Comparison of osseointegration on various implant surfaces after bacterial contamination and cleaning: a rabbit study.

PURPOSE: To examine the osseointegration of various implant surfaces after bacterial contamination and cleaning. MATERIALS AND METHODS: Four types of implant surface were manufactured: machined (M); plasma-spray hydroxyapaptite (HA); sandblasted, large-grit, acid-etched (SA); and titanium anodic oxide (TAO) were manufactured. The surface characteristics of these implants were determined using a scanning electron microscope, an energy dispersive spectrometer, and a contact profilometer. Each surface was subdivided into control and test groups. Test implants were co-incubated with Prevotella intermedia for 2 weeks, then cleaned with cotton pellets, soaked in saline, and irrigated. Control implants underwent the same cleaning procedure, but without bacterial contamination. Four control or test implants with different surface types were randomly inserted into the tibia of 10 New Zealand white rabbits. After 6 weeks of healing, 5 rabbits were sacrificed for histomorphometry, and the rest for removal torque assay. RESULTS: Bacterial contamination adversely influenced every implant surface in terms of bone-to-implant contact (BIC) ratio and required removal torque. The negative results reached significant levels for rougher surfaces (HA and SA). For both contaminated and uncontaminated samples, HA and SA implants required significantly higher removal torque than that required for M implants. CONCLUSION: Bacterial contamination jeopardized osseointegration on every tested implant surface. A more negative effect on BIC was found for implants with rougher surfaces. However, contaminated rough-surfaced implants showed more removal torque resistance than contaminated smooth implants.

Dental implant failure associated with bacterial infection and long-term bisphosphonate usage: a case report.

Although the risk of developing osteonecrosis of the jaw for oral implants in patients using oral bisphosphonates (BPs) is low, the devastating complications still require caution. We document a case of severe periimplant infection that developed after the patient had used oral BPs for 3 years. Exposed bone and osteonecrosis persisted for more than 2 months after 1 infected implant was explanted by a dentist unaware that the patient was taking BPs. After oral BPs had been stopped, another involved implant was explanted, sequestra were removed, a primary closure was sutured, and the antibiotic was changed; then the wound was finally under control. The explanted implant with attached bone was processed for undecalcified ground sections, and specimens from the bony lesion were sent to pathology for examination. Osteonecrosis, severe inflammatory osteolysis, and heavy bacterial colonization were found. Patients at risk must be alerted about the potential risks of implant failure and developing BP-related osteonecrosis of the jaw.

Isolating stromal stem cells from periodontal granulation tissues.

Stem cell therapy is a promising area in regenerative medicine. Periodontal granulation tissues are often discarded during conventional surgery. If stromal stem cells can be isolated from these tissues, they can be used for subsequent surgery on the same patient. Fifteen human periodontal granulation tissue samples were obtained from intrabony defects during surgery. Immunohistochemistry (IHC) was carried out on five of the samples to identify STRO-1, a marker of mesenchymal stem cells. Five samples underwent flow cytometry analysis for the same marker. The remaining five samples were characterized by "colony formation unit-fibroblast" (CFU-f) assay and selected for proliferation assay, flow cytometry of stem cell markers, immunocytochemistry (ICC), multipotent differentiation assays, and repairing critical-size defects in mice. The ratio of STRO-1(+) cells detected by IHC was 5.91 ± 1.50%. The analysis of flow cytometry for STRO-1 was 6.70 ± 0.81%. Approximately two thirds of the CFU-f colonies had a strong reaction to STRO-1 in ICC staining. The cells were multipotent both in vitro and in vivo. Mice given bone grafts and stem cells showed significantly better bone healing than those without stem cells. Multipotent stromal stem cells can be isolated from human periodontal granulation tissues. These cells improve new bone formation when transplanted in mouse calvarial defects. Isolating stem cells from relatively accessible sites without extra procedures is clinically advantageous. This study demonstrated that human periodontal granulation tissues contain isolatable multipotent stem cells. The cells may be a good source for autotransplantation in subsequent treatment.