Incisor Dentin Research Articles

Recovery of rat incisor dentin from abnormal mineralization produced by strontium and fluoride.

AbstractRats were injected with 5 mg NaF/100 g or 125 mg SrCl2/100 g. Animals injected once were killed at intervals of 4, 6, 12 and 24 days after injection. Other animals received pairs of injections, separated by intervals of four or nine days. One maxillary incisor from each animal was embedded in methacrylate, sectioned transversely, and microradiographs prepared. The other incisor was demineralized, sectioned, and the sections stained with histochemical methods for polysac‐charide‐protein complexes.In the microradiographs, the abnormally mineralized layers of dentin produced by the injections became less distinct as they aged. This recovery was detectable in all animals within two weeks after injection. The histochemical changes were less marked, but the weakly stained (hypomineralized) layers of matrix became more nearly normal as recovery occurred. Apparently, fluoride accelerates the maturation (secondary mineralization) of a thin layer of dentin, while both fluoride and strontium inhibit primary mineralization of predentin. In time, mineralization in the hypomineralized layers overtakes the normally mineralized dentin, and the normally mineralized dentin overtakes the hypermineralized layers.

Dental pulp citrate during the development of abnormally mineralized dentine

The calciotraumatic response in the rat incisor allows examination of both alterations in a developing mineralized tissue (dentine) and changes in the components of the adjacent connective tissue (pulp). The histological development of the response in rat incisor dentine produced by injected strontium, fluoride, and parathyroid extract has been described previously. In the present report, the concentration of citrate, an agent suggested as acting locally to regulate mineralization and mediate resorption, was examined in the pulps of the incisors. Doses of strontium (200–400 mg SrCl 2 · 6H 2O/kg) and fluoride (50 mg NaF/kg) were selected which produced a histologically demonstrable response. The dose of parathyroid extract used (500 units/kg) produced no histologically detectable response in dentine but is well within the range used to induce experimental hyperparathyroidism. Rats were injected subcutaneously with these agents and sacrificed at periodic intervals up to 16 hr after injection. The pulps were removed and analysed for total citrate. An increase could be demonstrated after each agent, but the magnitude and duration of the increases vary with the agents injected. Microradiographs demonstrated both hypo- and hypermineralized layers in the dentine during the citrate increase after fluoride but only a hypomineralized layer after strontium. No change in mineralization was evident after parathyroid extract. The increases in the total pulp citrate concentration were apparently not crucial in producing or controlling the changes in mineralization.

The effects of diets deficient in calcium or phosphorus in the presence and absence of supplements of vitamin D on the secondary cementum and alveolar bone of young rats

Weanling rats were maintained for 14 weeks on diets low in calcium (0.026 per cent) or low in phosphorus (0.06 per cent) with or without the addition of vitamin D. The formation of secondary cementum was most severely disturbed by a double deficiency of calcium and vitamin D. The disturbance caused by diets deficient in phosphorus and vitamin D whilst serious was not so severe. In contrast a simple deficiency of phosphorus caused a greater disruption of cementum formation than did a simple lack of calcium. The observation that phosphorus deficiency per se caused a greater metabolic disturbance in the forming secondary cementum than a simple deficiency of calcium is in accord with previous findings for bone and incisor dentine. In relation to a deficiency of phosphorus, cementum reacts in a manner similar to bone, in relation to calcium deficiency its behaviour is more akin to that of the incisor dentine.

MICRORADIOGRAPHY OF RAT INCISOR DENTIN DURING THE DEVELOPMENT OF THE RESPONSE TO INJECTED FLUORIDE.

AbstractFifty day old Sprague‐Dawley rats were given sodium fluoride (50 mg/kg) and killed at times between one half hour and 32 days after injection. Transverse sections of the upper incisor 40 μ thick were radiographed, demineralized and stained with hematoxylin and eosin. The response seen in hematoxylin and eosin stained material agreed with previous descriptions of the “calciotraumatic response” and consisted of three components. However, in the radiogram only two components could be distinguished: an external hypermineralized zone and an adjacent hypomineralized zone. The radiographic response was first recognized four hours after injection as a narrow zone of hypermineralized dentin at the dentin‐predentin junction. When the radiograms were compared to the H and E stained sections in animals killed up to 19 hours after injection, two important features were observed: (1) the width of the predentin had increased markedly, and (2) the hypermineralized zone had increased to its final width. This was interpreted as concurrent formation of both hypermineralized and hypomineralized components. At 24 hours normal dentin formation had resumed. Since both components were forming simultaneously it is believed that sodium fluoride does not cause the response by interfering with the humoral mechanisms of mineralization, but, rather, its effect is most likely on collagen or ground substance.

