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At least 19 recordsLinked to original sources
PubMed2002

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies.

The behavior of epithelial cells during tooth root formation in porcine molars was investigated using TUNEL, immunohistochemical and transmission electron microscopic methods. Cells of Hertwig's epithelial root sheath (HERS) expressed bcl-2, but were TUNEL-negative. Epithelial cells of HERS were tightly connected and surrounded by a continuous basement membrane. When dental papilla cells were attached to the inner HERS, they became positive for osteopontin (OPN). The inner basement membrane was intermittent immediately after those cells started to synthesize dentin matrix, and the intercellular spaces of the HERS became wider. Dental sac cells then migrated between the fragmented HERS and were directly connected to epithelial cells by desmosome-like structures. After the cementum was synthesized by these mesenchymal cells, epithelial cells aggregated to form cell clusters, which were again surrounded by a continuous basement membrane. These results suggest that fragmentation of the HERS is due to the invasion of dental sac cells, but is not related to cell death. Furthermore, the differentiation of dental papilla cells into odontoblasts occurred following their connection to the HERS through the basement membrane. Moreover, it is suggested that the differentiation of dental sac cells into cementoblasts occurred upon their direct connection to epithelial cells of the HERS.

Animals↗
PubMed1998

[Tooth root length and tooth neck diameter as indicators in sex determination of human teeth].

The length of the dental root and the diameter of the tooth neck are odontometric parameters which to date have rarely been used for the differentiation of the sexes. Teeth of 166 individuals from the early medieval burial ground of Eichstetten (south Germany) were available for examination. A correlation analysis was performed to show the possible dimensional interrelation of teeth which, however, applies only to the dental neck parameters. Using only diameters of the tooth neck and length of dental roots, it was possible to perform a new sex determination for 68 of the 166 individuals. It shows a good coincidence with a traditional sex determination. A traditional sex determination, performed in advance, as well as the archeological assignment of typical sex related grave goods were used for verification. For future sex determination based on teeth, examinations are recommended to be restricted to the six-year molar, the first upper premolar and, in particular, the canine. Also the dental neck diameter proved to be more useful than the crown diameter. Dental root lengths can be neglected. By comparing the results with those of a second Alamannic burial ground it could be established that discriminant analyses performed within the same population are highly congruent.

Female↗
PubMed1990

[Experimental study of bone resorption after tooth extraction with implanted hydroxyapatite tooth root substitute].

Hydroxyapatite (HAP) tooth root substitute implantation have been applied to extraction sockets in many studies for purpose of preservating alveolar bone. Dimensional changes were measured with sectioned study cast of cephalometric X-ray photo. In this study, dimensional changes were determined by newly developed evaluation system which utilizing image analyzer (Immunomedica Co., Ltd.), in a view of conserving alveolar ridges beneath the denture base. Cone shaped HAP tooth roots (5 or 6 mm in length) were implanted to one subject and disk-like shaped HAP tooth roots (2 mm in length) were also implanted to the other subject. Preservation of alveolar bone was observed in both shaped HAP tooth roots implanted site compared to control site. Bony ankylosis between HAP tooth root and alveolar bone, observed on 1 month after histological specimens, may contribute to this result. Smaller changes of blood flow compared to controls were obtained on implanted site, which were measured with Laser Doppler blood flow meter (Perimed KB; Sweden) on buccal mucosa. We consider that HAP shows good biocompatibility and HAP tooth roots implantation decrease the wound volume consequently.

Alveolar Bone Loss↗
PubMed2003

Role of Hertwig's epithelial root sheath cells in tooth root development.

During tooth development, after the completion of crown formation, the apical mesenchyme forms the developing periodontium while the inner and outer enamel epithelia fuse below the level of the crown cervical margin to produce a bilayered epithelial sheath termed Hertwig's epithelial root sheath (HERS). The role of HERS cells in root formation is widely accepted; however, the precise function of these cells remains controversial. Functions suggested have ranged from structural (subdivide the dental ectomesenchymal tissues into dental papilla and dental follicle), regulators of timing of root development, inducers of mesenchymal cell differentiation into odontoblasts and cementoblasts, to cementoblast cell precursors. The characterization of the HERS phenotype has been hindered by the small amount of tissue present at a given time during root formation. In this study, we report the establishment of an immortal HERS-derived cell line that can be maintained in culture and then induced to differentiate in vitro. Characterization of the HERS phenotype using reverse transcriptase-polymerase chain reaction and Western blot immunostaining suggests that HERS cells initially synthesize and secrete some enamel-related proteins such as ameloblastin, and then these cells appear to change their morphology and produce a mineralized extracellular matrix resembling acellular cementum. These studies suggest that the acellular and cellular cementum are synthesized by two different types of cells, the first one by HERS-derived cementoblasts and the later by neural crest-derived cementoblasts.

