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Regulation of cellular function is key to bone formation at endosseous implant surfaces. Osseointegration was "discovered" prior to the discovery of genetic regulation of osteoinduction or characterization of mesenchymal stem cells. Understanding osseointegration in cellular and molecular terms has benefited from genome-wide characterization of this healing process at endosseous implants in vivo. These in vivo studies also demonstrate a role for osteoprogenitor cells and cells involved in immune regulation and osteoclastogenesis. The identification of noncoding RNAs, including microRNAs, as key factors controlling cell function has highlighted the role of microRNAs in cell differentiation control. This review summarizes emerging in vitro and in vivo investigations emphasizing the role of microRNAs in the osseointegration process. Many microRNAs influence key osteoinductive pathways controlling Osterix, runt-related transcription factor 2 (RUNX2), and bone morphogenetic protein (BMP)/SMAD function. Others influence the monocyte/ macrophage lineage. While significant progress has been made in elucidating the mechanisms associated with the regulation of surface modulation of osteoblast differentiation by microRNAs, knowledge gaps are evident in the identification and characterization of microRNAs linked to osseointegration. Given existing knowledge regarding the varied expression of microRNAs and their role in inflammation, it is important to understand how microRNA expression may influence the process of bone accrual at implant surfaces during osseointegration. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the expression pattern of micro RNAs (miRNAs) on a surface with nanotopography compared with a smooth surface (control). Materials and Methods: Human mesenchymal stem cells (hMSCs) were plated on different surfaces and compared at 3, 7 and 14 days for alkaline phosphatase (ALP) activity, expression of genes (osterix [OSX], runt-related transcription factor 2 [RUNX2], bone morphogenetic protein 2 [BMP2], and ALP), and expression of miRNAs. Western blot was also used to detect osteogenic proteins (BMP2, OSX, and osteocalcin [OCN]). Scanning electron microscopy of cells plated onto the surfaces was obtained. Results: ALP activity on different surfaces was significantly greater in the nanotopography surface. At day 14, there was a 3.5-fold and a 9-fold increase for the RUNX2 and OSX genes, respectively. BMP2 and ALP also increased by fourfold and sevenfold compared with the control. Protein levels for OSX and BMP2 were also upregulated compared with the control group. Using RNA sequencing technology (RNA-Seq), a total of 117 miRNAs were found to be differentially expressed comparing the control (day 7) with the nanosurface (day 14). Forty-five miRNAs were upregulated, and 72 were downregulated. Several of the miRNAs that were differently expressed regulate osteogenic genes. For example, hsa-miR-135b-5p targets OCN, BSP, RUNX2, COL15A1, and OSX; hsa-miR-122-5p targets OPN; hsa-miR-196a-5p targets BMP4; hsa-miR-26b-5p targets BMP2 and hsa-miR-148b-3p targets OPN. Conclusion: Surfaces with nanotopography have the potential to improve the osseointegration response in order to reduce the osseointegration time and also increase bone formation around the implants, improving areas with low bone quality. Within the limitation of this study, nanotopography surfaces affected MSC differentiation to osteoblasts. Several miRNAs were differentially regulated by surface topography. These miRNAs could be related to the differentiation response to help control the osseointegration process. [ABSTRACT FROM AUTHOR]

Objectives Materials and methods Results Conclusion This study evaluates the clinical performance of implants with hydrophilic surface and two different macrostructures: cylindrical with perforating triangular threads (CT) and cylindrical‐tapered with the association of square and condensing and perforating triangular threads (TST).This was a multicenter split‐mouth, simple‐blinded, randomized, and controlled trial. Thirty patients with edentulous mandible received two CT and two TST implants. Primary stability was determined by insertion torque and resonance frequency analysis (RFA). Implants were loaded with full fixed‐arch prostheses within 24 h after insertion. Clinical parameters (visible plaque index, marginal bleeding index; bleeding on probing; probing depth; and clinical attachment level) and the RFA were assessed at 2, 6, 12, and 24 months after implant loading. Marginal bone level changes were measured by comparison of standardized radiographs taken on the day of implant placement and 6, 12, and 24 months thereafter.Twenty‐eight patients completed the 2‐year follow‐up. The survival rates were 99.16% for CT implants and 100% for TST implants. One CT implant was lost until the 2 months follow‐up. No significant differences were found between the two implant types for marginal bone level changes (CT 0.34 [0.24; 0.55 mm]; 0.33 [0.18; 0.55 mm]; 0.41 [0.12; 0.7 mm] vs TST 0.36 [0.14; 0.74 mm]; 0.33 [0.23; 0.63 mm]; 0.30 [0.20; 0.64 mm] at 6, 12, and 24 months, respectively) and other clinical parameters.The macrostructure of the implants had no influence on survival rate, primary and secondary stability, marginal bone level changes, and peri‐implant clinical parameters outcomes. Both implants can be predictably used for immediate loading of full‐arch mandibular prostheses. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether a hydrophilic surface treatment compared with a hydrophobic implant surface can enhance osseointegration by analysis of calcium deposition, bone-to-implant contact (BIC), bone volume (BV), and upregulation of genes involved in bone formation., Materials and Methods: Sixty implants (n = 60) with a hydrophobic (SAE) or hydrophilic (SAE-HD) surface treatment were placed bilaterally in each femur of 3-month-old male mice (n = 30). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were utilized for quantifying the presence of calcium on the implant surface 7 days after implant placement. The specimens were analyzed after 14 and 21 days for BIC and BV by Nano CT scanning followed by histologic evaluation. Additionally, 1, 3, and 7 days postsurgery, femurs were harvested, implants were explanted, and gene expression (Sp7, Bsp, Sost, IL-1α, and IL-10) by quantitative real-time polymerase chain reaction was studied. Moreover, implants were characterized for surface roughness area. Data were statistically analyzed with two-way analysis of variance (ANOVA) followed by the Tukey test (P < .05)., Results: The amount of calcium on the surface was higher for SAE-HD after 7 days. Nano CT revealed significantly more BV in the SAE-HD than the SAE surface. The histologic assessment showed increased BIC in SAE-HD in comparison to SAE. SAEHD showed significantly increased levels of genes involved in bone formation., Conclusion: Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE-HD presented a better response compared with SAE.

Rehabilitating atrophic maxilla poses many challenges. Reconstructive techniques that require sinus grafting are viable and acceptable; however, these techniques also are considered to be expensive, invasive, and time-consuming. Tilted implants anchored in distal areas using available bone have been reported as a less invasive and highly predictable treatment option. This article presents a case involving implant anchorage via tilted implants as an alternative technique to bone grafting procedures.