Vestibular dysfunction in adult patients with osteogenesis imperfecta.

Progressive hearing loss is a major symptom in osteogenesis imperfecta (OI), a genetic brittle bone disease. Vertigo is frequently associated with otosclerosis in which the hearing loss clinically resembles that in OI. Vertigo is also common in basilar impression (BI) found in up to 25% of adult OI patients. In order to evaluate the cause, frequency, and characteristics of vertigo in OI, 42 patients were studied by interview, clinical examination, and audiological examination supplemented with electronystagmography (ENG) and lateral skull radiography. Audiometry showed hearing loss in 25 patients (59.5%). Nine patients (21%) displayed abnormal skull base anatomy in the forms of basilar impression, basilar invagination, or both, all designated here as BI. Twenty-two patients (52.4%) reported vertigo, mostly of floating or rotational sensation of short duration. Patients with hearing loss tended to have more vertigo than patients with normal hearing. Vertigo was not correlated with type of hearing loss or auditory brain-stem response (ABR) pathology. ENG was abnormal in 14 patients (33.3%). No dependency was found between vertigo and deviant ENG results. Patients with BI tended to have more vertigo than patients with normal skull base but the difference was not statistically significant. Neither ENG pathology, nor the presence or type of hearing loss showed correlation with BI. In conclusion, vertigo is common in patients with OI. In most cases, it may be secondary to inner ear pathology, and in only some patients does BI explain it. Since some OI patients without BI or hearing loss also suffer from vertigo, further clinical and neurological studies are needed to define the pathogenesis of vertigo in OI.

A novel type of developmental dentin defect.

We describe a developmental dentin disorder distinct from dentin defects characterized thus far. The proband was a 9-year-old boy who was the only family member known to be affected in five generations. The dental defect was not associated with any general disease or developmental disorder. The teeth appeared normal with the exception of the pink hue seen in some primary teeth. Radiographs showed pathological resorption of primary teeth and abnormally shaped pulp chambers and denticles in permanent teeth. Root canals were wide in developing teeth, but appeared thin in erupted teeth. Histological examination of two primary molars revealed canal-like defects in dentin. In the crown, the canals appeared as clusters, which alternated with columns of normal tubular dentin, and in the virtually atubular root dentin they were haphazardly distributed. Scanning electron microscopic examination confirmed the distribution pattern of the canals. In transmission electron microscopy, the defects were found to contain symmetrically banded, segmental collagenous structures. The canal contents immunostained with antibodies to the N-terminal propeptide of type I procollagen, suggesting retention of the propeptide extension in type I collagen. Whereas type III collagen reactivity was barely detectable in the canal region, staining for type V collagen and the non-fibril-forming type VI collagen was strong. The findings imply that the pathogenesis of the defect could be related to a local failure of odontoblasts to produce normal dentin matrix.

Microanatomy of the dental enamel in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED): report of three cases.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal recessive disease composed of failure of various endocrine glands, chronic mucocutaneous candidiasis, and an ectodermal dystrophy complex including hypoplasia of the dental enamel. To characterize the enamel defect further, we studied enamel microanatomy by light microscopy and scanning electron microscopy in clinically affected permanent teeth from three APECED patients. In all three cases, the enamel was partially hypoplastic and morphologically aberrant. Hypoplasia was evident as a horizontal band or as rows of pits. The incremental pattern in the abnormal enamel was obscure, and the prisms were either barely detectable or accentuated and disoriented. In scanning electron microscopy, imprints of the Tomes processes were seen on the enamel surface, but the perikymata were poorly contoured. The distribution pattern of the defective enamel corresponded to the sequence of tooth development and was suggestive of a transient insult. In the enamel affected with a hypoplastic pitted from of amelogenesis imperfecta, studied for comparison, only local hypoplastic defects were seen. Together with normal parathyroid function in one patient and normal calcification of dentin in one of the two patients with hypoparathyroidism, morphology of the enamel in APECED appears to preclude calcium deficiency as the primary cause of the enamel dystrophy.

Mild forms of dentinogenesis imperfecta in association with osteogenesis imperfecta as characterized by light and transmission electron microscopy.