Alkaline Phosphatase↗
PubMed2005

Insulin-like growth factor-I stimulates cell proliferation in the outer layer of Hertwig's epithelial root sheath and elongation of the tooth root in mouse molars in vitro.

To elucidate the mechanism of root formation in tooth development, we examined the role of insulin-like growth factor I (IGF-I) on early root formation in mandibular first molar teeth from 5-day-old mice. Immunohistochemistry revealed the specific localization of the IGF-I receptor in Hertwig's epithelial root sheath (HERS) in the tooth root. The effect of IGF-I on root development, especially on HERS, was subsequently examined in vitro. The control culture showed normal development of HERS and the periodontium, resembling that in vivo. However, the presence of 100 ng/ml IGF-I resulted in elongation of HERS and increased cell proliferation in its outer layer. These effects were negated by the addition of antibodies specific for IGF-I. Thus, we propose that IGF-I is involved in early root formation by regulating the mitotic activity in the outer layer of HERS.

Animals↗
PubMed2003

Tooth-root form and function in platyrrhine seed-eaters.

Research into the functional and adaptive basis of tooth crown form has provided a useful framework for the inference of diet in extinct primates. However, our understanding of variation in tooth-root form is limited. Studies within the clinical literature emphasize the influence of tooth-root surface area on stress resistance, but it is not known if root form has diversified during primate evolution in relation to dietary specialization. This hypothesis was tested by quantifying maxillary canine and postcanine tooth-root surface areas in four platyrrhine species that differ in the material properties of their diet: Cebus apella, Cebus albifrons, Chiropotes satanas, and Pithecia pithecia. Pairwise comparisons between closely related taxa support predictions based on dietary differences. Taxa that regularly consume resistant seeds (Cebus apella and Chiropotes satanas) exhibit significantly larger relative surface area values for those teeth used in seed processing than closely related taxa that consume resistant foods less often (Cebus albifrons and Pithecia pithecia). Additionally, relative molar-root surface area appears to be greater in Pithecia than in Chiropotes, as predicted from the more folivorous diet of Pithecia. Tooth-root surface area was also found to vary along the tooth row and should therefore have a significant influence on antero-posterior bite-force gradients. The results of this study suggest a close relationship between tooth-root form and patterns of occlusal loading. Further elucidation of this relationship could improve our inferences of diet in extinct taxa, and augment research into the mechanics and evolution of feeding.

Animals↗
PubMed1983

Attachment, growth and synthesis by human gingival fibroblasts on demineralized or fibronectin-treated normal and diseased tooth roots.

Regeneration of a fibrous attachment to tooth roots previously exposed to periodontal pockets requires interaction between the root surface and fibroblasts. Experiments were designed to assess whether or not fibroblasts will attach, grow and synthesize normally on tooth roots and determine the efficacy of various treatments of diseased root surfaces on these activities. Extracted teeth were collected, washed and stored frozen until used. The roots were sectioned and the surface area determined. All roots were thoroughly planed to remove most of the cementum and some were then treated with fibronectin or citric acid. Each root was placed in a Linbro well and a suspension of fibroblasts in Dulbecco Vogt medium with 10% fetal calf serum added. After cell attachment, each root was transferred to a fresh well and incubated. Some roots were examined by scanning electron microscopy. Attachment and growth were assessed by harvesting and counting cells after various incubation times. The pattern of protein synthesis was determined by preparing fluorographs from cultures pulse labeled with radioactive S35-methionine. Cells attach and grow on planed root surfaces. The number that attach to normal and diseased roots is greatly enhanced by pretreatment with fibronectin or citric acid. By day three, the cells become confluent at approximately 20,000/cm2. The pattern of proteins produced is comparable to that seen in cultures maintained in petri dishes. After root planing, cells attach, grow and synthesize equally well on diseased and normal roots.

Cell Adhesion↗
PubMed1992

Comparison of phosphoprotein isolated from mature and immature human tooth roots.

Mature (average patient age = 29.5 yr, closed apical foramen) and immature (average patient age = 17.5 yr, open apical foramen) root shards were placed in dialysis tubing and demineralized to completion using either 10% disodium EDTA plus protease inhibitors or 0.6 N HCl. The demineralized shards were re-extracted (five times) with 0.05 M tris-HCl, 1.0 M NaCl and then collagenase digested. No major differences were observed in chromatograms of extracts, re-extracts or collagenase digests from root shards demineralized in either way. In contrast, chromatograms of immature and mature roots showed qualitative differences. Chromatograms of mature roots demineralized in either way showed broader protein peaks and less organic phosphorus than those from immature tooth roots. A distinct band amid degraded phosphoprotein (150 K) was found in SDS-PAGE gels (7.5%) from EDTA-extracted immature tooth roots but not from mature tooth roots. Electroelution of this band revealed a typical phosphoprotein amino-acid profile containing increased aspartic acid and serine residues. Comparison of the total phosphoprotein and amino acid composition of extracts, re-extracts and collagenase digests revealed that phosphoprotein, serine and to a lesser extent aspartic acid were recovered in greater quantities from immature roots than mature tooth roots. These data suggest that the degree of maturation is crucial to the isolation of an intact phosphoprotein and provides additional evidence that human dentine phosphoprotein undergoes amino acid compositional changes during maturation.

