In our study, the primary stability of immediately loaded implants was above 60 ISQ, while most of the delayed implants showed low stability (as low as 20 ISQ). Ostman and colleagues  used a primary stability value of 60 ISQ as a threshold value for immediate loading. Another study found an increase in implant loss with ISQ values lower than 60 for immediately loaded implants . Primary stability is crucial for the achievement of implant secondary stability, as implants with good primary stability have a shorter healing period with an increase in stability during the healing period [35, 36].
During the follow-up period, the stability of IPL implants increased by 10 ISQ after one month, while the increase was only 2 ISQ in the second month. This result indicates that implant stability increases to a greater extent during the first month of healing. When we compared IPL and DL implants after 3 months, we found that the increase in the ISQ was the same (13 ISQ for IPL implants and 12 ISQ for DL implants). After 6 months of loading with a provisional crown, the IPL implants continued to show an increase in stability, although the increase was minimal (only 3 ISQ). Conversely, DL implants showed a larger increase of 8 ISQ. At the 6-month reading, both techniques achieved nearly the same implant stability but over different time periods.
Immediately loaded implants may show a decrease in stability after one month ; however, we did not observe this phenomenon in our study when implants were progressively loaded. Compared with DL implants, immediately loaded implants can recover their stability and show increased stability after completion of the healing period . Many studies have reported that implant loading can increase implant stability and bone density of the bone around the implant, especially in soft bone [34, 38]. 59ce067264