Assessment of microdamage caused by orthodontic miniscrew pilot holes

Abstract

Introduction: The clinical success of orthodontic miniscrew implants may be improved after pre-drilling a pilot hole. However, the amount of microdamage to the bone surface produced by the pilot hole is largely unknown. The present study aimed to quantify the damage to cortical bone after the creation of a pilot hole. Materials and methods: Porcine tibia bone was prepared into 30 rectangular bone block specimens with widths of 1.5, 2.0 or 2.5 mm. A pilot hole (0.9 mm diameter) was drilled into each bone specimen. Sequential staining allowed the microdamage on the entry and exit surfaces to be imaged by a confocal laser scanning microscope. Image analysis software was used to measure histomorphometric parameters. Results: The specimens had a mean total damage area of 0.95 mm2, a maximum damage radius of 0.66 mm and a maximum crack length of 0.18 mm. There were no significant differences between the three bone thicknesses for any of the histomorphometric parameters on the entry and exit surfaces (p > 0.05). The total damage area was significantly greater on the exit surface compared to the entry surface (p < 0.0001). Conclusions: Microdamage caused by the creation of a pilot hole in the cortical bone was minimal and did not appear to be influenced by bone thickness. Therefore, pilot hole pre-drill protocols may be implemented without introducing significant cortical bone microdamage.