Osteogenesis imperfecta (OI) results from various gene mutations leading to defects in type I collagen, which is the major component of both bone and dentin. Yet dentinogenesis imperfecta (DI) is found only in half of the patients with OI. Here we document patients from three families with OI and DI lacking the clinical and radiographic features of DI in permanent teeth. However, light and transmission electron microscopic studies of dentin of deciduous and permanent teeth revealed various changes in the morphology of the dentinal tubules and collagen fibers. In one family, diagnosis of DI preceded that of OI. The grade of severity of dentinal manifestations in patients with OI apparently forms a continuum from normal dentin structure to severe DI, and the marked difficulty in diagnosing mild DI may have led to underestimating its frequency. Furthermore, patients with DI should be carefully examined for the possible presence of OI.

Unusual forms of collagen in human dentin.

Unusual fibrillar and segmental forms of collagen have been documented in several tissues, including rodent dentin - but not human dentin, which was analyzed here for the presence of such structures. Of six normal human permanent and deciduous teeth examined, cusps of two deciduous molars displayed atypical formations, designated here symmetrical collagen segments (SCSs). They were detected inside of dentinal tubules. It was evident that the 264-nm long, cross-banded SCSs were occasionally arranged vertically and laterally in a staggered manner into thick, irregularly shaped aggregates. Two deciduous incisors from patients with dentinogenesis imperfecta associated with osteogenesis imperfecta were also studied. SCSs were not observed, but fibrous long-spacing-like collagen was rarely found intratubularly in one tooth.

Immunoreactivity of tenascin-C in dentin matrix in dentinogenesis imperfecta associated with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heterogeneous group of heritable connective tissue disorders, assigned to different mutations in type I collagen genes. A variety of structural abnormalities of dentin have been described in dentinogenesis imperfecta (DI) associated with OI. To clarify further the constitution of the dentin matrix in OI, we immunostained frozen and paraffin sections of deciduous teeth from four patients, each from a different family, with two monoclonal antibodies (MAbs) to the matrix glycoprotein tenascin-C (TN-C). One of the MAbs recognizes an epitope common to all TN-C isoforms (BC-4), and the other is specific for a splicing variant (BC-2). Normal teeth, oral mucosa, and skin were analyzed for comparison. Staining patterns with the two MAbs did not differ markedly. Normal dentin matrix and odontoblasts were lacking reactivity, but the pulp stained clearly. TN-C reactivity was present in the dentin matrix of all teeth obtained from two patients with different OI phenotypes and DI, and in one out of three teeth from one patient who also had DI. The reactivity was distributed in layers, but the staining patterns varied from one patient to another and from tooth to tooth. Intratubular staining seen in a tooth from the patient with clinically and histologically normal teeth was comparable with that present in normal deciduous teeth. The variation in TN-C expression suggests that, besides genetic heterogeneity, epigenetic factors could influence the composition of the dentin matrix in OI.

Ultrastructure of dentin matrix in heritable dentin defects.

Heritable dentin defects form a group of diseases which exclusively affect dentin among the various dental tissues. While one type is associated with the generalized connective tissue disorder, osteogenesis imperfecta, other types occur as single traits. The clinical manifestations of the dentin defects vary from insignificant to severe enough to cause aesthetical and functional failure of the teeth. Scanning and transmission electron microscopic studies, reviewed in this paper, have markedly clarified the ultrastructure of the aberrant dentin matrix. Both similar and different changes seem to occur in the various forms of heritable dentin defects. Abnormalities in the appearance and organization pattern of collagen fibers in the defective dentin partly resemble those observed in skin in generalized connective tissue diseases. The similarity of ultrastructural findings in dentin defects, which are currently classified as distinct entities, and even in diseases affecting other tissues, could be related to the complicated interactions between the extracellular matrix macromolecules. Thus, many of the changes observed may be secondary in nature. Ultrastructural studies can help us to understand the pathogenesis of the different types of heritable dentin defects as well as aid in diagnostics and classification of these diseases.

Altered collagen expression in human dentin: increased reactivity of type III and presence of type VI in dentinogenesis imperfecta, as revealed by immunoelectron microscopy.

