Bone Disorders Short Notes
Question 1. Ossifying fibroma.
Answer:
Table of Contents
- The ossifying fibroma (OF) is a benign neoplasm that occurs in the adult population (3rd and 4th decades of life). It has a preference for females. Both the maxilla and mandible are affected, but mandibular involvement is common. The occurrence of this tumor in children is called juvenile ossifying fibroma and has aggressive pro¬gression.
- It appears as a single, painless, and slow-growing tumor in the posterior mandible, specifically in the premolar-molar region.
Read And Learn More: Periodontology Important Question And Answers
Ossifying fibroma Histological features:
- The excessive proliferation of periodontal ligaments gives rise to this lesion.
- Both cementum-like calcification and bone materials are present in a single lesion.
Ossifying fibroma Radiographic findings: Ossifying fibroma presents in two patterns:
- Cystic lesions, either unilocular or multi-locular.
- Mixed-density lesions.
- The radiographic boundaries are well- circumscribed and corticated. Cortical plate expansion is present. The lesion is initially radiolucent and appears as mixed radiolucent and radiopaque areas during maturation. The older lesions are radiopaque surrounded by a radiolucent halo.
- Loss of lamina dura, root resorption, and divergence of associated teeth may also be present.
Ossifying fibroma Management: Enucleation treats the small lesions. Larger lesions require radical resection.
Question 2. Cemento-osseous dysplasia
(or)
Florid cemento-osseous dysplasia.
Answer: Cemento-osseous dysplasia is a common form of fibro-osseous lesions. By their clinical and radiographic features, it is divided into three groups: Periapical, focal, and florid cemento-osseous dysplasia.
Periapical Cemento-Osseous Dysplasia (PCOD):
- The term cementoma is often used for this condition. It is an asymptomatic benign lesion occurring in the anterior mandible of patients aged above 30 years.
- It is common in women, and there is a noticeable prevalence for black women. Lesions may be single or multiple. Involved teeth are vital.
Cemento-osseous dysplasia Radiographic Findings:
It shows three different characteristics:
- Osteolytic period, circular and elliptical resorption areas.
- Cementoblastic period or intermediate period, a mixed radiolucent and radiopaque appearance.
- Late periods display massive calcifications.
Focal Cemento-osseous Dysplasia (FCOD):
- It is a benign lesion. May occur in any area of the jaws, but the posterior mandible is the predominant site. They are asymptomatic.
- Radiographically, the lesion appears as completely radiolucent or completely radiopaque or a mixed pattern. Usually solitary and no treatment are required.
Florid Cemento-osseous Dysplasia (FLCOD):
- It is a reactive type of fibro-osseous lesion. The lesion contains multiple radiopaque cementum-like masses and is present at various sites of jaws in all quadrants. The pathogenesis is unclear.
- It is otherwise known as gigantiform cementoma, chronic sclerosing osteomyelitis, and sclerosing osteitis. It occurs in black adult women, aged above 40 years. It may be asymptomatic and observed on radiographs taken for other purposes.
- Radiographic findings: Multiple radiopaque masses surrounded by a radiolucent boundary.
Cemento-osseous dysplasia Treatment: This asymptomatic condition does not require any treatment.
Cemento-osseous dysplasia Clinical Significance: Extraction of the associated teeth will cause delayed wound healing and sequestrum formation.
Question 3. Differentiate fibrous dysplasia and ossi¬fying fibroma.
Answer:
Question 4. Describe the clinical and radiographic features of cherubism.
Answer:
- Cherubism is an autosomal dominant disease characterized by fibrous tissue replacement of the bone tissues in affected bones. The prevalence is more among boys than girls with a ratio of 2:1.
- It frequently involves children aged between 2-7 years. There will be an exacerbation immediately after early manifestation followed by a stable period or complete resolution after puberty.
- The lesion starts as a simultaneous enlargement of the maxilla and mandible on both sides with a characteristic round face, chubby cheeks, and upward-looking eyes (eyes looking towards heaven). These features give the appearance of cherubs.
- The presence of cervical and submandibular lymphadenopathy is the specific early finding.
Cherubism Classification:
- Grade 1—Bilateral involvement of the ascending ramus.
- Grade 2—Bilateral involvement of the ascending ramus and maxillary tuberosity.
