Partial rehabilitation of the posterior edentulous maxilla using axial and tilted implants in immediate function to avoid bone grafting. 
There is a need to create rehabilitation solutions for partial edentulism in the posterior maxilla, thereby reducing the need for grafting in these areas.  The purpose of this study was to report the results of partial edentulism rehabilitation in the posterior maxilla with a three- to four-unit bridge supported by two implants: anterior implant placed in axial position and posterior implant tilted distally.  A theoretical analysis of the concept including a biomechanical discussion is also provided.  The clinical study included 35 patients (21 women, 14 men) with an age range of 37 to 80 years (mean = 55.5 years), rehabilitated with an implant-supported partial bridge, followed between 4 months and 8 years, with a mean follow-up time of 53 months.  ASSESSMENT DATA:The success criteria included clinical parameters (ie, implant fulfilled its purported function as support for reconstruction; was stable when individually and manually tested; had absence of infection; demonstrated a good esthetic outcome of the rehabilitation; allowed fabrication of the implant-supported fixed prosthesis, which provided patient comfort and hygiene) and radiographic parameters (ie, implant probability of long-term stability, as judged by annual bone loss).  The implant survival estimate was computed using the Kaplan-Meier product limit estimator.  Data were analyzed with descriptive and inferential analyses.  The survival rates were 97.1% and 98.8% at 8 years (Kaplan-Meier), using the patient and implant as units of analysis, respectively.  The overall average marginal bone resorption was 1.05 mm (SD = 0.65 mm) at 1-year follow-up, and 1.47 mm (SD = 0.37 mm) at 5-year follow-up, with no significant differences between axial and tilted implants in the 1-year (P = 0.107) and 5-year (P = 0.211) evaluations.  DISCUSSION OF RESULTS:The results indicate that within the limitations of this preliminary study the present protocol is valid for the rehabilitation of partial edentulism in the posterior maxilla.  The clinical results confirmed the theoretical analysis on biomechanics and load distribution, with high survival and success rates in the long-term, low implant marginal bone resorption, and low frequencies of complications.