Osteogenesis imperfecta


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Oral Pathology

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Osteogenesis imperfecta

  2. 2. OSTEOGENESIS IMPERFECTA  Comprises a heterogeneous group of heritable disorders characterized by impairment of collagen maturation.  It arises due to mutations in one of two genes that guide the formation of type 1 collagen : COL 1 A1 gene on chromosome 17 and COL 1 A2 gene on chromosome 7.  Collagen forms a major portion of bone, dentin,sclerae,ligaments and skin; osteogenesis imperfecta demonstrate a variety of changes that involve these sites.
  3. 3. CLINICAL FEATURES  Extreme fragility and porosity of the bones, with proneness to fracture.  Some affected individuals also have blue sclera , altered teeth , hypoacusis , long bone and spine deformities , and joint hyperextensibility.  Many patients also have a tendency towards capillary bleeding.
  4. 4. Opalescent dentin in patient with osteogenesis imperfecta
  5. 5. CLASSIFICATION  Based on Sillence et al classification, 4 types of osteogenesis imperfecta exist – 1. TYPE 1 Osteogenesis imperfecta 2. TYPE 2 Osteogenesis imperfecta 3. TYPE 3 Osteogenesis imperfecta 4. TYPE 4 Osteogenesis imperfecta
  6. 6. TYPE 1 OSTEOGENESIS IMPERFECTA  Most common and mildest form.  Symptoms include blue sclera , in utero fractures in 10 % of patients , mild to moderate bone fragility with frequency of fractures decreasing after puberty , hearing loss , easy bruising and short stature.  It is an autosomal dominant trait.
  7. 7. TYPE 2 OSTEOGENESIS IMPERFECTA  Most severe form.  Exhibits extreme bone fragility and frequent fractures.  In utero fractures are present in 100% of cases.  Blue sclera may be present , hearing loss is not common.  Small nose, micrognathia and short trunk may be present.  Both autosomal recessive and dominant patterns may occur.
  8. 8. TYPE 3 OSTEOGENESIS IMPERFECTA  Most severe form noted in individuals beyond the prenatal period.  Sclera of variable hue , limb shortening and progressive deformities and pulmonary hypertension.  In utero fractures occur in 50% of cases.  No hearing loss reported in this type.  Both autosomal recessive and dominant patterns may occur.
  9. 9. TYPE 4 OSTEOGENESIS IMPERFECTA  Associated with mild to moderately severe bone fragility.  Symptoms include normal sclera, normal hearing, fractures that begin in infancy and mild angulation and shortening of long bones.  The frequency of fractures decreases with puberty.  This variant is an autosomal dominant trait.
  10. 10. RADIOGRAPHIC FEATURES  The radiographic hallmarks of osteogenesis imperfecta include osteopenia, bowing, angulation or deformity of the long bones, multiple fractures and wormian bones ( sutural bones ) in the skull.  Radiograph typically reveal premature pulpal obliteration , although shell teeth rarely may be seen.
  11. 11. HISTOLOGIC FINDINGS  The bone cortex is thin and porous. The bone trabeculae are thin delicate and widely separated.  Osteoblastic activity appears retarded and imperfect and for this reason the thickness of long bone is deficient.  Failure of woven bone to become transformed to lamellar bone.  Defective microvascular system and decreased collagen fibril diameter have been observed.
  12. 12. Microscopic changes of OI
  13. 13. TREATMENT AND PROGNOSIS  There is no cure for OI, thus symptomatic improvement is the primary goal of currently available treatment options.  The mainstays of treatment are PHYSIOTHERAPY, REHABILITATION and ORTHOPEDIC SURGERY.  The prognosis varies from relatively good to very poor.
  14. 14. OSTEOPOROSIS  Also known as – MARBLE BONE DISEASE , ALBERS-SCHONBERG DISEASE , OSTEOSCLEROSIS FRAGILIS GENERALISATA.  It is a rare hereditary bone disease of heterogeneous pathophysiology in which failure of osteoclastic bone resorption leads to increased bone mass.  A German radiologist, Albers- schonberg, first described osteoporosis in 1904.
  15. 15. ETIOLOGY  The primary underlying defect is failure of the osteoclasts to resorb bone.  Defective osteoclastic bone resorption , combined with continued bone formation and endochondral ossification , results in thickening of cortical bone and sclerosis of the cancellous bone.  Heterogeneous molecular or genetic defects can result in impaired osteoclastic function.
  16. 16. CLINICAL FEATURES  Three distinct forms of the disease are based on age and clinical features – ADULT ONSET, INFANTILE , and INTERMEDIATE.  The infantile and intermediate types have an autosomal recessive mode of transmission, while adult onset type shows autosomal dominant inheritance.  If untreated, infantile type results in death by first decade of life.  Adult onset type are asymptomatic and have good long term survival rates.
  17. 17. INFANTILE OSTEOPOROSIS  Also called MALIGNANT OSTEOPOROSIS.  Diagnosed early in life.  Failure to survive and growth retardation are symptoms.  Bony defects occur  Nasal stuffiness due to mastoid and paranasal sinus malformation is often the presenting feature.  Cranial nerve entrapment neuropathies occur.  Manifestations include deafness, proptosis and hydrocephalus.
  18. 18.  Dentition might be delayed.  Bones are fragile and can fracture easily, osteomyelitis of mandible is common due to deficient blood supply.  Patients might have anemia, easy bruising, bleeding, recurrent infections, hepatospleenomegaly, hypersplenism, hemolysis, sleep apnea and blindness.
  19. 19. ADULT OSTEOPOROSIS  Also called BENIGN OSTEOPOROSIS.  Diagnosed in late adolescence or adulthood.  Approximately one half of the patients are asymptomatic and diagnosis is made incidentally or is based on family history.  Other patients might present with osteomyelitis or fractures.  Many patients have bone pain.  Bones are fragile and might fracture easily.
  20. 20.  Bony defects are common and include cranial nerve entrapment neuropathies and osteoarthritis.  40% of patients have recurrent fractures while osteomyelitis of mandible occur in 10% of patients.  Other manifestations include visual entrapment, hepatospleenomegaly, short stature, large head and nystagmus.
  21. 21. RADIOGRAPHIC FEATURES  Patients usually have generalized osteosclerosis.  The bones might appear club like or show an appearance of a bone within bone.  Vertebrae are extremely radiodense. They may show alternating bands, known as the Rugger – jersy sign.  The entire skull is thickened and dense , especially at the base.  The roots of the teeth often are difficult to visualize because of the density of the
  22. 22. HISTOPATHOLOGIC FEATURTES  Several patterns of abnormal endosteal bone formation have been described.These include the following –  Tortuous lamellar trabeculae replacing the cancellous portion of bone.  Globular amorphous bone deposition in the marrow spaces.  Osteophytic bone formation.  Numerous osteoclasts may be seen, but there is no evidence that they function.
  23. 23. TREATMENT AND PROGNOSIS  Calcitriol appears to help by stimulating dormant osteoclasts and thus stimulating bone resorption.  Erythropoietin can be used to correct anemia.  Corticosteroids have been used with the hope of stimulating bone resorption and treating the anemia.  Treatment with gamma interferon has been shown to produce long term benefits.  No specific medical treatment exists for the adult type.