Response to Intentional Root Damage with Miniscrew Implants

Objectives: To damage the roots of beagle dog premolars during miniscrew implant placement and evaluate the tissue response after 12 and 6 weeks with the miniscrew implants remaining in place. Methods: Seven mature beagle dogs were used for this experiment. Their maxillary second, third and fourth premolars were randomly assigned to one of three observation periods: immediate damage, after 6 weeks and after 12 weeks of damage. Intentional damage was caused by inserting one miniscrew implant (1.8 x 8 mm) into the roots of six teeth per dog using a radiographic guide. The tissues were evaluated histologically using Stevenol's Blue and van Geison Picro-fuscion staining. Results: The majority (73.8%) of the sample was damaged during the insertion of the MSIs. The degree of damage varied from invasion of the pulp chamber (14.2%), damage of the dentin (26.2%), damage to the cementum (19%), and finally, damage limited to the periodontal ligament and surrounding bone (14.4%). There were no differences in the damage observed between the three observation periods. Conclusions: Substantial damage of the roots and surrounding structures can occur during MSI placement, independent of the duration of the time that the MSI remains in situ.