Root and bone response to the proximity of a mini-implant under orthodontic loading.
OBJECTIVE
To determine the histological reaction of the root and bone as a mini-implant approaches the root.


METHODS
Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root.


RESULTS
The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion.


CONCLUSIONS
There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability.
Lee
Yang-Ku
YK
Department of Orthodontics, Seoul National University, Korea.
Kim
Jong-Wan
JW
Baek
Seung-Hak
SH
Kim
Tae-Woo
TW
Chang
Young-Il
YI
D016301:Alveolar Bone Loss / Q000209:etiology / Q000473:pathology; D000539:Alveolar Process / Q000473:pathology*; D000818:Animals; D025021:Cementogenesis / Q000502:physiology; D003739:Dental Cementum / Q000473:pathology; D015921:Dental Implants / Q000009:adverse effects; D003804:Dentin / Q000473:pathology; D004285:Dogs; D005260:Female; D008297:Male; D052280:Orthodontic Anchorage Procedures / Q000009:adverse effects / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D010513:Periodontal Ligament / Q000473:pathology; D012391:Root Resorption / Q000209:etiology / Q000473:pathology; D020254:Tooth Ankylosis / Q000209:etiology / Q000473:pathology; D014082:Tooth Fractures / Q000209:etiology / Q000473:pathology; D014092:Tooth Root / Q000293:injuries / Q000473:pathology*
D015921:Dental Implants