Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tooth Germ”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources
PubMed1985

Ampicillin concentrations in human serum, gingiva, mandibular bone, dental follicle, and dental pulp following a single oral dose of talampicillin.

Eighty-one patients who underwent the extraction of impacted mandibular third molars in the nonfasting state were given a single oral dose of talampicillin (500 mg) preoperatively. Specimens of venous blood (n = 132), gingiva (n = 70), mandibular bone (n = 78), dental follicle (n = 63), and dental pulp (n = 59) were obtained during the operation and assayed for ampicillin content. The mean peak concentrations in serum (9.64 micrograms/ml), gingiva (4.72 micrograms/mg), mandibular bone (1.77 micrograms/ml), dental follicle (3.46 micrograms/ml), and dental pulp (5.53 micrograms/mg) all occurred at approximately 150 minutes after administration of talampicillin. The ratios of the corresponding serum concentration to the peak concentrations in the various oral tissues when both were plotted as drug concentration curves were: gingiva, 0.50; mandibular bone, 0.16; dental follicle, 0.34; and dental pulp, 0.52. Talampicillin was absorbed well by the intestine, and sufficient concentrations of the resulting metabolite, ampicillin, were found in oral tissues.

Administration, Oral↗
PubMed1988

Autogenic tooth transplantation: a report of ten cases.

Modifications in the surgical procedure for transplantation of the unerupted mandibular third molar to the first molar socket are presented, and the clinical and radiographic data on ten cases with a 3-year follow-up are described. The proposed method of treatment makes it possible to stabilize the transplant without a splint by using a suture crossed over the occlusal surface of the tooth.

Adolescent↗
PubMed1988

The origin of tooth number of the human deciduous dentition: a hypothesis.

The constant number of 5 teeth per quadrant in the human deciduous dentition is seen to be a result of the mitotic activity within the dental lamina which leads to a constant number of centers in which cells are compressed together. These centers in which, due to the compression, the cells become narrow and cylindrical and, due to subsequent bulging, wedge-shaped, are the prerequisite for the formation of the constant number of five tooth buds per quadrant.

Dentition↗
PubMed1983

Lysosomes and removal of the basal lamina of ameloblasts in early stages of odontogenesis.

Differentiation of ameloblasts is characterised by the development of cytoplasmic organelles and changes in the distal cytoplasm and surface adjacent to the basal lamina. Examination of rat tooth germs prepared for thin section electron microscopy and for freeze fracture, and also stained for acid phosphatase, reveals that three concomitant events occur in this region. The distal surface membrane becomes progressively more undulated, there is an increase in acid phosphatase-containing membrane-bound vesicles (lysosomes) and the basal lamina becomes less apparent and finally disappears. Since the progressive disappearance of the basal lamina is accompanied by an increase in lysosomes, it is possible that lysosomal enzymes are involved in the breakdown of the basal lamina or, alternatively, that the basal lamina is broken down by enzymes derived from odontoblasts, and that its remnants are taken up by the many coated pits and invaginations of the distal surface membrane to be further degraded iun the lysosomal system.

Ameloblasts↗
PubMed1990

Effects of beta-D-xyloside on morphogenesis and cytodifferentiation in cultured embryonic mouse molars.

Embryonic mouse molars were grown on a semi-solid medium supplemented with 2 mM beta-D-xylopyranoside (beta-xyloside), a specific inhibitor of proteoglycan synthesis. The induced glycosaminoglycan depletion in the extracellular matrix was monitored by immunohistochemistry employing monoclonal antibodies to chondroitin 4- and chondroitin 6-sulfates. beta-Xyloside inhibited formation of the dental bell and delayed the appearance of the first odontoblasts. Odontoblast functional differentiation proceeded in the absence of chondroitin sulfate in the basement membrane. Predentin secreted in the presence of beta-xyloside triggered the polarization of ameloblasts, but did not allow the maintenance of polarized odontoblasts. These results support the hypothesis that, in the tooth germ, chondroitin sulfate proteoglycans participate in the regulation of cell kinetic-dependent morphogenesis (Mark et al., 1990. Differentiation 43, 37-50). On the other hand, the possibility that chondroitin sulfate might play a role in odontoblast terminal differentiation is definitively ruled out.

Ameloblasts↗
PubMed2004

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage.

