Nanomechanical Assessment of Bone Surrounding Implants Loaded for 3 Years in a Canine Experimental Model.

Publication date: Available online 17 August 2017
Source:Journal of Oral and Maxillofacial Surgery
Author(s): Rodolfo B. Anchieta, Márcia V.M. Guimarães, Marcelo Suzuki, Nick Tovar, Estevam A. Bonfante, Pablo Atria, Paulo G. Coelho
PurposeThis work evaluated bone nanomechanical properties around submerged and immediately loaded implants after 3 years in vivo. It was hypothesized that bone nanomechanical properties would significantly increase in immediately and functionally loaded implants compared to submerged.MethodsThe second, third, and fourth right premolars and the first molar of ten adult Doberman dogs were extracted. After six months, four implants were placed in one side of the mandible. The mesial implant received a cover screw and remained unloaded. The remaining three implants received fixed prostheses within 48 hours after surgery which remained in occlusal function for three years. After sacrifice, the bone was prepared for histological and nanoindentation analysis. Nanoindentation was carried out under wet conditions on bone areas within the plateaus. Indentations (n=30 per histological slide) were performed with a maximum load of 300 μN (loading rate: 60 μN/s) followed by a holding and unloading time of 10s and 2s, respectively. Elastic modulus (E) and hardness (H) were computed in GigaPascal (GPa). The amount of bone-to-implant contact (BIC) was also evaluated.ResultsThe E and H values for cortical bone regions were higher than trabecular bone regardless of load condition, but not statistically significant (p>.05). The E and H values were higher for loaded implants than submerged (p<.05), for cortical and trabecular bone. For the same load condition, the E and H values for cortical and trabecular bone were not statistically different (p>.05). The loaded and submerged implants presented (mean ± SD) 57.4 ± 12.1 % and 62 ±7.5% BIC (p>.05).ConclusionThe elastic modulus and hardness of bone around dental implants, measured by nanoindentation, were higher for immediately loaded compared to submerged implants.



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