Anchieta Rodolfo B, Guimarães Márcia V M, Suzuki Marcelo, Tovar Nick, Bonfante Estevam A, Atria Pablo, Coelho Paulo G
Assistant Professor, Centro Universitario do Norte Paulista (UNORP), São Jose do Rio Preto, SP, Brazil; Visiting Scholar, Department of Biomaterials and Biomimetics, New York University, New York, NY; Department of Restorative Denstistry, Araçatuba, Universidade Estadual Paulista (UNESP), SP, Brazil.
Private Practice, Guaratingueta, SP, Brazil.
J Oral Maxillofac Surg. 2018 Jan;76(1):71-79. doi: 10.1016/j.joms.2017.08.016. Epub 2017 Aug 17.
This work evaluated the nanomechanical properties of bone surrounding submerged and immediately loaded implants after 3 years in vivo. It was hypothesized that the nanomechanical properties of bone would markedly increase in immediately and functionally loaded implants compared with submerged implants.
The second, third, and fourth right premolars and the first molar of 10 adult Doberman dogs were extracted. After 6 months, 4 implants were placed in 1 side of the mandible. The mesial implant received a cover screw and remained unloaded. The remaining 3 implants received fixed dental prostheses within 48 hours after surgery that remained in occlusal function for 3 years. After sacrifice, the bone was prepared for histologic and nanoindentation analysis. Nanoindentation was carried out under wet conditions on bone areas within the plateaus. Indentations (n = 30 per histologic section) were performed with a maximum load of 300 μN (loading rate, 60 μN per second) followed by a holding and unloading time of 10 and 2 seconds, respectively. Elastic modulus (E) and hardness (H) were computed in giga-pascals. The amount of bone-to-implant contact (BIC) also was evaluated.
The E and H values for cortical bone regions were higher than those for trabecular bone regardless of load condition, but this difference was not statistically significant (P > .05). The E and H values were higher for loaded implants than for submerged implants (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 BIC values (mean ± standard deviation) of 57.4 ± 12.1% and 62 ± 7.5%, respectively (P > .05).
The E and H values of bone surrounding dental implants, measured by nanoindentation, were higher for immediately loaded than for submerged implants.
本研究评估体内植入3年后，潜入式和即刻负重种植体周围骨组织的纳米力学性能。研究假设为，与潜入式种植体相比，即刻功能负重种植体周围骨组织的纳米力学性能将显著提高。
拔除10只成年杜宾犬右侧的第二、第三和第四前磨牙以及第一磨牙。6个月后，在下颌骨一侧植入4枚种植体。近中种植体植入覆盖螺丝，保持无负重状态。其余3枚种植体在术后48小时内安装固定义齿，并保持咬合功能3年。处死后，对骨组织进行组织学和纳米压痕分析。在湿润条件下对平台区内的骨组织进行纳米压痕测试。每个组织切片进行30次压痕，最大载荷为300μN（加载速率为每秒60μN），随后分别保持10秒和卸载2秒。以吉帕斯卡为单位计算弹性模量（E）和硬度（H）。同时评估骨与种植体接触面积（BIC）。
无论负重情况如何，皮质骨区域的E值和H值均高于松质骨，但差异无统计学意义（P > 0.05）。皮质骨和松质骨中，负重种植体的E值和H值均高于潜入式种植体（P < 0.05）。在相同负重条件下，皮质骨和松质骨的E值和H值差异无统计学意义（P > 0.05）。负重种植体和潜入式种植体的BIC值（平均值±标准差）分别为57.4 ± 12.1%和62 ± 7.5%（P > 0.05）。
通过纳米压痕测量，即刻负重种植体周围骨组织的E值和H值高于潜入式种植体。
