Osteogenesis Imperfecta

April 23, 2020

  

Osteogenesis Imperfecta (OI) is a condition involving paediatrics, genetics and osteology. As the name suggests, this disease occurs because of the imperfect formation of bone. The condition is more famously known as the brittle bone disease. It was found in an Egyptian mummy from 1000 B.C. and it wasn't until 1788, when research finally began to decode the disease.

How does a person contract Osteogenesis Imperfecta?

OI is a genetic disorder. It is a condition that can be both autosomal dominant and recessive. Collagen, a structural protein, makes up for 90% of the organic bone. In Osteogenesis Imperfecta, the genes responsible for collagen production are mutated. There are various types of collagen in the body, of which Type I is predominantly found in skin, tendons, bone, vasculature and various organs. The defect in collagen synthesis robs the bone of its internal strength. This leads to the formation of brittle bones.

While most of the cases of OI see a defect in Type I collagen, there are cases reported wherein deficiencies of other types of collagen have led to OI.

How is OI diagnosed?

Genetic testing is the primary diagnostic test for OI. A important differential diagnosis of OI is child abuse, where multiple fractures are present. Other differential diagnosis includes deficiency of Vitamin D, osteomalacia and other skeletal syndromes.

What are the signs and symptoms of OI?

Since the collagen itself is deficient, the bones of a victim of OI will be absolutely fragile. Muscle weakness is a common sign and collapse of blood vessels is also seen. The deformity in the structural connective tissues affects the central nervous system in which it is embedded. This leads to neurological complications thereby affecting the life expectancy of an individual. Recurrent abdominal pain, chronic constipation and hearing loss are other commonly seen symptoms in OI. The sclera of the eye develops thinner comparatively due to the dysfunction in Type-I collagen thereby giving it a greyish-blue discoloration.

In the dental world OI due to Type-I collagen defect is of paramount importance. This is because Type-I defect is further classified as IA and IB. Dentinogenesis Imperfecta (DI) , a condition wherein the dentin formation is hampered severely, leads to an opalescent appearance of the teeth. This is a characteristic feature of IB type of collagen defect and is not seen in IA.

How is osteogenesis Imperfecta treated?

Bisphosphonate therapy is more commonly used in patients of OI. This class of drugs acts by increasing bone mineral density. However, a review in 2016 suggested that it is still uncertain if Bisphosphonate can reduce the rate of bone fractures or improve the quality of life of patients with OI.

Surgery often involves insertion of stainless steel metal rods in the intermedullary canals of long bones. Physiotherapy is recommended for improving muscle strength and motility.

How are dental manifestations of OI treated?

Beginning with infants of 6 months of age, DI should be suspected if the child has OI. At this stage, preventive and precautionary measures of maintain proper oral hygiene should be explained to the child's parents. It is often recommended to place sealants on the biting surface of molars in children so that they are at a lesser risk for developing cavities.

At the age of 7 years, an orthodontic intervention can help in rectifying an open bite or any other form of malocclusion. If skeletal discrepancies exist, orthognathic surgery needs to be carried out.

Primary teeth should be more frequently checked for chipping, cracking and abrasion since they are more vulnerable to damage compared to permanent teeth. If teeth are wearing out more excessively, preformed stainless steel crowns are fabricated on primary teeth. Cast metal or ceramic crowns are preferred for adults.

Impacted teeth need to be carefully extracted because of the brittleness in the bones. An orthodontic pull of the impacted teeth is initially recommended in these cases.

Cosmetic procedures like veneers can help in masking the discolored teeth caused due to the improper dentin formation. Prosthodontic and endodontic interventions are done based on the individual health of each tooth.

How do patients of OI spend their life?

Since there is no cure for this condition, patients often resort to living an extremely cautious life wherein they need to make sure they nullify their chances of a traumatic accident. Short height, respiratory distress, malocclusion often add up to their cultural challenges. Complications like dissection of the cervical artery and aortic dissection further negate their quality of living
 

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