Osteogenesis imperfecta type I with unusual dental abnormalities

Osteogenesis imperfecta tooth level phenotype analysis: Cross-sectional study

INTRODUCTION

Dental anomalies in Osteogenesis imperfecta (OI), such as tooth discoloration, pulp obliteration (calcified dental pulp space), and taurodontism (enlarged dental pulp space) vary between and within patients. To better understand the associations and variations in these anomalies, a cross-sectional study was designed to analyze the dental phenotype in OI patients at the individual tooth type.

METHOD

A cohort of 171 individuals with OI type I, III and IV, aged 3-55 years, were recruited and evaluated for tooth discoloration, pulp obliteration, and taurodontism at the individual tooth level, using intraoral photographs and panoramic radiographs.

RESULTS

Genetic variants were identified in 154 of the participants. Patients with Helical α1 and α2 glycine substitutions presented the highest prevalence of tooth discoloration, while those with α1 Haploinsufficiency had the lowest (<10%). C-propeptide variants did not cause discoloration but resulted in the highest pulp obliteration prevalence (~%20). The prevalence of tooth discoloration and pulp obliteration was higher in OI types III and IV and increased with age. Tooth discoloration was mainly observed in teeth known to have thinner enamel (i.e. lower anterior), while pulp obliteration was most prevalent in the first molars. A significant association was observed between pulp obliteration and tooth discoloration, and both were associated with a lack of occlusal contact. Taurodontism was only found in permanent teeth and affected mostly first molars, and its prevalence decreased with age.

CONCLUSION

The dental phenotype evaluation at the tooth level revealed that different genetic variants and associated clinical phenotypes affect each tooth type differently, and genetic variants are better predictors of the dental phenotype than the type of OI. Our results also suggest that tooth discoloration is most likely an optical phenomenon inversely proportional to enamel thickness, and highly associated with pulp obliteration. In turn, pulp obliteration is proportional to patient age, it is associated with malocclusion and likely related to immature progressive dentin deposition. Taurodontism is an isolated phenomenon that is probably associated with delayed pulpal maturation.

A rare presentation of a simple bone cyst

Simple bone cyst is an oft-described entity, which goes by many sobriquets and has been presented in the literature as early as 1926. It is a lesion of unclear etiology with many proposed hypothesis for its pathogenesis and nonspecific histopathological presentation. We present a case of a solitary bone cyst, which clinically presented as a solitary lesion, but radiological examination revealed multiple lesions peppering the maxilla and the mandible, thereby highlighting the importance of atypical presentation and “surprise” lesions that may show up on radiological examination.

Immortalized mouse dental papilla mesenchymal cells preserve odontoblastic phenotype and respond to bone morphogenetic protein 2

Odontogenesis is the result of the reciprocal interactions between epithelial–mesenchymal cells leading to terminally differentiated odontoblasts. This process from dental papilla mesenchymal cells to odontoblasts is regulated by a complex signaling pathway. When isolated from the developing tooth germs, odontoblasts quickly lose their potential to maintain the odontoblast-specific phenotype. Therefore, generation of an odontoblast-like cell line would be a good surrogate model for studying the dental mesenchymal cell differentiation into odontoblasts and the molecular events of dentin formation. In this study, immortalized dental papilla mesenchymal cell lines were generated from the first mouse mandibular molars at postnatal day 3 using pSV40. These transformed cells were characterized by RT-PCR, immunohistochemistry, Western blot, and analyzed for alkaline phosphatase activity and mineralization nodule formation. One of these immortalized cell lines, iMDP-3, displayed a high proliferation rate, but retained the genotypic and phenotypic characteristics similar to primary cells as determined by expression of tooth-specific markers and demonstrated the ability to differentiate and form mineralized nodules. Furthermore, iMDP-3 cells had high transfection efficiency as well as were inducible and responded to BMP2 stimulation. We conclude that the establishment of the stable murine dental papilla mesenchymal cell line might be used for studying the mechanisms of dental cell differentiation and dentin formation.

The genetic basis of inherited anomalies of the teeth. Part 2: syndromes with significant dental involvement

Teeth are specialized structural components of the craniofacial skeleton. Developmental defects occur either alone or in combination with other birth defects. In this paper, we review the dental anomalies in several multiple congenital anomaly (MCA) syndromes, in which the dental component is pivotal in the recognition of the phenotype and/or the molecular basis of the disorder is known. We will consider successively syndromic forms of amelogenesis imperfecta or enamel defects, dentinogenesis imperfecta (i.e. osteogenesis imperfecta) and other dentine anomalies. Focusing on dental aspects, we will review a selection of MCA syndromes associated with teeth number and/or shape anomalies. A better knowledge of the dental phenotype may contribute to an earlier diagnosis of some MCA syndromes involving teeth anomalies. They may serve as a diagnostic indicator or help confirm a syndrome diagnosis.

