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This microsurgical clinical study evaluated if teeth that have undergone endodontic retreatment are associated with more dentinal defects than primary root canal-treated teeth.One hundred fifty-five patients who underwent periapical microsurgery treatment in a private practice setting were evaluated. The root ends were resected, and the roots were inspected for the presence of dentinal defects through the surgical operating microscope with the help of a 0.8-mm-diameter light-emitting diode probe light and methylene blue dye. The root canal treatment history (primary vs retreatment) of the teeth was documented and related to the presence or absence of dentinal defects. Bivariate analysis was performed using the chi-square test, and a multivariate analysis was performed using logistic regression to evaluate possible confounding effects of patient age, sex, and tooth location on the association between treatment and the presence of dentinal defects.Of the 155 treated teeth, 33 were excluded (3 fractured and 30 missing treatment history). Of the remaining 122 included teeth, 73 (59.8%) had undergone primary root canal treatment and 49 (40.2%) retreatment. Sixteen teeth (22.5%) of the primary root canal group versus 33 (64.7%) of the retreatment group had dentinal defects. The proportion of retreated teeth with dentinal defects compared with primary treatment was statistically significant (P .001) with a higher proportion of retreated teeth having dentinal defects. In the multivariate analysis, only the type of treatment was statistically significant (P .001).This clinical study showed that root canal-retreated teeth are associated with more dentinal defects than primary root canal-treated teeth.

Dentin dysplasia (DD) is a rare developmental dentin disorder that causes root malformation. It is divided into radicular DD type 1 (DD-1) and coronal DD type 2 (DD-2). Recently, a new entity causing localized root malformation of permanent first molars that resembles DD-1b has been described as molar-incisor malformation (MIM). We report and compare 4 new cases that exhibit similar clinical, histologic, and radiographic features to the new entity, MIM. We believe MIM and our 4 cases to be the same entity, which is nonhereditary and, because of the isolated but bilaterally symmetric pattern of involvement, may be caused by a short-duration environmental insult that disrupts normal development/function of Hertwig's epithelial root sheath. We propose the name symmetrical multiquadrant isolated dentin dysplasia as the most appropriate descriptive designation for this unusual but highly distinctive anomaly.

Objectives Amelogenesis imperfecta, dentinogenesis imperfecta, and dentin dysplasia are the most common non-syndromic dental disorders. In this study, we analysed and localised the gene(s) responsible for inherited non-syndromic dental disorders in a Chinese family. Methods This study identified and researched non-syndromic dental disorders in a four-generation Chinese family, including four affected individuals whose clinical phenotype was atypical. Linkage analysis with seven polymorphic markers that localise to six different autochromosomes showed that the family was linked through chromosome 4q. All exons and exon–intron boundaries of dentin sialophosphoprotein (DSPP), enamelin (ENAM), and ameloblastin (AMBN), which are located on chromosome 4q, were sequenced in nine of the family members. Results Direct DNA sequence analysis revealed the existence of a G to A transversion in exon 4 (g.13081786G > A, c.727G > A, p.Asp243Asn, based on reference sequences NM_014208.3 ) of the DSPP gene, and this sequence variation correlated exactly with the presence of the disease. Conclusion These results indicate that mutation p.Asp243Asn is a highly probable cause of non-syndromic dental disorder in this Chinese family. The presence of symptom heterogeneity is possible, as the clinical classification system is hampered by the lack of close correlation between the subtype and the molecular defect.

Dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) are highly phosphorylated proteins that belong to the family of small integrin-binding ligand N-linked glycoproteins (SIBLINGs), and are essential for proper development of hard tissues such as teeth and bones. In order to understand how they contribute to tissue organization, DSPP and DMP-1 have been analyzed for over a decade using both in vivo and in vitro techniques. Among the five SIBLINGs, the DSPP and DMP-1 genes are located next to each other and their gene and protein structures are most similar. In this review we examine the phenotypes of the genetically engineered mouse models of DSPP and DMP-1 and also introduce complementary in vitro studies into the molecular mechanisms underlying these phenotypes. DSPP affects the mineralization of dentin more profoundly than DMP-1. In contrast, DMP-1 significantly affects bone mineralization and importantly controls serum phosphate levels by regulating serum FGF-23 levels, whereas DSPP does not show any systemic effects. DMP-1 activates integrin signalling and is endocytosed into the cytoplasm whereupon it is translocated to the nucleus. In contrast, DSPP only activates integrin-dependent signalling. Thus it is now clear that both DSPP and DMP-1 contribute to hard tissue mineralization and the tissues affected by each are different presumably as a result of their different expression levels. In fact, in comparison with DMP-1, the functional analysis of cell signalling by DSPP remains relatively unexplored.

Objectives This review groups the newest results of molecular analyses of DSPP gene for patients diagnosed either with dentinogenesis imperfecta type II/III or dentine dysplasia and tries to link the phenotypes with specific mutations in the DSPP gene. Data The review includes biochemical data introducing a specificity of DSPP protein which justifies it as a critical factor for dentine mineralization and maturation. The majority of the review analyzes mutations in the DSPP gene which result in phenotypes of dentinogenesis imperfecta types II or/and III or dentine dysplasia. Sources An electronic search was conducted in the databases of Pub Med and supplemented by manual study of relevant references. Study selection 52 out of 108 references were finally selected for the review based on the novelty and/or originality of data. Conclusion Hereditary dentine disorders dentinogenesis imperfecta type II/III and dentine dysplasia are currently proposed to be one disease with distinct clinical manifestations reflecting various mutations in the same DSPP gene. For years both disorders were linked exclusively to mutations in the DSP code but a growing number of papers describe mutations which manifest a similar phenotype but are localized in the strongly repetitive sequence of the 3′ terminus of the DSPP which codes DPP protein. Our search suggests that the localization of mutation in the sequence of the DSPP gene might result in a different phenotype due to the diverse cellular fate of the mutated protein. Thus comprehensive research on the cellular fate and processing of both normal and mutated DSPP is still required.

During development, Dlx3 is expressed in ectodermal appendages such as hair and teeth. Thus far, the evidence that Dlx3 plays a crucial role in tooth development comes from reports showing that autosomal dominant mutations in DLX3 result in severe enamel and dentin defects leading to abscesses and infections. However, the normal function of DLX3 in odontogenesis remains unknown. Here, we use a mouse model to demonstrate that the absence of Dlx3 in the neural crest results in major impairment of odontoblast differentiation and dentin production. Mutant mice develop brittle teeth with hypoplastic dentin and molars with an enlarged pulp chamber and underdeveloped roots. Using this mouse model, we found that dentin sialophosphoprotein (Dspp), a major component of the dentin matrix, is strongly down-regulated in odontoblasts lacking Dlx3. Using ChIP-seq, we further demonstrate the direct binding of Dlx3 to the Dspp promoter in vivo. Luciferase reporter assays determined that Dlx3 positively regulates Dspp expression. This establishes a regulatory pathway where the transcription factor Dlx3 is essential in dentin formation by directly regulating a crucial matrix protein.

Inherited dental malformations constitute a clinically and genetically heterogeneous group of disorders. Here, we report on a severe developmental dental defect that results in a dentin dysplasia phenotype with major microdontia, oligodontia, and shape abnormalities in a highly consanguineous family. Homozygosity mapping revealed a unique zone on 6q27-ter. The two affected children were found to carry a homozygous mutation in SMOC2. Knockdown of smoc2 in zebrafish showed pharyngeal teeth that had abnormalities reminiscent of the human phenotype. Moreover, smoc2 depletion in zebrafish affected the expression of three major odontogenesis genes: dlx2, bmp2, and pitx2.

