Stability measurements of 1-stage implants in the maxilla by means of resonance frequency analysis: a pilot study

PURPOSE: The objective of the present study was to determine standard Implant Stability Quotient (ISQ) values for apparently successfully osseointegrated 1-stage implants in the maxilla. MATERIALS AND METHODS: To measure implant stability, resonance frequency analysis (RFA) was performed in 35 patients (18 women, 17 men) with a total of 120 maxillary ITI implants. Based on the time interval between implant placement and measurements, the ISQ values of anterior and posterior implants were divided into subgroups: unloaded (n = 41), loaded < or = 12 months (n = 31), and loaded > 1 year (n = 48). Statistical analysis was performed using a mixed-effects model with the variables lading, implant location, and gender as fixed effects. RESULTS: The mean ISQ of all measured implants was 52.5 +/- 7.9 (range 40 to 68). Statistical analysis showed no significant differences in ISQ values between the 3 tested time intervals: unloaded (48.8 +/- 3.6), loaded < or = 12 months (54.1 +/- 7.0), and loaded > 1 year (53.1 +/- 9.5). Neither for the location in the jaw nor for bone quality (assessed using radiographs) could a significant difference be found. Gender was the only parameter which was found to be significant (P < .003); on average, men showed higher implant stability than women (56.3 +/- 6.6 versus 48.7 +/- 7.4). DISCUSSION: Standard values for osseointegrated maxillary ITI implants exhibited an individual range. Single RFA measurements of an implant do not allow assessment of its current status or prediction of its performance. Repeated measurements over a longer time period would be necessary. CONCLUSIONS: No significant differences in ISQ values were found between implants with regard to loading period or location in the jaw. Postmenopausal women exhibited significantly lower ISQ values compared to men of the same age group.