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG 1 (18 patients), eruption of the second molars had either not yet taken place or was not complete. In PG 2 (15 patients), the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been carried out, and the first and second molars on both sides had completely erupted. Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum, and that tipping of the first molars in patients in whom the second molar was still at the budding stage was thus greater. In patients whose second molars had erupted completely, the degree of tipping was greater again when a third molar bud was located in the direction of movement. After previously completed germectomy of the wisdom teeth, almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars. However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost. Statistical analysis of the results of dental-angular measurements showed significant differences in the degree of molar tipping and reciprocal incisor protrusion. The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1). For instance, the measured angles were 0.9 degrees +/- 3.43 degrees (to the palatal plane) and 0.8 degrees +/- 3.4 degrees (to the anterior cranium floor) in PG 2, and -0.33 degrees +/- 0.58 degrees and 0.67 degrees +/- 2.08 degrees, respectively, in PG 3, contrasting with respective values of 5.89 degrees +/- 3.74 degrees and 5.36 degrees +/- 3.49 degrees in PG 1. Tipping of erupted second molars was much more marked in PG 2 (7.92 degrees +/- 5.83 degrees to the palatal plane and 7.55 degrees +/- 5.28 degrees to the anterior cranium floor), but much less pronounced in PG 3 (2 degrees +/- 1.73 degrees to the palatal plane and 2 degrees +/- 2 degrees to the anterior cranium floor) than the corresponding movement of the second budding-stage molars in PG 1 (4.06 degrees +/- 2.15 degrees and 3.97 degrees +/- 2.27 degrees, respectively). The degree of incisor protrusion occurring reciprocally with molar distalization was much less in these patients (measured angles of 3.28 degrees +/- 1.97 degrees and 2.89 degrees +/- 2.17 degrees to the palatal plane and anterior cranium floor, respectively) than in the patients presenting different stages of the dentition (angles of 5.5 degrees +/- 3.33 degrees and 6.03 degrees +/- 4.29 degrees, respectively, in PG 2, and angles of 5.5 degrees +/- 3.28 degrees and 6.67 degrees +/- 3.09 degrees, respectively, in PG 3). Moreover, measurement of dental casts in the horizontal plane showed not only the targeted mesiobuccal rotation of both maxillary molars, but also a vestibular drift of the unbanded second molars.

Activator Appliances↗
PubMed2004

The effect of hereditary disorders on tooth components: a radiographic morphometric study of two syndromes.

OBJECTIVE: The purpose of this study was to compare tooth components (enamel and dentin) in Familial Dysautonomia (FD) and Down syndrome (DS) in order to assess the extent to which each was affected. DESIGN: The design was cross-sectional. The sample consisted of 20 FD patients and 45 DS patients. The control group comprised 250 healthy subjects. Mesio-distal crown width (CW), enamel and dentin thickness and pulp chamber dimensions were measured on standardized bitewing radiographs of mandibular second primary and first permanent molars. Statistical analyses were performed between groups using SAS programs. RESULTS: CW was reduced in both hereditary disorders. In the DS group enamel height (EH) and dentin thickness were reduced. In FD enamel thickness in the primary and permanent molars as well as dentin height (DH) in permanent molars was increased. CONCLUSIONS: In both syndromes the reduction in CW suggests reduced proliferation during tooth germ formation. However, the differences in enamel and dentin thickness suggest that ameloblasts and odontoblasts were affected differently in the later phases of cell function. In FD cell function is stimulated resulting in thicker enamel and dentin. In DS cell function is reduced resulting in thin enamel and dentin.

Adolescent↗
PubMed2005

Dental epithelial histo-morphogenesis in the mouse: positional information versus cell history.

Reciprocal epithelial-mesenchymal interactions control odontogenesis and the cap stage tooth germ mesenchyme specifies crown morphogenesis. The aim of this work was to determine whether this mesenchyme could also control epithelial histogenesis. Dental mesenchyme and enamel organ were dissociated from mouse first lower molars at E14. At this early cap stage, the enamel organ consists of four cell types forming the inner dental epithelium (IDE), primary enamel knot (PEK), outer dental epithelium (ODE) and the stellate reticulum (SR). Pelleted trypsin-dissociated single dental epithelial cells, which had lost all positional information, were reassociated to either dental mesenchyme or dissociated mesenchymal cells and cultured in vitro. Although with different timings, teeth developed in both types of experiments showing a characteristic dental epithelial histogenesis, cusp formation, and the differentiation of functional odontoblasts and ameloblasts. The rapid progression of the initial steps of histogenesis suggested that the cell history was not memorized. The dental mesenchyme, as well as dissociated mesenchymal cells, induced the formation of a PEK indicating that no specific organisation in the mesenchyme is required for this step. However, the proportion of well-formed multicusped teeth was much higher when intact mesenchyme was used instead of dissociated mesenchymal cells. The mesenchymal cell dissociation had consequences for the functionality of the newly-formed PEK.