Pulp stones: a review

Pulp stones are a frequent finding on bitewing and periapical radiographs but receive relatively little attention in textbooks. A review of the literature was therefore performed, initially using the PubMed database and beginning the search with 'pulp calcifications' and 'pulp stones'. Each term provided more than 400 references, many of which related to pulp calcification in general rather than pulp stones, and focussed largely on the problems these changes presented to clinicians. A manual search using references from this source was carried out. Contemporary textbooks in endodontology were also consulted, and an historic perspective gained from a number of older books and references. The factors involved in the development of the pulp stones are largely unknown. Further research may determine the reasons for their formation, but with current endodontic instruments and techniques this is unlikely to alter their relevance to clinicians.

Oral health in prevalent types of Ehlers-Danlos syndromes

BACKGROUND

The Ehlers-Danlos syndromes (EDS) comprise a heterogenous group of heritable disorders of connective tissue, characterized by joint hypermobility, skin hyperextensibility and tissue fragility. Most EDS types are caused by mutations in genes encoding different types of collagen or enzymes, essential for normal processing of collagen.

METHODS

Oral health was assessed in 31 subjects with EDS (16 with hypermobility EDS, nine with classical EDS and six with vascular EDS), including signs and symptoms of temporomandibular disorders (TMD), alterations of dental hard tissues, oral mucosa and periodontium, and was compared with matched controls.

RESULTS

All EDS subjects were symptomatic for TMD and reported recurrent temporomandibular joint (TMJ) dislocations. Abnormal pulp shape (13%) and pulp calcification (78%) were observed in subjects affected with classical EDS. Caries experience was higher in EDS compared with controls and was related to poor oral hygiene, influenced by increased mucosal fragility and restraint of (wrist) joint mobility. The overall periodontal status in EDS was poor, with 62% of EDS subjects presenting high periodontal treatment needs (community periodontal index for treatment need, CPITN = II).

CONCLUSION

Oral health may be severely compromised in EDS as a result of specific alterations of collagen in orofacial structures. When considering dental treatment in EDS, a number of tissue responses (mucosa, periodontium, pulp) and precautions (TMJ dislocation) should be anticipated.

A newly recognized syndrome of skeletal dysplasia with opalescent and rootless teeth

A Thai girl with skeletal dysplasia and dental anomalies was seen. Her anomalies consisted of disproportionately short stature, short neck, broad and depressed nasal bridge, broad chest in the anteroposterior dimension, kyphosis, widely spaced nipples, and protruded abdomen. Radiographic testing indicated that she had a large sella turcica, platyspondyly, hypoplastic acetabulum, and a small body of mandible. Both her deciduous and permanent teeth were equally opalescent, and most were rootless, with root development of the mandibular teeth more severely affected. Some maxillary roots were extremely short and tapered. Hypodontia was also observed. These findings represent a unique and hitherto undescribed syndrome of skeletal dysplasia with concomitant dental anomalies.

Multiple idiopathic mandibular bone cysts in a patient with osteogenesis imperfecta

Although the most common oral manifestation of osteogenesis imperfecta is dentinogenesis imperfecta, several authors have described jaw fractures and radiolucent bone lesions associated with this disease. We report a case of a 23-year-old white woman with osteogenesis imperfecta and dentinogenesis imperfecta who developed multiple unilocular, bilateral, radiolucent lesions of the mandible 5 years after presenting with a condylar fracture. This is the first documentation by surgical and histopathologic examination that the radiolucent lesions in this particular case represent multiple idiopathic bone cysts.

Heritable dentin defects: nosology, pathology, and treatment

Heritable dentin defects have been divided into 2 main categories: dentinogenesis imperfecta (DI) and dentin dysplasia (DD). Recent studies have shown that they share many features in common. Of the connective tissue diseases, only osteogenesis imperfecta (OI) has been linked to these disorders. So far, no definitive relation between the type of OI and the dental involvement can be established. Familial occurrence of DI with OI cannot be comprehensively explained by mutations in type I collagen genes. No information about the gene defects in DD is available. At the ultrastructural level, the organization of the normally cross-striated collagen fibers in the dentin matrix varies markedly in patients affected by DI.

Dentin dysplasia type II: absence of type III collagen in dentin

A three-generation family with dentin dysplasia (DD) Type II is presented. Affected family members share common radiologic features with clinically varied expression of tooth discoloration and occlusal wear. Both the primary and the permanent dentition appear to be affected. No generalized connective tissue involvement is found. The mode of inheritance is autosomal dominant. Histologically, the findings are consistent with DD Type II. In indirect immunofluorescence, the irregular radicular dentin of an affected permanent tooth failed to stain with specific antibodies against Type III collagen and the N-terminal propeptide of Type III procollagen.