radiation and MRONJ Flashcards
general considerations for patients with radiation therapy
A complication that may arise in irradiated patients that undergo surgical dental procedures at the level of the bone and soft tissues is failure to heal, exposure of necrotic bone, pain and predisposition to infection termed OSTEORADIONECROSIS
Every patient that reports a history of head and neck tumor should be questioned directly as to whether or not they were treated with radiation therapy.
typical appearance of radiation caries
Typical
radiographic appearance of radiation caries. Note the erosion around
the cervical portion of the teeth
Progressive course of osteoradionecrosis. A, Radiograph showing radiolucencies in right mandible and around apex of molar tooth.
B, Six months later, during which time antibiotics and local irrigations were used, radiolucent process is spreading into ramus. The molar was removed
at this time. C, Five months after tooth removal, the extraction site did not heal and the destructive process spread, resulting in pathologic fracture
of the mandible. D, Radiograph after removal of devitalized bone, showing extent of process. (
pathophysiology of osteoradionecrosis
Radiotherapy for head and neck cancer to leading to
1. destruction of osteocytes
2. loss of osteoblasts
3. increased osteoclastic bone destruction
leading to
1. defective osteolysis and osteogenesis
leading to
1. radiation induced fibrosis / atrophy and then late necrosis
sequestreum – area of dead / necrotic bone
where is more prone to osteoradionecrosis and why
mandible
- bone density is high and the vascularization is poor
thought behind hyperbaric O2 tx?
hyperbaric O2 tx stimulates tissue angiogenesis in the hypovascular irradiated tissue,
intermittent high o2 levels stimulate fibroblasts to secrete ac collagen matrix - which cappillaries follow during angiogenesis which leads to more fibroblastic activity
pentoxifylline
free radical scavenger
aiding in a situation of osteoradionecrosis
radiation dose to be mindful of
higher than 55 gray
or over 6500 RADS - increased risk of osteoradionecrosis
MRONJ previously referred to
BRONJ
bisphosphonates are leading cause of the MRONJ
medications most commonly used and more associated with development of MRONJ
usually prescribed for?
- fosamax / oral aledronate
- boniva / oral ibandronate
- actonel / risedronate
usually prescribed for osteopenia or osteoporosis
general mechanism of the bisphosphonates
they essentially deactivate the osteoCLAST
the osteoclast is the cell that resorbs bone
with this inhibition
- the osteblast is also inhibited
- decreased turnover of bone
with interference
- bone becomes stronger - but unable to heal or turnover following
IV bisphosphonates that are more commonly used / known
more used for?
pemidronate / aredia
zoledronate / zometa
more potent in IV and more commonly used for malignancies related to cancer
denosumab
Briefly, denosumab is a fully human monoclonal antibody that inhibits RANKL and helps regulate turnover in healthy bone. Denosumab binds with high specificity and affinity to the cytokine RANKL, inhibiting its action; as a result, osteoclast recruitment, maturation and action are inhibited, and bone resorption slows
cumulative incidence of MRONJ in patients with malignancy?
if exposed to dentoalveolar surgery, risj increases at least?
cumulative incidence of BRONJ in patients with malignancy is 0.8-12%
if dentoalveolar surgery –> risk can increase at least 7x
mandible vs maxilla risk of MRONJ?
other areas of increaed risk?
mandible : maxilla
2:1
tori areas
cumulative incidence of MRONJ in patients taking oral bisphophonates?
associated with a duration of?
0.01-6%
associated with duration of taking them for over 3 years
