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PubMed2006

Epidemiology of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" in patients with cleft lip and palate.

OBJECTIVE: Type and prevalence rates of the symptoms of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" were studied in patients with clefts. PATIENTS: Data of 263 patients with nonsyndromic clefts of lip (alveolus and palate) or isolated cleft palates were examined in a retrospective study. SETTING: The clefts were classified as cleft lip or cleft lip and alveolus, cleft palate, unilateral cleft lip and palate, and bilateral cleft lip and palate. All patients were scrutinized for 28 individual symptoms. Prevalences of the individual symptoms were statistically evaluated regarding cleft type and gender by using the chi-square test and were also compared with findings in patients without clefts. RESULTS: In 97.7% of the patients with clefts, at least one symptom was found. Microdontia of individual teeth, hypodontia, and hyperodontia were the symptoms most frequently recorded. Comparison of the different cleft types revealed differences regarding the prevalences of supernumerary lateral incisors (p = .051), infraposition of deciduous molars (p < .001), and atypical tooth bud position (p = .030). Comparison of the prevalences of 10 symptoms recorded in the patients with clefts with the prevalences recorded in patients without clefts showed nine symptoms were found much more frequently in the population with clefts. CONCLUSION: These findings support the hypothesis that clefting is part of a complex malformation associated with other dental anomalies resulting from disturbed development of the dentition. Patients with clefts are also likely to present other deficiencies of dental development and tooth eruption in both dentitions, even in regions not affected by the cleft.

Adolescent↗
PubMed2006

Continuous tooth generation in mouse is induced by activated epithelial Wnt/beta-catenin signaling.

The single replacement from milk teeth to permanent teeth makes mammalian teeth different from teeth of most nonmammalian vertebrates and other epithelial organs such as hair and feathers, whose continuous replacement has been linked to Wnt signaling. Here we show that mouse tooth buds expressing stabilized beta-catenin in epithelium give rise to dozens of teeth. The molar crowns, however, are typically simplified unicusped cones. We demonstrate that the supernumerary teeth develop by a renewal process where new signaling centers, the enamel knots, bud off from the existing dental epithelium. The basic aspects of the unlocked tooth renewal can be reproduced with a computer model on tooth development by increasing the intrinsic level of activator production, supporting the role of beta-catenin pathway as an upstream activator of enamel knot formation. These results may implicate Wnt signaling in tooth renewal, a capacity that was all but lost when mammals evolved progressively more complicated tooth shapes.

Animals↗
PubMed1996

Onion bulb cells in mice deficient for myelin genes share molecular properties with immature, differentiated non-myelinating, and denervated Schwann cells.

Onion bulb formation is a pathological feature observed in peripheral nerves of patients suffering from inherited peripheral neuropathies such as Charcot-Marie-Tooth and Déjérine-Sottas diseases. An onion bulb consists of small circumferentially oriented (supernumerary) cells and their processes surrounding a large caliber axon. In the present study, we investigated the molecular phenotype of supernumerary cells at the light and electron microscopic levels. The major motor (quadriceps muscle) branch of the femoral nerve from 16- to 24-month-old mice with an inactivated allele of the myelin protein zero gene or deficient for myelin-associated glycoprotein (MAG; P0(+)- and MAG--mice, respectively), which have numerous onion bulbs, was teased to obtain single nerve fibers, which were then processed for immunocytochemistry. Corresponding nerves from wild-type mice served as controls. In both P0(+)- and MAG--mice, supernumerary cells expressed S-100, the low-affinity nerve growth factor receptor (p75, NGFr), the cell adhesion molecule L1, the neural cell adhesion molecule (N-CAM), and glial fibrillary acidic protein (GFAP). At the electron microscopic level, the cell surface of supernumerary cells was NGFr immunoreactive and L1 and N-CAM were expressed at points of contact between supernumerary cells. NGFr, L1, and N-CAM were also present in the basal lamina surrounding myelinated axons associated with onion bulbs. Both S-100 and GFAP immunoreactivities were seen in the cytoplasm of supernumerary cells. In contrast, in wild-type mice myelinating Schwann cells only expressed S-100 intracellularly and L1 and N-CAM in their basal lamina, whereas non-myelinating Schwann cells expressed all five molecules investigated. The present study indicates that supernumerary cells in onion bulbs have a molecular phenotype characteristic of immature, differentiated non-myelinating, and denervated Schwann cells, thus excluding the possibility that supernumerary cells are perineurial cells.

Animals↗
PubMed1998

Adenomatous polyposis coli protein is expressed in alternate stages of the ameloblast life cycle.

