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PubMed2004

Delayed formation of a lower second premolar.

Delayed odontogenesis of a lower second premolar is presented in a case treated without extraction and focuses on the 7-year follow-up of the delayed tooth bud. The follow-up was initiated when the crown formation was diagnosed and was finished when the tooth erupted completely into the orthodontically provided space, which enabled the orthodontic leveling and alignment of the delayed premolar. The long follow-up indicates that delayed tooth buds may develop completely and normally.

Bicuspid↗
PubMed1990

Repair potential in localized juvenile periodontitis. A case in point.

An aggressive form of localized juvenile periodontitis (LJP) in a 12-year old West African female is reported. The case was treated with scaling, root planing, debridement, and tetracycline therapy, which resulted in complete resolution of the disease, including elimination of periodontal inflammation, regeneration of lost periodontal structures, and spontaneous repositioning of teeth that had pathologically migrated. A hopelessly involved mandibular right first molar was successfully replaced by an incompletely developed maxillary third molar tooth bud whose roots and pulp structure continued to develop after autotransplantation. It is suggested, that LJP can be successfully treated without periodontal surgery and that the potential for repair in LJP cases is apparently greater than what one can anticipate in adult forms of periodontitis.

Aggressive Periodontitis↗
PubMed2000

Porcine fetal enamel matrix derivative stimulates proliferation but not differentiation of pre-osteoblastic 2T9 cells, inhibits proliferation and stimulates differentiation of osteoblast-like MG63 cells, and increases proliferation and differentiation of normal human osteoblast NHOst cells.

BACKGROUND: Embryonic enamel matrix proteins are hypothesized to be involved in the formation of acellular cementum during tooth development, suggesting that these proteins can be used to regenerate periodontal tissues. Enamel matrix protein derived from embryonic porcine tooth germs is used clinically, but the mechanisms by which it promotes the formation of cementum, periodontal ligament, and bone are not well understood. METHODS: This study examined the response of osteoblasts at 3 stages of osteogenic maturation to porcine fetal enamel matrix derivative (EMD). Proliferation (cell number and [3H]-thymidine incorporation), differentiation (alkaline phosphatase and osteocalcin), matrix synthesis ([35S]-sulfate incorporation; percentage of collagen production), and local factor production (prostaglandin E2 [PGE2] and transforming growth factor-beta 1 [TGF-beta1]) were measured in cultures of 2T9 cells (pre-osteoblasts which exhibit osteogenesis in response to bone morphogenetic protein-2 [BMP-2]), MG63 human osteoblast-like osteosarcoma cells, and normal human osteoblasts (NHOst cells). RESULTS: EMD regulated osteoblast proliferation and differentiation, but the effects were cell-specific. In 2T9 cell cultures, EMD increased proliferation but had no effect on alkaline phosphatase-specific activity. EMD decreased proliferation of MG63 cells and increased cellular alkaline phosphatase and osteocalcin production. There was no effect on collagen synthesis, proteoglycan sulfation, or PGE2 production; however, TGF-beta1 content of the conditioned media was increased. There was a 60-fold increase in cell number in third passage NHOst cells cultured for 35 days in the presence of EMD. EMD also caused a biphasic increase in alkaline phosphatase that was maximal at day 14. CONCLUSIONS: EMD affects early states of osteoblastic maturation by stimulating proliferation, but as cells mature in the lineage, EMD enhances differentiation.

Alkaline Phosphatase↗
PubMed1995

Differential mRNA regulation of integrin subunits alpha V, beta 1, beta 3, and beta 5 during mouse embryonic organogenesis.

Cell interactions with extracellular matrices play important roles in morphogenetic processes during embryonic development. Extracellular matrix receptors of the integrin family have been implicated in these steps. Recent studies indicate that a variety of integrins can be differentially expressed during development, consistent with diverse roles for integrins in embryogenesis. The present study compares the expression patterns of several major members of the alpha V integrin subfamily, focusing on mRNA expression of alpha V, beta 1, beta 3, and beta 5 subunits during mouse embryonic organogenesis using Northern blot analysis and in situ hybridization. The alpha V and beta 1 subunits showed widespread tissue expression, although most tissues expressed alpha V at relatively low or basal levels. The mRNA for beta 5 was also expressed in a variety of embryonic organs and showed unusual localization patterns in certain organs. Striking, high-level expression of beta 5 transcripts was detected in the ependymal layer of the central nervous system, glomeruli of the kidney, epicardial region of the heart, and in the tooth germs, suggesting specific functions for this molecule during morphogenetic events in these organs. In contrast, few beta 3 transcripts were expressed during mid-gestation mouse embryogenesis except in megakaryocytes within the embryonic liver. These observations of differing expression spectra suggest that members of the alpha V integrin subfamily have distinct roles and also suggests that they have different transcriptional regulation. The beta 5 integrin is unique in its degree of tissue-specific mRNA regulation associated with morphogenesis of embryonic organs.

Animals↗
PubMedDate not supplied

Fetus in fetu: a case with complete umbilical cord and fetal sac.

