BDS10006 Bone Disease (2) PDF - 2021

BDS10006 Bone disease (2) [congenital disease of bone (osteopetrosis and osteogenesis imperfecta) and osteoporosis] Date : //2021 Aims: The aim of this lecture is to detail the clinical and histopathological features of congenital bone disease and osteoporosis of the maxilla and/or mandible Objectiv...

BDS10006 Bone disease (2) [congenital disease of bone (osteopetrosis and osteogenesis imperfecta) and osteoporosis] Date : //2021 Aims: The aim of this lecture is to detail the clinical and histopathological features of congenital bone disease and osteoporosis of the maxilla and/or mandible Objectives: On completion of this lecture, the student should be able to: Understand the principle clinical and histopathological aspects of osteopetrosis, osteogenesis impefecta and osteoporosis Understand the impact of such disease upon the orofacial hard tissues Hereditary Bone Diseases Affecting any bone type Affecting endochondral bone Achondroplasia Osteogenesis imperfecta Osteopetrosis Cherubism Cleido-cranial dysplasia Osteogenesis imperfecta Is a rare hereditary bone disease characterized by brittle bone that is prone to fracture, it is separated into 8 types with broad range of severity & clinical outcome The disease is caused by mutation in COL1A1 & COL1A2 genes that results in deficiency in type 1 collagen Because collagen forms a major portion of bone, dentin, sclera & ligaments, therefore, a variety of changes involve these sites Osteogenesis imperfecta Type I: The most common and mildest form. Patient has normal life span Clinical features Mild to moderate bone fragility. Hypermobile joints Hearing loss [due to conduction defect in middle & inner ear bones] Osteogenesis imperfecta Type I Clinical features blue sclera (due to its reduced collagen content allowing pigmented choriod to show through) Dental alterations identical to dentinogenesis imperfecta Osteogenesis imperfecta Type II: This is the severest form Clinical features Extreme bone fragility and frequent fractures patients are still born & 90% of patients die before 4 weeks of age. Osteogenesis imperfecta Radiographic features Thinning of the cortex Osteoporosis multiple fractures Normal Osteogenesis imperfecta Radiographic features  Bowing of long bones,  Increased number of Wormian bones in the skull [Wormian bones are small sutural bones arranged in a mosaic pattern] Osteogenesis imperfecta Histopathologic features Thin & widely separated bone trabeculae Osteoclastic activity is normal Normal Osteopetrosis (Marble bone disease) It is a group of rare hereditary skeletal disorders characterized by markedly increased bone density. It results from failure of osteoclastic bone resorption Continuous bone formation & lack of resorption will lead to more dense sclerotic bone (increase bone mass, less vascular) but of poor mechanical properties Osteopetrosis (Marble bone disease) There are three major clinical patterns: 1. Autosomal recessive infantile (“malignant”) type 2. Autosomal recessive intermediate type 3. Autosomal dominant adult (“benign”) type Infantile “malignant ” type Adult “benign” type severe form diagnosed at birth or in early infancy. most common type discovered in adolescence or adulthood Osteopetrosis (Marble bone disease) Clinical manifestations The bones are weak & fracture easily Narrowing of skull foramina causes compression of cranial nerves resulting in blindness, deafness & facial pulsy Narrowing of marrow spaces aplastic anemia & thrombocytopenia accompanied by hepatosplenomegaly due to compensatory hematopoeisis Osteopetrosis (Marble bone disease) Oral manifestations Increased susceptibility to osteomyelitis following extraction due to agronulocytopenia Failure of tooth eruption Ankylosis of erupted teeth Osteopetrosis (Marble bone disease) Radiographic features There is increased skeletal density, with marble like appearance Differential Diagnosis Advanced stage of Paget’s disease Chronic diffuse sclerotic osteomyelitis Osteomyelitis Osteopetrosis (Marble bone disease) Histopathology Absence of bone resorption Numerous osteoclasts may be seen, but no evidence that they function because Howship's lacunae are not visible. Normal bone Cherubism Cherubism is an autosomal dominant hereditary disease characterized by bilateral symmetrical expansion of the jaws The name "cherubism" is applied because the patient’s facial appearance is similar to the plump-cheeked little angels (cherubs). Cherubism Clinical features : Age: 2 to 5 years of age. No sex predilection & males = females The characteristic clinical feature is painless, bilateral symmetrical expansion which involves the posterior mandible This feature typically progress until puberty, then stabilize and may slowly regress.  Any management should be delayed after cessation of skeletal growth.Occasionally, surgical contouring to improve esthetics is required, with no attempts to remove the entire lesion Cherubism Clinical features: Maxilla may be affected; the maxillary involvement usually occurs in the tuberosity areas. The patient shows "eyes upturned” look with exposure of a wide rim of sclera below the iris [due to stretching of upper facial skin that pulls the lower eye lid downwards & ♣ involvement of orbital floor that tilt the eyeballs upward] Cherubism Clinical features : Extensive jaw involvement causes: The developing teeth are displaced and fail to erupt. Tooth mobility Speech difficulties Random alignment of teeth causing severe malocclusion. Cherubism Radiographic features : The lesions are typically bilateral, multilocular radiolucencies Unerupted & displaced teeth Resorption of adjacent tooth roots Cherubism Histopathology Numerous multinucleated giant cells in granulation tissue, showing increased vascularity Differential Diagnosis Cherubism Hyperparathyroidism