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PubMed2002

Relationships between dental calcification stages and skeletal maturity indicators in Thai individuals.

The purpose of this study was to investigate the relationship between the stages of calcification of various teeth and skeletal maturity stages among Thai individuals. The study subjects consisted 139 male subjects and 222 female subjects ranging in age from 7 years to 19 years. A total of 361 hand-wrist and panoramic radiographs were obtained and analyzed. The tooth development of the mandibular canines, first and second premolars, and second and third molars were assessed according to the Demirjian's system. Skeletal age and skeletal maturity stages were determined from hand-wrist radiographs by using the method outlined in the atlas of Greulich and Pyle and the Fishman's system, respectively. The Spearman rank order correlation coefficient revealed significant relationships (r = 0.31-0.69, P < .01) between dental calcification stages and skeletal maturity stages. The second premolar was the tooth showing the highest correlation (r = 0.66 in male subjects, r = 0.69 female subjects). The third molar demonstrated the poorest correlation (r = 0.47 in male subjects, r = 0.31 in female subjects). The canine stage F for both sexes (63.2% for female subjects, 54.1% for male subjects) coincided with the MP3 stage. The second molar stage E for female subjects (51.4%) and stage G for male subjects (66.7%) were related to the S stage and the MP(3cap) stage, respectively. This suggests that tooth calcification stages from panoramic radiographs might be clinically useful as a maturity indicator of the pubertal growth period. However, further study is recommended in a larger sample size, and future studies should address development of the canines and second molars.

Adolescent↗
PubMed2005

Histological description of tooth formation in adult Eretmodus cf. cyanostictus (Teleostei, Cichlidae).

The Eretmodini, a tribe of closely related cichlids (Teleostei, Cichlidae) originating from Lake Tanganyika, possess oral tooth shapes ranging from conical (in Tanganicodus) over cylindrical (in Spathodus) to spatulate (in Eretmodus). Prior to a study aiming to understand how these distinctly different tooth shapes can be acquired in such closely related taxa, a detailed histological study was required of tooth formation in a representative of the eretmodines. Here, we present a histological description of replacement tooth development in Eretmodus cf. cyanostictus. Using light-microscopic observations on semithin as well as on ground sections, microradiographs and stereo-microscopic observations of both alizarine red S stained and unstained jaws we can conclude that tooth formation in adult E. cf. cyanostictus roughly corresponds with what is known for teleost tooth development in general. Remarkable features include the localization and shape of the epithelial downgrowth, the transient presence of a layer intermediate between inner dental epithelium (IDE) and outer dental epithelium (ODE), the asymmetric shape of the enamel organ, the fact that the pulp cavity recedes in front of the forming enameloid during enameloid formation, and finally, the pattern of matrix mineralisation and maturation, and the presence of pigment in the enameloid. The observation that the enamel organ in adult E. cf. cyanostictus develops asymmetrically is significant for understanding tooth shape variation in the Eretmodini.

Animals↗
PubMed1978

Ultrastructural and cytochemical studies on the matrix vesicle calcification in the teeth of the killifish, Oryzias latipes.

Tooth germs of killifish were examined by both ultrastructural and cytochemical methods. The ultrastructure of the dentin in the early calcification stage of its development resembled that of mammals. Numerous extracellular membrane-bounded vesicles, matrix vesicles, were seen in the predentinal space, especially abundantly in the basal portion of the tooth germ. They were more numerous and more uniform in appearance than in any other higher vertebrates. Where calcification was going to start, slightly identifiable needles of apatite crystals were found in the vesicular structures. Crystals increase in number filling up the vesicles and then ther surroundings, finally to form many calcified spherules. Where calcification was more extensive, the matrix vesicles were no longer visible having been buried calcified among spherules. Contrary, to popular belief, there was no relationship seen between collagen fibrils and the initial deposits of minerals, that is, collagen fibrils did not seem to work as the initial site of calcification. Instead, matrix vesicles and plasma membranes of odontoblasts likely were involved in calcification as they both showed alkaline phosphatase activity. The ultrastructural and cytochemical findings from this study thus indicated that calcification of the killifish tooth germs was initiated not in the enamel, but in their dentin by the matrix vesicles which were liberated into the dentin matrix from odontoblasts mainly by way of fragmentation of cell processes.

