Immediate implant placement in molar regions: a 12-month prospective, randomized follow-up study

To evaluate marginal bone changes radiographically and clinically around immediately placed implants in molar regions associated with three bone regenerative techniques 12 months after loading.

Ninety-two patients received an implant after random allocation to a bone reconstruction method of remaining peri-implant bone defects using either Autologous bone (AB) chips, Ossix membrane (OM) or a combinations of AB chips and OM. After 4 months of healing, a re-entry surgery was performed to connect a healing abutment. A screw-retained crown was mounted 4-6 weeks afterwards. Seventy-six patients attended a follow-up visit 12 months after loading. Marginal bone level was assessed radiographically before re-entry surgery and at the 12-month follow-up; probing pocket depth (PPD) and probing defect depth (PDD) at the implant platform level without the mounted crown were assessed after and just before crown delivery respectively and at the 12-month follow-up.

Fifteen implants were judged as failures at re-entry surgery, and one patient died before follow-up. A statistically significant bone loss was seen in the three groups after 12 months (average 0.48 mm), but no significant differences were found among the groups. Likewise, no differences in PPD or PDD could be found between the groups. An average bone loss of 0.48 mm was recorded at the 12-month follow-up examination resulting in an average peri-implant bone level of approximately 1.1 mm related to an average PPD of 3.1 mm and an average PDD of 1.3 mm.

After 12 months of loading, no significant differences in peri-implant bone level were observed after the use of three bone regenerative techniques in connection with immediately placed implants in molar regions.