DEVELOPMENT OF THE RESPONSE IN RAT INCISOR DENTIN TO INJECTED STRONTIUM AND FLUORIDE.

DEVELOPMENT OF THE RESPONSE IN RAT INCISOR DENTIN TO INJECTED STRONTIUM AND FLUORIDE.

FINER STRUCTURE OF THE MATRIX OF THE RESPONSE IN RAT INCISOR DENTIN TO INJECTED STRONTIUM.

FINER STRUCTURE OF THE MATRIX OF THE RESPONSE IN RAT INCISOR DENTIN TO INJECTED STRONTIUM.

RESPONSE IN RAT INCISOR DENTIN TO INJECTED STRONTIUM, FLUORIDE, AND PARATHYROID EXTRACT.

S>Rat incisor dentin was examined by microradiography after subcutaneous injection of 1 to 8 mg NaF/100 g body thyroid extract (PTE)/100 g. With NaF, some alteration in mineralizition was domonstrable in every incisor examined; even at a dose of 1 mg/100 g, a distinct hypermineralized layer of dentin was present. At 2 mg/100 g, the hypermineralized layer was wider, and a slightly hypomineralized layer could be detected. The lowest dose of SrCl/sub 2/ (2 mg/ 100 g) produced no response, but at 5 mg/100 g a hypomineralized layer was detectable and a 20 mg/100 g and higher the hypomineralized component produced by NaF areas examined. Its thickness was frequently greater than that of the hypomineralized component produced by NaF, and the Sr-hypomineralized layer was usually more radiolucent. No distinct hypermineralized component was found. In animals injected wth PTE, no response was found with doses of 100 units/100 g and lower but at higher doses a hypomineralized layer was clearly defined, continuous, and wider than the hypomineralized component producerd by F. As in the Sr series, no hypermineralized component was found. These findings are contrary to the conclusions reached from examination of hematoxylin-stained sections, where the responses in dentin produced bymore » NaF, SrCl/sub 2/, and PTE appeared identical. When examined in microradiographs, the Sr and PTE responses contained a hypomineralized component but no hyperjmineralized component, while the F response included both. The hypomineralized components in the Sr and PTE responses were wider than that of the F response. These differences suggest that the etiology of the response is different for each of these causative agents. (BBB)« less

The citrate content of teeth.

SummaryDentin and enamel from 13 species comprising the primate, canine, bovine, feline, porcine and the rodent were analyzed for citrate. A wide variation in citrate concentration of the dental tissues was found. The dentin and enamel of the teeth of man contained 0.880% and 0.100% citrate, respectively. Similar dental tissues of the monkey, another primate, contained 0.510% and 0.053% citrate, respectively. The dentin and enamel of the teeth of the pig contained 1/6 and 1/10 as much citrate, respectively, as the same dental tissues in the human. The dentin and enamel of the molars of the rodent contained more citrate than the corresponding tissues of the incisors. A 4- to 5-fold variation was seen in the citrate content of the dentin of molars and incisors among the 5 rodents. The white rat had the highest concentration of citrate in the dental tissues, namely, 0.470% and 0.054% in molar dentin and enamel, respectively, and 0.110% and 0.024% in incisor dentin and enamel, respectively. The dentin and ena...

Microscopy of the response of rodent dentin to injected fluoride.

AbstractRats were injected subcutaneously with 50 mg/kg body weight of sodium fluoride. The hypermineralized and hypomineralized components of the response in incisor dentin were identified in ground sections using contact microradiography and analyzed microscopically for matrix alterations. In demineralized sections the hypomineralized component stained weakly for acid polysaccharide (alcian blue, Hale's iron method), was less dense (interference microscopy) and more birefringent than normal matrix. The hypermineralized component stained intensely for acid polysaccharide and was less birefringent than normal matrix. In the electron microscope, the inorganic crystals in the hypomineralized component were less numerous and larger than normal, while those of the hypermineralized component were more numerous but of normal diameters.These observations indicate that the hypomineralized component results from an inhibition of polysaccharide‐collagen interaction, resulting in a paucity of apatite nucleation sites and a more soluble organic matrix. The hypermineralized component results from an increased period of time for matrix aggregation with the formation of more nucleation sites and therefore more numerous crystals and a less soluble organic matrix. The presence of a hypermineralized component in organic matrix of nearly normal density indicates that mature rodent incisor dentin is less completely mineralized than the bone of mature osteons.