- Grade 3—Complete involvement of the maxilla and mandible.
Cherubism Dental Alterations:
- Early exfoliation of deciduous teeth, impaction, and displacement of permanent teeth.
- Ectopic tooth eruption, agenesis of the second and third molars due to involution of their germs.
- Root resorption of existing teeth.
- Malocclusion
Cherubism Radiographic Findings:
- Orthopantomographic findings:
- Multilocular radiolucent lesions involving the posterior regions of the maxilla and mandible, bilaterally.
- Bone changes start as bilateral radio-lucent lesions of the body and ascending ramus. Condylar involvement is rare, but lesions extend up to the coronoid process. Displacement of the mandibular canal is common.
- Teeth appear as floating in radiolucent areas known as floating tooth appearance.
- Computed tomography is useful for treatment planning to locate the extensions of bony involvement.
- MRI is helpful to see the orbital involvement.
Cherubism Management:
- Natural remission by biological stabilization is the preferred choice.
- After regression of disease activity, cosmetic osteoplasty of the affected jaws, and curettage of the lesions may be considered.
- Medical management is provided with calcitonin.
Question 5. Briefly describe rickets and osteomalacia.
Answer:
- Incomplete mineralization of osteoid tissues due to lack of calcium salts manifests as rickets in children (6-24 months of age) and osteomalacia in adults.
- Rickets is a metabolic disorder characterized by the deficiency or impaired metabolism of vitamin D, phosphorus, or calcium.
- In rickets, delayed eruptions, and enamel hypoplasia are the common oral findings. Other notable features include bowed legs, widened epiphyses of long bones, and greenstick fractures in the weight-bearing bones.
- Osteomalacia is caused by poor intestinal absorption of vitamin D. Bone pain, muscle weakness, greenstick fracture, tetany, and a waddling gait are the associated symptoms.
- Cortical thinning and large radiolucency (pseudofractures) are common in long bones, and no radiographic manifestation is seen in the jaws.
Question 6. Describe osteopetrosis
(or)
Marble bone disease.
Answer:
- Osteopetrosis or Albers-Schonberg disease is a condition in which marrow space is filled with compact bone, resulting in extremely dense, hard, and brittle bones. It occurs both in congenital and acquired forms.
- In congenital osteopetrosis, the osteoclasts are defective in either number or function. Multiple bone fractures are common. A neurological symptom like deafness is due to nerve compression at the foramina due to surrounding dense bone. The severe form is fatal, but in mild cases, the child can be expected for an average lifespan.
- The acquired form is associated with increased fluoride deposition in the bone due to excess consumption.
Osteopetrosis Dental Complication: Bone fracture is a complication during extraction.
Osteopetrosis Management:
- Bone marrow transplantation
- Medical management includes gamma interferon and calcitriol.
Question 7: Define alveolar bone.
Answer:
The alveolar process is that part of the maxilla and mandible that forms and supports teeth. Although it is a part of the maxilla and mandible, it is considered separately because of its distinct structural, functional, and developmental characteristics.
Question 8: Write a note on the development of alveolar bone.
Answer:
Alveolar bone is derived from the dental follicle proper and is a product of the first arch epithelium that appears around the second week of intrauterine life.
- After the initial development, further growth is governed by the surrounding ectomesenchymal tissue around the early tooth germ.
- The alveolar bone is of ectomesenchyme origin, while the basal bone and bone in other parts of the body are of ectodermal origin.
Question 9: Describe the gross anatomy of the alveolar bone.
Answer:
Alveolar bone is subdivided into alveolar bone proper and supporting alveolar bone depending on their anatomical location and function concerning teeth.
Alveolar Bone Proper/Cribriform Plate/Lamina Dura
- Alveolar bone proper refers to the thin lamella of bone that surrounds the root of the tooth and provides attachment to the principal fibers of the periodontal ligament.
- The inner surface of the alveolar bone proper is known as the bundle bone because of the abundance of periodontal ligament Sharpey’s fibers that are inserted into the bone.
- Sharpey’s fibers have been classified based on their distribution into arborized, continuous, severed, and adhesive.
Supporting Alveolar Bone
Supporting alveolar bone is the bone that surrounds the alveolar bone proper and gives support to the socket. It is a spongy or trabecular bone that fills the space between cortical plates and the alveolar bone properly. It comprises the cortical plates and spongy (cancellous bone).
