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Guided Bone Regeneration

The challenge of treating cancer patients

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When dental practice faces neoplastic patients, risk and failure increase. An overview of influencing factors and suitable treatments.

Prof. Rogerio Belle de Oliveira | Brazil

Cancer is a worldwide disease with high rates of mortality. The International Agency for Research on Cancer (IARC) works constantly to update information about cancer-causing agents, key origin factors and prevention strategies. Education and knowledge are essential to avoid the main contributing factors and to improve early cancer detection. Access to diagnosis and treatments influence the possibility for improving knowledge. But early diagnosis is the most critical element, because it increases treatment success and survival rates.1 

Influencing factors

The combination of aging and cancer is a significant factor, with an increase in cancer prevalence in the elderly. There are, for example, age and gender related functional and structural changes in soft and hard tissues, metabolic impairment and physical limitations.

Patients must receive overall oral health and radiographic assessments. Before performing cancer therapy, the clinician must pay attention to the removal of ill-fitting prostheses, plaque and caries, gingivitis or periodontitis, and the extraction of hopeless teeth. Treatment of these conditions can prevent future undesirable oral complications during cancer therapy. During this phase of treatment, successful socket grafting can be done with Geistlich Bio-Oss® and Geistlich Bio-Gide® in alveolar sockets 90-days before radiotherapy and 45-days before chemotherapy, with final healing at six months.2-4

Cancer treatment options

Cancer treatment depends on several factors, including the cell-cause relationship, location, and timing. The best options are separate or combined treatments of surgery, chemotherapy and/ or radiotherapy. In the dental office, patients who win the battle against cancer require the most challenging treatment planning for reconstructive therapy. Surgical procedures, chemotherapy and radiotherapy entail comorbidities that affect function and structure of bone and soft tissues for a long time. Osteopenia and osteoporosis are possible complications that could impair treatment after cancer therapy.5-9 

Radiotherapy is a high-energy radiation targeted at the cancer site, damaging the DNA synthesis of highly mitotic and healthy cells and decreasing soft tissue and bone vascularization around primary and secondary sites. Therapeutic radiation doses in the head and neck region will depend on the location, tumor size and associated lymphatic chain. The energy ranges from 30 to 70 Gy in 20 to 40 irradiations. The clinical dose-related consequences expected are tumor regression, xerostomia, oral mucositis, possibility of severe trismus, radiation-induced fibrosis and risk of developing osteoradionecrosis. The risk for osteoradionecrosis is age, time and energy dependent. Therefore, lower doses and fewer irradiation intervals decrease the chances of osteoradionecrosis development. Osteoradionecrosis is a well-described condition characterized by a hypovascular medullary bone deterioration, impossibility of bone repair and a primary inflammatory process leading to severe bone loss. Irradiation residual effects on bone are permanent, and even 24 months after radiation, lower levels of vascularization are observed, especially in the mandible and posterior maxilla.4,7,10-13 Hyperbaric oxygen therapy is one option for preventing osteoradionecrosis and for improving bone graft and dental implant success, but there is limited scientific evidence for its use.14

Chemotherapy has a systemic cytotoxic effect on target neoplastic cells as well as normal cells. The worst side effects include myelosuppression, thrombocytopenia and an increased risk of infection. There is also a decrease in the number of stem cells and a reduced function in bone marrow, though cell recovery occurs 180 days after the last chemotherapy dose. Some patients’ treatment regimes may include monoclonal antibody to RANKL with or without systemic bisphosphonates, and these patients require more attention for the increased risk of bone necrosis.4,9,10,14-16

Focus on the patient

When quantity and quality of bone are crucial for implant success and reconstruction, GBR is a well-described graft technique with successful results.6 (Fig. 1) GBR in cancer patients is a time-dependent technique. Minimally invasive approaches can be performed with appropriate results after 180 days of chemotherapy and after 360 days of radiotherapy. When monoclonal antibodies to RANKL and/ or systemic bisphosphonates are employed, during active therapy or for maintenance, GBR must be delayed for 24-months. Also, in this case, minimally invasive surgical approaches and short implants are preferable, but evaluation of the patient-specific situation is highly recommended.4,13,15-17

Before surgery, the patient should undergo a global clinical and radiographic assessment. Evaluation of bone mineral density and laboratory exams are essential diagnostics for planning minimally invasive bone graft procedures. According to the latest systematic review, C-terminal cross-linking telopeptide of type-1 collagen has no predictive value in determining the risk for osteonecrosis in bisphosphonate patients,14 and the same applies to cancer therapy. The best option is evaluation of serum levels: calcium, alkaline phosphate, parathyroid hormone, vitamin 25-hydroxyvitamin D3, albumin, and also assessment of bone mineral density at the lumbar spine and femoral neck. Another significant diagnosis using radiographic or CBCT examination of the target area is the evaluation of previous surgical sites or sockets for proper bone healing. Poor healing is a significant indication for higher risk of bone necrosis.4,6,9,16,17

Because of its less vascularized bone structure, the posterior maxillary region is more prone to complications, and, in order to avoid a second surgical harvest site, autologous bone grafts are not recommended for patients after cancer therapy.11,16 The best option for this kind of patient is xenografts and collagen membranes. A minimally invasive flap approach helps correct horizontal and vertical bone defects for immediate or delayed insertion of dental implants with excellent stability. With minimal residual bone, shorter and smaller implants can be a good choice.4,13 Moreover, careful manipulation of the mucoperiosteal flap and primary closure of the flap are essential during the surgical procedure. Rinsing the surgical site with a solution of 500 mg tetracycline in 20 ml sterile saline may improve outcomes.

Prof. Rogerio Belle de Oliveira

Prof. Rogerio Belle de Oliveira | Brazil

Pontifical Catholic University of Rio Grande do Sul

Department of Oral and Maxillofacial Surgery

Porto Alegre, Brazil

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