Effect of Dietary Iron on Phosphate Metabolism.

ConclusionsIncreasing the amount of iron by means of stomach tubing FeSO4 to rats significantly increases liver iron content. When 50 mg phosphate is given simultaneously with iron, a significant reduction in liver iron content results, as well as a significant diminution in calcium and phosphorus content of newly forming incisor dentin. These results, compared with a significant reduction in blood phosphorus concentration, suggest that increasing the iron content of the diet for prolonged periods of time without significantly increasing the dietary phosphorus content may result in improperly calcified tissues.

Some characteristics of purified saliva-parotin-A.

Purified Saliva-parotin-A, almost homogeneous electrophoretically and ultracentrifugally, consisted of 18 kinds of amino acids. Its biological activities were extremely powerful and the minimum effective dose for rabbit serum calcium decreasing activity was 5-10μg, for circulating leucocytes activity 0.25-0.5μg and for calcification of rabbit incisor dentine 2μg.The biological activities were extremely stable in acid and neutral solutions but comparatively unstable in alkaline solution.It was partly digested by proteolytic enzymes without loss of its biological activities. It was inactivated by formaldehyde but not by nitrous acid, iodine, thioglycollic acid or cysteine.It was not denatured by urea nor by guanidine.Amino, tyrosine-phenyl and sulfhydryl groups in Saliva-parotin-A molecule were not responsible for revealing its biological activities.

Wheat Cereal Diets, Rat Caries, Lysine and Minerals

Diets containing wheat flours, dry or toasted bread, or shredded wheat biscuit, cerelose or lactose, and liver powder resulted in a high incidence of severe smooth-surface caries in white rats. Autoclaving whole wheat flours with cerelose or lactose increased their caries potential whereas toasting of bread had no such influence. A lysine supplement reduced the dental caries produced by diets containing autoclaved wheat flour and toasted bread. Mineral supplementation with calcium carbonate plus sodium acid phosphate or with milk ash, significantly reduced the caries produced by wheat cereal diets. Neither calcium carbonate nor calcium acid phosphate alone was cariostatic, whereas sodium acid phosphate alone significantly reduced the caries produced by a wheat flour diet. The percentage of ash, calcium and phosphorus of the dentin and enamel of both incisor and molar teeth was unaffected by extreme deficiency in dietary calcium and a low phosphorus content. These analytical data were unrelated to the smooth-surface caries as diagnosed in the molar teeth.

The effect of dihydrotachysterin (AT10) on the collagen maturation in the dentin of rat incisors.

The effect of dihydrotachysterin (AT10) on the collagen maturation in the dentin of rat incisors.

On the occurrence of a parotin-like substance (saliva-parotin) in the human saliva; studies on the salivary gland hormones. XXVII.

By purifying the dried powder, which was precipitated from the human saliva by the addition of acetone, as shown in Fig. 1, parotin-like protein was isolated and named “Saliva-parotin”.Its isoelectric point was pH 3.4 and its purity in the electrophoretic analysis was 72.7%(by the ascending).It gave all the color reactions of proteins and precipitated with acids or heavy metals, but did not coagulate in aqueous solution by heating.By paper partition chromatogrophy of the hydrolyzate of saliva-parotin seventeen kinds of amino acids were identified. Saliva-parotin possesses an entirely the same biological action as parotin; decrease of serum calcium level, promotion of calcifying the incisor dentine, increase of the number of circulating leueocytes and rise of the bone marrow temperature were clearly observed in rabbits. The fall of the blood pressure in an anesthetized dog was recognized with an insufficiently purified preparation, but not in the case of the preparation with 72.7% purity.Acknowledgement. The authors greatly appreciative of the cooperation of Dr. H. Takatani, Tasaka Internal Medical Department, University of Tokyo, Prof. S. Huse and Mr. N. Matsuda, Department of Dental Surgery, School of Medicine, Gunma University, Mr. H. Takigawa, Endocrinological Laboratory, School of Medicine, Gunma University, and Mr. Y. Morioka, Teikoku Hormone Manufacturing Co., and co-workers in this study.