Cortical Plates
The cortical plates tend to be thicker in the lingual/palatal surfaces when compared to the buccal surfaces. On the buccal surfaces, the cortical plates are thinner in the maxilla than in the mandible. The thickest plate in the mandible is in the region of the molars.
- Conversely, palatal plates in the molar region of the maxilla are thicker than in the mandible. In both the maxillary and mandibular anterior areas, the supporting bony plates are thin and sometimes there is no spongy bone.
- This is especially true in cases where the teeth are too far labially or lingually placed. Hence, the structural anatomy depends to some extent on the position of teeth in the arch.
Macrostructure
The bone contour normally conforms to the prominence of the roots. The labial and lingual cortical plates are positioned apical to the interdental septum.
- The bone margins are thinned to a knife edge. The height and thickness of the facial and lingual bony plates are affected by the alignment of the teeth, angulation of the roots to the bone, and occlusal forces.
- The thinner labial plate is comprised of bundle bone vulnerable to both resorption and iatrogenic damage and is thus frequently lost following traumatic extraction, and restorative procedures.
Alveolar Crest/Interdental Septum
The alveolar crest is the junction where the buccal/lingual cortical plate and alveolar bone proper meet. The shape and outline of the alveolar crest depend on the position of teeth and the presence or absence of disease.
- The mesiodistal angulation of the crest of the interdental septum usually parallels a line drawn between the cementoenamel junction of the approximating teeth. In health, the alveolar crest extends to approximately 1.5–2 mm from the cementoenamel junction.
- The alveolar crest has a scalloped appearance buccally and lingually and is more pointed in anterior teeth than in posterior teeth where they are flattened.
- As in the case of cortical plates, the location and shape of the alveolar crest also depend on the presence or absence of disease and the position of teeth in the arches.
- In health, therefore, the alveolar bone is described as exhibiting a positive architecture with the
interdental bone placed at a more coronal level when compared to the labial or lingual bone.
Question 10: What are dehiscences and fenestrations?
Answer:
Local areas with facial or lingual bone missing over the roots of the teeth result in a defect termed, a dehiscence. When there is a marginal ring of labial or lingual bone but some root surface that is not covered by bone, this is termed a fenestration (window).
- These usually occur as a result of tooth malalignment. Dehiscence and fenestration defects account for roughly 20% of anatomic defects in the alveolar process.
Clinical Implications
- The presence of these defects tends to complicate therapy when root coverage procedures are attempted.
- They also influence the pattern of bone loss observed in periodontal disease.
Question 11: Describe in detail the histology of the alveolar bone.
Answer:
Microstructure
Cortical plates consist of longitudinal lamellae (layers of thin plates) and Haversian systems. Maxillary buccal cortical plates are perforated by small vascular openings.
- The structural unit of cortical bone is osteons which are longitudinally oriented cylindrical structures built around blood vessels.
- Although the clinical significance is not clear, the alveolar process spongiosa (cancellous bone) is classified into two main types depending on its appearance on radiographs.
Type 1
The interdental and inter radicular trabeculae are regular and horizontal in a ladder-like arrangement
Type 2
The trabeculae are numerous, irregularly arranged, delicate interdental, and interradicular trabeculae (usually in the maxilla).
- The cancellous bone predominates in the interradicular and interdental spaces and is limited to the facial and lingual aspects.
- In the case of buccal and lingual cortical plates, they are covered by periosteum which is rich in collagen and osteoblast/osteoblast precursors. The internal surface of the alveolar process is covered by the endosteum.
Alveolar Bone Proper
The bone comprising the tooth socket is referred to as the alveolar bone proper. It is perforated by openings that carry branches of the interalveolar nerves and bleed vessels into the periodontal ligament.
- More perforations are present in the cervical region than in the middle and apical thirds, and there are a greater number of perforations for the posterior than for the anterior teeth. The alveolar bone proper is therefore also called
cribriform plate. - Histologically, alveolar bone proper consists of lamellated and partly of bundle bone. Bundle bone is that bone in which the principal fibers of the periodontal ligament are anchored (so-called because the bundles of principal collagen fibers insert into the bone as Sharpey’s fibers).
