Excess NF-κB induces ectopic odontogenesis in embryonic incisor epithelium.

Nuclear factor kappa B (NF-κB) signaling plays critical roles in many physiological and pathological processes, including regulating organogenesis. Down-regulation of NF-κB signaling during development results in hypohidrotic ectodermal dysplasia. The roles of NF-κB signaling in tooth development, however, are not fully understood. We examined mice overexpressing IKKß, an essential component of the NF-κB pathway, under keratin 5 promoter (K5-Ikkß). K5-Ikkß mice showed supernumerary incisors whose formation was accompanied by up-regulation of canonical Wnt signaling. Apoptosis that is normally observed in wild-type incisor epithelium was reduced in K5-Ikkß mice. The supernumerary incisors in K5-Ikkß mice were found to phenocopy extra incisors in mice with mutations of Wnt inhibitor, Wise. Excess NF-κB activity thus induces an ectopic odontogenesis program that is usually suppressed under physiological conditions.

An idiosyncratic post-traumatic tetrad: compound odontome, dentigerous cyst, impaction, and double-dilaceration.

OBJECTIVE: This report describes the case of a 13-year-old patient who experienced traumatic intrusion of the primary maxillary right central incisor and subsequently suffered an atypical tetrad, comprising of an unerupted compound odontoma associated with a dentigerous cyst, and an impacted, doubly dilacerated permanent maxillary right central incisor; however, the high interconnectivity of the occurrence of four pathologies together is unusual has not previously been reported. SUMMARY: The pathologies were detected 7 years after trauma; surgical removal of odontome along with the dentigerous cyst was performed, followed by orthodontic extrusion of the impacted double-dilacerated permanent central incisor. The 18-month follow-up shows no pathology, no gingival recession, and normal probing depth.

YAP overexpression affects tooth morphogenesis and enamel knot patterning.

Teeth develop through distinct morphological stages. At the cap stage, a compactly clustered and concentrically arranged cell mass, the enamel knot, appears at the tip of the enamel organ. Cells in this knot express sets of key molecules, and as such have been proposed to act as a signaling center directing tooth morphogenesis and tooth cusp formation. YAP is a transcriptional co-activator of the Hippo signaling pathway that is essential for the proper regulation of organ growth. In this study, we analyzed the tooth phenotype in transgenic mice that overexpressed a constitutively active form of YAP in the dental epithelium. We found that overexpression of YAP resulted in deformed tooth morphogenesis with widened dental lamina. In addition, the enamel knot was mislocated to the upper portion of the enamel organ, where it remained devoid of proliferating cells and contained apoptotic cells with intense Edar transcripts and reduced E-cadherin expression. Interestingly, some signaling molecules, such as Shh, Fgf4, and Wnt10a, were not expressed in this mislocated enamel knot, but remained at the tip of the enamel organ. Analysis of these data suggests that the signaling center is induced by reciprocal epithelial-mesenchymal interactions, and its induction may be independent of the enamel knot.

Single tooth odontodysplasia. Case report.

Odontodysplasia (ghost tooth) is an uncommon, nonhereditary developmental condition of unknown origin, affecting both mesodermal and ectodermal elements of the dental organ. To our knowledge, this case is unique in that it is only the second reported case of odontodysplasia affecting a single tooth. Based on clinical, radiographic and histologic findings, we diagnosed this tooth as a ghost tooth.

[Prevalence of hypodontia at the department of pedodontics and orthodontics of Semmelweis University]. / A hypodontia elofordulási gyakorisága a Semmelweis Egyetem Gyermekfogászati és Fogszabályozási klinikaján.

Examination of hypodontia as one of the most frequent developmental disorder receives high importance in the national as well as in the international literature. As the disorder can affect the dental and mental development of the children therefore early diagnosis and treatment are necessary. The authors analyzed the OP radiograms of patients aged 6 to 18 who were registered between 2006 and 2011 at the Department of Pedodontics and Orthodontics of Semmelweis University, excluding children suffering from general diseases or other syndromes. The aim of the examination was to determine the occurrence of missing teeth germ cases in the registered database of the Department, diagnose the prevalence of aplasia and compare the results with the national and international literature. Out of the 900 patients (372 boys and 528 girls) included in the examination missing germs were diagnosed in 94 cases (10,44%). In most cases the germ of the lower second premolars was missing (34,64%), then came the upper lateral incisors (27,38%) and the aplasia of the upper second premolars (21,23%). There was no relevant difference between the two sides. The number of affected girls was higher by 25% than the number of boys. Most of the results are close to the result in international literature.