Each gart of the dentin of rabbit's incisor shows itsdinerent reactitvity for varied irritations

Each gart of the dentin of rabbit's incisor shows itsdinerent reactitvity for varied irritations

The effect of a high-sucrose diet on the calcium and phosphorus content of the enamel and dentine of rat incisors.

The effect of a high-sucrose diet on the calcium and phosphorus content of the enamel and dentine of rat incisors.

Changes in the mineral composition of enamel and dentin of the incisors in vitamin E-deficient rats.

Acta Physiologica ScandinavicaVolume 21, Issue 2-3 p. 124-130 Changes in the Mineral Coinposition of Enamel and Dentin of the Incisors in Vitamin E-Deficient Rnts1 HENRIK DAM, HENRIK DAM Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this authorHUMBERTO GRANADOS, HUMBERTO GRANADOS Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this authorLORENS MALTESEN, LORENS MALTESEN Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this author HENRIK DAM, HENRIK DAM Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this authorHUMBERTO GRANADOS, HUMBERTO GRANADOS Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this authorLORENS MALTESEN, LORENS MALTESEN Departments of Biology and Chemistry A, Polytechnic Institute, Copenhagen, DenmarkSearch for more papers by this author First published: April 1950 https://doi.org/10.1111/j.1748-1716.1950.tb00720.xCitations: 15 1 This work was aided bp a grant from Rask-Orsted Pondet AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume21, Issue2-3April 1950Pages 124-130 RelatedInformation

Effect of Magnesium Deficiency on Dentin Apposition and Eruption in Incisor of Rat

Summary and ConclusionsIn magnesium deficiency the rate of eruption of the incisor is reduced to approximately one-third the normal. The outstanding effect is on dentin apposition which is progressively decelerated, the enamel-covered dentin being affected more acutely than the cementum-covered portion. Temporary local cessations of growth may occur. The formation of alveolar bone is also decelerated to one-half or less of the normal rate and the periodontal membrane is abnormally wide. The dentin of the rat incisor acts not only as a kymograph of calcium metabolism (Fig. 2), but also as a growth kymograph (Fig. 1, D.2).

The nasopalatine block injection as an aid in operative procedures for maxillary incisors

Local anesthesia as an aid in operative procedures involving the dentine and pulp of the maxillary incisors has been a failure in the hands of many dentists. This has resulted in the substitution of dental obtundants, pressure anesthesia, or pulp devitalization pastes in an attempt to perform painless operative procedures on these teeth. The reason so many dentists fail to obtain satisfactory anesthesia of the pulps of these teeth is due primarily to a misunderstanding of their innervation. Injections on the labial aspect of these teeth based upon the assumption that the incisors are innervated by the anterior superior alveolar nerves has nearly always resulted in incomplete anesthesia. The experience of the Detroit Department of Health Root Surgery Clinic in which over 2,000 vital pulps were extirpated painlessly from maxillary incisors using only the nasopalatine injection, together with a consideration of the embryologic development of the face and jaws and a series of anatomie dissections, has shown the definite relationship of the nasopalatine nerves to these teeth. Profound anesthesia of the pulps of the maxillary incisors may be readily obtained by inserting the syringe needle high into the incisive canals and depositing slowly 1 4 c.c. of anesthetic solution at this level. Contrary to popular belief, the incisive canal injection is not painful when properly administered. In fact, children report less discomfort during the injection and after anesthesia has dissipated than with the labial injections. The utilization of this injection as an aid in painful operative procedures involving the dentine or pulp of the maxillary incisors should result in the discontinuance of many of the unsatisfactory procedures now commonly practiced for this purpose.

A pound of Vitamin-C

Mutation of vitamin D receptors (vdr) results in resistance to the vitamin's normal effects which may compromise dentin formation. The objective of this study was to investigate the effect of vdr deficiency on post-natal dentin maturation in mice. The dentin in mandibular incisors of 70.5-day-old vdr wild-type and vdr knockout mice was compared at different levels along the long axis. Expression of biglycan and decorin was detected by immunolocalisation. Scanning electron microscopy was used to observe the ultrastructure of the dentin, and micro-computerised tomography was used to determine the degree of dentin mineralisation density. In the vdr knockout mice, the pulp chamber was larger and the dentin wall was thinner compared with the wild-type mice. In addition, the pre-dentin layer was thickened with an irregular front line and diffuse expression of biglycan and decorin. Fewer tubules, lower mineralisation density and pore-like defects were observed in the dentin at the eruptive region and level with the first molar. In conclusion, vdr deficiency compromises dentin maturation.