Dentinogenic ghost cell tumor (DGCT) is a rare neoplasm, representing 1.9% to 2.1% of all odontogenic tumors. Few cases of DGCT have been reported and only 11 show no bone involvement. A rare case of peripheral DGCT is reported, located in the anterior mandible of a 45-year-old man. The patient presented a slow painless growth in the canine region of an edentulous mandible. Radiographically, no bone involvement was registered. The lesion was enucleated and microscopically characterized by islands of epithelial cells showing ameloblastomalike features in fibrous tissue. Dysplasic dentin and ghost cells were frequently observed. Areas showing a connection between tumor cells and the overlying mucosa were also identified. Immunohistochemical analysis demonstrated positivity for pan-cytokeratin, cytokeratin-14, and 2 neural markers. Denditric cells (Langerhans cells and melanocytes) were identified inside tumoral islands. A rare case of peripheral DGCT is reported, with immunohistochemical analysis and a review of the English literature.

Dentin sialophosphoprotein (DSPP) is critical for proper mineralization of tooth dentin, and understanding its structure and function should yield important insights into how dentin biomineralization is controlled. During the recent six years, I have focused on characterizing DSPP-derived proteins isolated from developing porcine teeth. Porcine DSPP is expressed and secreted by odontoblasts and is processed by BMP-1, MMP-20 and MMP-2 into three main parts: dentin sialoprotein (DSP), dentin glycoprotein (DGP), and dentin phosphoprotein (DPP). We have learned that DSP is a proteoglycan that forms covalent dimers, DGP is a phosphorylated glycoprotein, and DPP is a highly phosphorylated intrinsically disordered protein that shows extensive length polymorphisms due to the genetic heterogeneity of its coding region.

Histological and ultrastructural observations of dentin of two patients affected with rare types of type I collagen disorders are presented. In the first case, a homozygous nonsense mutation in ADAMTS2 (substitution of a codon for tryptophan by a stopcodon) causes type VIIC Ehlers-Danlos syndrome (EDS) with multiple tooth agenesis and focal dysplastic dentin defects. In the second case, a missense mutation in COL1A1 (substitution of arginine by cysteine) results in a type I EDS phenotype with clinically normal-appearing dentition. Tooth samples are investigated by using light microscopy (LM), transmission electron microscopy (TEM) and immunostaining for types I and III collagen, and tenascin. These are compared with samples from patients with types III and IV osteogenesis imperfecta (OI) in association with dentinogenesis imperfecta (DI), showing a consistently abnormal appearance of the dentin in all specimens, with variations being primarily those of degree of change. Similarities in histological changes include the alternating presence of normal and severe pathological areas in primary and secondary dentin, the latter being characterized by large canal-like structures in atubular areas. Ultrastructural evidence of pathological dentinogenesis include abnormal distribution, size and organization of collagen fibers, which may also be found in clinically unaffected teeth. The histological and ultrastructural changes seen can be explained on the basis of odontoblast dysfunction which may be secondary to the collagen defect, interfering with different levels of odontoblast cell function and intercellular communication. These observations on (ultra)structural dentin defects associated with the two novel gene mutations are the first ever reported.

CCAAT enhancer binding proteins (C/EBP) comprise a family of basic-leucine zipper transcription factors that regulate cellular differentiation and function. To determine the role of C/EBP transcription factors in osteoblasts and odontoblasts, we generated a transgenic (TG) mouse model with Co1a1 (pOBCol3.6) promoter-targeted expression of a FLAG-tagged dominant negative C/EBP isoform, p20C/EBPβ (previously LIP). Two of the four transgenic lines presented with abnormalities in the developing incisors, including breakage, overgrowth, and malocclusion. Histological examination revealed that the amount of alveolar bone was reduced in TG compared to wild-type (WT) mice. By microcomputed tomography (microCT), the bone volume fraction of the mandible was reduced at the level of the first and third molars, demonstrating a severe mandibular osteopenia. The lingual dentin morphology of TG incisors differed dramatically from WT. Labial dentin (enamel side) showed normal thickness and tubular dentin structure, whereas the lingual dentin was thinner (25–30% of WT at the alveolar crest) with an amorphous globular structure characteristic of dentin dysplasia. FLAG immunostaining was seen in both lingual and labial odontoblasts, indicating that the site-specific defect was not due to a lack of labial transgene expression. Northern blot analysis demonstrated reduced osteocalcin expression in TG mandibles, while bone sialoprotein was increased, consistent with prior results in calvariae and long bones. Dental sialophosphoprotein, a marker of the odontoblast lineage whose absence causes dentin dysplasia, was modestly reduced in TG mice by Northern blot and in situ hybridization analysis. By fluorescence microscopy, pOBCol2.3-GFP, a marker of the odontoblast lineage, was expressed in both labial and lingual odontoblasts, although GFP-marked lingual odontoblasts were more flattened than WT cells. Moreover, GFP-positive processes in the lingual dentin tubules were truncated and less organized than those in WT dentin. MicroCT analysis showed reduced tissue density in the lingual dentin. These data suggest that C/EBP transcription factors may be involved in the regulation of odontoblast polarization and dentin matrix production.