Regional odontodysplasia. A literature review and three case reports.

AIM: The purpose of this article is to report some unusual characteristics related to gender, location and manifestations of severe Regional Odontodysplasia detected in three subjects. Regional Odontodysplasia is a rare disturbance of dental development whose aetiology is still unknown. Anomalies involve enamel, dentin, pulp and dental follicle causing atypical structure, colour, shape, size and eruptive disturbances of the affected teeth. Its early onset may lead to craniofacial development disturbances. CASES REPORTS: This article reports three cases with unusual characteristics observed in male children who were assisted by a paediatric dentist. Generally the disease affects one hemiarch and it is very rare that it crosses the midline as in one of the presented cases. Regional Odontodysplasia has been predominantly described in the maxilla and in women, however these three cases are in boys and two of them occured in the mandible. CONCLUSION: Regional Odontodysplasia is a rare disease, causing severe dental, growing and craniofacial development anomalies. Treatment needs to be personalised, aiming at preservation of the affected teeth taking into account their risk to develop severe infections. Parents should be made aware of the need for an extensive follow-up.

Concomitant hypodontia and hyperodontia: an analysis of nine patients.

INTRODUCTION: Congenital absence of tooth germs and presence of supernumerary teeth (CHH) are anomalies which are classified as embryologically determined disorders. Both disorders can occur together (CHH), but relatively rarely. OBJECTIVE: The aim of the present study was to present and analyze nine cases collected during the past 24 years, where congenitally missing teeth occurred with supernumerary teeth in the same patient. MATERIALS AND METHODS: Dental records, radiographs and casts of nine patients, six boys and three girls (aged 9-29 years, mean age: 19 years) were examined. All the family members of the patients were also investigated regarding the presence of tooth disorders. RESULTS: The boys showed hypo-hyperodontia twice as often as the girls (6:3). Congenital absence of tooth germs was more common than the presence of supernumerary teeth (25:11). CAP were not present in the other family members. CONCLUSIONS: The full diagnosis of hypo-hyperodontia is only possible on the basis of radiographic examination, because some teeth may remain unerupted or missing. The results of this study showed that concomitant hypo-hyperodontia is rare and sex-related, with predominance of hypodontia. The genetic influence seems unclear.

Dental Findings and Management in a Mucopolysaccharidosis Type IIIB Patient.

Mucopolysaccharidosis type IIIB (MPS IIIB) is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme a-N-acetylglucosaminidase. Affected subjects present developmental delay, attention deficit disorder, uncontrollable hyperactivity, and aggressive behavior, followed by progressive dementia and death in late adolescence. The purpose of this paper is to report the dental findings and treatment in a child with MPS IIIB. His primary molars and permanent mandibular incisors presented obliterated pulp chambers and root canals, which may be a clinical manifestation of this disorder.

Histological and immunohistochemical analyses of molar tooth germ in enamelin-deficient mouse.

Amelogenesis imperfecta (AI) is associated with mutations in a number of genes, including AMELX and ENAM. However, the precise mechanism leading to enamel malformation in different AI types remains to be elucidated. In the present study, we investigated morphological change in tooth germ obtained from ENAM-mutant mice (Enam(Rgsc521) homozygotes) as a model for human AI using histological and immunohistochemical methodologies. The results showed that ameloblasts detached from developing dentin and lost cell polarity in mutant mice at post-natal day 3. Cyst-like structures, including amelogenin-immunopositive materials, were observed between these detached cells and the dentin. No enamel-like structure, however, was observed in the cusp of the crown. These results suggest that enamelin acts as an adhesion molecule and is involved in ameloblast cell differentiation during the early stages of tooth development.

