DEFINITION
Literally: "dead bone from poor blood flow",a bone marrow disease with either dead bone or bone marrow that has been slowly strangulated or nutrient-starved.
EPIDEMIOLOGY
- Maxillofacial osteonecrosis has been microscopically confirmed in patients as young as 12 years of age and as old as 94, and has been reported in both genders.Typically, however, more than 80% of patients are 35-55 years of age and an equal proportion are women.
- The wisdom tooth sites are the most often involved sites (45%),perhaps because they are the place where the pressures are less and the flow is irregular > both conditions favor the formation of clots.
Any part of the jaw, however, can be involved:the tooth bearing bones,the temporomandibular joint or the ramus of the mandible.
- irregular ulcerative lesion with bone exposure (1-5 cm)
- pain and swelling of the jaw
- infection often associated with purulence
- difficulty in eating and speaking
- bleeding
- paresthesia of the lower lip
DIAGNOSIS
presence of hollow spaces or "cavitation" within the marrow spaces that represent "dry rot" of the bone and fatty marrow,a process which can only be explained by slow and chronic strangulation of the bone's blood supply
- histopathological examination
- liquefactive or coagulative necrosis,where numerous fat globules and oil cysts are within a background film of fibrin and hemorrhage
- desiccated necrosis,where other cavitations are completely dry or desiccated
dilatation of capillaries, veins and sinusoids suggest venous occlusion with intramedullary hypertension
intramedullary fibrous scars with fewer remaining adipocytes
medullary infarction or microinfarction due to blockage of small medullary vessels by microclots
presence of fibrin or platelet aggregates within abnormal marrow or plugging the vessels of the marrow
ischemic bone changes:thin trabeculae,widely spaces,minimal or no osteoblastic or osteoclastic activity
bone loss between the roots of molar teeth (furcation involvement) is often an early sign of osteonecrosis of the jaw
PATIENT RISK FACTORS
Thrombotic
Genetic
Acquired
Vascular
Genetic
Acquired
Hormonal
Acquired
- estrogens decrease
- menopause
- oral contraceptives
- inhibitors of aromatase
JAW SPECIFIC RISK FACTORS
anatomical (dependent on its structure)
a).greater blood supply than other bones
b).terminal circulation
c).peculiar microcirculation due to a higher composition of cortical bone (whereas maxillary bone has a higher composition of medullary bone),that might also explain why osteonecrosis occurs more than twice as often in the mandible as in the maxilla
d).exposition to external agents due to teeth perforations through the jaw bone and mucosa
e).thin overlying mucosa,which can easily be traumatized
physiopathological (dependent on its daily activity)
-stimulated circulation
-high bone remodeling and density
-faster bone turnover rate
-exposure to repeated microtraumas and lesions
COMPLICATIONS