An unusual case of generalised pulpal calcifications (pulp stones) with normal clinical crowns is reported in a 13-year-old boy. Radiographic examination revealed pulp stones in the single rooted and premolar teeth, situated at the midroot level, with the roots bulging around them. The apical portion of the roots, periodontal ligament space, and surrounding bone had a normal radiographic appearance, apart from the upper premolars, and no periapical pathology was discernible. The upper premolars exhibited considerably shortened roots. No medical, dental, or family history was found to be contributory. Reviewing the literature revealed similar cases, but with differing diagnoses including dentine dysplasia (DD) or idiopathic cases. This report suggests either a variation of DD or possibly a new nonsyndromic dentine defect, and highlights the difficulties in establishing a definitive diagnosis by traditional methods. The recent discovery that mutation of the bicistronic dentine sialophosphoprotein gene (DSPP) is involved in DD may provide solutions to this problem.

Dentin dysplasia is a rare autosomal dominant genetic disease characterized by defect of dentin development and the causal gene is DSPP (Dentin Sialophosphoprotein gene). We report in the present study a large Moroccan family in which dentin dysplasia is clearly transmitted as an autosomal recessive trait. Four males and females family members born from healthy consanguineous parents are carriers of the typical features of the dentin dysplasia type I. Polymorphic markers that span the DSPP gene, allowed us to show that this locus is not linked to dentin dysplasia in our family. We also excluded in our family the SMOC2 gene (Sparc Related Modular Calcium Binding Protein 2) which was recently identified as a causal gene in dentin dysplasia type I with microdontia and misshapen teeth. This family represents, a new description of autosomal recessive pattern of inheritance of dentin dysplasia type I. Moreover, this form of dentin dysplasia is not allelic to the autosomal dominant dentin dysplasia and the genetic cause is to be discovered.

Dentin dysplasia type I is a rare hereditary disturbance of dentin formation characterized clinically by nearly normal appearing crowns and severe hypermobility of teeth. Radiographic analysis shows obliteration of all pulp chambers, short, blunted, and malformed roots, and periapical radiolucencies of noncarious teeth. This paper presents 2 cases demonstrating both classic and atypical features of type I dentin dysplasia in the mixed and permanent dentitions. The clinical, radiographic, and histopathologic\findings of this condition and treatment are described.

Transforming growth factor (TGF)-beta1 is expressed in developing tooth from the initiation stage through adulthood. Odontoblast-specific expression of TGF-beta1 in the tooth continues throughout life; however, the precise biological functions of this growth factor in the odontoblasts are not clearly understood. Herein, we describe the generation of transgenic mice that overexpress active TGF-beta1 predominantly in the odontoblasts. Teeth of these mice show a significant reduction in the tooth mineralization, defective dentin formation, and a relatively high branching of dentinal tubules. Dentin extracellular matrix components such as type I and III collagens are increased and deposited abnormally in the dental pulp, similar to the hereditary human tooth disorders such as dentin dysplasia and dentinogenesis imperfecta. Calcium, one of the crucial inorganic components of mineralization, is also apparently increased in the transgenic mouse teeth. Most importantly, the expression of dentin sialophosphoprotein (dspp), a candidate gene implicated in dentinogenesis imperfecta II (MIM 125420), is significantly down-regulated in the transgenic teeth. Our results provide in vivo evidence suggesting that TGF-beta1 mediated expression of dspp is crucial for dentin mineralization. These findings also provide for the first time a direct experimental evidence indicating that decreased dspp gene expression along with the other cellular changes in odontoblasts may result in human hereditary dental disorders like dentinogenesis imperfecta II (MIM 125420) and dentin dysplasia (MIM 125400 and 125420).