- Bundle bone is characterized by scarcity of intrinsic matrix. On X-ray films, the alveolar bone proper appears as a continuous radiopaque line called the lamina dura. The periodontal surface of the alveolar bone proper is not covered by the periosteum and may be considered as an endosteal surface.
- The alveolar bone proper is covered by a thin layer of osteoid and osteoblasts in various stages of matrix synthesis are seen lining the alveolar bone proper. When teeth are too far labially placed, as is sometimes the case in the mandibular anterior, the labial cortical plate and alveolar bone proper are the same without any trabecular bone in between.
- In newborns, all bone cavities are occupied by red bone marrow. In adults, red bone marrow is found in the maxillary tuberosity, the maxillary and mandibular molar, and premolar areas.
Clinical Implications
The lower marrow content means that intraoral sites are not a great source of osteoprogenitor cells, which is one of the reasons for the sometimes suboptimal performance of autografts.
Question 12: What is osteogenesis?
Answer:
Osteogenesis is the process by which bone formation occurs. There are two main processes:
-
- Endochondral and
- Intramembranous/membranous ossifiation.
- Endochondral ossification occurs by the invasion of the osteoblast into a cartilaginous template.
- Intramembranous ossification occurs by direct differentiation of mesenchymal cells into osteoblast, which in turn lays down the bone matrix. Intramembranous ossification occurs in the bones of the face.
Question 13: What are the cells of bone and their functions?
Answer:
- To keep up with the functional demands, the alveolar bone proper has to undergo constant remodeling. This is achieved by continuous cellular activity in the alveolar bone.
- The cells of the bone consist of (1) preosteoblasts, (2) osteoblasts, (3) osteocytes, (4) osteoclasts, and (5) bone-lining cells.
- Osteogenic cells arise from primitive mesenchymal cells contained in the stroma of bone marrow and from pericytes adjacent to small blood vessels in the connective tissue.
Preosteoblasts
Periosteal and connective tissue preosteoblast have a morphologic appearance of an inactive fibroblast, containing many free ribosomes, a few rough endoplasmic reticulum, and a small Golgi complex.
- They appear as long, thin cells. These are stem cell populations to generate osteoblasts. During differentiation, preosteoblasts make contact with adjacent preosteoblasts or with previously
differentiated osteoblasts, develop cytoplasmic polarity, and greatly increase the amount of rough
endoplasmic reticulum and Golgi cisternae.
Osteoblasts
These are seen lining the alveolar bone proper and are technically considered cells of the periodontal ligament. Their function is to manufacture osteoid.
- When these cells are active they have an intensely basophilic cytoplasm and are highly positive for alkaline phosphatase.
- At the electron microscopic level, they have all the characteristics of synthetic cells such as rough endoplasmic reticulum.
Osteocytes
Osteoblasts that are incorporated in newly formed bone are osteocytes. They reside in bone lacunae and are connected by channels that are called canaliculi.
- The canaliculi bring oxygen and nutrients to the osteocytes via blood vessels and remove metabolic waste products blood vessels incorporated into growing bone become surrounded by concentric lamellae of bone called theosteons. The vascular channels are called Haversian canals. They have a mechanosensory function.
Osteoclasts
These multinucleated cells are found in areas of bone resorption. They are located in bay-like depressions in the bone called Howship’s lacunae.
- They have prominent mitochondria, lysosomes, vacuoles, and little rough endoplasmic reticulum.
- The part of the cell in contact with bone shows a convoluted surface, and ruffle border if a site is active. It has been suggested that osteoclasts are formed from monocytes.
Bone Lining Cells
They extend flt cytoplasmic sheets over the bone surface. 80% of the total bone surface is covered by bone lining cells. They act as gatekeepers, protecting the bone surface from osteoclasts, regulating the ionic composition of bone flids, and regulating the initiation of new bone formation and bone resorption.
Clinical Implication
- The need for constant remodeling is very high in the alveolar bone as it is constantly exposed to masticatory load.
- This remodeling necessitates a high cellular activity that allows new bone to be resorbed and formed at a pace that equals functional demand.
- It is also made possible because the cells have an osteoblast-osteoclast coupling mechanism whereby both the cell types are dependent on each other for their survival and differentiation.
Question 8:Write the composition of bone.
Answer:
- Bone matrix consists of:
- 65% inorganic material usually in the form of hydroxyapatite
- 35% organic material.
