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PubMedDate not supplied

Calcification associated with the nasolacrimal system of a horse: case report and mineralogic composition.

A 12-year-old Paso Fino mare was evaluated for a chronic nasal and ocular discharge. A calcification was identified eroding through the nasal mucosa of the middle meatus. Differential considerations for this mass included dacryolith, nasal calculus, or calcified tooth root abscess. Anatomical location and case history and progression supported a dacryolith. Following removal, the calculus was submitted for mineralogic analysis. The calculus was primarily carbonate hydroxylapatite (Ca10(PO4)3(CO3)3(OH)2) with a minor NaCl halite constituent. Dacryoliths, or nasolacrimal calculi, are an uncommon occurrence in animals, and sparsely reported in humans. The etiopathogenesis of dacryolith formation is unknown. The objective of this article was to report the first case report of an equine nasolacrimal system dacryolith and its mineralogic composition.

Animals↗
PubMed2003

Regulatory mechanisms of periodontal regeneration.

The periodontal ligament, located between the cementum and the alveolar bone, has a width ranging from 0.15 to 0.38 mm. Regeneration and homeostasis of the periodontal ligament are highly significant functions in relation to periodontal therapy, tooth transplantation or replantation, and orthodontic tooth movement. The purpose of this review is to discuss the regulatory mechanisms of regenerative and homeostatic functions in the periodontal ligament based on currently published studies and also on our own experimental data. We consider the capability of the ligament tissue to promote or to suppress calcification in connection with bone and cementum formation and the maintenance of the periodontal ligament space. Also discussed are the involvement of the periodontal ligament tissue in the regenerative ability, cell proliferation, growth and differentiation factors, extracellular matrix proteins, homeostatic phenomena, function of Malassez epithelial rests, tooth movement, or occlusal loading. Regulatory mechanisms for regeneration and homeostasis of the periodontal ligament are hypothetically proposed.

Animals↗
PubMed2005

Differential regulation of dentin sialophosphoprotein expression by Runx2 during odontoblast cytodifferentiation.

Dentin sialophosphoprotein (DSPP) consists of dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). The spatial-temporal expression of DSPP is largely restricted during differentiational stages of dental cells. DSPP plays a vital role in tooth development. It is known that an osteoblast-specific transcription factor, Runx2, is essential for osteoblast differentiation. However, effects of Runx2 on DSPP transcription remain unknown. Here, we studied different roles of Runx2 in controlling DSPP expression in mouse preodontoblast (MD10-F2) and odontoblast (MO6-G3) cells. Two Runx2 isoforms were expressed in preodontoblast and odontoblast cells, and in situ hybridization assay showed that DSPP expression increased, whereas Runx2 was down-regulated during odontoblast differentiation and maturation. Three potential Runx2 sites are present in promoters of mouse and rat DSPP genes. Runx2 binds to these sites as demonstrated by electrophoretic mobility shift assay and supershift experiments. Mutations of Runx2 sites in mouse DSPP promoter resulted in a decline of promoter activity in MD10-F2 cells compared with an increase of its activity in MO6-G3 cells. Multiple Runx2 sites were more active than a single site in regulating the DSPP promoter. Furthermore, forced overexpression of Runx2 isoforms induced increases of endogenous DSPP protein levels in MD10-F2 cells but reduced its expression in MO6-G3 cells consistent with the DSPP promoter analysis. Thus, our results suggest that differential positive and negative regulation of DSPP by Runx2 is dependent on use of cytodifferentiation of dental ectomesenchymal-derived cells that may contribute to the spatial-temporal expression of DSPP during tooth development.

Animals↗
PubMed1992

Further evidence on relative dental maturation and somatic developmental rate in hominoids.

New data on hominoid dental development are presented. Individual bivariate pairings of all mandibular teeth were made for African apes and humans. Data were analyzed with a full linear regression model. No statistically significant differences were found among apes, although a consistent pattern of earlier incisal development was observed in Pan relative to Gorilla. This is concordant with an earlier fusion of the premaxillary:maxillary suture in Pan. Only one tooth pair differed significantly by sex among apes. Two biologically distinct human samples (Libben and Hamann-Todd), although assessed differently (extraction and radiography) yielded virtually identical results. Humans differ from apes only by earlier relative calcification of their anterior teeth. This can be viewed as a consequence of reduced facial prognathism and a shift in hominid canine function.