Central giant cell granuloma Aneurysmal bone cyst Cleidocranial Dysplasia It is a Hereditary rare disease by mutations in the RUNX2 gene (essential for osteoblast differentiation) Characterized by deficient growth of bones especially, cranial vault, maxilla and the clavicles which are usually hypoplastic or entirely absent. It was believed to affect membranous bones only but now known to affect endochondral ossification, as well Cleido cranial Dysplasia Oral Manifestations The maxilla is narrow and V-shaped with high arched palate. Crown may be conical in shape. Some teeth may show gemination. Cleidocranial Dysplasia Oral Manifestations Delayed shedding of deciduous teeth (retained). Delayed eruption of permanent teeth. Presence of unerupted multiple supernumerary teeth. Cleidocranial Dysplasia Oral Manifestations Many teeth may exhibit enamel hypoplasia. Many unerupted teeth have hooked roots. Lack of cellular cementum is usually found. Multiple dentigerous cysts may develop in relation to some of the unerupted teeth. Achondroplasia It is the most common type of genetic skeletal disorder and manifests itself as ‘disproportionate dwarfism’ It is caused by defect in endochondral bone growth, due to mutation in fibroblast growth factor 3 (FGFR3) on chromosome 4, causing a defect in the maturation of chondrocytes Prenatal diagnosis of achondroplasia is usually suspected on routine ultrasound and can be confirmed by molecular testing (FGFR3 mutational testing) Achondroplasia Clinical manifestations Bones of extremities are short and thick. Axial skeleton and organ development are normal. Normal intelligence and are able to lead independent and productive lives Achondroplasia Oral manifestations Delayed dental development leading to delay in the eruption of the primary and permanent teeth [due to altered bone growth] Maxillary hypoplasia and relative mandibular prognathism Class III Malocclusion Osteoporosis  Osteoporosis is a common metabolic bone disease characterized by low bone mass, microarchitectural weakening leading to bone fragility, and increased fracture risk. [which result in increased morbidity and mortality risks]. Osteoporosis WHO defined osteoporosis as a disorder where the bone mineral density (BMD) is 2.5 SD (standard deviation) below the mean peak value in young adults Osteoporosis Primary Most common form Postmenopausal Age related Secondary consequence of systemic disease or pharmacological intervention Diabetes hyperthyroidism, hyperparathyroidism, rheumatoid arthritis osteogenesis imperfecta Osteoporosis  Nowadays the commonly accepted methods for BMC/BMD measurements are dual-photon (DPA) and dual X-ray energy absorptiometry (DXA)  Effect of Osteoporosis in the jaws may present a risk for accentuation of alveolar bone loss after wearing full dentures and in cases of periodontitis Osteoporosis Prevention & Risk factors  Calcium: adequate calcium intake. Calcium needs change during one’s lifetime. The body’s demand for calcium is greater during childhood and adolescence [when the skeleton is growing rapidly], also during pregnancy and breastfeeding and in postmenopausal women and older men [So low estrogen level (menopause), and low testosterone level in men old age can bring on osteoporosis -- low calcium intake induce osteoporosis] Vitamin D: Adequate Vitamin D intake, as it plays an important role in calcium absorption and bone health. [low Vit D intake induce osteoporosis] Osteoporosis Prevention & Risk factors  Exercise: bone is living tissue that responds to exercise by becoming stronger. Weight-bearing and resistance exercises are the best for your bones. [An inactive lifestyle or extended bed rest tends to weaken bones] Smoking: affects bones negatively, as it may cause lower levels of estrogen in women and may affect calcium absorption from diet. Osteoporosis Prevention & Risk factors  Alcohol: Those who drink heavily are more prone to bone loss and fracture [due to poor nutrition and increased risk of falling]  Medications Several medications can contribute to bone loss such as long-term use of glucocorticoids [some anticonvulsants can lead to loss of bone density and fractures] Osteoporosis Histopathologic features  Thin trabeculae disconnected from each other  Increase in osteoclastic activity and surfaces with resorptive pitting Normal Osteoporosis Treatment Bisphosphonate therapy (IV or oral) and denosumab, these medications inhibit osteoclastic function and differentiation and thus reduce bone resorption Key points In osteogenesis imperfecta , brittle bone that is prone to fracture, is mainly due to mutation in COL1A1 & COL1A2 genes that results in deficiency in type 1 collagen. In osteopetrosis, there is continuous bone formation without resorption leading to dense sclerotic but of poor mechanical properties. Cherubism is one of giant cell lesions, which doesn’t require surgical treatment. Osteoporosis is a common disease characterized by bone fragility, and increased fracture risk, however, it is preventable Aims: The aim of this lecture is to detail the clinical and histopathological features of congenital bone disease and osteoporosis of the maxilla and/or mandible Objectives: On completion of this lecture, the student should be able to: Understand the principle clinical and histopathological aspects of osteopetrosis, osteogenesis impefecta and osteoporosis Understand the impact of such disease upon the orofacial hard tissues Reading material: Students are advised to review any relevant teaching provided in the first year. In addition they are advised to read relevant sections of the following texts: Robinson M et al. Soames’ and Southam’s Oral Pathology. 5th edition. Oxford University Press, 2018 Odell E.W. Cawson’s Essentials of Oral Pathology and Oral Medicine. 9th Edition. Elsevier, 2017 Thank you