1. OSTEOMYELITIS Definition It is inflammation of the bone and the bone
marrow, develop in the jaws from odontogenic
infection.
Types
Acute.
Subacute.
Chronic.

2. Acute Suppurative Osteomyelitis
Definition
It is a serious sequela of periapical infection which results in a diffuse
spread of infection throughout the medullary spaces which cause
necrosis of the bone.
Causes
1- Dental infection is the most common cause.
- If the periapical infection (abscess) virulent and not walled off, the
infection spread throughout the bone.
- Chronic periapical infection (granuloma or cyst) that is walled off , it
may undergo an acute exacerbation if the are traumatized.
2- The causative organisms are; Staphylococcus aureus and
Staphylococcus albus.
Clinical Features
Acute or subacute affect either the maxilla or the mandible.
In the maxilla usually well localized, while in the mandible more diffuse and wide spread.
Occur at any age.

3. Histological Features
Symptoms
- Sever pain.
- Elevated temperature, with regional lymphadenopathy.
- Elevated WBC count.
-The teeth in the area affected are loose and eating is difficult.
- Parasthesia of the lip in the mandibular area.
Radiological Features
- Diffuse lytic changes in the bone begin to appear. The individual trabeculae becomes fuzzy with the presence of radiolucent areas.
Histological Features
- The medullary spaces are filled with inflammatory exudate which does not
progressed to actual formation of pus. The inflammatory cells are
neutrophils, polymorphonuclear leukocytes, also lymphocytes and plasma
cells are also seen.
- The osteoblasts bordering the bony trabeculae are destroyed. The
trabeculae lose their viability and begin to undergo slow resorption. As
a result of the progression of the disease the bone lost its viability and begin
separate from the living bone. Each separated fragment of the dead bone is
called sequestrum.
- Each sequestrum, gradually exfoliated through the mucosa , when large
sequestrum is formed it can be removed surgically.
- When sequestrum becomes surrounded by new living bone called INVOLUCRUM.

4. Chronic Suppurative Osteomyelitis
- It occur after the acute phase has subsided or from dental infection.
Clinical Features
- As the acute phase except that all the signs and symptoms are milder.
- The pain is less severe.
- The temperature is still elevated.
- Leukocytes is slightly elevated.
- The teeth may not be loose.
- Acute exacerbation of the chronic stage may occur periodically. The suppuration may perforate the bone, skin or the mucosa to form fistulous tract.

5. Chronic Focal Sclerosing Osteomyelitis (Condensing Osteitis)
Definition
It is an unusual reaction of the bone to infection with high tissue resistance or with low grade infection.
Clinical Features
Age : It occur in young age before 20 years old.
Site : It affect the lower 6 Th. Tooth.
Symptoms : Mild pain with infected pulp.

6. Radiological Features
- Well circumscribed radiopaque mass of sclerotic bone extending below the apex of one or both roots.
- The root outline is visible (differential diagnosis from benign cementoma, which is smooth, and blend into the surrounding bone).
- N.B : Chronic focal sclerosing osteomyelitis is a reaction of bone to a mild bacterial infection of bone in persons with high degree of tissue resistance and reactivity. In this type of infection the tissues react by proliferation rather than destruction and the infection acts as a stimulus rather than an irritant.
Histological Features
- Dense mass of bony trabeculae within the interstitial bone marrow tissue, osteoblastic activity is completely absent

7. Chronic Diffuse Sclersoing Osteomyelitis
Definition
- It resembles the focal form except the portal of entry of the infection as in this case it occur through diffuse periodontal disease.
Clinical Features
- Age : It affects old persons, with edentulous mandible.
- Sex : It affects black, old females.
- Symptoms : The patients complain of vague pain and bad taste in the mouth. This occurs in acute exacerbation of the chronic infection leading to mild suppuration with the formation of fistula, opening into the mucosal surface to drain the pus.

8. Radiological Features
- There is diffuse sclerosis of the bone.
- This radiopaque lesion is extensive and bilateral.
- The borders between the sclerosis and the normal bone
is indistinct (differential diagnosis from Paget’s disease
by having a cotton- wool appearance).
Histological Features
- Dense irregular trabeculae of the bone bordered by
active layer of osteoblasts. Focal areas of osteoblastic
activity are sometimes seen.
- The bone show mosaic pattern which is due to repeated
periods of resorption followed by repair.
- The soft tissue between the trabeculae is fibrous and
show proliferating fibroblast , small capillaries,
lymphocytes, plasma cells, and polymorphonuclear leukocytes may
be present if the lesion undergo active phase.

9. Sclerotic Cemental Masses
As scleroting osteomyelitis, the tissue was sclerotic bone in cemental masses, the tissue was cementum . The cementum was in the form of large solid masses with smooth , lobulated margins with globular pattern.

10. Chronic Osteomyelitis with Proliferative Periostitis (Garre’s Chronic Non-Suppurative Sclerosing Ositits, Periostitis Ossificans))
Definition
It is described by Garre (1893), as a focal gross thickening of the periostium of the long bone with peripheral reactive bone formation resulting from mild infection.
Clinical Features
Age : It occur before 25 years old.
Site : It involve the anterior surface of the tibia, and mostly in the mandible.

11. Symptoms - Bony hard swelling on the anterior surface of the jaw.
- Toothache or pain in the jaw.
- Bony hard swelling on the anterior surface of the jaw.
- This reactive periostitis results of an overlying soft tissue infection or cellulitis which involve deeper periostium.
Radiological Features
- Carious tooth opposite the hard bony mass.
- Focal overgrowth of the bone on the outer surface of the cortex described as a duplication of the cortical layer of the bone.
- This mass is smooth, well calcified, show thin and definite cortical layer.
Histological Features
- The subperiosteal mass composed of reactive new bone and osteoid tissue, with osteoblasts bordering the trabeculae. This trabeculae are perpendicular to the cortex and the trabeculae are arranged parallel to each other in a retiform pattern. The connective tissue between the trabeculae are fibrous with patches of lymphocytes , plasma cells.
- The periosteal reaction is a result of infection from carious tooth perforation, the cortical palate and stimulating the periostium rather than producing suppurative periostitis