I have a 35-year old female patient, medical history is non-contributory, non-smoker, non-drinker. I did a simple extraction of 3 mandibular anterior teeth with no periodontal issues or bone defects. I placed bone graft material in the extraction sites, released tissue and sutured via primary closure. I prescribed clindamycin, dexamethasone and Vicodin. Post-operative visits, 1st at 2 weeks (suture removal) and 2nd at 3 months when radiographs were taken. Soft tissue and bone graft looked healthy and "normal". 4 months after the surgery, I accessed the area to place the implants and the bone graft sites were soft. Seems as if "hardened" bone had not formed. Any ideas as to what went wrong in my technique? Thank you in advance for your help.