JOURNAL OF BIOLOGICAL REGULATORS & HOMEOSTATIC AGENTS 0393-974X (2019) Copyright © by BIOLIFE, s.a.s. This publication and/or article is for individual use only and may not be further reproduced without written permission from the copyright holder. Unauthorized reproduction may result in fnancial and other penalties DISCLOSURE: ALL AUTHORS REPORT NO CONFLICTS OF INTEREST RELEVANT TO THIS ARTICLE. Vol. 33, no. 6 (S2), 1-12 (2019) AbstractPurpose: This pilot study aimed at investigating if implants without primary stability may osseointegrate and support functional prosthesis. Materials and Methods: Patients received one Trabecular Metal implant each in posterior sockets two months after tooth extraction, combined with xenograft and a resorbable membrane. Implants were divided in three groups, based on the primary stability assessed by resonance frequency analysis. Implant stability quotient (ISQ) was measured at placement, and re-assessed fve months later (at uncovering), and after 6 months of function. Marginal bone loss was radiographically evaluated. After checking normality of the distributions, Student’s t-test was used for statistical comparisons. Results: 25 consecutive patients were included. At placement, mean ISQ signifcantly differed among groups, being undetectable (n=8 implants), 65.00±4.25 (standard deviation, n=6) and 77.95±3.13 (n=11) in the very low, medium and good primary stability groups, respectively. After fve months of healing, mean ISQ had increased to >70 in all groups. All implants successfully osseointegrated and were restored as planned. Six months after loading, no signifcant difference in mean ISQ (range 79.19-81.92), and in mean marginal bone level change (range 0.21 to 0.28 mm) was observed among the three groups. Conclusion: Rehabilitation of wide postextraction defects may achieve successful outcomes even in the absence of primary stability. EARLY POSTEXTRACTION IMPLANTS MAY ACHIEVE OSSEOINTEGRATION IN THE ABSENCE OF PRIMARY STABILITY. A PILOT STUDY S. BIANCONI 1 , G. ROMANOS 2 , F. FONTANELLA 3 , C. MORTELLARO 4 and M. DEL FABBRO 5,6 1 Oral Surgeon, Department of Oral Surgery and Dentistry, General Hospital, Bolzano, Italy; 2 Professor, Department of Periodontology, Stony Brook University, School of Medicine, Stony Brook, NY, USA; 3 Head of Department of Oral Surgery and Dentistry, General Hospital, Bolzano, Italy; 4 Research Laboratory in Regenerative Medicine and Tissue Engineering Saint Camillus International University of Health Sciences, Rome , Italy; 5 Associate Professor, Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy; 6 IRCCS Orthopedic Institute Galeazzi, Milan, Italy