The authors present a retroperitoneal fetus in fetus in a 3-month-old girl. A 15-cm cystic mass with a monstrous fetuslike structure surrounded by a complete sac containing serous fluid was removed from the left retroperitoneal space. The draining vessel of the cystic mass was connected to the right renal vein of the host. The included fetus weighed 380 g. It had a well-developed umbilical cord, four extremities, head, buttock, and vertebral bodies with a meningomyelocele. The thoracic cavity of the included fetus had only a saclike foregut structure, but the abdominal cavity revealed a full length of intestine with a Meckel diverticulum, bilateral ovaries, urinary bladder, and cloaca with external opening. The cephalic end was composed of well-developed tooth germs, tongue and buccopharynx, mandible, maxilla, sphenoid bone, and salivary glands. Chromosomal study showed 46,XX with a normal G banding pattern. We report this case as an example of fetus in fetu with a complete umbilical cord and fetal membrane.

Chromosomes, Human↗
PubMed2005

Caspase 3 activation in the primary enamel knot of developing molar tooth.

Mammalian teeth develop during embryogenesis as epithelio-mesenchymal organs. The primary enamel knot is considered as a signaling center in tooth morphogenesis. After tooth bell formation, this epithelial structure undergoes apoptosis. Activation of caspase 3 represents a crucial step in the intracellular death machinery. Procaspase 3 and caspase 3 molecules were localized in the primary enamel knot of the field vole using immunohistochemistry. Different fixation procedures in cryopreserved and paraffin-embedded tissues and detection systems based on peroxidase and alkaline phosphatase mediated color reactions were applied. Apoptosis was detected using morphological criteria and the TUNEL assay. Procaspase 3 was found in both the epithelial and mesenchymal part of the tooth germ. Active caspase 3 was localized particularly in the primary enamel knot, its distribution correlated with dental apoptosis and showed a similar pattern in the field vole as in the mouse.

Animals↗
PubMed2006

Loss of permanent mandibular lateral incisor and canine tooth buds through extraoral sinus: report of a case.

Extraoral sinus tract may occur as a result of an inflammatory process associated with the necrotic pulp. Several non odontogenic disorders may also produce an extraoral sinus tract, the differential diagnosis of these clinical findings is of prime importance in providing appropriate clinical care. Presented here is a case report of 4 year old female child with extraoral sinus tract through which the tooth buds of mandibular permanent left lateral incisor and mandibular permanent left canine were lost. The extraoral sinus was due to mandibular left primary canine with class IX fracture (Ellis and Davey's classification).

Child, Preschool↗
PubMed1990

[Dental lamina as presumptive source of odontogenic cyst].

The possibility of the dental lamina as a source of odontogenic cyst was investigated. The mandibular first molar tooth germs with the dental lamina and surface oral epithelium were cut from 17.5-day-old C3H mouse embryos. The following 5 kinds of grafts were prepared: (I) recombinant of the dental lamina and dental papilla, (II) dental lamina, (III) dental papilla, (IV) recombinant of the oral epithelium and dental papilla and (V) oral epithelium. After the renal subcapsular transplantation to the 3-month-old syngenic male mice, each graft was harvested at timed sequences from 2 to 24 weeks and was examined histopathologically. The recombinant of the dental lamina and dental papilla (1) grew into a cyst lined by para-keratinized stratified squamous epithelium. The cyst enlarged gradually and might be compared to the odontogenic keratocyst of the human being. The recombinant of the oral epithelium and dental papilla (IV) and the oral epithelium (V) developed into a cyst lined by orthokeratinized stratified squamous epithelium which differed from the epithelium seen in Experiment (I). The dental papilla (III) grew to be a bone tissue while nothing developed from the dental lamina (II). These results suggest that the dental lamina is one of the sources of the odontogenic keratocyst and the dental papilla plays an important role in its histogenesis.

Animals↗
PubMed1976

[Maturation of residual tissue, left in the jaw after injury].

An eight-year old patient was observed for a period of eleven months: after the traumatic loss of a front tooth, the root of which had not fully grown, the maturing of the remnants of the follicle which were probably injured by the avulsion and not yet fully mineralized, was studied. In the histological examination of the enucleated dental hard material, regions of irregular dentin were found.

Child↗
PubMedDate not supplied

[Tooth transplantation].

In the light of the thesis of J. Thibault, the authors suggest, in association with transplantation of wisdom tooth buds into the alveolus of the first molar, a technique consisting of placing the graft in its pre-eruptive position, removing in a block the bud, the gubernaculum and the sub-jacent gingival mucosa. Under these conditions, eruption occurs at the same time as development of the roots, which represents the most physiological solution. At the same time as formation of the root, the authors noted a paradoxal rhizalysis, hypercementosis resulting in ankylosis and conservation of vitality. In addition, almost all the teeth transplanted proved to be highly vulnerable to caries.

Female↗
PubMed1976

[Development of the fetal mandible of rats in transplants onto the chorioallantoic membrane of chick embryos].

The evolution of mandibles of 15 to 17 days old fetal rats has been studied after transplantation on the chorio-allantoïc membrane of chicken embryos. The histological study of the samples grafts showed a remarkable adaptation of Meckel cartilage to the transplantation medium as well as the continuation of the ossification processes of membranous and endochondral origin. An important thickening of the oral epithelium, accompanied by an increased keratinization appeared in the grafts collected at 17 days "in utero". Only one tooth germ could be found in a graft collected at 17 days "in utero".

Allantois↗