| Abstract|| |
Dentinogenesis Imperfecta and dentin dysplasia are genetic oral diseases inherited in a simple autosomal dominant mode, with high penetrance and a low mutation rate. Both of them are present with bulbous crowns, marked cervical constrictions, severe attritions, few periapical radiolucencies, and premature tooth loss. The diagnosis is based on family history, and detailed clinical examination, while genetic diagnosis may become useful in the future once sufficient disease-causing mutations have been discovered. Here, we present a case with overlapping features of both dentinogenesis imperfecta and dentin dysplasia asserting both the anomalies to be part of the same continuum of the genetic event.
Keywords: Dentin dysplasia, dentin sialophosphoprotein gene, dentinogenesis imperfecta
|How to cite this article:|
Gulati N, Juneja S, Singh A, Singh I. A histological continuum between dentinogenesis imperfecta and dentin dysplasia: A case report with literature review. Indian J Dent Res 2019;30:643-6
|How to cite this URL:|
Gulati N, Juneja S, Singh A, Singh I. A histological continuum between dentinogenesis imperfecta and dentin dysplasia: A case report with literature review. Indian J Dent Res [serial online] 2019 [cited 2020 Feb 24];30:643-6. Available from: http://www.ijdr.in/text.asp?2019/30/4/643/271055
| Introduction|| |
Developmental disorders affecting dentin are uncommon anomalies occurring due to the genetic defect in structural or regulatory proteins in dentin. They include dentinogenesis imperfecta, dentin dysplasia, regional odontodysplasia, and dentin hypocalcification. Dentinogenesis imperfecta was first recognized by Barret in 1882, which is a hereditary localized mesodermal dysplasia and is observed in the histo-differentiation affecting both the primary and permanent dentition dentin in the nonexistence of any systemic disorder. The term, 'dentinogenesis imperfecta' was coined by Robert and Schour in 1939 and it results in the appearance of opalescent teeth often referred to as Capdepont's Teeth and Tulip Teeth. There are two types of dentinogenesis imperfecta, Type 1 with partial or total precocious obliteration of pulp chamber and root canals with continued dentin formation, and blunt short root and; Type 2 with normal enamel, thin dentin, and large pulp chambers (shell teeth). On the other hand, Dentin Dysplasia as categorized in 1939 has two major patterns i.e. type I (radicular dentin dysplasia) and type II (coronal dentin dysplasia), characterized by normal enamel but atypical dentin formation with abnormal pulpal morphology. Clinically, Dentin Dysplasia Type I are tremendously mobile and show hasty premature exfoliation because of the shortened roots whereas type II exhibits numerous overlapping features with dentinogenesis imperfecta. Since the two diseases have overlapping clinical features, here we present a case of developmental anomaly involving dentin with overlapping features of dentinogenesis imperfecta and type 1 dentin dysplasia.
| Case|| |
A 25-year-old patient reported with a chief complaint of unusually discolored teeth since birth along with missing teeth in lower front tooth region since 2 years. His history revealed chipped teeth in primary dentition. He also gave family history of similar features present in his mother and maternal uncle. There was no associated systemic bone abnormality. The clinical examination revealed multiple missing teeth and deep caries with pulpal involvement in 15, 16, 34, 35, 37, 43 and 44. The generalized color of the teeth present had opalescent brown hue with worn incisal and occlusal facets [Figure 1].
|Figure 1: Intraoral photograph showing the grey to amber colored opalescent teeth, severe attrition and thin buccolingual dimensions of the incisors|
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The radiographic examination revealed that the teeth had marked constriction at the cervical area, thin to absent enamel, obliterated pulp chambers with short, blunt, conical malformed roots. Based on the clinical and radiographic findings, a provisional diagnosis of dentinogenesis imperfecta was made [Figure 2].
|Figure 2: Panoramic radiograph showing complete pulp obliteration of permanent teeth, bulbous crown, and short root with horizontal type of bone loss|
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The lower left permanent second molar was extracted due to periodontally poor prognosis and submitted for histopathological examination. The tooth was sectioned into two halves and observed under stereomicroscope to assess the gross anatomy revealing brown to amber discolored dentin obliterating the pulp cavity along with few areas of sclerotic dentin [Figure 3].
|Figure 3: (a) Gross tooth specimen. (b) Longitudinal section of tooth showing obliterated pulp chamber with discolored dentin. (c) Coronal dentin rimmed by thin enamel. (d) Radicular dentin showing few flecks of sclerotic dentin|
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The ground section of the tooth revealed portion of coronal dentin which was atypical surrounded by few flecks of chipped enamel with prominent crack lines. The dentinoenamel junction was flattened and radicular areas showed whorls of tubular atypical dentin with obliterated pulp chamber due to calcified dentin. Apical to the point of disorganization, calcified tubular dentin and fused denticles, the central portion of the root showed whorls of tubular dentin and atypical osteodentin. These whorls exhibit a peripheral layer of normal dentin, giving the root the appearance of a “lava flowing around boulders” (attempted failure of root formation) [Figure 4].
