Background and objectives: Implant stability is an indicator of osseointegration. Maxillary and mandibular anatomy differs in the amount of trabecular and cortical bone. The aim of this study was to test and compare dental implants stability placed in the maxilla and the mandible during three periods of time by resonance frequency analysis (RFA).

Methods: A No experimental prospective study was designed with 103 3i Biomet Osseotite Implants placed in 57 patients (50 in maxilla and 53 in mandible). An electronic RFA device (Osstell Mentor ^® ) was used to record the Implant Stability Quotient (ISQ values) at implant placement surgery, six weeks and two months later.

Results: Medians of values where compared using Friedman test for k dependent, while values distribution comparison of the ISQ values in maxilla and mandible was estimated with two-sample Kolmogorov–Smirnov Test. Concerning the maxilla, medians of values increases continuously after implant placement. In the mandible, medians of values seem to be similar at the first and the third evaluation time, but decreases in the second one. For both maxilla and mandible medians comparison was found highly significant ( p < 0.001). The Chi-square test was significant in the exact ( p < 0.05) for the first time (ISQ at implant placement) which indicates that medians on this time are different (mandible: 72 > maxilla: 67). In the other times, there were no significant differences ( p > 0.05).

Conclusions: In the maxilla, the initial stability of implants is increased in time. In the mandible, initial stability decreases at 6 weeks but increases again at 2 months reaching values similar to the initial. At Implant placement, mandibular ISQ values were higher than maxilla ISQ values.

Key words: implants stability; ISQ value; osseointegration