Osseointegrated Implants

Introduction

The technique of osseointegration was introduced by Per-Ingvar Branemark in the 1980s. The definition of osseointegration as defined by Zarb and Alberktsson is “a time dependent healing process whereby clinically asymptomatic rigid fixation of specifically designed alloplastic materials is achieved and maintained during functional loading.” Dental implant therapy has provided an improvement in function and quality of life to replace missing teeth and other structures resulting from surgical ablation of head and neck structures or chemo/radiation therapy.

The recommended parameters for osseointegration are implant biocompatibility, microscopic and macroscopic design of the surface of the implant, host (patient) and implant, surgical protocol, and the loading and prosthetic protocols. Dental implants are made of titanium, with a titanium oxide created on the surface when exposed to air. This oxide layer protects it from corrosion. Osseoinduction and osseoconduction are associated with the healing process.

Growth factors, surface roughness, and the design of the implant body contribute to such healing process. Spraying of various coatings on the surface aims at increasing the surface area of implant body with the goal of increased surface contact with bone as it undergoes the healing process via osseoinduction and osseoconduction. A greater area of surface contact between bone and implant is now considered to be an important factor in the success of implant therapy.

Key Operative Learning Points

• Careful patient selection and patient-centered treatment

• Anatomic region and associated defects from ablation or chemo/radiation therapy are crucial in planning.

• Multidisciplinary management

• Presurgical planning

• Radiation therapy greater than 55 Gy

  • Not a contraindication to implant therapy

  • Greater risk of implant failure

  • No consensus on appropriate time of implant placement

• Hyperbaric oxygen therapy (HBO) if prior radiation therapy

  • Research has not shown a significant impact of HBO therapy.

• Medical comorbidities affecting healing, immune state; smoking, diabetes, oral bisphosphonates, periodontal disease

  • Not contraindications

  • Higher risk of implant failure

• Dental implants can be placed in microvascularized fibula free flaps with or without prior radiation therapy

• Surgical technique

• Management of peri-implant soft tissues is required especially in reconstructions using fibula microvascular transfer

  • Stable peri-implant soft tissue

• Tissue management procedures include one or a combination of

  • Vestibuloplasty

  • Lip switch vestibuloplasty

  • Skin grafting

  • Rigid splinting with implant prosthesis

• Loading protocols of dental implants with prosthesis in patients with large defects or radiation therapy are often staged.

• Regular monitoring of patients is very important to

  • Manage events

  • Complications

  • Monitor for recurrent disease

Preoperative Period

Unlike natural teeth, dental implants are not at risk for caries, but they are at risk for developing peri-implant mucositis. Recent systematic reviews have shown no significant difference in implant survival at up to 10-year follow-up between patients with no gum (periodontal) disease and those with periodontal disease.

Osteoporosis, diabetes, immunosuppression, and the use of oral bisphosphonates continue to be evaluated, and current evidence shows a slightly higher risk of implant failure in this patient population. However, this does not mean that dental implants are contraindicated in this patient population. Rather, adequate screening and surgical and prosthetic planning with close communication with the managing physician are key to positive outcomes. Studies addressing other medical comorbidities, such as cardiovascular diseases, hypothyroidism/hyperthyroidism, human immunodeficiency virus (HIV), acquired immunodeficiency syndrome, ectodermal dysplasia, and scleroderma have shown no increased failure rate of implants in these patient populations when the comorbidity is medically controlled. It is important to note that these studies remain small in number and more research is needed in this area.

Ultimately, a multidisciplinary approach and patient-centered treatments are key to providing such therapy ( Fig. 188.1 ). Realistic patient expectations and understanding of treatment, especially for maintenance, as well as expected and unexpected events play an important role in acceptance of dental implants. The longest follow-up to 29 years from a patient population at the Mayo Clinic revealed that mechanical events (associated with the prosthesis) occurred approximately three times more often than biologic events (associated with the implants) in edentulous patients treated with dental implants ( Figs. 188.2 and 188.3 ). This same study showed that 92% of prostheses had an overall survival, free of implant failure; however, only 15% survived free of any event. This means that long-term management of the prosthesis is key to improving treatment outcomes.