Animals↗
PubMed1985

Ameloblastic secretion and calcification of the enamel layer in shark teeth.

Tooth primordia at early stages of mineralization in the sharks Negaprion brevirostris and Triaenodon obesus were examined electron microscopically for evidence of ameloblastic secretion and its relation to calcification of the enamel (enameloid) layer. Ameloblasts are polarized with most of the mitochondria and all of the Golgi dictyosomes localized in the infranuclear end of the cell toward the squamous outer cells of the enamel organ. Endoplasmic reticular membranes and ribosomes are also abundant in this region. Ameloblastic vesicles bud from the Golgi membranes and evidently move through perinuclear and supranuclear zones to accumulate at the apical end of the cell. The vesicles secrete their contents through the apical cell membrane in merocrine fashion and appear to contribute precursor material both for the basal lamina and the enameline matrix. The enamel layer consists of four zones: a juxta-laminar zone containing newly polymerized mineralizing fibrils (tubules); a pre-enamel zone of assembly of matrix constituents; palisadal zones of mineralizing fibrils (tubules); and interpalisadal zones containing granular amorphous matrix, fine unit fibrils, and giant cross-banded fibers with a periodicity of 17.9 nm. It seems probable that amorphous, non-mineralizing fibrillar and mineralizing fibrillar constituents of the matrix are all products of ameloblastic secretion. Odontoblastic processes are tightly embedded in the matrix of the palisadal zones and do not appear to be secretory at the stages investigated. The shark tooth enamel layer is considered homologous with that of other vertebrates with respect to origin of its mineralizing fibrils from the innerental epithelium. The term enameloid is appropriate to connote the histological distinction that the enamel layer contains odontoblastic processes but should not signify that shark tooth enamel is a modified type of dentine. How amelogenins and/or enamelins secreted by amelo- blasts in the shark and other vertebrates are related to nucleation and growth of enamel crystallites is still not known.

Ameloblasts↗
PubMed1980

Clinicopathologic features of fluoride toxicosis in cattle.

Cattle normally ingest variable low-level amounts of fluorides with no known adverse effects, but when excessive amounts are ingested, adverse effects are induced. Several sources may contribute to the total fluoride intake. The many recognized factors that influence structural and functional responses of animals to fluorides are cited. Signs and lesions of fluoride toxicosis in cattle have been characterized. Major fluorotic lesions occur in the permanent teeth and in the bones. Dental lesions occur when excessive amounts of fluoride are ingested during the period of tooth formation and calcification. Bone effects can be induced at any time during an animal's life. A table relating structural changes and functional processes in cattle of various ages has been compiled as a guide for diagnosing and evaluating fluoride toxicosis. Recommended fluoride tolerance levels for cattle have been established. Prevention and control of fluoride toxicosis in cattle can be accomplished when the nature of the disease is realized; the symptomatology, lesions and pathogenesis are properly interpreted, correlated and evaluated; and the source(s) of excessive fluorides are eliminated.

Animals↗
PubMed1982

Interglobular dentine in first and third molars: relation to hours of sunshine during growth in two archeological populations from England.

