Survival, differentiation capability, and activity of cells are strictly related to structural features and the composition of the extracellular matrix, and its variation affects tissue homeostasis. Placement of a dental implant in bone tissue activates a sequence of molecular and cellular events that lead to the apposition of newly-formed bone directly onto the titanium surface. Due to implant's interaction with the mineralized tissue, osseointegration is affected by the surface structure of the implanted material.Surface nanotopography and microtopography can modify the shape and activity of mesenchymal stem cells leading to a higher differentiation rate of these cells into osteogenic lineage with the upregulation of osteoblastic genes. Several approaches for implant surface modification are currently under investigation or have been recently proposed to improve osseointegration. Most surface treatments are aimed at the formation of a thick layer of titanium oxide, at the alteration of surface chemical composition by incorporating bioactive molecules and drugs, and at the creation of a surface topography that is more attractive for osteoblast differentiation, adhesion, and osteogenic activity. Data on the cellular-substrate interaction, as well as in vivo studies assessing the response to these novel surfaces, are reviewed in the present study.The application of modern surfaces in dental clinical practice might increase and accelerate implant osseointegration, but could also reduce the occurrence of periimplant bone loss and favor the re-osseointegration of an affected surface. K E Y W O R D Simplant surface, mesenchymal stem cells, nanotopography, osseointegration, surface roughness, titanium implants

Purpose. The aims of this study were to assess the treatment outcome of immediately loaded full-arch fixed bridges anchored to both tilted and axially placed implants in the edentulous maxilla and to evaluate the incidence of biological and prosthetic complications. Materials and Methods. Thirty-four patients (18 women and 16 men) were included in the study. Each patient received a maxillary full-arch fixed bridge supported by two axial implants and two distal tilted implants. A total of 136 implants were inserted. Loading was applied within 48 hours of surgery and definitive restorations were placed 4 to 6 months later. Patients were scheduled for followup at 6, 12, 18, and 24 months and annually up to 5 years. At each followup plaque level and bleeding scores were assessed and every complication was recorded. Results. The overall follow-up range was 12 to 73 months (mean 38.8 months). No implant failures were recorded to date, leading to a cumulative implant survival rate of 100%. Biological complications were recorded such as alveolar mucositis (11.8% patients), peri-implantitis (5.9% patients), and temporomandibular joint pain (5.9% patients). The most common prosthetic complications were the fracture or detachment of one or multiple acrylic teeth in both the temporary (20.6% patients) and definitive (17.7% patients) prosthesis and the minor acrylic fractures in the temporary (14.7% patients) and definitive (2.9% patients) prosthesis. Hygienic complications occurred in 38.2% patients. No patients' dissatisfactions were recorded. Conclusions. The high cumulative implant survival rate indicates that this technique could be considered a viable treatment option. An effective recall program is important to early intercept and correct prosthetic and biologic complications in order to avoid implant and prosthetic failures.