Epithelial cysts

    Developmental odontogenic cysts
        Odontogenic keratocyst
        Dentigerous cyst (follicular cyst)
        Eruption cyst
        Lateral periodontal cyst
        Gingival cyst of adults
        Glandular odontogenic cyst (sialo-odontogenic)
        
        
    Inflammatory odontogenic cysts

        Radicular cyst (apical and lateral)
        Residual cyst
        Paradental cyst
        
    Non-odontogenic cysts

        Nasopalatine cyst
        Nasolabial cyst
    
Non-epithelial cysts (not true cysts)

    Solitary bone cyst
    Aneurysmal bone cyst

Acute suppurative osteomyelitis

• Serious sequela of periapical infection.
• Leads to spread of pus through the medullary cavities of bone.
• Depending upon the main site of involvement of bone, can be of two types-

1. Acute intramedullary
2. Acute subperiosteal

Acute Intramedullary Osteomyelitis

CLINICAL FEATURES:

• Patient experiences dull , continuous pain , indurated swelling forms over the affected region of jaw involving the cheek , febrile.
• When mandible involved, loss of sensation occurs on lower lip on affected side due to involvement of inferior alveolar nerve.
• Teeth become loose later along with tender on percussion
• Pus discharge , trismus , foul smell , regional lymphadenopathy , weakness

RADIOGRAPHIC FEATURES

• Earliest radiographic change is that trabeculae in involved area are thin, of poor density & slightly blurred.
• Subsequently multiple radiolucencies appear which become apparent on radiograph.
• In some cases there is saucer shaped area of destruction with irregular margins.
• Loss of continuity of lamina dura, seen in more than one tooth.

HISTOLOGIC FEATURES:

• Dense infiltration of marrow by polymorphonuclear leukocytes.
• Bone trabeculae in involved site (sequestrum) are devoid of cells in the lacunae.
• separation of considerable portions of devitalized bone.

Acute Subperiosteal Osteomyelitis

CLINICAL FEATURES

• Pain , febrile condition , i/o and e/o swelling , parasthesia
• Bone involvement limited to localized areas of cortex.
• Pus ruptures rapidly through the overlying cortex, tracks along the surface of mandible under the periosteal sheath.
• Elevation of periosteum from cortex is followed eventually by minute cortical sequestration.

Garre’s Osteomyelitis (Chronic Osteomyelitis with Proliferative Perosteitis)

• Chronic Non Suppurative Sclerosing Osteitis/ Periostitis Ossificans.
• Non suppurative productive disease characterized by a hard swelling.
• Occurs due to low grade infection and irritation
• The infectious agent localizes in or beneath the periosteal covering of the cortex & spreads only slightly into the interior of the bone.
• Occurs primarily in young persons who possess great osteogenic activity of the periosteum.

Clinical Features

• Uncommonly encountered, described in tibia and in the head and neck region, in the mandible.
• Typically involves the posterior mandible & is usually unilateral.
• Patients present with an asymptomatic bony, hard swelling with normal appearing overlying skin and mucosa.
• On occasion slight tenderness may be noted
• pain is most constant feature
• The increase in the mass of bone may be due to mild toxic stimulation of periosteal osteoblasts by attenuated infection.

Radiographic features

• Laminations vary from 1 – 12 in number, radiolucent separations often are present between new bone and original cortex. (“onion skin appearance”)
• Trabeculae parallel to laminations may also be present.

Histologic Features

• Reactive new bone.
• Parallel rows of highly cellular & reactive woven bone in which the individual trabeculae are oriented perpendicular to surface.
• Osteoblasts predominate in this area.

D/D for Garre’s Osteomyelitis

• Ewing's sarcoma
• Caffey’s disease
• Fibrous dysplasia
• Osteosarcoma

Treatment

• Removal of the offending cause.
• Once inflammation resolves, layers of the bone consolidate in 6 – 12 months, as the overlying muscle helps to remodel.
• If no focus of infection evident, biopsy recommended.