Dentin dysplasia, type II, is an inherited autosomal dominant disorder in which primary teeth are amber and translucent, with pulp chambers obliterated by abnormal dentin. The permanent teeth have a normal coronal morphologic character and coloration but exhibit "thistle tube"-shaped pulp chambers as well as numerous pulpal calcifications. The disorder has traditionally been thought to be somewhat rare; however, this article presents 2 new families in which several generations with the disorder were reported to the authors within a 1-year period. It also includes a review of the literature documenting a total of 17 previously reported families.

Five cases of dentin dysplasia type I within one family are described. Clinically and radiologically, such patients are characterized by a delayed eruption pattern, opacity of the incisional margins, hypermobility of the teeth, short and defective roots, and obliterated pulp chambers. A conservative attitude toward the treatment of common conditions in dentin dysplasia type I favors the preservation of a vulnerable dentition.

Dentin is the major mineralized extracellular matrix of the tooth. The organic components of dentin consist of type I collagen (90%) with 10% noncollagenous proteins, which are also components of bone. Two dentin proteins, dentin sialoprotein and dentin phosphoprotein, have been shown to be tooth-specific being expressed mostly by odontoblast cells. In this study, we screened a mouse molar tooth library for dentin sialoprotein and dentin phosphoprotein cDNA clones. Analysis of the clones resulted in characterization of a 4420-nucleotide cDNA that contained a 940-amino acid open reading frame. The signal peptide and NH2-terminal sequence was 75% homologous to the cDNA sequence of rat dentin sialoprotein. The continued open reading frame, however, contained a RGD sequence followed by a region of repeated aspartic acid and serine residues. This portion of the protein codes for amino acid sequence consistent with that of dentin phosphoprotein. The noncoding region contains three potential polyadenylation signals, two of which were shown to be utilized. Northern blot analysis indicated the presence of two major transcripts of 4.4 and 2.2 kilobases in odontoblasts. Chromosomal mapping localized the gene to human chromosome 4. These data suggest that the previously identified dentin extracellular matrix proteins, dentin sialoprotein and dentin phosphoprotein, are expressed as a single cDNA transcript coding for a protein that is specifically cleaved into two smaller polypeptides with unique physical-chemical characteristics. Therefore, we propose that the gene be named dentin sialophosphoprotein. The location of the human dentin sialophosphoprotein gene on chromosome 4 suggests that this gene may be a strong candidate gene for the genetic disease dentinogenesis imperfecta type II.

This is a report of a kindred of at least 181 members, of whom 35 exhibit or are reported to have dentin dysplasia type I. Six others are suspected of having the condition. Radiographic evidence that included obliterated or semilunar pulp chambers and short or undeveloped roots confirmed the diagnosis in 18 persons. The autosomal dominant mode of inheritance has been confirmed. One hundred percent penetrance has been demonstrated. There were insufficient data to determine the degree of expressivity.

Generalized pulpal calcifications arouse suspicion of diseases or conditions of systemic or hereditary origin. This case report describes a 45-year-old patient with generalized pulpal calcifications and bulging of the roots in areas corresponding to the pulp chambers in otherwise normal teeth. Similar findings were present in the patient's daughters and brother. This pattern of pulpal calcifications is consistent with the hereditary condition of dentinal dysplasia type Id.