Effect of computerized delivery intraligamental injection in primary molars on their corresponding permanent tooth buds.

OBJECTIVE: To evaluate the prevalence of developmental disturbances in permanent teeth in which buds were exposed to intraligamental injection (ILI) delivered by a computer controlled local anaesthetic delivery (C-CLAD). METHODS: The study population consisted of 78 children (age 4.1-12.8 years) who received ILI-C-CLAD to 166 primary molars. A structured form was designed to include information regarding age at treatment, gender, type of treated tooth, tooth location, type of dental treatment, and type of developmental disturbance(s) present in the associated permanent tooth. Teeth, which received regular anaesthesia or were not anaesthetized by local anaesthesia, served as controls. RESULTS: Five children had developmental defects. In C-CLAD-ILI exposed teeth, one child had two hypomaturation defects. The corresponding primary teeth were extracted. No defects were found on the control side. In two children, hypoplastic defects were found only in the control teeth (one in each child). One suffered from a dentoalveolar abscess in the corresponding primary tooth. Diffuse hypomaturation defects were found in two children on both the C-CLAD-ILI exposed and control sides. CONCLUSION: In the primary dentition, C-CLAD-ILI does not increase the danger of developmental disturbances to the underlying permanent dental bud.

Sulfotransferase Ndst1 is needed for mandibular and TMJ development.

Heparan sulfate proteoglycans (HS-PGs) regulate several developmental processes, but their possible roles in mandibular and TMJ formation are largely unclear. To uncover such roles, we generated mice lacking Golgi-associated N-sulfotransferase 1 (Ndst1) that catalyzes sulfation of HS-PG glycosaminoglycan chains. Ndst1-null mouse embryos exhibited different degrees of phenotypic penetrance. Severely affected mutants lacked the temporomandibular joint and condyle, but had a mandibular remnant that displayed abnormal tooth germs, substandard angiogenesis, and enhanced apoptosis. In mildly affected mutants, the condylar growth plate was dysfunctional and exhibited thicker superficial and polymorphic cell zones, a much wider distribution of Indian hedgehog signaling activity, and ectopic ossification along its lateral border. Interestingly, mildly affected mutants also exhibited facial asymmetry resembling that seen in individuals with hemifacial microsomia. Our findings indicate that Ndst1-dependent HS sulfation is critical for mandibular and TMJ development and allows HS-PGs to exert their roles via regulation of Ihh signaling topography and action.

[Regulatory peptides influence on hypoxia induced tooth germ pathology of new born albino rats].

Intrauterine hypoxia decreased the nucleolar organizator quantity in enameloblasts of newborn albino rats tooth germ. Influence the leu-encepgalin synthetic analog dalargin and non-opiate synthetic leu-encephalin on newborn rats from 2 to 6 day abolished the intrauterine hypoxia affect. The main mechanism of peptide antioxidant effect may be NO system stimulation.

Aberrant cementum phenotype associated with the hypophosphatemic hyp mouse.

BACKGROUND: Cementogenesis is sensitive to altered local phosphate levels; thus, we hypothesized a cementum phenotype, likely of decreased formation, would be present in the teeth of X-linked hypophosphatemic (Hyp) mice. Mutations in the phosphate-regulating gene with homologies to endopeptidases on the X chromosome (Phex) cause X-linked hypophosphatemia, characterized by rickets, osteomalacia, and hypomineralized dentin formation, a phenotype recapitulated in the Hyp mouse homolog. Here, we report a developmental study of tooth root formation in Hyp mouse molars, focusing on dentin and cementum. METHODS: Light and transmission electron microscopy were used to study molar tissues from wild-type (WT) and Hyp mice. Demineralized and hematoxylin and eosin-stained tissues at developmental stages 23 to 96 days postcoital (dpc) were examined by light microscopy. Immunohistochemistry methods were used to detect bone sialoprotein (BSP) distribution in Hyp and WT mouse molar tissues, and transmission electron microscopy was used to study similar molar tissues in the non-demineralized state. RESULTS: Dentin in Hyp mice exhibited mineralization defects by 33 dpc, as expected, but this defect was partially corrected by 96 dpc. In support of our hypothesis, a cementum phenotype was detected using a combination of immunohistochemistry and transmission electron microscopy, which included thinner BSP-positive staining within the cementum, discontinuous mineralization, and a globular appearance compared to WT controls. CONCLUSION: Mutations in the phosphate-regulating Phex gene of the Hyp mouse resulted in defective cementum development.

