incisor of 9 ovariectomized and 10 control rats was calculated from the distance between two fluorescent labels injected at known time intervals. The rate of dentine apposition was measured at 117 and 201 days after ovariectomy. In both groups, the distance between the fluorescent labels was significantly correlated with the time interval between the injections. There was no significant difference between the rate of dentine calcification in either group. Transient changes in dentine apposition may have occurred post-ovariectomy which would be undetected at either 117 or 201 days after operation. There was thus no evidence for an effect of ovariectomy on either the rate of mandibular growth or dentine apposition.

Animals↗
PubMed1997

Analysis of a general principle of crystal nucleation, formation in the different hard tissues.

We have found, at high EM magnification, on ultrathin sections of shock-frozen, freeze-dried, embedded pieces of the developing hard tissues, that the primary crystallites consist of strands composed of nanometer-sized apatitic islands, which rapidly coalesce to needles and afterward to platelets. By small-area electron diffraction, with energy-filtered electrons, it was clarified that these strands are already crystallographically oriented along the bipolar c-axis so that the center-to-center distances between the islands would reflect the distances between crystal-nucleating sites along the matrix. The EM analysis of the cross-cut stained unmineralized and of the unstained mineralized collagen fibers of turkey tibia tendon shows that the staining "nuclei" and the early crystallites, appearing as dark dots, surround "light" round structures, which we interpret as the collagen microfibrils, surrounded by the apatitic crystallites.

Animals↗
PubMed1998

[The role of basic fibroblast growth factor on expression of mineralization of periodontal ligament cell population and clones].

OBJECTIVE: To determine the effect of basic fibroblast growth factor (bFGF) on mineraliztion of PDL cell clone. METHODS: The PDL tissue that derived from three human donors was cultured and cells were cloned. The mineralizing ability were detected with or without bFGF treatment in the presence of dexamethasone. Cloned progenitor populations were assayed for their constitutive capacity to bind CAP and express ALP. RESULTS: The results show that bFGF increases clone mineralization (11%), but not in PDL cell population. The cell clones that mineralized only in the presence of bFGF have higher CAP binding ability and lower ALP expression compared with other mineralized clone cells. CONCLUSION: bFGF enhances mineralizing expression of PDL clone. The clones that mineralized only with bFGF treatment are different cell types from the bFGF-undependent mineralized clones.

Adult↗
PubMed1990

[Effects of EDTPO on hard tissues in rats. 2. Changes of serum components and morphology of hard tissues due to various doses of EDTPO].

Dose dependent effects of EDTPO on morphology and mineralization of hard tissues as well as calcium (Ca), inorganic phosphorus (IP) and alkaline phosphatase (ALP) levels in serum were examined in growing rats. Five groups of male S.D. rats weighing 110-120g were received s.c. injections of 0 (control), 1, 2, 4, and 8mg P/kg body wt. of EDTPO once daily (at noon) for 10 days respectively. Tetracycline (Tc.) were i.p. injected three times, one day before drug treatment (1st), 5th (2nd) and 10th (3rd) day of experimental period. All rats were received i.p. injection of 185kBq (5 microCi) of 45Ca six hours after the 10th injection of EDTPO. On the next day, blood samples were taken from the carotid artery. Then the animals were killed and both tibias, submandibular teeth and right femur were removed. Serum Ca, IP and ALP were determined by spectrophotometry. Wet, dry and ash bone weight were measured and bone calcium was determined by atomic absorption method. 45Ca activity was counted by the liquid scintillation counter. Serum Ca levels revealed decreasing tendency at the dose of 1mg P/kg and 2mg P/kg of EDTPO but increasing tendency at 4mg P/kg and significant increase at the dose of 8mg P/kg. Specific activity of 45Ca in serum increased slightly at 2mg P/kg, but at the dose of 8mg P/kg increased five times compared to that of control. Decrease of IP and increase of ALP level were observed only at the dose level of 8mg P/kg. Wet, dry, and ash weight, and Ca content of femur and 45Ca activity were decreased dose-dependently. In histological examination, changes of tibia and teeth were observed at the dose of 2mg P/kg and following dose increase these changes were more significantly. Ultraviolet line of Tc. appeared three in proximal metaphysis of tibia and dentin at the dose of 1mg P/kg and 2mg P/kg, but at the dose of 4mg P/kg and 8mg P/kg 2nd and 3rd line could not be detected. These result indicated that the effects of EDTPO on serum ingredients, long bone and teeth are initiated at the dose of 2mg P/kg, appeared at the dose of 4mg P/kg significantly, and at the dose of 8 mg P/kg severely. In addition, increase of the ratio of 45Ca specific activity between serum and bone observed at the dose of 4mg P/kg and 8mg P/kg suggested that these effects of EDTPO would be due to inhibitory action on mineralization.

Alkaline Phosphatase↗
PubMed1982

Does correlation exist between mineralization in collagen-rich hard tissues and that in enamel?

Quantitative electron microscopy has shown that strands of crystallites with a dotlike substructure are formed and arranged in relation to the collagen structure. Many such parallel-arranged crystallites unite rapidly to form ribbons or long platelets which penetrate the microfibrils, producing the positive biomechanical quality. We assume that, in enamel, strands of crystallites with dotlike substructure may also exist in the earliest stage. These substructures unite with neighboring ones to form larger entities. Several needlelike (or ribbonlike) crystallites will form large crystallites, healing most of the lattice defects.

Animals↗
PubMed1980

Assessment of gestational age of Nigerian newborns using teeth calcification.

The relationship between fetal teeth calcification and gestational age was evaluated in 54 Nigerian newborn chest radiographs. The first deciduous molar was found to calcify at the 33rd week of gestation and the second molar at the 36th week. The pattern of calcification of fetal teeth is no significant difference in teeth calcification between the sexes.

Black People↗