Histomorphometry of 2 Immediately Loaded Mini Implants Retrieved From Human Mandible After 3 Months: A Light and Scanning Electron Microscopy Report

Today, mini implants represent an additional choice for patients and surgeons. They are largely used as anchorage when a severely resorbed mandible is to be rehabilitated with an overdenture, their major advantages being flapless, painless surgery and easy placement in thin alveolar crests without any split-crest or bone-grafting procedure. Unfortunately, the literature provides little information on histomorphometric analysis of immediately loaded mini implants placed in the posterior region of the human mandible. The aim of the present in vivo research is to carry out a histologic evaluation of the bone surrounding 2 mini implants placed in human mandible and immediately loaded with an overdenture after 12 weeks. A patient who underwent extraction of 14 periodontally compromised teeth was selected for the present study. After the extractions, 2 mini implants with ball attachment were placed in sites 19 and 30. Mini implants were immediately loaded with a temporary immediate overdenture. Three months after the extractions, the mini implants were harvested and processed for light and scanning electron microscopy. The bone-to-implant contact and the percentage of bone between the threads of the screw were, respectively, 86.3% and 72.6% for the right implant and 69.8% and 71.9 % for the left implant. Newly formed bone between the implant surface and the preexisting bone was present, with poorly represented medullary spaces. Under a scanning electron microscope it was possible to appreciate the presence of well-organized, newly formed lamellar bone with osteons in the areas near the implant body. From the present in vivo report it is possible to state that immediate load applied on mini implants, placed into the posterior regions of the mandible, leads to a clinically and histologically effective osseointegration.