We used transmission immunoelectron microscopy and polyclonal antibodies to study the reactivities of Types III and VI collagen in dentin of normal human permanent and primary teeth and in primary teeth from five patients with dentinogenesis imperfecta (DI) associated with osteogenesis imperfecta and occurring as a single trait. In the normal permanent tooth, reactivity of Type III collagen was occasional and, where present, peritubular. Staining of normal primary teeth was less occasional but still rare, whereas the abnormal dentin stained more uniformly. Atypical, non-striated fibrillar structures that also showed Type III collagen reactivity were observed in dentin of two of the three patients with DI as a single trait. Later, these two patients proved to be first cousins. Unlike antibodies to the N-terminal pro-peptide of Type I pro-collagen, antibodies to the C-terminal telopeptide of Type I collagen, used for comparison stained the affected dentin homogeneously. Reactivity of Type VI collagen, not detected in normal teeth, was seen in the dentin of all abnormal teeth, in association with non-fibrillar delicate material. This study also shows that although readily detectable in dentin affected by DI, Type III collagen is a minor constituent of normal human dentin matrix.

Hyperfibers and vesicles in dentin matrix in dentinogenesis imperfecta (DI) associated with osteogenesis imperfecta (OI).

Dentin matrix of deciduous teeth from two patients affected by dentinogenesis imperfecta (DI) associated with types IB and IVB osteogenesis imperfecta (OI) displayed previously undescribed structures in transmission electron microscopic examination. Vesicles were seen in dentin of both patients, and abnormally thick collagen fibers (hyperfibers) were found in dentin of the patient with the rare type IB OI. Both vesicles and hyperfibers were situated in abnormal, atubular areas of dentin. Matrix vesicles, which have normally been identified in mantle dentin only, were abundant in selected areas of the affected dentin, thereby supporting the concept that dentin matrix in OI is elaborated by successive cell generations. The hyperfibers, not previously described in either normal or abnormal human dentin, have possibly been formed by fusion of several collagen fibers. Further ultrastructural studies of dentin in DI with OI may help to clarify the marked clinical variation in teeth of patients affected by OI.

Transient expression of type III collagen by odontoblasts: developmental changes in the distribution of pro-alpha 1(III) and pro-alpha 1(I) collagen mRNAs in dental tissues.

The expression of pro-alpha 1(III) and pro-alpha 1(I) collagen mRNAs in mouse and human dental tissues during tooth development and after its completion was analyzed by in situ hybridization, with use of [35S]-labeled RNA probes. The expression of pro-alpha 1(III) mRNA was also compared to that of the protein product, as localized by immunostaining with polyclonal antibodies to type III collagen and the N-terminal propeptide of type III procollagen. Contrary to many previous reports, our results suggest that odontoblasts express type III collagen. While pro-alpha 1(III) transcripts were less intensely expressed in odontoblasts than pro-alpha 1(I) transcripts, the amounts of both mRNAs increased in odontoblasts with progressing dentin formation, and decreased toward its completion. In contrast to pro-alpha 1(III) mRNA, pro-alpha 1(I) mRNA was still detectable in odontoblasts of fully developed teeth. Type III collagen immunoreactivity was observed in the early predentin, and again in predentin toward the completion of dentinogenesis, when mRNA was no longer detected. Also in the pulp, the protein product, unlike pro-alpha 1(III) mRNA, was relatively strongly expressed. Hence, these immunostaining patterns were inversely related to the expression of pro-alpha 1(III) mRNA, suggesting accumulation of the protein. The mesenchymal cells, when condensed in the region of the future mandibular bone, expressed pro-alpha 1(III) mRNA intensely, whereas osteoblasts expressed pro-alpha 1(I) but not pro-alpha 1(III) transcripts strongly. Cell type- and developmental stage-related differences in the expression of the two mRNAs suggest that type I/type III collagen ratio influences the structure of dental tissues.

Expression of aspartylglucosaminidase in human tissues from normal individuals and aspartylglucosaminuria patients.

