Bone Damage Associated with Orthodontic Miniscrew Implants

Objective: The purpose of this study was to quantify bone damage associated with insertion of miniscrew implants (MSIs) and relate the amount of bone damage to monocortical plate thickness. Methods: Non-drilling (n=28), self-drilling (n=28) MSI (6X1.6mm, Dentaurum, Newtown, PA) and pilot holes (n=26) were placed bilaterally in the maxilla and mandible of five adult dogs immediately after sacrifice. Bone blocks were cut, bulk stained with 1% basic fuchsin, embedded in methyl methacrylate, sectioned, and mounted. Monocortical plate thickness was measured on both the coronal and basal sides of the insertion site using a calibrated computer program (MicroSuite, Olympus, Tokyo, Japan). Total fractional damaged area (%), fractional microdamaged area (%), and fractional diffuse damaged area (%) were quantified for each specimen using standard histomorphometric methods. Damage was quantified at distances of 0-0.5mm (adjacent region) and 0.5-1mm (distant region) from the bone-implant interface. Results: Monocortical plate thickness of specimens from the mandible was significantly (p<0.001) greater than specimens from the maxilla (2.2 mm and 0.9 mm, respectively). The three damage parameters were greater with self-drilling MSIs than non-drilling MSIs in the mandible, but there were no differences in the maxilla. Fractional microdamaged area associated with both MSIs was greater in the mandible than in the maxilla. Conclusions: SD MSIs are associated with greater bone damage than ND MSIs in bone with monocortical thickness of 2.2 mm, but there is no difference in damage between SD and ND MSIs in bone with monocortical thickness of 0.9 mm. Bone damage associated with MSI insertion is greater in bone of 2.2 mm monocortical thickness than 0.9 mm thickness for both self-drilling and non-drilling MSIs. Advisors/Committee Members: Huja, Sarandeep.