- The inorganic matter is composed of calcium, phosphates, carbonate, citrate, and traces of ions such as sodium, magnesium, and fluoride.
- The organic components of the bone matrix are:
- Mostly type I collagen along with
- Glycoproteins (osteocalcin osteonectin, bone morphogenetic proteins)
- Proteoglycans (decorin, biglycan)
- Other proteins.
- Among the other proteins, the bone morphogenetic proteins (BMPs) are considered part of the bone matrix. These BMPs have been shown to retain a strong potential to induce bone formation.
Clinical Implications
The inorganic including the hydroxyapatite crystals give density to the bone while the organic content is important for the regulation of bone cell activity.
- During formation, the osteoid, the organic matrix is formed first and then the process of mineralization occurs. During resorption, however, the process is reversed, that is demineralization occurs first and then the organic matrix is formed.
- Following regenerative therapy, the new bone formed is hence, woven bone that is incompletely mineralized. It is therefore not ideally suited for load-bearing areas like implant-supported restorations.
Question 14: What is bone remodeling and its implication to periodontal disease?
Answer:
Bone is in a constant state of flux with restructuring taking place on a physiologic basis as old bone is replaced by new bone.
- When lamellae reach a certain thickness they are replaced by Haversian systems to fulfill nutritional demands. Osteoclasts cause resorption and then stop activity.
- New bone synthesized by osteoblasts then replaces the lost/resorbed bone. At the junction of old and new bone, a dark cementing line, a reversal line can be noted.
- When bone is laid down there are periods of activity followed by periods of inactivity. These periods of inactivity also show up in bone as resting lines.
Remodeling of Bone
The remodeling process helps the bone to respond to mechanical stress, repair wounds, and maintain calcium and phosphate homeostasis. Bone remodeling may be decreased with aging since the cellular composition changes with aging.
- The parathyroid gland is an important regulator of remodeling. A reduction of calcium levels results in the secretion of parathyroid hormone which stimulates osteoblasts. The osteoblasts in turn release interleukin 1 and 6 which stimulate the migration of monocytes to the site of resorption.
- The osteoblasts also secrete the receptor activator of nuclear factor κ B ligand (RANKL) which binds to the receptor activator of nuclear factor κ B receptor (RANK) on preosteoclasts (monocytes), resulting in the formation of multinucleated osteoclast.
- These osteoclasts bind to bone, develop ruffle borders, and secrete hydrolytic enzymes that digest the organic portion of the bone. To dissolve the mineral component an acid environment is created by the proton pump. This process results in an eroded bone surface called the Howships’s lacunae.
- The breakdown of the bone matrix releases various osteogenic substances such as bone morphogenetic proteins which are bound to collagen and this in turn stimulates the differentiation of osteoblasts. The interdependency of osteoblasts and osteoclasts in remodeling is called osteoblast-osteoclast coupling.
Clinical Implications
As mechanical load is necessary for bone remodeling, splinting of mobile teeth should be done using a semi-ridged splint.
- The absence of mechanical stress results in a decrease in bone density. Bone responds to pressure by resorption and to tension by bone apposition.
- When heavy forces are placed on the teeth, bone generally responds by increasing the number of trabeculae in the spongiosa.
- These trabeculae are arranged perpendicularly to the vector of force. Buccal and lingual cortical plates may become thickened and overgrowth of bone, termed exostosis, may occur. This ability of bone to respond to mechanical stress is used to move teeth in orthodontics.
Question 15: Write a note on the blood and nerve supply.
Answer:
- Blood supply is from the branches of the alveolar artery, periosteal vessels, and alveolar vessels via the interdental septum
- The nerve supply is from the second and third branches of the trigeminal nerve.
Clinical Implication
Autogenous grafts are to be harvested from the mandible, either from the symphysis or ramus areas with complete awareness of the critical nerve/blood vessel supply as iatrogenic damage may result in paresthesia and profuse hemorrhage.
Bone Disorders Essay Questions
Question 1. List the bony disorders with oral manifestations and add brief notes about Paget’s disease.