Thin ground sections of first molars (M1), third molars (M3), and second premolars (P2) were scanned by light microscopy for relative amounts of interglobular dentine (IGD) in the top half of the crown. Two well-dated cemetery series of English provenance were sampled: the Saint Bride's Church collection (SB) from eighteenth century London, for which the sex, age, and calendar year at death of each individual are known; and the early Anglo-Saxons from Abingdon (A-AS), near Oxford. A lesser number of prehispanic aboriginal Guanche teeth from Tenerife (TG) were also studied. Estimates of insolation in the past were developed indirectly by reference to delta 0(18) mass spectrometer analyses of dated layers of the Greenland ice sheet. In the M1 and M3 of the SB and the A-AS populations, IGD varied as an inverse linear function of average annual hours of bright sunshine below a certain critical level, the insolation deficit threshold being significantly higher and IGD formation faster in the M1 than in the M3. No such dose-response gradient was apparent in the P2 data, presumably because the calcification of this tooth during the fourth year of life coincides with serious pediatric illnesses and weaning of the child onto cereal foods rich in phytate, which together confound and overwhelm the insolation deficit effect. IGD in all three types of teeth of the small TG series was considerably higher than had been predicted on the basis of bright sunshine availability; but the discrepancy is readily explainable in terms of this population's dietary, which relied on barley as the main staple.

Adolescent↗
PubMedDate not supplied

CT features of cystic teratoma of the diaphragm.

Cystic teratomas of the diaphragm are exceedingly rare. This report presents the first case described in the English literature. The CT appearance was similar to that of teratomas occurring in the ovaries. The mass contained soft tissue, fat, areas of calcification, and a tooth.

Aged↗
PubMed1993

Tooth formation in patients with oligodontia.

Oligodontia is defined as the congenital absence of many teeth. The aim of the present study was to evaluate tooth formation in patients with oligodontia who were missing six or more teeth. The oligodontia sample was compared to a control group matched for race, sex and age. Calcification stages of the teeth of the left side of the mandible were rated. Patients with oligodontia showed a tendency for delayed tooth formation. Significant differences in tooth formation were found between males with oligodontia and the control group for several stages of tooth formation. In females only stage 5 of the second mandibular molar showed a significant difference. Because of the great individual variation in tooth formation in patients with oligodontia, tooth formation in patients with oligodontia should be individually examined before starting treatment.

Adolescent↗
PubMed1964

CALCIFICATION OF DECIDUOUS TEETH IN RHESUS MONKEYS.

The rhesus monkey probably has the same sequence of calcification of deciduous teeth as man: central incisor, first molar, lateral incisor, cuspid, and second molar. Initial calcification of the deciduous molar cusps is somewhat similar to that of man.

Animals↗
PubMed1980

Tooth mineralization as an indicator of the pubertal growth spurt.

The commencement of adolescent peak growth velocity in body height and facial growth is closely related in timing to certain ossification events which occur in the hand and wrist. An investigation into calcification patterns of the teeth revealed a high degree of correlation between the stage of mineralization of the lower canine and these events. The possibility of the use of this tooth as a maturational indicator of the pubertal growth spurt is discussed.

Adolescent↗
PubMed1991

A one-stage calcific barrier technique in a root-fractured incisor tooth: a case report.

This paper describes the use of calcium hydroxide powder as an immediate plug before root canal obturation in the case of a root-fractured upper central incisor that had been unresponsive to 18 months of treatment to create a calcific barrier. The calcium hydroxide plug allowed both good condensation of the filling material and prevention of extrusion of the root filling material which could have been detrimental to continued healing of the fracture.

Calcium Hydroxide↗
PubMed2003

Age dependencies of 90Sr incorporation in dental tissues: comparative analysis and interpretation of different kinds of measurements obtained for residents on the Techa River.

