Etiology
• Dentinogenesis imperfecta can be found either isolated, characterized as type II, or as type I simultaneously with other features of osteogenesis imperfecta, a group of genetic collagen disorders characterized by anomaliesin bones, joints, eyes and teeth.
• The gene responsible for type II has been found on the 4q chromosome, whereas in type I (osteogenesis imperfecta), mutant genes have been found in chromosomes 7q and 17q.
Occurrence in children
• Type I, one per 2500–5000 (osteogenesis imperfecta).
• Type II, one per 8000.
Localization
• All teeth, primary and permanent.
Clinical features
• Striking amber translucent and discolored teeth (Fig. 1.42).
• Enamel suffering from non-accidental fractures, resulting not only from dentine defect, but also from the presence of defect in the enamel–dentine junction.
• Fragile roots and loose teeth.
• Gradual attrition or non-accidental fractures of the entire crown (Figs. 1.43, 1.44), resulting in decreased occlusal height.
• Type I may present a wide range of clinical features in the same patient, varying from easily detectable defects in all teeth, primary and permanent, to only mild pigmentation of few teeth.
• Type II shows greater uniformity, with more severe clinical features.
Radiological features
• Characteristic short roots.
• Obliteration of pulp chambers and root canals (Fig. 1.45).
• Reduced cervical diameter and radiographic contrast of dentine.
• Frequent periapical radiolucencies.
Complications
• Occlusal distortion, fragile teeth, abscesses.
Treatment
• Prosthetic rehabilitation, overdentures.
Fig. 1.42 Isolated dentinogenesis imperfecta of the primary and permanent teeth (type II)
Fig. 1.43 Dentinogenesis imperfecta (type I) of the primary teeth, revealing severe attrition in a patient with osteogenesis imperfecta type I
Fig. 1.44 Dentinogenesis imperfecta (type I) of the primary teeth, revealing less severe attrition in a patient with osteogenesis imperfecta type I (the brother of the patient in Fig. 1.43)
Fig. 1.45 Radiological features of primary and permanent molars in dentinogenesis imperfecta (type I) in a patient with osteogenesis imperfecta type I
Dentine Dysplasia
Definition
• Dentine dysplasia is usually divided into two distinct types: type I, or radicular dysplasia, and type II, or coronal dysplasia.
Etiology
• The defect results from epithelial invagination of the dental organ cells into the dental papilla, producing ectopic formation of dentine.
• The condition is transmitted an as autosomal dominant trait.
Occurrence in children
• One per 100 000.
Localization
• In both types, all teeth, primary and permanent.
Clinical features
• Type I, teeth with normal crowns of regular or slightly amber translucency. Tendency toward complete obliteration of pulp cavities. Abnormal spaces between the teeth, malalignment, malposition, and severe mobility as a result of poor root formation (Fig. 1.46).
• Type II, semi-transparent opalescent primary teeth, similar to those in dentinogenesis imperfecta, and normal clinical appearance in the permanent teeth. Incomplete obliteration of pulp cavities, particularly in the primary teeth, and frequently pulp stones (Fig. 1.47).
Radiological features
Type I
• Extremely short roots.
• Obliterated pulp chambers and root canals before eruption.
• Frequently periapical radiolucencies around the defective roots.
Type II
• Complete obliteration of pulp chambers and root canals after eruption.
• Frequently, pulp stones.
• Absence of periapical radiolucencies.
Complications
• Occlusal distortion, abscesses.
Treatment
• Prosthetic rehabilitation, overdentures.
Dentine Defects Associated with Genetic Disorders or Syndromes
Definition
• Some genetic disorders or syndromes may be associated, with variable incidences, with dentine defects. In these cases, the defect is not termed "dentinogenesis imperfecta."
Genetic disorders, syndromes
• Hypophosphatasia
• Osteogenesis imperfecta types I, III, IV (dentinogenesis imperfecta type I)
• Unger–Trott syndrome
• Vitamin D–resistant rickets
• De Toni–Debré–Fanconi syndrome
• Albright hereditary osteodystrophy (pseudohypoparathyroidism)
• Mucopolysaccharidosis III (Sanfilippo syndrome)
• Tumoral calcinosis
• Ehlers–Danlos syndrome
• Epidermal nevus syndrome
• Brachioskeletogenital (BSG)syndrome
• Dentine–osseous dysplasia
Fig. 1.46 Radiological features of radicular dentine dysplasia (type I)