Effects of Drilling Technology on Mini-Implant Primary Stability: A Comparison of the Mechanical Drilling and Femtosecond Laser Ablation

• Published in: Frontiers in physics Vol. 9
• Main Authors: Zhang, Wenbin, Alghannam, Fahad, Zhu, Yingchao, Zhang, Jianfei, Wohl, Gregory R, Haugen, Harold K., Qin, Zhipeng, Xie, Guoqiang, Fang, Qiyin, Shen, Steve Guofang
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 22.12.2021
• Subjects: femtosecond laser; laser ablation; mini-implant; primary stability; site preparation
• ISSN: 2296-424X; 2296-424X
• DOI: 10.3389/fphy.2021.766644

Objectives: Primary stability is a fundamental prerequisite in predicting the prognosis of a mini-implant (MI) as a skeletal anchorage. This study aims to evaluate the influence of implant site preparation technology on the primary stability of MI. Methods: A total of 108 bovine cortical bone samples were fabricated to three thicknesses (0.5, 1.0, and 1.5 mm). For each thickness group, the samples were divided into three subgroups: I (without site preparation), II (site preparation with a mechanical drill), and III (site preparation with femtosecond laser ablation). After MI insertion into these samples, the pull out strength of MI was measured by lateral pull out tests. Results: For the 0.5 mm thickness samples, the lateral pull-out strength was 9.9±2.7 N in subgroup I, 6.7±2.1 N in subgroup II, and 15.2±2.6 N in subgroup III. For the 1.0 mm thickness samples, the lateral pull-out strength was 39.3±2.5N in subgroup I, 38.2±2.7N in subgroup II, and 46.3±1.7 N in subgroup III. For the 1.5 mm thickness samples, the lateral pull-out strength was 73.9±4.8 N in subgroup I, 70.1±2.8 N in subgroup II, 75.0±2.2 N in subgroup III. No signs of carbonization or substantial cracking were visible in any of the bone samples. Conclusion: Site preparation with laser ablation significantly improved the lateral pull-out strength over mechanical preparation and control (no site preparation) in thinner cortical bone samples (1.0 and 0.5 mm). Such improvement in lateral pull-out strength decreases as the samples become thicker and diminishes in thick (1.5 mm) cortical bone samples.