The literature is reviewed to determine the radiographic appearance of the reported cases of dentin dysplasia. The sometimes confusing nomenclature is rationalized. Four distinct forms of dentin dysplasia type I and one form of dentin dysplasia type II are identified. There seems to be no need to identify more than two distinct types of this relatively rare inherited defect of human dentin, but a proposed subclassification of type I dentin dysplasia could make identification of the two types easier.

Pulpal calcifications are relatively common. However, their occurrence in the entire dentition is relatively infrequent. The presence of such calcification arouses suspicion of systemic or hereditary origin. This case report describes twin sisters with pulpal calcifications in their entire dentitions. No systemic cause was detected. The pattern of calcification was partially consistent with the hereditary condition of dentinal dysplasia.

A case report on dentin dysplasia type I, a congenital disease (autosomal dominant gene defect) affecting deciduous and permanent teeth, is depicted including representations of clinical and histological features, X-ray and CT-findings. Therapy includes extraction of all teeth, ectomization of cystic alteration, revision of paranasal sinus. Aesthetic and functional rehabilitation by means of insertion of a complete denture was achieved.

Radicular dentin dysplasia is a peculiar anomaly in which abnormal dentin resembling the plici-dentin found in certain fish and reptiles obliterates the pulp chamber. The almost complete absence of roots leads to the early loss of teeth and predisposes to paradontal infection and the formation of cysts.

Dentin dysplasia Type I is a rare hereditary disturbance in dentin formation characterized by teeth with short blunted roots, complete pulpal obliteration, periapical abscesses or cysts without an obvious causative factor, and spontaneous exfoliation. This report describes the clinical, radiographic, histologic, ultrastructural, and genetic features of dentin dysplasia Type I in a 17-year-old boy and discusses the features which separate it from dentin dysplasia Type II and dentinogenesis imperfecta.

A new, nonsyndromic dentin defect, focal odontoblastic dysplasia, is described on the basis of clinical, radiographic, histologic, and scanning electron microscopic criteria. A provisional classification is proposed for this disease entity according to the nosology of Shields and associates. Four additional cases in the literature which possibly represent this new entity are presented, and a possible genetic etiology is discussed.

The second reported family with an unusual dentin abnormality is presented. This abnormality is characterized by involvement of both the deciduous and the permanent dentitions, but the involvement in each is different. The deciduous teeth resemble the condition known as hereditary opalescent dentin, both clinically and radiographically. However, the permanent teeth appear normal clinically, but dilated pulpal chambers and pulp stones are evident radiographically.

Dentin dysplasia II is a rare developmental defect of dentin and pulp. It is shown by thistle tube-shaped coronal pulp chambers that contain pulp stones. Often, the root canal is threadlike. This paper describes three patients with this defect. The deciduous teeth are brown and translucent; the permanent teeth have normal coloration with significant pulpal and dentin abnormalities.

Dentin dysplasia type I (DD-I) is a rare autosomal dominant disorder which affects both the deciduous and permanent dentitions. The affected deciduous and permanent teeth have short conical roots with sharp, apical constrictions and frequently periapical radiolucencies in the absence of caries. Apical to a thin layer of normal coronal dentin are large, calcified, dentin masses which nearly obliterate the pulp chamber and canals. Presented here are light microscopic and scanning electron microscopic observations of deciduous teeth from three unrelated persons with the disorder. In general, the deciduous teeth had (1) normal enamel, (2) a thin layer of normal dentin adjacent to the dentinoenamel junction, (3) a crescent-shaped pulpal remnant below the normal dentin, (4) dysplastic dentin masses (ranging from atubular to a few small tubules) between which are spaces presumed to previously have contained smaller remnants of the original mesenchymal dental papilla, and (5) root dentin, which is dysplastic throughout. The SEM-defined phenotype, however, was noticeably variable among all three persons. Based on the current concepts of tooth morphogenesis, it is most likely that the abnormal root morphology of DD-I teeth is secondary to the abnormal differentiation and/or function of the ectomesenchymally derived odontoblasts.

