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Results for “Tooth Calcification”

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At least 91 records · Page 5Linked to original sources
PubMed1991

[Extremely delayed mineralisation of a first premolar in conjunction with submerged deciduous molars--a case report].

This case report presents a patient with extremely delayed mineralisation of a first upper right premolar and simultaneously congenitally missing second premolars. While the germs of the first premolars are usually detectable on dental X-ray films at the age of three or four years, the demonstrated patient was older than 13 years when the first premolar became visible. As the right first bicuspid actively erupted normal root growth took place, and once the tooth is in its normal position its anatomy can be considered normal. With the eruption of the permanent tooth the periodontal situation improved considerably in the region where depression of its predecessor had taken place. As a practical clinical consequence one should take into consideration that mineralisation of a first premolar can be extremely delayed in cases with congenitally missing second premolar teeth.

Adult↗
PubMed1991

[Maturation of enamel and tooth eruption].

The tertiary maturation of the erupting tooth needs much more time than it is supposed in literature. Possibly the completion is in accord with the decline of the caries activity at the end of the second decade of lifetime. With the aid of polarizing microscopy, electron microprobe, microhardness testing (Vickers) and scanning electron microscopy different stages of posteruptive maturation from human and other mammalian teeth were analysed. The mineralization level in the outer surface of human enamel is completing little by little in more than 5 years after eruption. This state is in the ruminant tooth obvious never within reach in consequence of the specific physiological conditions. The maturating mineralization after our preliminary findings is fundamentally different to remineralization.

Animals↗
PubMed1990

[The crystallinity of hypomineralized rat enamel caused by fluoride administration].

It has been well known that there are extreme amounts of inter-crystalline spaces and large amounts of enamel matrix in fluorosed human enamel. Our previous study discussed the fact that amelogenins in developing fetal enamel matrix protein may have a role in regulating or controlling enamel crystal growth. These results positively suggest that amelogenins degradation may be associated with the etiology of fluorosed enamel. The purpose of this study was to examine the relationship of the crystallinity of fluorosed enamel of rats and the molecular weight of enamel matrix protein. The crystallinity of fluorosed enamel of rats, caused by the ingestion of fluoride containing water was evaluated with the microbeam x-ray diffraction analysis and the molecular weight of enamel matrix protein was examined by SDS-polyacrylamide-gel electrophoresis. The results obtained in the study are summarized as follows. 1) The plasma fluoride level of rats increased linearly with the fluoride concentration in the drinking water. 2) The microradiographs of maturing incisor enamel of the group with 100 ppmF- and 200 ppmF- injected showed diffused radiolucent zone from the subsurface toward the dento-enamel junction. The disturbances in enamel mineralization were most apparent in the 200 ppmF- group. 3) The crystallinity of the radiolucent zone of the fluorosed enamel decreased in both the a and c-axis directions, and particularly decreased more in the a-axis compared with the control. 4) The pattern of the SDS-polyacrylamide gel electrophoresis of the enamel protein in the mature stage showed higher remaining molecular weight of amelogenins in rats in the 100 ppmF- and 200 ppmF- group. These results suggest that in hypomineralized enamel caused by long-term administration of fluoride containing water, the degradation of amelogenin protein was disturbed, and consequently the crystallinity of enamel apatite decreased.

Amelogenin↗
PubMed1990

[Comparisons of effects of vitamin D3 metabolites on mineralization: utilization of incisor dentin in parathyroidectomized rats].

The rat incisor is continuously growing throughout the animal's life recording the state of mineralization within its dentin at all times. Therefore, it was assumed that the incisor dentin was suitable material for studying the effects of various drugs on such mineralization. The present study set out to examine the effects of vitamin D3 metabolites on the remineralization of dentin and the serum calcium level in parathyroidectomized (PTX) rats. Male Wistar rats weighing about 200-250 g were parathyroidectomized. Each rat was given daily 12 g of a synthetic diet containing 0.1% Ca and 0.4% P (normal P) or 0.06% P (P deficient) without vitamin D. Exp. I: Three groups of rats given a normal P diet were orally administered vehicle, 25 (OH) D3 (50 IU/rat) or 1,25 (OH)2D3 (5 IU/rat) for 5 days from the 28th day after PTX, respectively. Exp. II: Two groups of rats given a normal P diet or a P deficient diet were further divided into 4 sub-groups and intramuscularly administered 0, 5,000, 10,000 or 20,000 IU of vitamin D3 on the 9th day after PTX, respectively. The active vitamin D3, 1,25 (OH)2D3 restored the mineralization of the dentin which had been suppressed following PTX, and elevated the serum calcium level to about 9 mg/dl. However, the 25 (OH) D3 neither restored the mineralization of the dentin nor elevated the serum calcium level in the PTX rats. At doses below 1,000 IU, vitamin D3 could not restore the mineralization of the dentin. However, at massive doses above 5,000 IU, the mineralization was restored in proportion to the dose. The serum calcium levels also increased in proportion to the dose. It is assumed that the increase of the serum calcium level was mainly due to the enhancement of calcium absorption from the intestine by vitamin D3. Both remineralization of the incisor dentin and increase of the serum calcium level were more marked in groups of rats given a P deficient diet than in those given a normal P diet. In all cases in the present experiments, the degree of mineralization of the dentin seemed to correspond with the degree of elevation of the serum calcium levels. These results suggest that the remineralization of the dentin in the PTX rats was attributable to the effect of the vitamin D3 metabolites on serum calcium regulation. Relative biological activities of 1,25 (OH)2D3, 25 (OH) D3 and vitamin D3 on the remineralization of dentin were estimated to be 1, less than 0.02 and less than 0.001, respectively.