Mutations of the adenomatous polyposis coli gene protein (APC) are associated with familial polyposis and also sporadic colon adenomas, both preconditions to cancer formation. Some familial polyposis patients also develop Gardner's syndrome, a condition characterized by supernumerary teeth, mandibular osteomas, and other maladies. We investigated participation of APC in normal tooth development. Using a monoclonal antibody to study APC expression in the forming rat incisor, we found no APC staining in differentiating ameloblasts, then strong staining in secreting ameloblasts and stratum intermedium cells, followed by cells in the transition stage which did not stain. Intense APC staining resumes in maturation-stage ameloblasts and proximal papillary cells. APC staining disappears again in reduced ameloblasts at the conclusion of amelogenesis. APC staining was not seen in any other odontogenic cells. We report a unique system in which APC expression is upregulated and downregulated twice during the normal life cycle of ameloblasts. APC, therefore, is important in the normal maturation of both colonic epithelium and odontogenic epithelium. At this point, we cannot rule out any of the known functions of APC, which include: modulation of cell adhesion by binding to catenin, regulation of beta-catenin as a differentiative signaling molecule, and promotion of microtubule assembly. In this respect, the rat incisor enamel organ provides a unique tissue for studying the regulation and functions of APC.

Adenomatous Polyposis Coli↗
PubMed1980

[An interesting case of chondroektodermal dysplasia (author's transl)].

A case of chondroectodermal dysplasia, by Ellis, van Creveld, is described manifested both by changes in oral cavity and in the skeleton. The patient is a nine-year-old girl with shallow vestibulum oris, supernumerary mucosal plicae in the frontal part of the vestibulum oris, oligodontia and involvement of tooth shape. Among other symptoms there were polydactylia (corrected by surgery), club-shaped fingers and koilonoychia. Bone X-ray showed alterations typical for this type of enchondral dysplasia. This case can, in our opinion, be managed only by prosthesis. This syndrome, fortunately, is but rarely seen.

Anthropometry↗
PubMed2006

Control of tooth morphogenesis by Runx2.

Odontogenesis is a complex process in which the interplay of signaling cascades of the epithelium and mesenchyme is critical. Evidence for the involvement of Runx2--a well-known osteogenic master transcription factor--in odontogenesis, has been accumulating. Haploinsufficiency of Runx2 in humans results in cleido-cranial dysplasia (CCD), characterized by supernumerary teeth; in Runx2-/- mice, molar odontogenesis does not proceed beyond the late bud stage. In this article, we discuss the role of Runx2 in tooth development, specifically in the signaling interplay of the epithelium and mesenchyme during the transition from bud stage to cap stage. Runx2 is an important molecule of the dental mesenchyme; its expression is induced by epithelial fibroblast growth factor (FGF), and it is involved in regulating the induction of mesenchymal signaling back to the dental epithelium for epithelial morphogenesis. In addition, we discuss the role of the two major isoforms of Runx2, and other Runx family genes, in odontogenic processes.

Animals↗
PubMed1996

Conservative treatment of dens evaginatus of anterior teeth.

Dens evaginatus is a developmental malformation characterized by the presence of an extra cusp. In the anterior dentition, dens evaginatus is more commonly found in the maxilla and on the palatal surface of the tooth. Treatment may include root canal therapy followed by either an aesthetic restoration or a full crown coverage. In cases of mesiodens, supernumerary teeth or crowded dentition, extraction is often indicated. Presented is a case of a conservative treatment modality of dens evaginatus in a mandibular central incisor.

Child↗
PubMed2005

Oral and dental findings in Fanconi's anemia.

Fanconi's anemia is an autosomal recessive disorder characterized by progressive pancytopenia and congenital malformation of the skeleton. This study investigated the oral health status of 15 children with Fanconi's anemia, including oral lesions, gingival and periodontal status, and dental abnormalities. All children in the group were found to have a tendency to develop tooth decay and were in need of dental treatment. Two had aggressive periodontitis. In one patient supernumerary teeth were found, while in another teeth were congenitally missing. The increased tendency toward periodontal disease in patients with Fanconi's anemia may be due not only to the anemia, leukopenia, and defective detoxification of oxygen radicals that are characteristic of the disease itself, but also to medications applied during intense immunosuppressive treatment, such as prednisolone.

Adolescent↗
PubMed1993

Chemical analysis of a dens invaginatus by SEM microanalyses.

A patient with a supernumerary right maxillary lateral incisor with dens invaginatus presented. After extraction, the invaginated area of the tooth as well as another of similar ages but with normal hard tissues, were prepared for scanning electron microscopic observation. Outer and invaginated enamels were identified the latter showing more density. Chemical analysis by the scanning microanalyses revealed differences in mineral contents between: a) the external and cut surface of the outer and the invaginated enamel, and b) the external and cut surface of the normal tooth. The outer and invaginated enamels are quite different concerning the quantity and quality of minerals, the latter having no magnesium at all. Magnesium was also non existent in the dentin.

Calcium↗
PubMed2003

Impacted teeth in the maxilla: usefulness of 3D Dental-CT for preoperative evaluation.