The first reported case of endodontic therapy in dentinal dysplasia, Type I, is described. The first histologic diagnosis of periapical granuloma instead of periapical cyst in dentinal dysplasia, Type I, is also reported.

A syndrome of scanty, fine, curled hair, thin dysplastic nails, taurodontic molars, hypoplastic-hypomature enamel, dysplasia of dentin, and hypohidrosis segregating as an autosomal dominant trait is described in a Japanese family. The patients received repeated doses of tetracycline during odontogenesis which fortuitously assisted in interpreting the pathogenesis of the dentin defect. The condition was previously described as familial congenital ectodermal dysplasia by Westerholm and as odontogenesis imperfecta by Siirilä and Heikinheimo. It is suggested that the name trichoonychodental (TOD) syndrome is a better descriptive term for the condition.

Patients with teeth showing all of the clinical, radiographic, and histologic features of radicular dentine dysplasia (type I) have been found to have dense sclerotic bone and skeletal anomalies of the wrists and hand bones. The association of these defects of teeth and bone was found to be transmitted as an autosomal dominant trait over four generations. Review of theliterature failed to disclose a previous description of this disorder.

A young man presented a condition of the teeth in which the pulp cavities were extremely large, with thin dentine walls but normal enamel. The roots were short. The size of the pulp cavities was not due to resorption, but to insufficient and defective dentine formation. The condition is compared with that found in hereditary opalescent dentine.

Metallurgically polished and fractured sections of teeth with dentinal dysplasia were prepared and studied under the scanning electron microscope. The morphologic data obtained suggested that the defect was one of the epithelial root sheath. A hypothetical model for the defect is presented and is supported both by scanning electron microscopy and classic histopathology.

A brief survey of the literature on dentinal dysplasia and calcification of the dentinal papilla is given. It is still debatable whether these two anomalies are variants of a single clinical entity, different stages of a single disease, or two separate pathologic conditions. A case is described and illustrated with roentgenograms. This case has features of both anomalies and, therefore, lends support to the view assuming different degrees of severity of one and the same disease.

This report describes a family with hypophosphatemie rickets that is refractory to the usual vitamin D therapy. This form of rickets is usually transmitted as a sex-linked dominant trait; however, the genetic pattern in the father, son, and daughter reported herein was that of an autosomal dominant. The condition produced hypoplastic defects of the enamel and poorly calcified, dystrophic dentin in addition to the usual retardation in skeletal and facial growth. Dental eruption is usually normal, although skeletal age may be retarded. Radiographic and general chemical findings for each patient are presented.

Dentin dysplasia is an uncommon disturbance of odontogenesis characterized by normal enamel and crown morphology, but with atypical dentin formation, abnormal pulp morphology, and short roots (1, 2). It is reported as an autosomal dominant genetic disease and classified as type I (radicular dentin dysplasia) and type II (coronal dentin dysplasia) (3, 4). Of significant interest to endodontists is the development of periapical radiolucencies, representing granulomas, cysts, or abscesses involving apparently intact teeth. Loosening and premature exfoliation of teeth is also a reported clinical problem. The purpose of this paper is to report the type I condition in three siblings, two of whom developed periapical involvement, who were successfully treated endodontically. Three brothers during dental examinations were discovered to have dentin dysplasia. The boys were Caucasian and had no other discernible medical or skeletal abnormalities. At the time this report was prepared, the oldest boy was 19 (Fig. 1), the second boy 17 (Figs. 2 to 5), and the youngest 15 (Figs. 6 to 8). The 17-yr-old boy had recently completed orthodontic treatment.

Six teeth from five patients with sickle-cell anaemia were investigated by microradiography. The enamel, dentine, and cementum showed pronounced changes. There were diffused hypomineralized zones and accentuation of striae of Retzius in the enamel. Mineralization of the dentine showed disturbances, e.g., there were wide areas of interglobular dentine with scattered globules separated by hypomineralized areas. Unusual inclusions were present in the lumens of the dentinal tubules. The pulpal chamber contained denticle-like calcified bodies. Microradiography revealed that in most instances there was excessive cementum formation.