Irrupção ectópica de incisivo lateral inferior: relato de caso / Ectopic eruption of a mandibular lateral incisor: relate of case

A transposição dentária constitui uma rara e severa anomalia de desenvolvimento, sendo considerada um dos tipos de irrupção ectópica na qual dois dentes permanentes trocam de posição no arco. Este trabalho dis cuteas diferentes abordagens em casos de transposições existentes na literatura, bem como relata um caso clínico em que uma irrupção ectópica de incisivo lateralinferior foi interceptada a fim de evitar uma futura transposição incisivo lateral-canino

Idiopathic oligodontia in primary dentition: case report and review of literature.

Idiopathic oligodontia of the primary dentition is very rare. This is a case report of a 2 year and 6 month old boy, who presented with fourteen missing primary teeth. Review of previous case reports is done and the management of these cases is discussed.

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.

Alteration of the sialylation pattern of the murine tooth germ after ethanol exposure.

BACKGROUND: Ethanol consumption during pregnancy leads to changes in murine dental morphogenesis, dental size, cellular differentiation, enamel mineralization, and delayed eruption. It has been proposed that glycoproteins play a role during embryonic dental development that may determine the dental morphological pattern and extracellular matrix secretion. O-glycosylation and sialylation appear to actively participate in the differentiation and maturation processes. Because glycosylation may be affected by teratogens that can alter the maturation of several organisms, in this work we describe the main modifications of the sialylation pattern in prenatal day (PD) 18.5 murine tooth germs exposed to ethanol. METHODS: Pregnant female mice were divided into groups that were given 15% or 20% ethanol solutions, or water as a control. The histochemistry of tooth germs from PD 18.5 fetuses was revealed with lectins specific for sialic acid (Neu5Ac), such as Sambucus nigra (SNA), Maackia amurensis (MAA), and Machrobrachium rosenbergii (MRL), and for sialylated-O-glycosidically linked glycans, such as Amaranthus leucocarpus (ALL). RESULTS: The basement membrane, preameloblasts, inner-enamel epithelium, preodontoblasts, and subodontoblastic cells of the test groups showed changes in labeling according to the 4 lectins used. Intranuclear staining was observed with SNA (specific for Neu5Acalpha2,6Gal/GalNAc) in the control group, but this was reduced in the test groups. The nuclei of dental papillary cells under the experimental conditions were stained with MAA (Neu5Acalpha2,3Gal). CONCLUSIONS: Dental development involves different types of sialylated O-glycosidically linked glycans that are likely to regulate cell-to-cell and cell-to-matrix interactions. Our results suggest that ethanol consumption during pregnancy alters the sialylation pattern during murine dental morphogenesis.

Supernumerary premolars: a literature review.

Supernumerary premolars appear to be more common than previously estimated. The purpose of this report was to review most of the cases published in the dental literature since 1932. The authors found that supernumerary premolars occur 3 times more in males than in females, indicating a possible sex-linked inheritance, with the highest frequency of occurrence in the mandibular premolar region (74%). They are also the most common supernumerary teeth in the mandibular arch (7%), and their incidence is 1% (1 in 157)-much higher than previously reported. Maxillary supernumerary premolars were found to occur at a lower rate (26%). The possible mechanisms of development are described, with a localized hyperactivity of the dental lamina being the most widely accepted theory. Recurrence of supernumerary premolars after being surgically removed has been reported in 8% of the cases reviewed. Patients with a previous history of anterior conical or tuberculated supernumerary teeth at an early age have a 24% possibility of developing single or multiple supernumerary premolars at a later age. Early diagnosis and appropriate follow-up with panoramic radiographs is extremely important. Various treatment recommendations are also discussed.