Answer:
Bone Disorders Classification :
- Developmental diseases:
- Cherubism
- Osteopetrosis
- Osteogenesis imperfecta
- Cleidocranial dysplasia
- Endocrinal diseases:
- Hyperparathyroidism
- Hyperpituitarism
- Idiopathic diseases:
- Idiopathic osteosclerosis
- Langerhans cell disease (Histiocytosis-X)
- Paget’s disease
- Reactive diseases:
- Aneurysmal bone cyst
- Simple or traumatic bone cyst
- Fibro-osseous lesions:
- Fibrous dysplasia
- Cemento-osseous dysplasia
- Ossifying fibroma
- Inflammatory diseases:
- Tuberculosis
- Actinomycosis
- Osteomyelitis
- Neoplastic diseases
- Benign: Osteoma, osteoid osteoma, osteoblastoma, chondroma.
- Malignant: Osteosarcoma—Ewing’s sar-coma—chondrosarcoma.
- Metabolic disorders:
- Osteoporosis
- Osteopetrosis
- Osteomalacia and rickets.
- Paget’s disease is a chronic bone disease characterized by abnormal bone resorption and bone deposition, affecting either single (monostotic) or multiple bones (polyostotic).
- The etiology is associated with viral infection and inclusion bodies resembling nucleocapsid particles of paramyxovirus, and canine distemper virus are demonstrated in the bone cells of patients.
- In the initial course, the patient will be asymptomatic, and in later stages, pain, facial disfigurement, and fracture of the affected bone may occur. Nerve compression causes neurological symptoms like hearing loss.
Bone Disorders Pathogenesis:
Phase 1: Severe osteolytic process:
- Aggressive bone resorption.
- Bone turnover takes place at the rate of 20 times of the average rate.
Phase 2: Mixed osteolytic and osteoblastic phase:
- Immature bone formation.
- Poor mineralization.
Phase 3: Active osteoblastic activity:
- More amount of sclerotic bone formation in a disorganized pattern.
- The bone has reduced strength compared with the normal bone.
Bone Disorders Radiographic Findings:
- Phase 1: Radiolucent resorptive stage
- Phase 2: Granular or ground glass
- Phase 3: More opaque late stage.
Bone Disorders Management: Calcitonin, bisphosphonate, and mithramycin.
Question 2. Define fibrous dysplasia. Describe the pathogenesis and clinical and radiographic findings with a note on management.
Answer:
- Fibrous dysplasia is a developmental disorder characterized by atypical fibrous tissue that contains small, abnormally arranged bone trabeculae that replace normal bone cells.
- Craniofacial bone is involved in both monostotic and polyostotic forms and typically affects the maxilla, mandible, and rarely the calvarium.
Fibrous dysplasia Etiology: The etiology of fibrous dysplasia is unknown. The proposed causative factors are linked to a gene mutation where arginine is replaced either by serine or histidine. World Health Organization grouped this as a developmental disorder.
Fibrous dysplasia Classifications:
- Monostotic fibrous dysplasia
- Polyostotic fibrous dysplasia:
- Jaffe’s type
- McCune-Albright syndrome
- Craniofacial form.
Fibrous dysplasia Clinical Features:
- Monostotic fibrous dysplasia:
- This form is characterized by single-bone involvement and comprises about 70-80% of the reported cases. The involvement of maxilla or facial bones gave rise to a lion-like face to the affected persons and was referred to as leontiasis ossia.
- The etiopathogenesis is related to abnormal activity in the bone-forming mesenchymal tissue. The congenital form is an autosomal recessive pattern.
- The incidence of maxillary lesions is more than the mandibular involvement. Jaw lesions frequently present as painless, hard swelling with intact overlying mucosa that causes bone expansion. Malocclusion and displacement of teeth take place when the lesion enlarges.
- Polyostotic fibrous dysplasia: Polyostotic form affects more than one bone. Genetic mutation is stated as etiology.
Fibrous dysplasia Clinical Features:
- Jaffe’s type—Affects a variable number of bones. Skin pigmentation, known as cafe-au-lait spots which are light brown is a notable feature of this form. It is mild and nonprogressive.
- Albright’s syndrome—McCune-Albright syndrome is an association of polyostotic fibrous dysplasia, precocious puberty, cafe-au-lait spots, and other endocrinopathies.
Fibrous dysplasia Oral Findings: Jaw expansion and delayed eruption are common findings. The associated endocrine disorder is responsible for late eruption.