Animals↗
PubMed1990

[Demineralization behavior, enamel permeability and the morphological characteristics in relationship to the stage of eruption of the permanent teeth].

The posteruptive maturation of enamel is an important factor in caries disposition. In an experimental study the demineralization of enamel as well as its permeability and its morphological features in dependence of eruption stage were examined on extracted premolars. Chemical analysis showed variations in the Ca/P molar ratio. It is possible, that the instability of Ca-ions in crystalline configuration decreased during the time of eruption. The permeability of enamel decreased between 5 and 11.8%. It appears to be useful to concentrate preventive measure on this phase of dentition development.

Bicuspid↗
PubMedDate not supplied

[The effect of magnesium sulfate electrophoresis and galvanization on the mineralization of teeth and bones].

Effects of Mg2+ electrophoresis and galvanization on tooth and bone mineralization was experimentally studied with the use of radioactive Ca and P isotopes. Mg2+ electrophoresis and, to a lesser degree, galvanization enhanced 32P incorporation in incisors and maxillary bones. Mg2+ significantly increased 45Ca incorporation in teeth and maxillary bones. Experimental data permit clinical trials of Mg2+ efficacy in patients with disordered mineralization and remineralization.

Animals↗
PubMedDate not supplied

[Hypomineralization of milk teeth of prematurely born children--effect of some factors for its origination].

A comparative study was carried out between two groups of children--115 prematurely born and 4830 full-term babies in order to establish the effect of pregnancy duration of the origination of hypomineralization of the milk teeth. The effect of the following factors was also studied and compared: complications of pregnancy, feeding of the newborn and diseases during early childhood of full-term and prematurely born children. The authors established that the prematurely born children were a risk group for the origination of milk teeth hypomineralization. The complications of pregnancy, mixed or bottle feeding as well as the frequent illnesses are additional aggravating factors in the origination of milk teeth hypomineralization. The authors recommend timely follow-up care and prophylaxis of all prematurely born children.

Bottle Feeding↗
PubMed1989

[Evaluation of remineralization solutions on the milk teeth].

The milk incisors of 80 infant-school children were demineralized. For the following 3 weeks the children then rinsed their mouths with mineral solutions. By manifold replica yields (analysis by light- and scanning electron microscope) and colouring tests a positive influence of calcium and phosphorus holding solutions, among others with magnesium, too, on the remineralization was discovered.

Child, Preschool↗
PubMedDate not supplied

[De- and remineralization processes of the surface layer of the enamel in intact and pulp-extirpated teeth].

Clinico-laboratory investigation of 61 intact teeth and 61 teeth after pulp extraction was performed, including in vivo acid enamel biopsy and intravital staining with 2% methylene blue solution. The regularities were established governing Ca and P efflux from superficial enamel layer of intact and pulp-extracted teeth into the acid solution with respect to age, group of the tooth and pulp extraction terms. The pulp extraction factor was investigated with special reference to the tooth acid resistance and its remineralization rate.

Adolescent↗
PubMed1978

Crystallites dimensions of enamel.

In this paper the average diameter of enamel crystallites in mature, deciduous and fluorosed human enamel as well as in bovine enamel (in vivo and in vitro remineralized) is discussed. The investigation was carried out on broken surfaces of the various kinds of enamel with a scanning electron microscope. Corrections have been applied for the thickness of the gold-layer deposited. The average crystallite diameters for sound, deciduous and fluorosed human enamel were : 36 nm; 46 nm and 81 nm, respectively. The values for sound, remineralized in vitro and remineralized in vivo bovine enamel were 57 nm; 97 nm and 63 nm, respectively. The results indicate furthermore that if a correction for the sputtered goldlayer is applied, the results for SEM and TEM microscopy are in good agreement with each other. The difference between in vivo and in vitro remineralized bovine enamel is most likely due to differences in speed of remineralization and/or the presence of saliva.

Animals↗