OBJECTIVE: To compare the shapes of roots of impacted teeth shown in three-dimensional computed tomographic images (3D Dental-computed tomography (CT) images) and plain radiographs and to determine whether 3D Dental-CT images are useful for examination before performing an operation for extraction of a maxillary impacted tooth. METHODS AND PATIENTS: Images obtained from patients who had impacted teeth in the maxilla, including impacted mesial supernumerary teeth in 13 patients, impacted incisors in two patients, impacted canines in 11 patients, impacted premolars in four patients and impacted molars in three patients, were used in this study. In all patients, plain radiographs and 3D Dental-CT images were retrospectively reviewed by an oral radiologist for evidence of root dilaceration before operations to extract the impacted teeth were performed. The findings in the images were compared with intraoperative findings in all cases. RESULTS: The mean specificity and sensitivity of plain radiographs were 95 and 8%, respectively, while those of 3D Dental-CT images were 100 and 77%, respectively. There was a statistically significant (P<0.01) difference between the depiction capabilities of plain radiographs and 3D Dental-CT images with regard to dilacerations of roots of impacted teeth. DISCUSSION AND CONCLUSION: CT may enable radiologists to make a quick and accurate diagnosis of tooth impaction. 3D Dental-CT images are useful for determining the root shape of an impacted tooth in the maxilla.

Adolescent↗
PubMed1997

Anatomical variations in the dentition of the domestic cat.

Skulls (n = 155) of adult domestic cats were examined macroscopically and anatomical variations were documented. The maxillary second premolar tooth was absent in 7.9% of cases, and was found to have a single root in 27.7%, partly fused roots in 55.1% and two fully formed roots in 9.2% of cases. The maxillary first molar tooth was absent in 2.3% of cases; a single root was present in 35.0%, a partly fused root in 34.7%, and two roots in 28.0% of cases. Supernumerary roots were found on the maxillary third premolar teeth in 10.3% of cases. Other variations were found to be extremely rare.

Animals↗
PubMed2004

Delayed tooth eruption and suppressed osteoclast number in the eruption pathway of heterozygous Runx2/Cbfa1 knockout mice.

Genetic studies have recently identified a mutation of one allele of runt-related gene 2 (RUNX2/CBFA1) as the cause for an autosomal-dominant skeletal disorder, cleidocranial dysplasia (CCD), which is characterised by hypoplasia of the clavicles and calvariae and widened sutures and fontanelles. In addition, CCD is frequently affected with multiple supernumerary teeth and the impaction and delayed eruption of teeth, the causes of all these dental abnormalities are still unknown. To clarify the cellular mechanism of the delayed tooth eruption in CCD, the process of tooth eruption was examined in heterozygous Runx2/Cbfa1 (mouse homolog of RUNX2/CBFA1) knockout mice, known to mimic most of the bone abnormalities of CCD. The timing of the appearance of maxillary and mandibular teeth into the oral cavity was significantly delayed in heterozygous mutant mice compared with wild-type mice. From postnatal days 8 to 10, an active alveolar bone resorption and a marked increase of the osteoclast surfaces was observed in the eruption pathway of both genotypes, but this increase was significantly suppressed in the mutant mice. In contrast, the osteoclast surfaces did not show a significant difference between the two genotypes in the future cortical area of femora. These results suggest that haploinsufficiency of Runx2/Cbfa1 does not effect the femoral bone remodelling but is insufficient for the active alveolar bone resorption essential for the prompt timing of tooth eruption. These results also suggest the possibility that impaired recruitment of osteoclasts is one of the cellular mechanisms of delayed tooth eruption in CCD patients.

Animals↗
PubMedDate not supplied

Bilateral twinning: report of case.

Twinning is an anomaly in which one tooth has combined with another or enlarged itself to the point of doubling its substance. A discussion of the nomenclature and a report of bilateral twinning are presented. A possible cause of the twinning events in this case include gemination of the maxillary right and mandibular left canines and fusion of the maxillary left and mandibular right canines with supernumerary teeth.

Child, Preschool↗
PubMed1991

Upper central incisor and canine tooth crown size in 47,XXY males.

Enamel and dentin thicknesses were measured in permanent tooth crowns of 47,XXY (Klinefelter syndrome) males. In 47,XXY males, enamel thickness in maxillary central incisors was significantly greater than that in control males or females, and dentin thickness in incisors and canines was significantly greater than that in control females, but smaller than that in normal males. These findings confirm the concept that human dental growth is affected by sex chromosomes. Amelogenesis is promoted by both X and Y chromosome genes, and sexual dimorphism in average tooth size is evidently determined by a promoting effect of the Y chromosome on dentin growth, probably through cell proliferation. This effect can also explain sex predilection for males in the numbers of supernumerary and ordinary teeth.

Amelogenesis↗