Root resorption on torqued human premolars shown by tartrate-resistant acid phosphatase histochemistry and transmission electron microscopy.
OBJECTIVE
To identify clastic cells on the root surfaces of torqued human premolars.


METHODS
A continuous force of 600 cNmm was applied to upper first premolars in patients 13-16 years of age by using a precise biomechanical model with superelastic wires (NiTi-SE). The 28 teeth in 14 patients were divided into five groups (control [nonmoved], and moved for either 1, 2, 3, or 4 weeks) and processed for tartrate-resistant acid phosphatase (TRAP) histochemistry and transmission electron microscopy.


RESULTS
Mononuclear TRAP-positive cells appeared at 2 weeks, where as large multinucleated TRAP-positive cells were numerous at 3 and 4 weeks. Ultrastructural examination revealed many clastic cells in contact with resorption lacunae. In addition, some cementoblast-like cells appeared secreting new cementum over previously resorbed lacunae.


CONCLUSIONS
In general, resorption lacunae and the number of clastic cells, which increased with the duration of the applied force, were found on the cementum surface at the pressure areas. Some signs of cementum repair were also noticed, even with the maintenance of the level of the force.
Casa
Mauricio A
MA
Mineralized Tissue Biology, University of São Paulo, São Paulo, Brazil.
Faltin
Rolf M
RM
Faltin
Kurt
K
Arana-Chavez
Victor E
VE
D000135:Acid Phosphatase / Q000378:metabolism; D000293:Adolescent; D001641:Bicuspid / Q000293:injuries*; D025021:Cementogenesis; D003739:Dental Cementum / Q000293:injuries / Q000473:pathology; D003799:Dental Stress Analysis; D004548:Elasticity; D006651:Histocytochemistry; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009969:Orthodontic Wires / Q000009:adverse effects*; D010010:Osteoclasts / Q000473:pathology; D010513:Periodontal Ligament / Q000293:injuries* / Q000473:pathology; D012391:Root Resorption / Q000209:etiology / Q000473:pathology*; D013314:Stress, Mechanical; D000071681:Tartrate-Resistant Acid Phosphatase; D014087:Tooth Movement Techniques / Q000009:adverse effects*; D019415:Torque
D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase