Introduction
Scientific evidence supports that dental implants achieve high survival rates and success, understood by the presence and maintenance of osseointegration and function (ability to chew) after being subjected to load [Ossteointegration was defined as a direct, structural, and functional connection between the bone and the surface of an implant subjected to functional loading [Primary stability results from the mechanical interaction between the implant and the bony walls during the insertion [In recent years, implantology has focused on designs that increase implant-to-bone contact introducing modifications in the macrostructure of the implants as well as modifying the surgical technique; however, some bone characteristics cannot be modify. According to Misch in 1989, bone quality can be classified into four types (D1–D4) based on macroscopic and trabecular characteristics [This randomized clinical trial (RCT) aimed to compare the PS (immediate after implant placement) of sites prepared with underpreparation, expanders, and standard surgical instrumentation at different posterior maxillary bone types. The postulated null hypothesis was that surgical technique would not influence on implant primary stability measured as IT values and ISQ values after implant placement especially in bone type IV.