The use of osseointegrated dental implants with direct bone-to-implant contact became an increasingly important treatment modality for the replacement of missing teeth in completely and partially-edentulous patients in the 1980s. One of the prerequisites for predicting long-term prognosis for osseointegrated implants is a sufficient volume of healthy bone at recipient sites. However, a sufficient bone volume is frequently lacking as a result of trauma or infectious disease such as advanced periodontitis. Vertical bone loss in partially-edentulous patients constitutes a major challenge due to anatomical limitations and technical difficulties. The presence of the nasal cavity, the maxillary sinus and the alveolar nerve limit the bone height available for proper implant placement. Moreover, a large interarch space alters coronal length and form and produces an unfavourable crown-to-root ratio in the final prosthetic reconstruction.

A number of different techniques and biomaterials have been developed to reconstruct deficient alveolar ridges to allow dental implant placement in either a simultaneous or staged approach.

Guided bone regeneration (GBR) is a regenerative procedure derived from guided tissue regeneration (GTR) around natural teeth and is used for ridge augmentation. Autogenous bone has been applied to the traditional GBR technique, showing improved results in terms of regenerated bone volume and implant osseointegration.

Excellent results have been reported when applying these techniques for three dimensional bone augmentation, thus leading to the correct implant placement in relation to the final prosthetic treatment plan and challenging aesthetic demands.

Nevertheless, guided bone regeneration requires a second surgical site when using autogenous bone as the graft material in addition to an excellent soft tissue management to eliminate the chance of premature membrane exposure.

Clinicians strive to develop innovative techniques to decrease if not eliminate the need for a donor site, thus decreasing patients'morbidity and decreasing the sensitivity of the above-mentioned technique. Advances in utilizing xenografts as substitute for autogenous bone, and tissue engineering to provide potent growth factors to the wound area, are now approaching the bone regeneration field. Patients' demands for an optimal aesthetic rehabilitation are growing faster every day and we are able to apply these modern concepts to perform correct treatment plans.

The purpose of this special issue is to provide the clinician with precise indications for the use of regenerative techniques in everyday practice.

My gratitude goes to all the authors who have contributed to the success of this issue.

I also want to express my gratitude to the Editor Paul Mattout who gave us the possibility to develop this project.