Adolescent↗
PubMed1988

The tooth-root sign: a characteristic appearance of distal ureteric calculi.

Diagnostic accuracy in identifying calculi in patients with ureteric colic is poor. Lower ureteric calculi may be confused with other pelvic calcific opacities. A characteristic appearance of some larger lower ureteric calculi is described and likened to the root of a tooth. It is hoped that the tooth-root sign will be of assistance in the diagnosis of distal ureteric stones.

Humans↗
PubMed1999

High-altitude illness induced by tooth root infection.

High-altitude illness may occur after recent pulmonary infection, but high-altitude illness after root canal therapy has not been described previously. A 44-year-old man is presented who skied to a 3333 m high peak in the Eastern Alps one day after he had undergone root canal therapy because of a tooth root infection. After 4 hours above 3000 m severe symptoms of high-altitude illness, including pulmonary oedema, developed. His condition improved after immediate descent. The next day he presented with local and general signs of infection which were successfully treated with gingival incisions and antibiotics. In conclusion, acute tooth root infection and root canal therapy may induce high-altitude illness at an altitude just above 3000 m.

Adult↗
PubMed2002

Endoscopic visualization of the submarginal gingiva dental sulcus and tooth root surfaces.

BACKGROUND: Direct, real-time visualization of the hard and soft tissues within the gingival sulcus may aid the clinician in diagnosis and therapy of periodontal disease. This report describes an endoscope specifically designed for this purpose and the interpretation of dental endoscopic images. METHODS: Medical endoscope technology was modified for application in the dental environment. A fixed, fused fiber optic bundle, less than 1 millimeter in diameter, was coupled to an active matrix LCD-TFT flat panel video monitor for viewing by the clinician. A bilumen sheath was designed to provide irrigation of the sulcus and a sterile barrier between the patient and the fiber bundle. Standard dental curets and ultrasonic scalers were adapted for instrumentation aided by the endoscope. RESULTS: Endoscope technology has been successfully adapted for use in periodontal diagnosis and therapy. Techniques for identification and interpretation of the hard and soft tissue images, as well as the location of root deposits and caries, have been developed. CONCLUSIONS: The dental endoscope gives the clinician direct, real-time visualization and magnification of the subgingival tooth root surface, aiding in the location of deposits on the tooth root. The subgingival soft tissue, including the gingival attachment, sulcus wall, and sulcus contents, can be assessed. Identification and location of subgingival caries, root fractures, tooth root deposits, post perforations, and open restoration margins may aid the clinician in diagnosis and therapy.

Computer Terminals↗
PubMed1979

Tissue reaction to submerged ceramic tooth root implants. An experimental study in monkeys.

Tooth root replica implants made from alumina ceramic material of solid structure coated with a porous layer, were used as dental implants in monkeys. The porous coating was 1/2 mm thick and had pore sizes within 50--200 microns range, with a 30% degrees of porosity. Tne implants were inserted into prepared sockets in the mandible of 5 Cercopithecus monkeys. After submerged implantation periods varying from 5 to 15 weeks, a perforating steel post was introduced through the covering gingiva into the artificial root canal of the implants. The animals were sacrificed after 6 weeks, 2, 3 and 4 months. Three out of the total number of 10 implants were lost. The remaining 7 specimens were retrieved for histologic and microradiographic examination. Fibrous and mineralized tissue ingrowth of the porous layer of the implants was found. No adverse reactions of the adjacent bone were demonstrable. The implants became anchored to the host and no epithelial downgrowth along the ceramic was found.

Aluminum Oxide↗
PubMed1996

Tooth root abscesses in New World camelids: 23 cases (1972-1994).

OBJECTIVE: To determine typical clinical and radiographic findings in a group of New World camelids with tooth root abscesses and to determine outcome after medical and surgical treatment. DESIGN: Retrospective case series. ANIMALS: 23 llamas and alpacas with radiographic and clinical evidence of tooth root abscesses. PROCEDURE: Disease history, signalment, physical and radiographic examination findings, bacteriologic culture results, treatment, and short-term and long-term outcome were retrieved from the medical records. RESULTS: Local swelling was the most common clinical abnormality in camelids with tooth root abscesses. Mandibular molars were affected most commonly, and bacteriologic culture of samples from lesions often revealed facultative anaerobic bacteria. Antibiotic treatment for at least 30 days, surgical extraction of the affected tooth, and a root canal procedure were used successfully to treat tooth root abscesses. CLINICAL IMPLICATIONS: Both surgical and medical treatment of tooth root abscesses may lead to successful resolution of clinical signs in New World camelids.

Animals↗