Peri-implant bone density: immediate vs delayed placement?

We thought this study¹ evaluating the effects of the different loading protocols (immediate, early, and delayed) was very interesting considering the peri-implant bone density results after one-year follow up. Thirty-nine implants were placed in 39 patients.
The results:

Immediate-loaded group showed the lowest ISQ values, 1 month after placement. During the next follow-up visits, delayed-loaded group showed the lowest ISQ values while other groups showed comparable results…The peri-implant bone of early-loaded implants was significantly denser than that of immediate- and delayed-loaded implants, 1 year after placement. ¹
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Any thoughts?

1.Effects of different loading protocols on the secondary stability and peri-implant bone density of the single implants in the posterior maxilla. AkoÄŸlan M, et al.