**5. Conclusions**

Based on clinical, radiological, histological and histomorphometric analyses in this study with five patients, the use of an autogenous bone graft mixed with a biphasic calcium phosphate (BCP) in a maxillary sinus floor elevation procedure does not result in a higher bone formation, compared with the results of previously reported studies with pure BCP. However, a better distribution of new bone was seen throughout the entire augmented area, which might eventually improve the bone-to-implant contact.

**Author Contributions:** Conceptualization, W.F.B., C.M.t.B., and E.A.J.M.S.; methodology, W.F.B., N.B., C.M.t.B., and E.A.J.M.S.; validation, W.F.B., N.B., C.M.t.B., and E.A.J.M.S.; formal analysis, W.F.B. and N.B.; investigation, W.F.B., N.B., and C.M.t.B.; data curation, W.F.B.; writing—original draft preparation, W.F.B.; writing—review and editing, W.F.B., N.B., C.M.t.B., and E.A.J.M.S.; visualization, W.F.B.; supervision, E.A.J.M.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** We are grateful to H. van Essen for technical assistance.

**Conflicts of Interest:** The authors declare no conflict of interest.
