The present meta-analysis was limited to prospective clinical studies and utilized a rigorous inclusion and exclusion criteria. Studies included in the analysis were limited to cases in which implants placed in sites with adequate bone volume without grafting. Implants were placed in healed sites and loaded after at least 1–3 months of healing. All studies had at least 1-year follow-up. Patients were required to have adequate health to undergo implant surgery. Controlled medical conditions and smoking status were not excluded. Excluded were studies where implants were placed in sites that were initially deemed to have adequate bone; however, at the time of implant surgery, required the use of bone graft. Data from these studies could not be analyzed due to unclear documentation of which implants were grafted, thus preventing separation of the data for the analysis. The data from some of the survival studies were not able to be analyzed due to the lack of a clear description of implant length. The exclusion of these studies along with the rigorous inclusion criteria limited our meta-analysis to six studies. These six studies were well-documented with clear data on implant length, surface, and location.

The overall survival rate of wide-diameter implants based on the pooled data of the included six studies was 96.3 %, and this was within the reported range of wide-diameter and regular-diameter implant survival rates. Machined implants functionally integrate with the surrounding bone via a macroscopic interlock of the implant threads with the bone. Surface treatment of the machined threads increases the effectiveness of the interlock resulting in an improved bone-to-implant interface. However, our meta-analysis found no significant difference between the implant survivals of machined compared to surface-treated wide-diameter implants. Similarly, Al-Nawas et al. also reported no significant difference between machined and double-etched surface-treated standard-diameter implant survival.