Fibrous dysplasia Radiographic Findings:
- Conventional radiographic findings:
- Pseudotype: Orange or ground-glass appearance: Grainy appearance of density and radiolucency on radiographs resemble the outer peel of an orange.
- Whorled plaque: The core lesion presents radiographically as a radiodense structure intermediate between the bone and soft tissue densities. The amorphous lesion resembles an onion peel appearance or a whorled pattern.
- Diffuse sclerotic type: The lesion is uniformly radiodense and the boundaries of the lesion are merged with the normal bone.
- Cyst-like: In the early stage, the lesion is poorly mineralized and presents as an osteolytic cyst-like pattern with peripheral lamellar sclerosis giving a ground-glass appearance.
- Pagetoid type: The bony lesion is expansile with alternate radiopaque and radiolucent patterns similar to the picture of Paget’s disease. The expanded lower border of the mandible demonstrates the characteristic thumbprint appearance.
- Chalky type: The core lesion is an irregular radiodense mass with well-defined margins. This type occurs rarely.
Computed Tomography Findings: Computed tomography (CT) accurately establishes the diagnosis and extent of bone involvement. CT characteristics of fibrous dysplasia include bone expansion with three variable patterns of densities associated with scattered islands of bone formation.
- Egg-shell pattern: Cyst-like core lesion with peripheral radiodense onion-peel pattern referred to as egg-shell lesion.
- Ground-glass pattern: In the intermediate stage, mineralization of woven bone takes place and appears as an expanded lesion with the ground-glass pattern.
- Pagetoid pattern: In the later stage, the amount of osseous tissue increases and leads to multiple attenuations of the X-ray beam, giving rise to the heterogeneous pagetoid pattern.
Fibrous dysplasia Laboratory Findings:
- Serum calcium, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dishy- hydroxyvitamin D levels are normal.
- Serum alkaline phosphatase (ALP) is occasionally elevated.
Fibrous dysplasia Management: Treatment of fibrous dysplasia is based on their clinical presentation:
- Monostotic fibrous dysplasia tends to stabilize when skeletal growth stops. Hence surgical intervention should be delayed until growth spurts are completed.
- For symptomatic fibrous dysplasia, bisphosphonate therapy is attempted.
Question 3. Describe the classic features of Langerhans cell histiocytosis in jaw bones.
Answer:
- Abnormal proliferation of Langerhans cell or their precursor cells causes Langerhans cell histiocytosis and 10% of all affected individuals manifest oral lesions.
- Three forms exist, and all demonstrate the proliferation of reticuloendothelial cells.
Eosinophilic Granuloma:
- It appears in the skeleton either as unifocal or as a multifocal lesion.
- The unifocal type is the common form and has a preference for males. The associated symptoms are recurrent bone pain, swelling, and occasional pathologic fractures.
- Oral findings include swelling, ulcers, gingival necrosis, alveolar bone destruction, mobility, and loss of teeth.
Langerhans cell Radiographic Findings: Well-defined lesions with a punched-out periphery.
Langerhans cell Treatment:
- Surgical curettage is the treatment for oral lesions.
- Radiotherapy and chemotherapy should be considered for lesions that are not surgically manageable.
Langerhans cell Letterer-Siwe Disease:
- It is highly morbid and mortal. Involvement of the oral cavity is infrequent. Necrosis and ulceration of gingiva covered by grayish-white purulent exudates is the common finding.
- Both the maxilla and mandible are affected with the radiographic presentation of multiple radiolucent lesions. Corticosteroids and chemotherapy are the possible treatment options. The prognosis is poor.
Langerhans cell Hand-Schuller-Christian Disease:
- The classical triad of this disease is exophthalmos, diabetes insipidus, and lytic lesions in the calvarium. The skull is the common site of involvement.
- It primarily affects infants, children and adults are rarely affected. Facial bone involvement manifests facial asymmetry due to soft tissue swelling, pain, and otitis media. Oral manifestations include sore mouth, halitosis, gingivitis, unpleasant taste, and loose teeth. Oral findings are the earliest signs of this disease. Complication includes failure of healing in the extracted sockets.
- Radiographic examination reveals sharply outlined individual lesions. The large serpiginous, punched-out skull lesions give the name geographic skull.
- There is a scooped-out pattern of bone loss in the posterior mandibular alveolus starting at the mid-root region. Extensive alveolar involvement causes the teeth to appear as floating in the air.
