Effects of intentional damage of the roots and surrounding structures with miniscrew implants.
BACKGROUND
The purposes of the study were to evaluate the immediate damage to roots and periodontal structures after initial miniscrew implant (MSI) placement and the short- and long-term damage after MSIs were left in situ.


METHODS
The roots of the maxillary second, third, and fourth premolars of 7 mature beagle dogs were randomly assigned to undergo immediate, short-term (left for 6 weeks), or long-term (left for 12 weeks) damage. Intentional damage was inflicted with self-tapping screws (1.8 x 8 mm) placed with a stent. Alternating tetracycline and calcein labels were administered at 6-week intervals. Undecalcified sections were stained and evaluated histologically to determine the extent of damage; healing was evaluated by using fluorescence labels.


RESULTS
Histology showed damage to 73.8% of the teeth, ranging from displacement of bone into the periodontal ligament to invasion of the pulp chamber. Displacement of bone into the periodontal ligament and direct damage to the periodontal ligament occurred in 3 (7.2%) instances. Damage was isolated to the cementum of 8 (19.0%) teeth, whereas damage occurred in the dentin of 11 (26.2%) teeth. Loss of bone in the furcation was evident in 3 (7.2%) teeth, and severe damage into the pulp occurred in 6 (14.2%) teeth. No differences in the amounts of damage were evident between the immediate, short-, and long-term groups. Healing often occurred with cementum around the unloaded MSIs.


CONCLUSIONS
Extensive damage can be caused by MSIs, with little to no differences evident over time. Unloaded MSIs that remain in contact with roots of teeth can show varying degrees of healing.
Hembree
Megan
M
Orthodontic Department, Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, TX 75246, USA.
Buschang
Peter H
PH
Carrillo
Roberto
R
Spears
Robert
R
Rossouw
P Emile
PE
D016301:Alveolar Bone Loss / Q000209:etiology / Q000473:pathology; D000539:Alveolar Process / Q000293:injuries / Q000473:pathology; D000818:Animals; D001641:Bicuspid; D001863:Bone Screws / Q000009:adverse effects*; D004396:Coloring Agents; D003739:Dental Cementum / Q000293:injuries / Q000473:pathology; D003786:Dental Pulp Cavity / Q000293:injuries / Q000473:pathology; D003804:Dentin / Q000293:injuries / Q000473:pathology; D004285:Dogs; D005456:Fluorescent Dyes; D017823:Furcation Defects / Q000209:etiology / Q000473:pathology; D008297:Male; D009336:Necrosis; D052280:Orthodontic Anchorage Procedures / Q000009:adverse effects / Q000295:instrumentation*; D010513:Periodontal Ligament / Q000293:injuries / Q000473:pathology; D010519:Periodontium / Q000293:injuries* / Q000473:pathology; D011897:Random Allocation; D013997:Time Factors; D014092:Tooth Root / Q000293:injuries* / Q000473:pathology
D004396:Coloring Agents; D005456:Fluorescent Dyes