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Ameloblastic fibroma is a rare mixed odontogenic tumour, which is extremely uncommon in the anterior maxillary region. A case report is presented where failure of eruption of an upper central incisor was the presenting feature.
A large intracoronal radiolucent lesion in an unerupted permanent molar was found during the routine assessment of a young male Caucasian prior to orthodontic treatment. The tooth was extracted. Histological examination indicated the lesion was caused by external resorption. The defect extended widely into the enamel and dentine, and was repaired in part by bone. The pulp chamber was not involved. The aetiology of these lesions is often obscure but in this case it appeared to have originated in the floor of two developmental pits on the occlusal surface of the tooth.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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The metabolic activity of bone cells is faithfully reflected in the surface topography of mineralized bone surfaces, and this can be easily detected by scanning electron microscopy (SEM). Forming bone surfaces exhibit knobby projections which represent foci of mineralization, resorbing surfaces are scalloped, and resting surfaces undergoing neither activity are smooth, as shown by Boyde and Hobdell 25 years ago. These phenomena are illustrated in vivo by tooth eruption, a local activity in alveolar bone where resorption and formation are polarized around an erupting tooth, and osteopetrosis, a metabolic bone disease characterized by a congenital reduction or absence of bone resorption. The ability to analyze bone metabolism over large areas of the skeleton by SEM offers a convenient and powerful microscopic technique to assess regional and global bone cell activity in an era where the investigative focus is increasingly molecular.
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The inflammatory paradental cyst has previously been described as the collateral inflammatory cyst, the inflammatory lateral periodontal cyst, the paradental cyst, or the mandibular infected buccal cyst. Clinical, radiographic, and histologic features of 29 inflammatory paradental cysts diagnosed over a 5-year period were studied. The cysts occurred in relation to a partly or fully erupted tooth with a vital pulp. Twenty-seven of the cysts were located in the mandible and the remaining two in the maxilla. The mandibular cysts were in all cases associated with a molar. The observation that the cysts are diagnosed within a few years after tooth eruption and the demonstration of a statistically significant difference (p = 0.001) in age distribution and in the type of tooth involved suggest that eruption is important for the development of the cysts. The consistent finding of a hyperplastic, nonkeratinized stratified squamous epithelium with an intense inflammation in the connective tissue is in accordance with the hypothesis that inflammation is important for the development of these cysts.
Cleidocranial dysplasia (CCD) is an autosomal dominant disorder characterised by defects of bone and tooth development. The dental manifestations in CCD patients include supernumerary teeth, delayed tooth eruption, tooth hypoplasia and absence of cellular cementum formation. This disorder is associated with mutations in the osteoblast-specific transcription factor Runx2. To identify morphological and molecular alterations associated with CCD dental tissues, human primary dental pulp cell cultures were established from age- and sex-matched CCD and normal patients. Dental pulp cells were compared for general morphology, proliferation rates, and gene expression profiles using cDNA microarray technology. CCD pulp cells were about four-fold larger than normal cells, however the normal pulp proliferation rates were two- and three-fold greater at time points tested than the CCD cells. Of the 226 genes analysed by blot microarray, 18.6% displayed significant differences at least two-fold in expression levels. This includes 25 genes (11.1%) that were up-regulated, while 17 (7.5%) that were down-regulated in the CCD cells as compared to the normal cells. Expression of selected genes was further verified by quantitative real-time polymerase chain reaction (qRT-PCR). Comparison between the CDD and normal cells revealed that gene expression of cytokines and growth factors, such as leukemia inhibitory factor (LIF), interleukin-6 (IL-6) and transforming growth factor beta receptor II (TGF-betaRII) and vascular endothelial growth factor B (VEGFB) were higher while bone morphogenetic protein 2 (BMP2) was lower in the CCD cells. Furthermore, potential Runx2 binding sites were found in all putative target gene promoters. This study suggests that in addition to bone and tooth cell differentiation, Runx2 may be involved in controlling cell growth during tooth development.
Tooth eruption across the mucosa in humans has been studied rarely, although there are disturbances of eruption that are attributed specifically to failure of the supraosseous eruptive migration. The aim of this study was to analyze the soft tissues covering normally erupting teeth so as to get an insight into the supraosseous phase of tooth eruption and to provide the basis for comparison with cases of eruption disturbances. Six opercula covering normally erupting permanent molars (primary opercula) and six of succedaneous teeth (secondary opercula) were surgically removed from 10 patients aged 7.5-17.5 years. Specimens were examined light and electron microscopically and analyzed morphometrically. All opercula contained strands and islands of odontogenic epithelium, prominent numbers of high endothelial venules, nerves, and mast cells. Nerves comprised normally structured, 1.5-3.5 microm thick myelinated (Adelta) and thinner unmyelinated (C) fibers. In primary opercula, the proportions of blood vessels and nerves were three- and sevenfold higher than the respective values for the secondary opercula. Furthermore, primary opercula contained multinucleated, fibroblast-like giant cells that were not observed in secondary opercula. As all teeth under investigation were erupting normally, neither the presence of the giant cells nor the atypical proportions of blood vessels and nerves appeared to be decisive in the eruption process. These conspicuous tissue components of opercula seem merely to accompany the eruptive tooth movement.
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Tooth eruption is a complex biological process which starts from the site of development in the jaw bone until the teeth reach their final functional position in the chewing plane. Various factors can disturb this process. Besides mechanical obstacles on the eruption path, a pathological position or axial orientation of the tooth germ, morphological aberrations of the tooth or pathological alterations of the periodontium, primary disorders of the eruption mechanism may lead to complete or partial retention of the tooth in the jaw bone. These morphological features bear upon the prognosis of orthodontic correction which is dependent upon the underlying cause. First and second molars are rarely affected by eruption disorders, with a prevalence of 0.01 to 0.08 per cent, however, marked consequences for function such as posterior open bite or elongation of the antagonists may result. Following an overview of pathogenetic factors of tooth eruption disorders, selected cases of impacted first and second permanent molars are presented with respect to their morphological causes.
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Disturbances in tooth eruption and tooth impactions make great demands on radiographic diagnostics. There is often need for radiographic images in various projections to assess the exact position of unerupted and impacted teeth. Digital volume tomography (DVT) is a method for localizing hard tissue structures such as bone and teeth on various planes. Moreover, it makes a three-dimensional image of the teeth, jaws and the viscerocranium possible. From an orthodontic point of view, digital volume tomography is indicated to detect impacted and ectopic teeth and to demonstrate the amount of bone available for orthodontic tooth movement. In patients with cleft lip and palate, DVT can be used to visualize the size of the alveolar cleft and to evaluate the position and development of multiple teeth, as these patients often suffer from disturbances in tooth eruption.