Human teeth have been considered as dosimeters for decades. Methods include the in vivo measurement of 90Sr/90Y in teeth with a tooth-beta counter, the radiochemical determination of 90Sr in whole teeth, and the measurement of dose in teeth by use of electron paramagnetic resonance. Presented in this paper are results of 2,514 tooth-beta counter measurements, 334 radiochemical measurements, and 218 electron paramagnetic resonance measurements for residents living in settlements along the Techa River. All three kinds of measurements indicate a sharp peak that corresponds to the uptake of 90Sr by tooth tissue. The results can be interpreted in terms of an intake function for 90Sr only if the period of calcification of each individual tooth is considered--such detail on a tooth-by-tooth basis is presented in this paper. The conclusion is reached that the tooth-beta counter data are the most reliable in terms of reconstruction of 90Sr intake; this is due in part to the fact that the tooth-beta counter measures four teeth (all at position 1) with essentially the same time periods of mineralization and because there are a large number of tooth-beta counter measurements. The main utility of electron paramagnetic resonance measurements is considered to be the validation of estimates of external dose; but for this purpose teeth with 90Sr taken up into enamel must be avoided.

Adolescent↗
PubMed2000

Ultrastructure of sea urchin calcified tissues after high-pressure freezing and freeze substitution.

The improvements brought by high-pressure freezing/freeze substitution fixation methods to the ultrastructural preservation of echinoderm mineralized tissues are investigated in developing pedicellariae and teeth of the echinoid Paracentrotus lividus. Three freeze substitution (FS) protocols were tested: one in the presence of osmium tetroxide, one in the presence of uranyl acetate, and the last in the presence of gallic acid. FS in the presence of osmium tetroxide significantly improved cell ultrastructure preservation and should especially be used for ultrastructural studies involving vesicles and the Golgi apparatus. With all protocols, multivesicular bodies, suggested to contain Ca(2+), were evident for the first time in skeleton-forming cells. FS in the presence of gallic acid allowed us to confirm the structured and insoluble character of a part of the organic matrix of mineralization in the calcification sites of the tooth, an observation which modifies the current understanding of biomineralization control in echinoderms.

Animals↗
PubMedDate not supplied

45Ca uptake in tooth germs: effects of parathormone, calcitonin and propranolol.

Tooth germs harvested from 6-day-old rats were incubated in a 45Ca-containing medium for 6 hours. The addition of PTH consistently stimulated the increase in 45Ca uptake, while calcitonin significantly reduced both the PTH-stimulated incorporation and the spontaneous one. Dibutyrul CAMP (3.5 mM) had no effects. Propranolol significantly inhibited the spontaneous and stimulated 45Ca uptake. Results obtained support the concept that the two hormones have a clear influence on calcium entering the tooth germs in full calcification process probably by early membrane effect.

Animals↗
PubMed1991

Mineralization disturbances of the developing rat molar induced by mono- and bisphosphonates.

Morphological changes have been reported previously in the developing dental tissues of the rat molar following administration of mono- or bisphosphonates. However, few studies have been published on the relationship between these and the possible mineralization disturbances. Two monophosphonates, phosphonoformic and phosphonoacetic acids, and two bisphosphonates, dichloromethylene bisphosphonate (Cl2MBP) and 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) in a dosage of 10-30 mg P/kg b.w. were injected in 5 day old rats and the induced changes analyzed by microradiographic and histologic examination. A single injection of mono- or bisphosphonates resulted in apparently identical disturbances of the developing enamel associated with subameloblastic cysts. Three different types of cysts were distinguished. In type 1 cysts, enamel hypoplasia near the cusp tip with an outer highly mineralized zone associated with calcified deposits in the cystic lining and inner hypomineralized enamel were discerned. The type 2 cysts were characterized by the formation of a thick enamel layer in the cervical area and deep in the fissures due to the development of internal enamel defects. The type 3 cysts were seen in the cervical area of the mesial or distal sides of the tooth without any remarkable changes in the underlying enamel matrix. Both Cl2MBP and HEBP induced two demarcation lines in the dentin layer. Additionally, HEBP resulted in the formation of niche-like defects of unmineralized dentin which healed by mineral deposition from the periphery. From these results, it can be concluded that mono- and bisphosphonates have similar effects on enamel mineralization and the type of response depends on the stage of enamel matrix secretion while bisphosphonates, in addition, interfere with the dentin mineralization.

Alveolar Process↗