The Influence of Nanostructured Hydroxyapatite Surface in the Early Stages of Osseointegration: A Multiparameter Animal Study in Low-Density Bone.

BACKGROUND AND OBJECTIVE: The success rates of dental implants in low-density bone have been reported as a challenge, especially for early or immediate loading in the maxilla posterior area. Nanoscale architecture affects the roughness, surface area, surface energy of the implant and can enhance osseointegration. This study aimed to evaluate the implant-surface topography and biomechanical, histomorphometric, and histological bone responses to a new nanostructured hydroxyapatite surface placed in the iliac crest of sheep. METHODS: Ten female sheep (2-4 years) received 30 implants (n=10/group): HAnano® coated (Epikut Plus®, S.I.N. Implant System, Sao Paulo, SP, Brazil), SLActive (BLX®, Straumann, Basel, Switzerland), and TiUnite (NobelActive®, Nobel Biocare, Göteborg, Sweden) surfaces. Scanning electron microscopy with energy-dispersive spectroscopy evaluated the implant surface topography, the insertion torque value, and resonance frequency analysis evaluated the primary stability, bone-implant contact, and bone-area fraction occupancy were evaluated after 14 and 28 days after implant placement. RESULTS: The surface morphology was considerably comparable between the implant groups'; however, the TiUnite® group presented a remarkable different surface. The SLActive® and TiUnite® groups presented an insertion torque average of 74 (±8.9) N/cm that was similar to that of HAnano® 72 (±8.3) N/cm (p >0.05). The resonance frequency evaluated with Osstell®/SmartPeg® or Penguin®/MulTipeg® showed similar results when assessing implants from the same group. BIC and BAFO significantly increased (p<0.05) throughout the experimental periods to all groups, but BIC and BAFO values were similar among the implants at the same time point. After 4 weeks, bone-implant contact was higher than 80% of the total length analyzed. New bone occupies around 60% of analyzed area around the implants. CONCLUSION: HAnano® coated surface promoted comparable osseointegration as SLActive and TiUnite in the sheep model. The three tested surfaces showed comparable osseointegration at the early stages of low-density bone repair in the sheep model.

Evaluation of a Titanium Surface Treated with Hydroxyapatite Nanocrystals on Osteoblastic Cell Behavior: An In Vitro Study.

PURPOSE: In the context of macrostructural and microstructural modifications to the design of dental implants, surface topography changes with different treatments have the purpose of accelerating bone formation. The aim of this study was to evaluate in vitro the influence of aggregated hydroxyapatite nanocrystals to surfaces treated with double acid etching (Nano) on osteoblastic cell behavior compared with a conventional double acid-etched surface (DE). MATERIALS AND METHODS: Commercially pure Grade 4 titanium discs (6 × 2 mm) were selected, and both cell proliferation and viability were assessed at 24, 48, and 72 hours using Trypan blue vital dye and MTT, respectively. The expression of type I collagen and osteopontin on such surfaces was evaluated using ELISA. Immunostaining for fibronectin was also performed. Quantitative data were analyzed statistically using two-way analysis of variance (ANOVA) followed by Bonferroni post-test with a 5% significance level. RESULTS: The results showed that in all evaluated time periods, cells expressed fibronectin on both surfaces. The cells presented greater morphologic spreading on the Nano surface when compared with the conventional DE surface in all assessed times. Increased cell proliferation and viability were detected in the Nano surface (P < .05) when compared with the conventional DE surface, especially after 72 hours. Osteopontin expression was higher after 24 hours in the Nano surface when compared with the conventional DE surface (P < .05). For type I collagen, a higher expression was observed with the Nano surface than with the DE surface, again after 72 hours (P < .05). CONCLUSION: This in vitro study showed that the treated Nano surface tested promoted increased cell proliferation and viability when compared with the control surface. Additionally, increased cell spreading as well as type I collagen and osteopontin secretion were observed, favoring the early events of osseointegration.