Читать книгу Bone and Soft Tissue Augmentation in Implantology - Группа авторов - Страница 34

To inhibit osteoclast activity, antiresorptive therapy using bisphosphonate or RANKL inhibitors is available.⁸³ The range of increased performance bisphosphonate drugs has increased in the past few decades. In addition, the human RANKL antibody Denosumab (Prolia) was approved in 2010 for the treatment of postmenopausal osteoporosis. As a subcutaneously administered drug, it extends the possibility of individualized osteoporosis medication, also interfering in bone metabolism.⁸⁷

To reduce the risk of occurrence of osseous disseminations, e.g. in patients with breast and prostate carcinomas and with multiple myeloma, a high dose of bisphosphonates is given. For these tumors, a high rate of new disease (antiresorptive drug-related osteonecrosis of the jaw – ARONJ) is continually observed every year.³¹ Usually, intravenously administered bisphosphonate therapy, which is used curatively as well as palliatively, means a reduction in the consequences of the oncological disease for these patients, since further metastasis growth in the bone is reduced.³¹ Since metastasis needs the help of the osteoclasts to remove bone, allowing for their growth, the strong inhibition of the osteoclasts will stop bone resorption: metastasis cannot grow inside the bone any longer.

Fig 2-4b Aphthoid mucosal lesion on the planum buccale and on the fixed mucosa on the alveolar ridge in osteoporosis-induced strontium therapy (Protelos).

Due to the change in bone metabolism, a careful dental examination is recommended to perform invasive dentoalveolar surgery prior to medication in order to avoid osteonecrosis in the oral cavity.

Osteoporosis is a disease that shows an increasing prevalence with increasing life expectancy, especially in females. If left untreated, it leads to a significant impairment of the quality of life of those affected. In Germany, a prevalence of 6.3 million people with osteoporosis is assumed, with an incidence of 885,000 new cases per year.³⁵ Bisphosphonate therapy for osteoporosis is administered through a weekly oral intake or a quarterly or yearly intravenous injection that lead to a stabilization of the skeletal system. A short-term intake of bisphosphonates shows no increased risk of osteonecrosis. After an intake of the medication for longer than 3 years, a higher prevalence of osteonecrosis as well as other general medical side effects are evidenced.⁸⁰ Classic open wound healing is absolutely contraindicated, especially after tooth extraction, due to extremely high risk of infection. In addition, after other dentoalveolar surgery, reduced bone regeneration is observed, and the risk for sequestration of the infected bone can occur³¹ (Fig 2-5a and b).

Fig 2-5a Bisphosphate-induced osteonecrosis in plasmacytoma with colonization of multi-resistant hemolyzing streptococci.

In this context, a few years ago, the systemic intake of bisphosphonates for the treatment of oncological disease or in osteoporosis was an absolute contraindication. Clinical experience shows that this contraindication needs to be reevaluated.^16,25 Bisphosphonate medication interferes with the physiology of bone metabolism, thereby limiting the function of the osteoclasts responsible for the bone resorption and remodeling processes.⁸⁹ Accordingly, the indication for techniques that require high osteoclastic activity for the remodeling must especially be reevaluated. In this case, techniques that involve the transplantation of autologous spongiosa are preferable to those that transplant purely cortical bone or xenogeneic bone substitute material that requires higher resorption kinetics to achieve a stable implant site.²⁰

Fig 2-5b CBCT evaluation of the available bone with contraindications for augmentation and implant therapy due to osteonecrosis of the jaw (ONJ).

For oncology therapy with regular infusions ranging from a few months to a few years, implant placement should be avoided.³¹ Even with long-term oral administration or intravenous administration in the form of so-called ‘depot injections’ of these preparations, the critical limit is set at 3 years. To avoid bisphosphonate-induced bone necrosis in patients receiving treatment for osteoporosis, a very strict indication for augmentation and implant therapy is recommended for these patients.^31,34

Since the success of implant therapy with bisphosphonate therapy is controversial,^42,87 the extent of treatment should be determined on an individual basis, depending on the patient’s health and dental history.