|Figure 4: (a) Longitudinal ground section of tooth specimen. (b) Coronal portion shows thin enamel with prominent striations and cracks with flat dentinoenamel junction and underlying atypical dentin with branching tubules. (c) Calcified tubular dentin in the central portion of the root showing whorls of tubular dentin, giving the root appearance of a “lava flowing around boulders”. (d) Fused denticles in the centre of the pulp chamber|
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Under polarizing microscopy, birefringence enamel flecks and the lava flowing around boulders appearance of atypical dentin was observed along with focal areas showing hypercementosis with increase in thickness of cellular cementum [Figure 5].
|Figure 5: (a) Hypercementosis seen around atypical dentin. (b) Branching tubules with dead tracts at the cusp tip. (c) Lava flowing around boulders appearance conspicuously seen under polarizing microscope. (d) Fused denticles obliterating the pulp chamber in radicular part of tooth|
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| Discussion|| |
The defective dentinogenesis imperfecta (DI) causing gene has been identified as Dentin Sialophosphoprotein (DSPP) and it has been mapped to chromosome 4q21.3. DSPP-related peptides are the major components of non-collagenous proteins and believed to have a crucial role in converting predentin into mineralized dentin. It initiates hydroxyapatite formation at low concentration and inhibits growth at higher concentration. The gene product is a precursor protein that is cleaved into two dentin-specific proteins, one as Dentin Sialoprotein (DSP) and other as Dentin Phosphoprotein (DPP). Out of eight mutations, seven are associated with DI and the eighth is known to produce dentin dysplasia type II. There is some evidence of a genotype-phenotype correlation, with Malmgren and colleagues showing one DSPP missense mutation being associated with a more severe phenotype in one family than that seen in another affected family with a different DSPP missense mutation. Dean and colleagues, noting the phenotypic similarity of dentinogenesis imperfecta, Shields type II, to that in the primary dentition in dentin dysplasia type II, hypothesized that these conditions may be due to different alleles of the same gene. Although for Type 1 gene mutated is unknown, for Type 2 variety it is documented that DSPP (Dentin Sialophosphoprotein) mutation occurs.
Subsequently, Rajpar and colleagues showed that a DSPP missense mutation was present in a family with dentin dysplasia type II, thereby confirming the hypothesis of Dean and colleagues. Further, the analysis of the DSPP gene in patients with Shields type II dentinogenesis imperfecta or dentin dysplasia type II suggests that these dominant phenotypes result from the disruption of signal peptide processing and/or related biochemical events that interfere with protein processing.,, Causative mutations are distributed rather evenly among missense/nonsense, splicing, and small deletions. This is consistent with the assertion that dentin dysplasia type II and Shields type II dentinogenesis imperfecta are milder and more severe forms, respectively, of the same developmental disease.,
This is consistent with the present case which manifests itself as a generalized disease affecting both the primary and permanent dentition due to the mutation of DSPP resulting in dentinogenesis imperfecta which on histological examination reveals features reliable with dentin dysplasia [Table 1]. Although a lot of other lesions present radiographic and histological features overlapping with a number of disorders such as Ehler Danlos syndrome, Brachioskeletogenital syndrome, Ellis Van Crevald syndrome, osteogenesis imperfect with dentinogenesis imperfect and certain systemic conditions such as tumoral calcinosis. In the present case there was no anchorage, with deranged homeostatic mechanisms of tooth as well as overload of masticatory and other stresses on crowns leading to early exfoliation. The overall treatment for such cases should include endodontic therapies, routine periodontal curettage, and space maintainers at very young age.
|Table 1: Summary of overlapping features observed in Dentinogenesis Imperfecta and Dentin Dysplasia|
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| Conclusion|| |
Thus, Dentinogenesis imperfecta and Dentin Dysplasia represent as manifestation of a common gene mutation involving DSPP and DPP gene and thus they are a part of histological continuum with overlapping clinical and histological features. An early diagnosis and treatment are therefore fundamental, which aim at obtaining a favorable prognosis, since a late intervention makes the treatment more complex.
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Conflicts of interest
There are no conflicts of interest.
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Dr. Nikita Gulati
Department of Oral and Maxillofacial Pathology and Oral Microbiology, ITS Centre for Dental Studies and Research, Muradnagar, Ghaziabad - 201 206, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]