Nasopalatine cyst

Radiology

The nasopalatine cyst appears as a well-defined, round radiolucency in the midline of the anterior maxilla . Sometimes it appears to be 'heart-shaped' because of super-imposition of the anterior nasal spine.

Radiological assessment should include examination of the lamina dura of the central incisors (to exclude a radicular cyst) and assessment of size (the nasopalatine foramen may reach a width of as much as 10 mm).

Pathology

The cyst is lined by a layer of pseudostratified ciliated columnar epithelium and/or stratified squamous epithelium. The capsule of the cyst is fibrous and may include the incisive canal neurovascular bundle.

Nasolabial cyst

Radiology

'Bowing' inwards of the anterolateral margin of the nasal cavity has been recorded

Pathology

The nasolabial cyst is lined by non-ciliated pseudostratified columnar epithelium, which is often rich in mucous cells.

Osteomyelitis

Osteomyelitis is an extensive inflammation of a bone. It involves the cancellous portion, bone marrow, cortex, and periosteum

Conditions that alter HOST IMMUNITY

Leukemia, Severe anemia, Malnutrition, AIDS, IV- drug abuse, Chronic alcoholism, Febrile illnesses, Malignancy, Autoimmune disease, Diabetes mellitus, Arthritis, Agranulocytosis

Conditions that alter vascularity of bone

Osteoporosis, Paget’s disease, Fibrous dysplasia, Bone malignancy, Radiation, Virulence of the organisms

Certain organisms precipitate thrombi formation by virtue of their destructive lysosomal enzymes.

Organisms proliferate in enriched host medium while protected from host immunity.

Etiology

- Odontogenic infections
- Trauma
- Infections of oro facial region
- Infections derived from hematogenous route
- Compound fractures of the jaws.

PATHOGENESIS

DEV . OF INFECTION --> BACTERIAL INVASION -->  PUS FORMATION -->  SPREAD OF INFECTION --> INCREASED INTRAMEDULLARY PRESSURE , BLOOD FLOW , OSTEOCLASTIC ACTIVITY --> INFLAMMATORY RESPONSES --> INCREASED PERIOSTEAL PRESSURE --> PROCESS BECOMES CHRONIC GRANULATION TISSUE FORMATION --> LYSIS OF BONE --> SEQUESTRUM FORMATION

Classification

Classification based on clinical picture, radiology, and etiology

Suppurative osteomyelitis

I. Acute suppurative osteomyelitis

II. Chronic suppurative osteomyelitis

– Primary chronic suppurative osteomyelitis

– Secondary chronic suppurative osteomyelitis

III. Infantile osteomyelitis

Nonsuppurative osteomyelitis

I. Chronic sclerosing osteomyelitis

  – Focal sclerosing osteomyelitis

  – Diffuse sclerosing osteomyelitis

II. Garre's sclerosing osteomyelitis

III. Actinomycotic osteomyelitis

IV. Radiation osteomyelitis and necrosis

Non-epithelial cysts (not true cysts)

Solitary bone cyst

Radiology

The solitary bone cyst appears as a well-defined but non-corticated radiolucency. Typically, it has little effect
on adjacent structures and 'arches' up between the roots of teeth .

The inferior dental canal may not be displaced, but the cortical margins of the canal may be lost where it overlies the lesion. Expansion is rare.

Pathology

The cyst is lined by fibrovascular tissue that often includes haemosiderin and multinucleate giant cells.

Aneurysmal bone cyst

Radiology

The aneurysmal bone cyst typically presents as a fairly well-defined radiolucency. Sometimes it has a multilocular appearance because of the occurrence of internal bony septa and opacification. Marked expansion is a feature.

Pathology

The predominant feature of an aneurysmal bone cyst is the presence of blood-filled spaces of variable size lying in a stroma rich in fibroblasts, multinucleate giant cells and haemosiderin. Deposits of osteoid are also seen