Objectives: To monitor the development of the stability of Straumann tissue-level implants during the early phases of healing by resonance frequency analysis (RFA) and to determine the influence of implant surface modification and diameter.
Material and methods: A total of twenty-five 10 mm length implants including 12 SLA RN v4.1 mm implants, eight SLActive RN v4.1 mm implants and five SLA WN v4.8 mm implants were placed. Implant stability quotient (ISQ) values were determined with Osstell mentor at baseline, 4 days, 1, 2, 3, 4, 6, 8 and 12 weeks post-surgery. ISQ values were compared between implant types using unpaired t-tests and longitudinally within implant types using paired t-tests.
Results: During healing, ISQ decreased by 3-4 values after installation and reached the lowest values at 3 weeks. Following this, the ISQ values increased steadily for all implants and up to 12 weeks. No significant differences were noted over time. The longitudinal changes in the ISQ values showed the same patterns for SLA implants, SLActive implants and WB implants. At placement, the mean ISQ values were 72.6, 75.7 and 74.4, respectively. The mean lowest ISQ values, recorded at 3 weeks, were 69.9, 71.4 and 69.8, respectively. At 12 weeks, the mean ISQ values were 76.5, 78.8 and 77.8, respectively. The mean ISQ values at all observation periods did not differ significantly among the various types. Single ISQ values ranged from 55 to 84 during the entire healing period. Pocket probing depths of the implants ranged from 1 to 3 mm and bleeding on probing from 0 to 2 sites/implant post-surgically.
Conclusions: All ISQ values indicated the stability of Straumann implants over a 12-week healing period. All implants showed a slight decrease after installation, with the lowest ISQ values being reached at 3 weeks. ISQ values were restored 8 weeks post-surgically. It is recommended to monitor implant stability by RFA at 3 and 8 weeks post-surgically. However, neither implant surface modifications (SLActive) nor implant diameter were revealed by RFA.