Animals↗
PubMed1989

The dentino-enamel junction: a structural and microanalytical study of early mineralization.

The spatial localization of enamel and dentin apatite crystals of the rat tooth has been studied by electron microscopic methods--bright field, selected-area dark field, and electron spectroscopic imaging. The sequential events of dentin calcification followed by the formation and growth of enamel crystals were determined and compared to previous studies. In dentin, initial sites of mineral deposition occur in areas subjacent to the dentino-enamel junction (DEJ). The subsequent expansion of these deposits progresses towards the DEJ to the terminal ends of dentin collagen fibrils. Concomitantly, an electron-dense enamel matrix is released by ameloblasts; with the presence of this matrix, the growth of enamel crystals occurs from the underlying calcified dentin. Enamel crystal growth continues to within close proximity of the plasma membrane of ameloblasts. A close spatial relationship between enamel and the crystals of calcified dentin collagen fibrils was observed by selected-area dark field imaging. Such areas of crystal intimacy show a co-localization of calcium and phosphorus extending from calcified collagen fibrils to enamel sheaths which encase enamel crystals. A working model of the spatial relationship between crystals of dentin and enamel is presented and discussed in light of mechanisms by which calcified dentin may promote the formation of enamel crystals.

Amelogenesis↗
PubMed1992

Mineralized nodule formation by cultures of human dental pulp-derived fibroblasts.

Pulp fibroblasts were isolated from human deciduous and supernumerary teeth and cultured in vitro. With continued culture in normal tissue-culture medium, six pulp fibroblast strains formed cell nodules after 10-15 days. By electron microscopy the nodules had matrix vesicles, and needle-shaped crystals associated with a dense network of collagen fibrils. The crystalline material exhibited a pattern consistent with hydroxyapatite when nodules were examined by X-ray diffractometry. Furthermore, the cells showed high levels of alkaline phosphatase activity, which could be increased more than seven-fold by the addition of 1,25(OH)2D3 (5 x 10(-9)-5 x 10(-8) M). In addition to the production of type I collagen, these cells also synthesized fibronectin and osteonectin. The formation of mineralized tissue nodules by pulp cells in vitro provides a useful system for study of the pathological calcification of pulp tissues.

Alkaline Phosphatase↗
PubMed1983

Soft-tissue calcifications of the dental follicle in regional odontodysplasia: a structural and ultrastructural study.

Soft-tissue calcifications of the dental follicle in regional odontodysplasia were studied via the correlated techniques of light microscopy, scanning electron microscopy (SEM), calcium x-ray cartography, and high-resolution transmission electron microscopy (TEM). The study revealed several types of calcification, mostly located within an area normally occupied by enamel formation. Some of them are produced without collagen being involved; others result from the mineralization of collagen fibers. Sometimes they were surrounded by a structureless homogeneous zone and resulted from the fusion of several smaller globules. High-resolution TEM revealed two different types of calcifications: a few composed of platelike crystallites, presenting a "sheath" characteristic of apatite formation, most of them poorly crystallized. The calcifications were in close contact with the cytoplasm of the neighboring connective tissue cells in which an abundance of microfilaments was found. It is suggested that these filaments might be involved in the formation of dystrophic soft-tissue calcifications.

Adolescent↗
PubMed2006

Multiple pulp stones and shortened roots of unknown etiology.

An unusual case of generalised pulpal calcifications (pulp stones) with normal clinical crowns is reported in a 13-year-old boy. Radiographic examination revealed pulp stones in the single rooted and premolar teeth, situated at the midroot level, with the roots bulging around them. The apical portion of the roots, periodontal ligament space, and surrounding bone had a normal radiographic appearance, apart from the upper premolars, and no periapical pathology was discernible. The upper premolars exhibited considerably shortened roots. No medical, dental, or family history was found to be contributory. Reviewing the literature revealed similar cases, but with differing diagnoses including dentine dysplasia (DD) or idiopathic cases. This report suggests either a variation of DD or possibly a new nonsyndromic dentine defect, and highlights the difficulties in establishing a definitive diagnosis by traditional methods. The recent discovery that mutation of the bicistronic dentine sialophosphoprotein gene (DSPP) is involved in DD may provide solutions to this problem.