Aspartylglucosaminidase (AGA: E.C. 3.5.1.26) is a lysosomal amidase that hydrolyzes the N-acetylglucosamine-asparagine linkage as one of the final steps in the breakdown of glycoproteins. Deficiency of this enzyme results in aspartylglucosaminuria (AGU), an inherited lysosomal storage disease. In an attempt to establish the tissue-specific expression of AGA in normal individuals and in AGU patients, we adapted biochemical and immunohistochemical techniques to analyze AGA polypeptides in human cells and tissues. The biochemical analysis revealed the existence of alpha- and beta-subunit structures of AGA in all tissues. Immunohistochemical staining demonstrated a cell specificity in the distribution of AGA: immunoreactivity was strongest in hepatocytes, pyramidal cells in the cerebral cortex, and proximal tubule cells in the kidney. In tissues from AGU patients, AGA immunoreactivity could be detected in hepatocytes and in proximal tubule cells but not in the pyramidal cells. The regulation of the expression of AGA was approached by analyzing the transcript levels and the methylation of the AGA gene. Both heavy methylation of the AGA gene and the constant level of AGA mRNA were typical of a "house-hold" type of enzyme that can be found in small quantities in all tissues. This was in contrast to the variability of the amount of AGA polypeptides observed in different cells and tissues, suggesting that the expression of AGA is regulated not at the transcriptional but rather at the translational level.

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.

Immunohistochemical localization of types I, V, and VI collagen in human permanent teeth and periodontal ligament.

Types I, V, and VI collagen were immunohistochemically localized in frozen and paraffin sections of human permanent teeth, periodontal ligament, and alveolar bone, by means of polyclonal antibodies. Hyaluronidase was effective in exposing epitopes of the various collagen types. The expression of type I collagen in predentin was strong in frozen sections, whereas the dental pulp stained relatively weakly. Staining intensity in the dentin matrix decreased toward enamel and cementum. Reactivity in the periodontal ligament was moderate, and it was weaker in the alveolar bone and also in cementum, which stained more intensely in paraffin sections. Staining for type V collagen was strong in the pulp. Weak reactivity in predentin became uniformly evident in frozen sections only, and dentin was negative. The periodontal ligament stained with moderate intensity, and a weak staining reaction was seen in cementum and bone. Staining for type VI collagen in the pulp and periodontal ligament was strong, whereas predentin and dentin were negative. The alveolar bone stained moderately, and non-uniform reactivity was present in cementum. In non-mineralized dental tissues, the use of frozen material enabled good immunohistochemical localization of the distinct collagen types to be carried out. Their distribution patterns in dental tissues not only differed, but the relative staining intensities for each collagen type in the pulp and predentin were inversely related. However, differences may exist in the exposure of the epitopes of collagen(s) between soft and mineralized tissues.

Transmission electron microscopic appearance of dentin matrix in type II dentin dysplasia.

Dentin matrix of demineralized primary and permanent teeth with type II dentin dysplasia was studied by transmission electron microscopy. The coronal dentin of a maxillary third molar exhibited a normal structure. In the radicular dentin, tubules were few in number; the major part of the dentin was composed of thick, curvy bundles of cross-striated collagen fibers. In the most aberrant areas of the radicular dentin, coarse collagen fibers measuring up to 140 nm in thickness were observed. The dentin of the primary tooth showed a similar, but somewhat less irregular, structure.

Geographic tongue during a year of oral contraceptive cycles.

The geographic tongue of a 23-year-old female student was examined daily for one year. The size, number and location of the lesions were recorded using transparent films. The phase of the oral contraceptive cycle appeared to have a marked effect on the initiation and duration of the circinate lesions, the tongue changes being severest on the 17th day of the cycle. There was a positive correlation between the subjective complaint and the clinical picture of the tongue.

PIP: The number, location and extent of tongue lesions in a 23-year old woman with a tongue disorder called geographic tongue, who was taking the oral contraceptive Marvelon (Organon), were plotted for a year by tracing them daily on transparent film marked with a grid. These lesions appear as desquamation of the filiform papillae forming smooth erythematous patches with elevated white edges, occurring in multiple zones. They often heal on one border while extending on another, hence the apparent migration or "geographic" distribution. The woman developed 123 new lesions during the study period, having only 34 asymptomatic days. Her lesions lasted 1-46 days, with a mean of 7.2 days. there were an average of 2.3 lesions at a time, ranging from 0-8. Lesions developing during the 1st quarter of the oral contraceptive cycle lasted significantly longer than those appearing at other times. The total number of lesions peaked on the 17th day of the pill cycle. Subjective symptoms also were at their maximum on days 16-20 of the cycle. The woman's lesions were typical of previously reported cases: they were usually located on the anterior two-thirds of the dorsal surface, or lateral surface of the tongue. Other family members had experienced this disorder. It was concluded that pill hormones may have influenced the patient's inflammatory response. This is the 1st published association of geographic tongue with oral contraceptive intake.