Animals↗
PubMed2004

Apoptosis-related factors (Fas receptor, Fas ligand, FADD) in early tooth development of the field vole (Microtus agrestis).

Fas (CD95/APO-1) belongs to the TNF receptor (TNFR) family. Fas ligand binding followed by Fas-receptor oligomerisation leads to formation of a death-inducing signal complex starting with recruitment of the Fas-adapter protein (FADD). Components of this initiation complex (Fas, Fas-L, FADD) were correlated with apoptotic cells, detected by specific DNA fragmentation and morphological criteria. Apoptotic cells can be detected throughout the embryonic development of molar teeth. Restricted temporospatial distribution suggests several important roles for apoptosis in tooth morphogenesis. However, the mechanisms employed in dental apoptosis remain unclear. Frontal sections of the field vole at stage 13.5-15.5 of embryonic development were exploited to investigate and correlate location of Fas, Fas-ligand, FADD molecules and apoptosis in developing first molars by immunohistochemistry. During these stages the primary enamel knot appears and is gradually terminated by apoptosis. Initially, apoptotic cells were demonstrated in the most superficial layer of the dental lamina. The number of TUNEL-positive cells expanded from late bud to cap stages. Restricted areas of apoptotic cells were found in the stalk and primary enamel knot. Fas, Fas-L and FADD were co-localised, particularly in the primary enamel knot, and the stalk, correlating with the occurrence of apoptosis in these areas. Fas-L, however, was also found in proliferating parts of the developing tooth germ, such as in the cervical loops. Interestingly, FADD molecules were also observed in areas, where Fas protein was not detected. According to the immunohistochemical data, Fas-mediated signalling may have a triggering or enhancing role in dental apoptosis. This remains to be functionally confirmed.

Animals↗
PubMed2006

Development of functional dentin incisors after a partial resection of the odontogenic organ of rat incisors.

The resection of the labial half of the odontogenic organ of rat incisors resulted in the development of teeth without enamel. Ten out of 26 operated rats developed a functional dentin incisor, i.e. a continuously growing and erupting tooth. These teeth were a little shorter and much thinner than normal incisors. The dentin and pulp presented a normal structure. Periodontal ligament and cement started to develop at the lingual face and gradually all tooth faces were invested by these tissues. The original socket space, to accommodate a thinner tooth, was narrowed by newly formed bone around the inner face of the socket. Eleven rats developed defective dentin incisors; these teeth showed signs of growth, however, their eruption was impaired. The operation failed in five rats. The odontogenic organ of the dentin incisor presented islands of epithelial cells at the labial aspect of a dense mass of mesenchyme cells. These islands, formed by densely packed, dark-staining cells encircling a few pale-staining cells, merged gradually, forming a root sheath and a cervical loop limiting a long apical foramen. The bulk of the bulbous part (apical bud) was absent; thus, there was no differentiation of ameloblasts and of the crown-analogue part of the incisor. The growth and eruptive behaviour of the dentin incisor, similar to that of a normal incisor, indicates that it has to bear a stem cell niche to retain its regenerative capacity. As in the apical bud, this niche is apparently located at the stellate reticulum of the cervical loop. The putative molecular mechanisms related to either the maintenance of the stem cell niche or the differentiation of the enamel organ and the root sheath are discussed. These data and our results, showing the development of a functional dentin incisor, suggest that the root-analogue part of the rodent incisor is an anatomic-physiological entity.

Animals↗
PubMed2004

Autotransplantation of immature third molars into edentulous and atrophied jaw sections.

