Early postextraction implants may achieve osseointegration in the absence of primary stability. A pilot study

This pilot study aimed at investigating if implants without primary stability may osseointegrate and support functional prosthesis. 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 five 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. Twenty-five consecutive patients were included. At placement, mean ISQ significantly 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 five 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 significant 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. Rehabilitation of wide postextraction defects may achieve successful outcomes even in the absence of primary stability.