Cortical bone microdamage produced by micro-osteoperforation screws versus orthodontic miniscrews: an in vitro study

Abstract Background/objective The alternative use of Orthodontic Miniscrew Implants (OMIs), traditionally used for skeletal anchorage, to facilitate micro-osteoperforations (MOPs) for accelerating orthodontic tooth movement has been reported in previous studies. The objective of the present in vitro study was to compare the microdamage generated by OMIs and MOP-purposed screws of similar dimensions in porcine cortical bone. Materials and methods Forty rectangular porcine cortical bone specimens of 1.5 mm thickness were produced and divided into two equal groups. According to group allocation, either a single MOP screw or OMI was inserted and later removed. A sequential staining protocol was carried out to distinguish true microdamage created upon screw insertion and removal from iatrogenic damage. The bone specimens were imaged by a confocal laser scanning microscope, and five histomorphometric measurements described and quantified the generated microdamage. Results On the entry (outer) bone surface, the OMI screws produced greater microdamage which reached statistical significance across all of the histomorphometric parameters. In contrast, a statistically significant increase in microdamage was created following MOP screw insertion on the exit (inner) bone surface, but only in three assessment parameters, recorded as total damage area, as well as diffuse damage area and radius. Conclusions Overall, the present study showed that 1.5 mm OMIs produced slightly greater microcrack-type and diffuse damage-type microdamage than the 1.6 mm diameter MOP screws. However, these differences were small and considered clinically insignificant.