The aim of the present study was to assess the results after transplantation of 85 immature third molars. Recipient site conditions varied and different surgical techniques were used. The long-term results after preparation of a new alveolus, splitting osteotomy of the alveolar process or use of free bone autografts were compared with the results after transplantation into a fresh extraction site (control group). Transplantations into prepared sockets showed equal results to the control group (94% respectively). Transplantations in connection with free bone autografts (84%) or after splitting osteotomy of the alveolar process (63%) showed poorer success rates, the differences between the latter and the control group being statistically significant. A possible correlation to revascularization disturbances of the pulp due to an insufficiency of the recipient site or to postoperative infection is suspected. The results show that transplantation of immature third molars is a safe, useful procedure when appropriate conditions of the recipient site are present. Where the alveolus is atrophic, a splitting osteotomy should be performed only in exceptional cases and preference should be given to alternative methods such as primary bone augmentation or bone-regenerative procedures.

Adolescent↗
PubMed2006

Radiographic evaluation of the fate of developing tooth buds on the fracture line of mandibular fractures.

PURPOSE: The goal was to suggest guidelines for the treatment of developing tooth buds located on the fracture line of mandibular fractures. PATIENTS AND METHODS: The long-term radiographic follow-up records of 28 patients with mandibular fractures involving 66 tooth buds were examined for the occurrence of abnormalities in development or eruption. The fates of the involved teeth were compared according to the fracture conditions and other factors, and the cause of the abnormalities was surveyed. RESULTS: Abnormal findings were observed in 30 of 66 developing teeth (45%); these included deficient root formation, abnormal bend of the root, nodule formation on the root, partial obliteration of the pulp cavity, impaction, growth arrest, and external resorption. No relationship was found between the presence of abnormalities and the condition of the fracture or the developmental stage of the tooth buds. However, infection, rotation of the tooth bud, and a surgical wire passing through the follicular space were associated with arrested growth and impaction. CONCLUSIONS: The tooth buds present on the fracture line should be preserved except in cases of infection, and careful attention should be paid to avoiding further injury to the tooth bud and the soft tissues of the follicle at the time of surgery.

Adolescent↗
PubMed2006

Preliminary study of tissue-engineered odontogenesis in the canine jaw.

PURPOSE: We previously reported a method for the development of tissue-engineered tooth. However, 1 drawback of the procedure was the inability to determine whether the tooth would function when transplanted in the jaw because it was formed in the omentum of the abdomen. Therefore, the present study was designed to evaluate whether transplantation of dissociated odontogenic cells could induce tissue-engineered odontogenesis in the canine jaw. MATERIALS AND METHODS: Cells were harvested from canine first molar tooth buds and the resulting heterogeneous cell population was seeded on a biodegradable polymer. These constructs were then transplanted into the same sockets after extracting the tooth buds. After transplantation, we evaluated the transplanted constructs using dental x-ray, micro-computed tomography, histology, and immunohistochemistry. RESULTS: After 24 weeks, micro-x-ray computed tomography showed regenerated hard tissues in the jaw, and hematoxylin and eosin staining showed tubular dentin and bone. In the regenerated tissue, osteopontin, osteonectin, and osteocalcin antibodies stained the dentinal matrix. However, enamel tissue and dental-root formation were not observed. CONCLUSION: These data show for the first time the formation of dentin and bone from dissociated odontogenic cells in the canine jaw.

Animals↗
PubMed2004

Does Vitamin D play a role on Msx1 homeoprotein expression involving an endogenous antisense mRNA?

Msx1 homeobox gene, a member of Msx family, has been implicated in numerous organs. Its participation was established in different events, such as morphogenetic field determinism and epithelio-mesenchymal interactions. Most of Msx1 target organs are also known for their sensitivity to Vitamin D: such as bone, tooth germ, and hair follicle. Whereas, the expression of Msx2, another member of Msx family, has been shown to be controlled by Vitamin D, no information is available for Msx1. This study aims to analyze the potential relationships between Vitamin D and Msx1 through: (1) comparative analysis of Vitamin D receptor (VDR) and Msx1 protein expression, (2) investigation of Msx1 expression in VDR null mutant mice, and (3) study of Msx1 overexpression impact on osteocalcin VDR expression in immortalized MO6-G3 odontoblasts. Results show the existence of cross-talks between Vitamin D and Msx1 regulation pathways. In odontoblastic cells, Msx1 overexpression decrease VDR expression, whereas in rickets Msx1 sense transcript expression is decreased. These cross-talks may open a new window in the analysis of rickets mineralized tissues physiopathology. In Vitamin D null mutants, the study of the natural Msx1 antisense transcript which has been recently described should be informative.

Animals↗
PubMed2006

Pathology of malignant and premalignant oral epithelial lesions.

