Biomimetic dental implants--new ways to enhance osseointegration.

E ndosseous dental implants are currently the most innovative and exciting treatment modality in dentistry. They are being widely used for a variety of indications, and most of the various techniques in use are evidence-based and predictable. However, in many cases, the intended implant site is compromised because of poor bone quality (i.e., low bone density, in the case of highly cancellous bone, or low vascularity, in the case of primarily cortical bone) or insufficient quantity of bone (in terms of the width or height of the alveolar ridge). Lack of sufficient alveolar ridge height is often related to the proximity of the implant site to other anatomical structures (i.e., the maxil-lary sinus or the mandibular canal). In these situations separate preparatory procedures may be required to augment the available volume of bone before placement of the implant, which may result in extra morbidity, longer treatment time, greater risk of complications and higher costs. Surgical procedures that have been developed to deal with the problems of insufficient alveolar ridge width or height include ridge augmentation with block grafts or particulate graft materials and protective barriers (a procedure known as guided bone regeneration), splitting of the alveolar ridge, direct or indirect sinus grafting or elevation, repositioning of the alveolar nerve bundle and distraction osteogenesis. Alternatively, orthodontic procedures have been used to extrude and eventually extract " hopeless " teeth or to move salvageable teeth into adjacent edentulous sites. Ultimately, this approach leads to regeneration of lost bone and enables implant placement in the vacated site. With most surgical approaches, the bone graft of choice has been autogenous (e.g., grafts taken from the chin, the ramus of the mandible, the maxillary tuberosity or the iliac crest of the same patient). However, as effective as these procedures may be, the risks of complications are greater than for single site procedures, and greater morbidity is associated with the existence of a second operative site. 1 Among the complications occurring at the donor site are infection, pain, sensory loss and hematoma formation. In addition, a donor site with sufficient quantity of bone is not always available. Allografts (i.e., bone taken from a different person and processed and managed by a tissue bank or commercial supplier) have often been substituted, but this method also has limitations, including inconsistent osteoinductive activity , unfavourable host immune responses, 2 delayed resorp-tion, and risk of prion and virus transmission. 3,4 …