Tissue healing following miniscrew implant damage

Objectives: Evaluate the healing potential of the roots and surrounding periodontium (cementum, PDL and bone) after intentional damage during miniscrew implant (MSI) placement for utilization as orthdontic anchorage. Methods: A randomized split-mouth design was used to evaluate healing six and twelve weeks after intentional root damage. Seven skeletally mature male beagle dogs had MSIs inserted into the roots of eight mandibular teeth (six premolars and two first molars). After root contact had been verified using insertion torques and radiographs, the MSIs were immediately removed and the sites were allowed to heal for six or twelve weeks. Sequential point labeling was performed every six weeks using Tetracycline and Calcein. Histologic evaluation of healing was completed using stained demineralized and undemineralized sections. Results: The insertion torque was twice as high with root contact (50.7 Ncm) than without contact(23.8 Ncm). Damage to the roots and periodontium ranged from cementum interruption to pulp invasion. New bone, new PDL and new cementum were observed in 64.3% of the teeth, with significant (p<.05) increases in the percentage of cementum over time. Healing at both six and twelve weeks was confirmed by sequential labeling. Abnormal healing was found in 35.7% of teeth; it included lack of PDL and bone regeneration, bone degeneration in the furcation area, ankylosis, and no healing associated with inflammatory infiltrate or pulpal invasion. Conclusions: In the absence of inflammation or pulpal invasion healing can occur when root damage caused by MSIs is limited to the cementum and/or dentin. Increase in resistance should be used as an indicator of possible root contact during MSI placement.