The irradiated hypocellular, hypovascular, and hypoxic tissues are the main cause of dental implants osseointegration failure. A meta-analysis found almost three-fold increased failure risk for implants placed in the irradiated bone and an almost six-fold risk for implants placed in irradiated bone in the maxilla compared to irradiated bone in the mandible.
Factors responsible for clinical success of implants in oral cancer patients:
Studies in which radiation doses exceeded 70 Gy (20-25) reported lower survival rates of dental implants in comparison to studies in which radiation doses were ≤70Gy.
Timeline from radiotherapy to implant surgery
Many investigators have recommended a waiting period of 12 months to 2 years after radiotherapy before starting the implant rehabilitation. Factors that can affect the choice of rehabilitation period are risk of tumor recurrence, risk of osteoradionecrosis, implant survival and patient acceptance. From a practical point of view, early rehabilitation is recommended. This is in accordance with patient expectations. The improvement of life quality for the patient is so high that early implant rehabilitation is justified.
Time between first and second stage implant surgery
Implant integration in irradiated bone takes place at a reduced speed. Wagner et al found a significantly higher implant failure when the time from first to second stage surgery was shorter than 4 months. Loading of the mucosa by a removable denture can also extend the healing time.
Risk for osteoradionecrosis in relation to implant surgery
Minimum surgical trauma to the mandible is known to cause osteoradionecrosis in the time period close to radiotherapy. Such trauma could comprise a tooth extraction or surgery for an osseointegrated implant. To minimize the risk for osteoradionecrosis, HBO is strongly advised. The use of HBO is still controversial. Some studies found it useful while others considered it as an additional burden of treatment.
Effect of Irradiation on Osseointegrated Dental Implants
There is a general concern among oncologists to irradiate with metal implants close to a tumor in the field of irradiation. There is limited information in the scientific literature as to the best way to handle these patients.
Dental implant therapy requiers careful consideration of patient's general health. In patients who have undergone surgical therapy for head and neck cancer, dental implants might serve as a great option for rehabilitation. However, proper assessment of treatment history is mandatory to avoid potential complications of radiotherapy on success of dental implant therapy.
Article by Dr. Siri P.B.
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