Adolescent↗
PubMed1997

Apexification: case report.

Apexification is a process/procedure well recognized and accepted by clinicians and researchers alike. Calcium hydroxide is most commonly used to induce an apical hard tissue barrier which may be composed of different tissues but its mechanism of action is still unknown. The epithelial cell rests of Malassez have been implicated in apexification although case reports exist which apparently dispute this. The following case report demonstrates an unusual case of apexification following root filling, surgery and retreatment where the role of the epithelial cell rests of Malassez is discussed.

Adult↗
PubMed1986

Demonstration of structural variation in rat incisor dentin as determined by the x-ray Laue method.

Rat incisor dentin was studied by an x-ray micro-Laue method to investigate the relationship between crystal orientation and structural variation in the dentin. The results showed that crystal orientation was very poor in the labial dentin, but that the crystals were well-oriented in the lingual dentin. In the lingual dentin, the axis of crystal orientation was parallel to the tooth axis. It is suggested that the difference in crystal orientation between the lingual and labial dentin is due to the different mode of calcification between the two.

Animals↗
PubMed1991

Hypophosphatasia and the extracellular metabolism of inorganic pyrophosphate: clinical and laboratory aspects.

Hypophosphatasia is a rare inherited disorder in which the activity of the bone/liver/kidney or tissue nonspecific form of alkaline phosphatase (ALP) is reduced. The clinical expression of the disease is highly variable, but in early life the severity tends to reflect the age of onset. Accordingly, the disease is often classified into perinatal, infantile, and childhood forms. Hypophosphatasia also occurs in adults. Some exhibit symptoms in adulthood for the first time, but others have a history of the disease in early life with an intervening symptom-free period. Defective mineralization of bones and teeth is the predominant clinical feature of all forms of the disease. Biochemically, the reduction in ALP activity is associated with alterations in the extracellular metabolism of various phosphorylated compounds, including inorganic pyrophosphate (PPi), phosphoethanolamine, and pyridoxal 5'-phosphate. Of these, PPi may have an especially important role in the development of the mineralization defect. Accordingly, the extracellular metabolism of PPi and its possible role in the regulation of mineralization will be discussed.

Adult↗
PubMed1992

Microscopes in endodontics.

The introduction of microscopes in clinical and surgical endodontics is fairly recent. Potential applications, including removal of fractured instruments, localizing calcified canals, soft tissue management and root-end procedures, are reviewed.

Apicoectomy↗
PubMedDate not supplied

Novel dental anomalies associated with congenital contractural arachnodactyly: a case report.

Congenital contractural arachnodactyly (CCA) is an inherited disorder of connective tissue similar to Marfan's syndrome. The craniofacial and oral features of a young girl with CCA are described. The patient has the typical features of CCA as well as some additional dental anomalies which have not previously been reported with this syndrome. These include banded pitted enamel hypoplasia and hypomineralization, long, spindly tapered roots, and pulp canal obliteration with multiple pulp stones. Dentists must be aware of the clinical features of a patient's syndrome to determine whether there are implications for dental treatment such as a need for antibiotic prophylaxis. It is important to exclude Marfan's syndrome as a differential diagnosis for CCA because the former has more associated complications and a less favorable prognosis.

Adolescent↗
PubMedDate not supplied

A clinical study of ferric sulfate as a pulpotomy agent in primary teeth.

Pulpotomies were performed on 83 primary molars in 62 patients. Ferric sulfate or formocresol was placed on the pulpal stumps, and teeth were followed for 3-, 6-, and 12-month periods. After the one-year follow-up, 28 of 29 teeth treated with ferric sulfate (FS group) were considered successful and 21 of 27 teeth treated with formocresol (FC group) were judged to be successful. The FS group demonstrated greater combined clinical and radiographic success than the FC group at the one-year recall (P < 0.05). Although the results of this study are promising, further study with longer observation periods is warranted before this technique can be recommended.

Chi-Square Distribution↗