Oral mucous membranes and the surrounding structures are largely composed of stratified squamous epithelium that is supported by a fibrous connective tissue lamina propria and a submucosa of fibroadipose tissue. Minor salivary glands, nerves, and capillaries course abundantly throughout the supporting collagen and fibro-fatty submucosa. Premalignant and malignant lesions arise most frequently from epithelium, and these epithelial lesions ultimately account for 95% of all cancers of the oral cavity. Malignant neoplasia of bone, cartilage, salivary glands, and connective tissue and those of lymphoproliferative derivatives are far less common occurrences in the oral cavity. Malignant neoplasms can and do arise from the tooth germ apparatus, but neoplasms of odontogenic elements are rare and are not included in this discussion.

Carcinoma in Situ↗
PubMed2000

Immortalization of bovine dental papilla cells with simian virus 40 large t antigen.

Primary cultures of dental papilla-derived cells have a limited lifespan in vitro and can be maintained only up to passage 7-9 before showing senescence, but in vitro investigations often require a large number of cells showing phenotypic characteristics of the original tissue. To overcome this shortcoming, second-passage cells established from calf molar tooth germs by enzymatic pretreatment of the dental papilla were transfected by electroporation with pSV3neo, coding for the oncogene simian virus 40 large t antigen and a neomycin-resistance gene. Under selection by G418 (neomycin), four cell clones were isolated by single cell dilution at passage 15. Integration of simian virus 40 large t antigen and expression of the gene products were determined in cell clones by polymerase chain reaction (PCR) and immunohistochemistry. Four transfected cell lines (clones B, C, D and no. 12) were maintained in culture for over 1.5 years. For cell characterization, gene expression of procollagen alpha1 (I) and osteocalcin was evaluated by reverse transcriptase (RT)-PCR with cDNA obtained from the established cell lines at passage 20. Expression of collagen type I, osteocalcin and dentine phosphoprotein was evaluated immunohistochemically at passage 20 and after 1.5 years of continuous cell culture. Gene expression and the expression of mineralized tissue-specific proteins was demonstrated with RT-PCR and immunohistochemistry within all four immortalized cell lines. Expression of dentine phosphoprotein was observed in three simian virus 40 large t antigen-transfected cell lines, suggesting the immortalization of odontoblast-like cells in vitro. Thus, transfection of bovine dental papilla-derived cells resulted in immortal cell lines exhibiting phenotypic characteristics of the original tissue.

Animals↗
PubMed1998

A scanning electron-microscopic study of developing human deciduous enamel on the dependence of the outline of surface pits on the angle of observation.

On the developing enamel surfaces of fetal human deciduous teeth, many of the surface pits were arcade-shaped with the arcade preferentially pointing in a cervical direction. The configuration of the interprism ridges between the pits contributed to this appearance. Surface cracks allowed verification of an incisal inclination of the subsurface prisms. This apparent paradox was solved when the specimens were tilted so that the pits were viewed in the directions of the prisms, giving the pits a compressed arcade-shape with the arcades pointing incisally. It is recommended that care should be exercised and due attention paid to the angle of observation when determining the orientation of pit arcades. Pit entry direction seems to be a more reliable feature for inferring the direction of tangential ameloblast movement.

Ameloblasts↗
PubMed2000

A histological study of the effect of growth hormone on odontogenesis in the Lewis dwarf rat.

The effect of growth hormone (GH) on the dentition has been described in children with pituitary dwarfism where teeth fail to form; those that do form tend to be reduced in size and the eruption potential is diminished. The aim here was to examine the effect of GH on odontogenesis via molar development in Lewis (control), dwarf (Dw) and Dw GH-treated (Dw+GH) rats aged 3, 6, 9, 12 and 15 days. Dw+GH animals received a twice-daily dose (65 microg/kg) of GH which commenced at 2 days of age. Animals were killed, mandibles removed, processed to embedding in paraffin, sectioned and stained for histological examination of molar morphology during development. Variations in enamel mineralization and root development were observed. In 6-day-old animals, enamel mineralization was delayed in Dw and Dw+GH animals. Root initiation was evident at 6 days of age in controls but was not observed until 9 days of age in Dw and Dw+GH animals. At 12 days of age, maturation of enamel in Dw and Dw+GH animals remained delayed. By 15 days of age no variation in tooth development was evident. These data indicate that enamel mineralization is affected by the level of circulating GH in the rat. A specific deficiency of GH did not appear to delay bone resorption prior to tooth emergence.

Animals↗