Langerhans cell Treatment: Surgical curettage or excision corrects the localized oral lesions. Intralesional injection of corticosteroids or a low-dose regimen of systemic oral corticosteroids can also be used. Radiotherapy is an alternative treatment for localized bone lesions.
Bone Disorders Multiple Choice Questions
Question 1. Enamel hypoplasia and loss of skull sutures are the findings.
- Paget’s disease
- Osteopetrosis
- Rickets
- Cherubism
Answer: 3. Rickets
Question 2. In the jaw bones, osteoporosis is more common.
- Anterior maxilla
- Anterior mandible
- Alveolar process
- interdental crest
Answer: 3. Alveolar process
Question 3. The biochemical values in rickets is characterized by lower plasma values of calcium and phosphorus.
- High plasma calcium and low phosphorus
- High plasma phosphorus and low calcium
- Lower plasma values of calcium and phos¬phorus
- Higher plasma values of calcium and phos¬phorus
Answer: 3. Lower plasma values of calcium and phos¬phorus
Question 4. A normal level of plasma alkaline phosphatase is seen in osteoporosis.
- Primary hyperparathyroidism
- Osteomalacia
- Osteoporosis
- Paget’s disease
Answer: 3. Osteoporosis
Question 5. Periapical resorption and hypercementosis are the radiographic features of Paget’s disease.
- Paget’s disease
- Hyperparathyroidism
- Rickets
- Osteopetrosis
Answer: 1. Paget’s disease
Question 6. In cherubism, jaw changes occur in the age of.
- 5-10 months
- 1-3 years
- 2-7 years
- 13-19 years
Answer: 3. 2-7 years
Question 7. Upward tilting of the eyes is a feature of.
- Fibrous dysplasia
- Cherubism
- Ossifying fibroma
- Hand-Schuller-Christian disease
Answer: 2. Cherubism
Question 8. The first radiographic sign of cherubism is seen in the.
- Symphysis region
- Premaxilla
- Alveolar bone
- Angle of mandible
Answer: 4. Angle of mandible
Question 9. The common site for ossifying fibroma is.
- Maxillary canine region
- Maxillary premolar-molar region
- Mandibular premolar-molar region
- Ramus of mandible
Answer: 3. Mandibular premolar-molar region
Question 10. Destruction of alveolar bone with localized periodontitis and sterile pus discharge is characteristic of eosinophilic granuloma.
- Fibrous dysplasia
- Florid cemento-osseous dysplasia
- Eosinophilic granuloma
- Metastatic jaw tumor
- Answer: 3. Eosinophilic granuloma
Bone Disorders Viva Voce
Question 1. What are the oral manifestations of hypothyroidism?
Answer: In children, delayed eruption and slow exfoliation of primary teeth are common. In adults no dental abnormalities are present.
Question 2. Discuss oral findings associated with hypophosphatemia.
Answer:
- Teeth may have a large pulp cavity.
- A periapical abscess is common.
Question 3. What are the features of osteopetrosis?
Answer: Due to defective osteoclast activity, normal bone resorption does not happen, leading to increased bone density. Delayed eruption and multiple unerupted teeth are common.
Osteopetrosis Radiologic features:
- High-dense appearance of jaw bones
- In jaw bones, the increased density makes it difficult to differentiate teeth and bone.
- High bone density hinders normal eruption.
- Reduced vascular supply may lead to osteomyelitis and pathological fractures.
Question 4. How to measure the bone marrow den¬sity?
Answer:
- Dual-energy X-ray absorptiometry (DEXA)— Measures the bone mineral content in grams per square centimeter.
- Quantitative computed tomography— Assess the right volumetric density by a separate estimation of trabecular and cortical density.
- Quantitative ultrasound.
Bone Disorders Highlights
- Bone is a mineralized connective tissue composed primarily (up to 60%) of calcium carbonate and calcium phosphate. The organic components (comprise 40%) are protein (collagen) and water. The bone forms a skeleton to support the visceral organs.
- It also provides an attachment site for muscles and aids in their movement. Approximately, 90% of the body’s calcium and 80% of phosphorus are stored in bones.
- The bone strength is determined by a bone mineral density that measures the weight of the mineral per unit volume of bone. This chapter highlights the bony disorders with characteristic oral lesions.
Leave a Reply